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Sample records for tissue doppler-derived strain

  1. Value of tissue Doppler-derived Tei index and two-dimensional speckle tracking imaging derived longitudinal strain on predicting outcome of patients with light-chain cardiac amyloidosis.

    Science.gov (United States)

    Liu, Dan; Hu, Kai; Herrmann, Sebastian; Cikes, Maja; Ertl, Georg; Weidemann, Frank; Störk, Stefan; Nordbeck, Peter

    2017-06-01

    Prognosis of patients with light-chain cardiac amyloidosis (AL-CA) is poor. Speckle tracking imaging (STI) derived longitudinal deformation parameters and Doppler-derived left ventricular (LV) Tei index are valuable predictors of outcome in patients with AL-CA. We estimated the prognostic utility of Tei index and deformation parameters in 58 comprehensively phenotyped patients with AL-CA after a median follow-up of 365 days (quartiles 121, 365 days). The primary end point was all-cause mortality. 19 (33%) patients died during follow-up. Tei index (0.89 ± 0.29 vs. 0.61 ± 0.16, p < 0.001) and E to global early diastolic strain rate ratio (E/GLSR dias ) were higher while global longitudinal systolic strain (GLS sys ) was lower in non-survivors than in survivors (all p < 0.05). Tei index, NYHA functional class, GLS sys and E/GLSR dias were independent predictors of all-cause mortality risk, and Tei index ≥0.9 (HR 7.01, 95% CI 2.43-20.21, p < 0.001) was the best predictor of poor outcome. Combining Tei index and GLS sys yielded the best results on predicting death within 1 year (100% with Tei index ≥0.9 and GLS sys ≤13%) or survival (95% with Tei index ≤0.9 and GLS sys ≥13%). We conclude that 1-year mortality risk in AL-CA patients can be reliably predicted using Tei index or deformation parameters, with combined analysis offering best performance.

  2. Assessment of sustained effects of levosimendan and dobutamine on left ventricular systolic functions by using novel tissue Doppler derived indices in patients with advanced heart failure.

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    Oner, Ender; Erturk, Mehmet; Birant, Ali; Kurtar Mansıroglu, Aslı; Akturk, Ibrahim Faruk; Karakurt, Huseyin; Yalcin, Ahmet Arif; Uzun, Fatih; Somuncu, Mustafa Umut; Yildirim, Aydin

    2015-01-01

    Previous studies comparing levosimendan vs. dobutamine have revealed that levosimendan is better in relieving symptoms. Echocardiographic studies have been done using second measurements immediately following a dobutamine infusion or while it was still being administered. The aim of our study was assessment of sustained effects of 24 h levosimendan and dobutamine infusions on left ventricular systolic functions. A total of 61 patients with acutely decompensated heart failure with New York Heart Association (NYHA) class III or IV symptoms were randomized to receive either levosimendan or dobutamine 2:1 in an open label fashion. Before and 5 days after the initiation of infusions, functional class was assessed, N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) levels and left ventricular ejection fraction (LVEF), mitral inflow peak E and A wave velocity, and E/A ratios were measured; using tissue Doppler imaging, isovolumic myocardial acceleration (IVA), peak myocardial velocity during isovolumic contraction (IVV), peak systolic velocity during ejection period (Sa), early (E') and late (A') diastolic velocities, and E'/A' and E/E' ratios were measured. The NYHA class improved in both groups, but improvements were prominent in the levosimendan group. NT-proBNP levels were significantly reduced in the levosimendan group. Improvements in LVEF and diastolic indices were significant in the levosimendan group. Tissue Doppler-derived systolic indices of IVV and IVA increased significantly in the levosimendan group. Improvements in left ventricular systolic and diastolic functions continue after a levosimendan infusion.

  3. Evaluation of Pulsed Doppler-Versus Tissue Doppler-Derived Tei Index of Right and Left Ventricle in Fetuses

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    Hamid Amoozgar

    2011-12-01

    Full Text Available Background: The myocardial performance index (MPI, also known as the Tei index, was introduced by Tei et al. to evaluate cardiac function in adults with dilated cardiomyopathy. This index is defined as the sum of isovolumic contraction time (ICT and isovolumic relaxation time (IRT, divided by ejection time (ET. Objectives: To determine the correlation between pulsed Doppler (PD- and tissue Doppler imaging (TDI-derived Tei indices in fetuses. Patients and Methods: Right and left ventricle PD and TDI echocardiographic data were obtained from 59 fetuses (11 pregnant women who were positive for anti-SSA-Ro or anti-SSB-La antibodies, 18 women who were referred due to dysrhythmia, and 30 women who had normal clinical findings. Results: Mean fetal gestational age was 27 ± 6.4 weeks. Mean PD Tei index of the mitral and tricuspid valve was 0.58 ± 0.05 and 0.53 ± 0.08, respectively. Mean TDI indices for the mitral and tricuspid valve were 0.56 ± 0.09 and 0.55 ± 0.08, respectively. There were no significant differences between mitral and tricuspid PD- and TDI-derived Tei indices (P = 0.87, P= 0.21, but the Bland-Altman diagrams showed no fine agreement between the indices (the mean difference ± 1 standard deviation of the right ventricular PD- and TDI-derived Tei indices was 0.24 ± 0.02 and 0.29 ± 0.04 for the left ventricle. There were no significant differences in PD- and TDI-derived Tei indexes between groups of evaluated fetuses (Mitral valve: PD-Tei P=0.69, TDI-Tei P=0.49; Tricuspid valve: PD-Tei P=0.41, TDI-Tei P=0.36. Conclusions: Although the mean values of the two indices did not differ significantly, the TDI-derived and PD-derived Tei indices did not have fine agreement.

  4. Quantitation of stress echocardiography by tissue Doppler and strain rate imaging: a dream come true?

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    Galderisi, Maurizio; Mele, Donato; Marino, Paolo Nicola

    2005-01-01

    Tissue Doppler (TD) is an ultrasound tool providing a quantitative agreement of left ventricular regional myocardial function in different modalities. Spectral pulsed wave (PW) TD, performed online during the examination, measures instantaneous myocardial velocities. By means of color TD, velocity images are digitally stored for subsequent off-line analysis and mean myocardial velocities are measured. An implementation of color TD includes strain rate imaging (SRI), based on post-processing conversion of regional velocities in local myocardial deformation rate (strain rate) and percent deformation (strain). These three modalities have been applied to stress echocardiography for quantitative evaluation of regional left ventricular function and detection of ischemia and viability. They present advantages and limitations. PWTD does not permit the simultaneous assessment of multiple walls and therefore is not compatible with clinical stress echocardiography while it could be used in a laboratory setting. Color TD provides a spatial map of velocity throughout the myocardium but its results are strongly affected by the frame rate. Both color TD and PWTD are also influenced by overall cardiac motion and tethering from adjacent segments and require reference velocity values for interpretation of regional left ventricular function. High frame rate (i.e. > 150 ms) post-processing-derived SRI can potentially overcome these limitations, since measurements of myocardial deformation have not any significant apex-to-base gradient. Preliminary studies have shown encouraging results about the ability of SRI to detect ischemia and viability, in terms of both strain rate changes and/or evidence of post-systolic thickening. SRI is, however, Doppler-dependent and time-consuming. Further technical refinements are needed to improve its application and introduce new ultrasound modalities to overcome the limitations of the Doppler-derived deformation analysis.

  5. Doppler derived gradient of ST Jude Mechanical Prosthesis, early postoperative assessment

    International Nuclear Information System (INIS)

    Shaikh, A.H.; Hanif, B.; Adil, A.; Hashimi, S.; Qazi, H.A.; Mujtaba, I.

    2010-01-01

    Objective: To determine the doppler derived mean gradients of St Jude mechanical prosthesis in early postoperative period in patients undergoing valve replacement at a tertiary care cardiac centre. Methods: Medical records of 190 consecutive patients who underwent 233 mitral, aortic or dual (mitral and aortic) valve replacement by St Jude bileaflet mechanical prosthesis at Tabba Heart Institute, between March 2006 to December 2008 were reviewed. Doppler derived mean gradients were assessed predischarge and recorded. Results: There were 98 (51.5%) males and 92 (48.5%) females in the study cohort. The mean age was 40 +- 14 years. Of the total, 101 (53%) had mitral, 46 (24.2%) had aortic and 43 (22.6%) patients had dual valve replacement. Doppler derived mean gradient was assessed across 144 mitral and 89 aortic St Jude mechanical prosthesis. Doppler derived mean gradient for St Jude mitral prosthesis was 3.5 mm Hg and for St Jude aortic prosthesis was 10.2 mm Hg. Conclusions: The study determines baseline gradients across mitral and aortic St Jude mechanical prosthesis in our population. These can be used as reference gradients to assess St Jude prosthetic valve function in patients who did not have early postoperative doppler assessment. (author)

  6. Tissue strain rate estimator using ultrafast IQ complex data

    OpenAIRE

    TERNIFI , Redouane; Elkateb Hachemi , Melouka; Remenieras , Jean-Pierre

    2012-01-01

    International audience; Pulsatile motion of brain parenchyma results from cardiac and breathing cycles. In this study, transient motion of brain tissue was estimated using an Aixplorer® imaging system allowing an ultrafast 2D acquisition mode. The strain was computed directly from the ultrafast IQ complex data using the extended autocorrelation strain estimator (EASE), which provides great SNRs regardless of depth. The EASE first evaluates the autocorrelation function at each depth over a set...

  7. Two-dimensional tracking and TDI are consistent methods for evaluating myocardial longitudinal peak strain in left and right ventricle basal segments in athletes

    OpenAIRE

    Lstefani, L.Stefani; Ltoncelli, L.Toncelli; Mgianassi, M.Gianassi; Pmanetti, P.Manetti; Vdi, V.Di Tante; Mrvono, M.R.Vono; Amoretti, A.Moretti; Bcappelli, B.Cappelli; Gpedrizzetti, G.Pedrizzetti; Ggalanti, G.Galanti

    2007-01-01

    Abstract Background Myocardial contractility can be investigated using longitudinal peak strain. It can be calculated using the Doppler-derived TDI method and the non-Doppler method based on tissue tracking on B-mode images. Both are validated and show good reproducibility, but no comparative analysis of their results has yet been conducted. This study analyzes the results obtained from the basal segments of the ventricular chambers in a group of athletes. Methods 30 regularly-trained athlete...

  8. Soft tissue strain measurement using an optical method

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    Toh, Siew Lok; Tay, Cho Jui; Goh, Cho Hong James

    2008-11-01

    Digital image correlation (DIC) is a non-contact optical technique that allows the full-field estimation of strains on a surface under an applied deformation. In this project, the application of an optimized DIC technique is applied, which can achieve efficiency and accuracy in the measurement of two-dimensional deformation fields in soft tissue. This technique relies on matching the random patterns recorded in images to directly obtain surface displacements and to get displacement gradients from which the strain field can be determined. Digital image correlation is a well developed technique that has numerous and varied engineering applications, including the application in soft and hard tissue biomechanics. Chicken drumstick ligaments were harvested and used during the experiments. The surface of the ligament was speckled with black paint to allow for correlation to be done. Results show that the stress-strain curve exhibits a bi-linear behavior i.e. a "toe region" and a "linear elastic region". The Young's modulus obtained for the toe region is about 92 MPa and the modulus for the linear elastic region is about 230 MPa. The results are within the values for mammalian anterior cruciate ligaments of 150-300 MPa.

  9. Soft Tissue Strain Rates in Side-Blast Incidents

    Science.gov (United States)

    2014-11-02

    increase of strain rate is known to cause the stiffening of soft connective tissues ( Haut and Haut 1997 [49]; Panjabi et al. 1998 [50]; Crisco et al...Réseau Québécois de Calcul de Haute Performance, with a peak compute performance of 27 596 GFlops). Figure 2: Torso motion imposed in the model...Yan YP. 2003. Mechanical properties of nasal fascia and periosteum. Clinical Biomechanics. 18:760-764. [49] Haut TL, Haut RC. 1997. The state of

  10. The influence of emotional stress on Doppler-derived aortic peak velocity in boxer dogs.

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    Pradelli, D; Quintavalla, C; Crosta, M C; Mazzoni, L; Oliveira, P; Scotti, L; Brambilla, P; Bussadori, C

    2014-01-01

    Subaortic stenosis (SAS) is a common congenital heart disease in Boxers. Doppler-derived aortic peak velocity (AoPV) is a diagnostic criterion for the disease. To investigate the influence of emotional stress during echocardiographic examination on AoPV in normal and SAS-affected Boxers. To evaluate the effects of aortic root diameters on AoPV in normal Boxers. DOGS: Two hundred and fifteen normal and 19 SAS-affected Boxers. The AoPV was recorded at the beginning of echocardiographic examination (T0), and when the emotional stress of the dog was assumed to decrease based on behavioral parameters and heart rate (T1). AoPV0-AoPV1 was calculated. In normal dogs, stroke volume index was calculated at T0 and T1. Aortic root diameters were measured and their relationship with AoPV and AoPV0-AoPV1 was evaluated. In normal dogs, AoPV was higher at T0 (median, 1.95 m/s; range, 1.60-2.50 m/s) than at T1 (median, 1.76 m/s; range, 1.40-2.20 m/s; P dogs, AoPV0 was higher than AoPV1 (P < .0001; reduction 7.3%). Aortic peak velocity was affected by emotional stress during echocardiographic examination both in SAS-affected and normal Boxers. In normal Boxers, aortic root size weakly affected AoPVs, but did not affect AoPV0-AoPV1. Stroke volume seems to play a major role in stress-related AoPV increases in normal Boxers. Emotional stress should be taken into account when screening for SAS in the Boxer breed. Copyright © 2014 by the American College of Veterinary Internal Medicine.

  11. Invasion of Porphyromonas gingivalis strains into vascular cells and tissue

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    Ingar Olsen

    2015-08-01

    Full Text Available Porphyromonas gingivalis is considered a major pathogen in adult periodontitis and is also associated with multiple systemic diseases, for example, cardiovascular diseases. One of its most important virulence factors is invasion of host cells. The invasion process includes attachment, entry/internalization, trafficking, persistence, and exit. The present review discusses these processes related to P. gingivalis in cardiovascular cells and tissue. Although most P. gingivalis strains invade, the invasion capacity of strains and the mechanisms of invasion including intracellular trafficking among them differ. This is consistent with the fact that there are significant differences in the pathogenicity of P. gingivalis strains. P. gingivalis invasion mechanisms are also dependent on types of host cells. Although much is known about the invasion process of P. gingivalis, we still have little knowledge of its exit mechanisms. Nevertheless, it is intriguing that P. gingivalis can remain viable in human cardiovascular cells and atherosclerotic plaque and later exit and re-enter previously uninfected host cells.

  12. Strain Elastography for Prediction of Malignancy in Soft Tissue Tumours--Preliminary Results

    DEFF Research Database (Denmark)

    Riishede, I; Ewertsen, C; Carlsen, J

    2015-01-01

    PURPOSE: To evaluate the ability of strain elastography to predict malignancy in patients with soft tissue tumors, and to compare three evaluation methods of strain elastography: strain ratios, strain histograms and visual scoring. MATERIALS AND METHODS: 60 patients with 61 tumors were analyzed...

  13. Strain-time cell death threshold for skeletal muscle in a tissue-engineered model system for deep tissue injury

    NARCIS (Netherlands)

    Gefen, A.; Nierop, van B.J.; Bader, D.L.; Oomens, C.W.J.

    2008-01-01

    Deep tissue injury (DTI) is a severe pressure ulcer that results from sustained deformation of muscle tissue overlying bony prominences. In order to understand the etiology of DTI, it is essential to determine the tolerance of muscle cells to large mechanical strains. In this study, a new

  14. Effect of bone-soft tissue friction on ultrasound axial shear strain elastography.

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    Tang, Songyuan; Chaudhry, Anuj; Kim, Namhee; Reddy, J N; Righetti, Raffaella

    2017-07-12

    Bone-soft tissue friction is an important factor affecting several musculoskeletal disorders, frictional syndromes and the ability of a bone fracture to heal. However, this parameter is difficult to determine using non-invasive imaging modalities, especially in clinical settings. Ultrasound axial shear strain elastography is a non-invasive imaging modality that has been used in the recent past to estimate the bonding between different tissue layers. As most elastography methods, axial shear strain elastography is primarily used in soft tissues. More recently, this technique has been proposed to assess the bone-soft tissue interface. In this paper, we investigate the effect of a variation in bone-soft tissue friction coefficient in the resulting axial shear strain elastograms. Finite element poroelastic models of bone specimens exhibiting different bone-soft tissue friction coefficients were created and mechanically analyzed. These models were then imported to an ultrasound elastography simulation module to assess the presence of axial shear strain patterns. In vitro experiments were performed to corroborate selected simulation results. The results of this study show that the normalized axial shear strain estimated at the bone-soft tissue interface is statistically correlated to the bone-soft tissue coefficient of friction. This information may prove useful to better interpret ultrasound elastography results obtained in bone-related applications and, possibly, monitor bone healing.

  15. An extended OpenSim knee model for analysis of strains of connective tissues.

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    Marieswaran, M; Sikidar, Arnab; Goel, Anu; Joshi, Deepak; Kalyanasundaram, Dinesh

    2018-04-17

    OpenSim musculoskeletal models provide an accurate simulation environment that eases limitations of in vivo and in vitro studies. In this work, a biomechanical knee model was formulated with femoral articular cartilages and menisci along with 25 connective tissue bundles representing ligaments and capsules. The strain patterns of the connective tissues in the presence of femoral articular cartilage and menisci in the OpenSim knee model was probed in a first of its kind study. The effect of knee flexion (0°-120°), knee rotation (- 40° to 30°) and knee adduction (- 15° to 15°) on the anterior cruciate, posterior cruciate, medial collateral, lateral collateral ligaments and other connective tissues were studied by passive simulation. Further, a new parameter for assessment of strain namely, the differential inter-bundle strain of the connective tissues were analyzed to provide new insights for injury kinematics. ACL, PCL, LCL and PL was observed to follow a parabolic strain pattern during flexion while MCL represented linear strain patterns. All connective tissues showed non-symmetric parabolic strain variation during rotation. During adduction, the strain variation was linear for the knee bundles except for FL, PFL and TL. Strains higher than 0.1 were observed in most of the bundles during lateral rotation followed by abduction, medial rotation and adduction. In the case of flexion, highest strains were observed in aACL and aPCL. A combination of strains at a flexion of 0° with medial rotation of 30° or a flexion of 80° with rotation of 30° are evaluated as rupture-prone kinematics.

  16. Whole genome characterization of non-tissue culture adapted HRSV strains in severely infected children

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    Kumaria Rajni

    2011-07-01

    Full Text Available Abstract Background Human respiratory syncytial virus (HRSV is the most important virus causing lower respiratory infection in young children. The complete genetic characterization of RSV clinical strains is a prerequisite for understanding HRSV infection in the clinical context. Current information about the genetic structure of the HRSV genome has largely been obtained using tissue culture adapted viruses. During tissue culture adaptation genetic changes can be introduced into the virus genome, which may obscure subtle variations in the genetic structure of different RSV strains. Methods In this study we describe a novel Sanger sequencing strategy which allowed the complete genetic characterisation of 14 clinical HRSV strains. The viruses were sequenced directly in the nasal washes of severely hospitalized children, and without prior passage of the viruses in tissue culture. Results The analysis of nucleotide sequences suggested that vRNA length is a variable factor among primary strains, while the phylogenetic analysis suggests selective pressure for change. The G gene showed the greatest sequence variation (2-6.4%, while small hydrophobic protein and matrix genes were completely conserved across all clinical strains studied. A number of sequence changes in the F, L, M2-1 and M2-2 genes were observed that have not been described in laboratory isolates. The gene junction regions showed more sequence variability, and in particular the intergenic regions showed a highest level of sequence variation. Although the clinical strains grew slower than the HRSVA2 virus isolate in tissue culture, the HRSVA2 isolate and clinical strains formed similar virus structures such as virus filaments and inclusion bodies in infected cells; supporting the clinical relevance of these virus structures. Conclusion This is the first report to describe the complete genetic characterization of HRSV clinical strains that have been sequenced directly from clinical

  17. Increased cytotoxicity and streptolysin O activity in group G streptococcal strains causing invasive tissue infections

    DEFF Research Database (Denmark)

    Siemens, Nikolai; Kittang, Bård R; Chakrakodi, Bhavya

    2015-01-01

    Streptococcus dysgalactiae subsp. equisimilis (SDSE) has emerged as an important cause of severe skin and soft tissue infections, but little is known of the pathogenic mechanisms underlying tissue pathology. Patient samples and a collection of invasive and non-invasive group G SDSE strains (n = 6...

  18. Strain modulations as a mechanism to reduce stress relaxation in laryngeal tissues.

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    Hunter, Eric J; Siegmund, Thomas; Chan, Roger W

    2014-01-01

    Vocal fold tissues in animal and human species undergo deformation processes at several types of loading rates: a slow strain involved in vocal fold posturing (on the order of 1 Hz or so), cyclic and faster posturing often found in speech tasks or vocal embellishment (1-10 Hz), and shear strain associated with vocal fold vibration during phonation (100 Hz and higher). Relevant to these deformation patterns are the viscous properties of laryngeal tissues, which exhibit non-linear stress relaxation and recovery. In the current study, a large strain time-dependent constitutive model of human vocal fold tissue is used to investigate effects of phonatory posturing cyclic strain in the range of 1 Hz to 10 Hz. Tissue data for two subjects are considered and used to contrast the potential effects of age. Results suggest that modulation frequency and extent (amplitude), as well as the amount of vocal fold overall strain, all affect the change in stress relaxation with modulation added. Generally, the vocal fold cover reduces the rate of relaxation while the opposite is true for the vocal ligament. Further, higher modulation frequencies appear to reduce the rate of relaxation, primarily affecting the ligament. The potential benefits of cyclic strain, often found in vibrato (around 5 Hz modulation) and intonational inflection, are discussed in terms of vocal effort and vocal pitch maintenance. Additionally, elderly tissue appears to not exhibit these benefits to modulation. The exacerbating effect such modulations may have on certain voice disorders, such as muscle tension dysphonia, are explored.

  19. Changes in diffusion properties of biological tissues associated with mechanical strain

    International Nuclear Information System (INIS)

    Tanaka, Kenichiro; Imae, T.; Mima, Kazuo; Sekino, Masaki; Ohsaki, Hiroyuki; Ueno, Shogo

    2007-01-01

    Mechanical strain in biological tissues causes a change in the diffusion properties of water molecules. This paper proposes a method of estimating mechanical strain in biological tissues using diffusion magnetic resonance imaging (MRI). Measurements were carried out on uncompressed and compressed chicken skeletal muscles. A theoretical model of the diffusion of water molecules in muscle fibers was derived based on Tanner's equation. Diameter of the muscle fibers was estimated by fitting the model equation to the measured signals. Changes in the mean diffusivity (MD), the fractional anisotropy (FA), and diameter of the muscle fiber did not have any statistical significance. The intracellular diffusion coefficient (D int ) was changed by mechanical strain (p<.05). This method has potential applications in the quantitative evaluation of strain in biological tissues, a though it poses several technical challenges. (author)

  20. Matrix production and organization by endothelial colony forming cells in mechanically strained engineered tissue constructs.

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    Nicky de Jonge

    Full Text Available AIMS: Tissue engineering is an innovative method to restore cardiovascular tissue function by implanting either an in vitro cultured tissue or a degradable, mechanically functional scaffold that gradually transforms into a living neo-tissue by recruiting tissue forming cells at the site of implantation. Circulating endothelial colony forming cells (ECFCs are capable of differentiating into endothelial cells as well as a mesenchymal ECM-producing phenotype, undergoing Endothelial-to-Mesenchymal-transition (EndoMT. We investigated the potential of ECFCs to produce and organize ECM under the influence of static and cyclic mechanical strain, as well as stimulation with transforming growth factor β1 (TGFβ1. METHODS AND RESULTS: A fibrin-based 3D tissue model was used to simulate neo-tissue formation. Extracellular matrix organization was monitored using confocal laser-scanning microscopy. ECFCs produced collagen and also elastin, but did not form an organized matrix, except when cultured with TGFβ1 under static strain. Here, collagen was aligned more parallel to the strain direction, similar to Human Vena Saphena Cell-seeded controls. Priming ECFC with TGFβ1 before exposing them to strain led to more homogenous matrix production. CONCLUSIONS: Biochemical and mechanical cues can induce extracellular matrix formation by ECFCs in tissue models that mimic early tissue formation. Our findings suggest that priming with bioactives may be required to optimize neo-tissue development with ECFCs and has important consequences for the timing of stimuli applied to scaffold designs for both in vitro and in situ cardiovascular tissue engineering. The results obtained with ECFCs differ from those obtained with other cell sources, such as vena saphena-derived myofibroblasts, underlining the need for experimental models like ours to test novel cell sources for cardiovascular tissue engineering.

  1. Intermittent straining accelerates the development of tissue properties in engineered heart valve tissue

    NARCIS (Netherlands)

    Rubbens, M.P.; Mol, A.; Boerboom, R.A.; Bank, R.A.; Baaijens, F.P.T.; Bouten, C.V.C.

    2009-01-01

    Tissue-engineered heart valves lack sufficient amounts of functionally organized structures and consequently do not meet in vivo mechanical demands. To optimize tissue architecture and hence improve mechanical properties, various in vitro mechanical conditioning protocols have been proposed, of

  2. A review of techniques for visualising soft tissue microstructure deformation and quantifying strain Ex Vivo.

    Science.gov (United States)

    Disney, C M; Lee, P D; Hoyland, J A; Sherratt, M J; Bay, B K

    2018-04-14

    Many biological tissues have a complex hierarchical structure allowing them to function under demanding physiological loading conditions. Structural changes caused by ageing or disease can lead to loss of mechanical function. Therefore, it is necessary to characterise tissue structure to understand normal tissue function and the progression of disease. Ideally intact native tissues should be imaged in 3D and under physiological loading conditions. The current published in situ imaging methodologies demonstrate a compromise between imaging limitations and maintaining the samples native mechanical function. This review gives an overview of in situ imaging techniques used to visualise microstructural deformation of soft tissue, including three case studies of different tissues (tendon, intervertebral disc and artery). Some of the imaging techniques restricted analysis to observational mechanics or discrete strain measurement from invasive markers. Full-field local surface strain measurement has been achieved using digital image correlation. Volumetric strain fields have successfully been quantified from in situ X-ray microtomography (micro-CT) studies of bone using digital volume correlation but not in soft tissue due to low X-ray transmission contrast. With the latest developments in micro-CT showing in-line phase contrast capability to resolve native soft tissue microstructure, there is potential for future soft tissue mechanics research where 3D local strain can be quantified. These methods will provide information on the local 3D micromechanical environment experienced by cells in healthy, aged and diseased tissues. It is hoped that future applications of in situ imaging techniques will impact positively on the design and testing of potential tissue replacements or regenerative therapies. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

  3. A strain-hardening bi-power law for the nonlinear behaviour of biological soft tissues.

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    Nicolle, S; Vezin, P; Palierne, J-F

    2010-03-22

    Biological soft tissues exhibit a strongly nonlinear viscoelastic behaviour. Among parenchymous tissues, kidney and liver remain less studied than brain, and a first goal of this study is to report additional material properties of kidney and liver tissues in oscillatory shear and constant shear rate tests. Results show that the liver tissue is more compliant but more strain hardening than kidney. A wealth of multi-parameter mathematical models has been proposed for describing the mechanical behaviour of soft tissues. A second purpose of this work is to develop a new constitutive law capable of predicting our experimental data in the both linear and nonlinear viscoelastic regime with as few parameters as possible. We propose a nonlinear strain-hardening fractional derivative model in which six parameters allow fitting the viscoelastic behaviour of kidney and liver tissues for strains ranging from 0.01 to 1 and strain rates from 0.0151 s(-1) to 0.7s(-1). Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  4. Whole body and tissue blood volumes of two strains of rainbow trout (Oncorhynchus mykiss)

    Science.gov (United States)

    Gingerich, W.H.; Pityer, R.A.; Rach, J.J.

    1990-01-01

    1. Estimates of apparent packed cell, plasma and total blood volumes for the whole body and for 13 selected tissues were compared between Kamloops and Wytheville strains of rainbow trout (Oncorhynchus mykiss) by the simultaneous injection of two vascular tracers, radiolabeled trout erythrocytes (51Cr-RBC) and radioiodated bovine serum albumin (125I-BSA).2. Whole body total blood volume, plasma volume and packed cell volume were slightly, but not significantly greater in the Wytheville trout, whereas, the apparent plasma volumes and total blood volumes in 4 of 13 tissues were significantly greater in the Kamloops strain.3. Differences were most pronounced in highly perfused organs, such as the liver and kidney and in organs of digestion such as the stomach and intestines.4. Differences in blood volumes between the two strains may be related to the greater permeability of the vascular membranes in the Kamloops strain fish.

  5. Strain-induced collagen organization at the micro-level in fibrin-based engineered tissue constructs

    NARCIS (Netherlands)

    Jonge, de N.; Kanters, F.M.W.; Baaijens, F.P.T.; Bouten, C.V.C.

    2013-01-01

    Full understanding of strain-induced collagen organization in complex tissue geometries to create tissues with predefined collagen architecture has not been achieved. This is mainly due to our limited knowledge of collagen remodeling in developing tissues. Here we investigate strain-induced collagen

  6. Effect of Strain, Region, and Tissue Composition on Glucose Partitioning in Meniscus Fibrocartilage.

    Science.gov (United States)

    Kleinhans, Kelsey L; Jackson, Alicia R

    2017-03-01

    A nearly avascular tissue, the knee meniscus relies on diffusive transport for nutritional supply to cells. Nutrient transport depends on solute partitioning in the tissue, which governs the amount of nutrients that can enter a tissue. The purpose of the present study was to investigate the effects of mechanical strain, tissue region, and tissue composition on the partition coefficient of glucose in meniscus fibrocartilage. A simple partitioning experiment was employed to measure glucose partitioning in porcine meniscus tissues from two regions (horn and central), from both meniscal components (medial and lateral), and at three levels of compression (0%, 10%, and 20%). Partition coefficient values were correlated to strain level, water volume fraction, and glycosaminoglycan (GAG) content of tissue specimens. Partition coefficient values ranged from 0.47 to 0.91 (n = 48). Results show that glucose partition coefficient is significantly (p < 0.001) affected by compression, decreasing with increasing strain. Furthermore, we did not find a statistically significant effect of tissue when comparing medial versus lateral (p = 0.181) or when comparing central and horn regions (p = 0.837). There were significant positive correlations between tissue water volume fraction and glucose partitioning for all groups. However, the correlation between GAG content and partitioning was only significant in the lateral horn group. Determining how glucose partitioning is affected by tissue composition and loading is necessary for understanding nutrient availability and related tissue health and/or degeneration. Therefore, this study is important for better understanding the transport and nutrition-related mechanisms of meniscal degeneration.

  7. Three-dimensional micro-scale strain mapping in living biological soft tissues.

    Science.gov (United States)

    Moo, Eng Kuan; Sibole, Scott C; Han, Sang Kuy; Herzog, Walter

    2018-04-01

    Non-invasive characterization of the mechanical micro-environment surrounding cells in biological tissues at multiple length scales is important for the understanding of the role of mechanics in regulating the biosynthesis and phenotype of cells. However, there is a lack of imaging methods that allow for characterization of the cell micro-environment in three-dimensional (3D) space. The aims of this study were (i) to develop a multi-photon laser microscopy protocol capable of imprinting 3D grid lines onto living tissue at a high spatial resolution, and (ii) to develop image processing software capable of analyzing the resulting microscopic images and performing high resolution 3D strain analyses. Using articular cartilage as the biological tissue of interest, we present a novel two-photon excitation imaging technique for measuring the internal 3D kinematics in intact cartilage at sub-micrometer resolution, spanning length scales from the tissue to the cell level. Using custom image processing software, we provide accurate and robust 3D micro-strain analysis that allows for detailed qualitative and quantitative assessment of the 3D tissue kinematics. This novel technique preserves tissue structural integrity post-scanning, therefore allowing for multiple strain measurements at different time points in the same specimen. The proposed technique is versatile and opens doors for experimental and theoretical investigations on the relationship between tissue deformation and cell biosynthesis. Studies of this nature may enhance our understanding of the mechanisms underlying cell mechano-transduction, and thus, adaptation and degeneration of soft connective tissues. We presented a novel two-photon excitation imaging technique for measuring the internal 3D kinematics in intact cartilage at sub-micrometer resolution, spanning from tissue length scale to cellular length scale. Using a custom image processing software (lsmgridtrack), we provide accurate and robust micro-strain

  8. Strain modulations as a mechanism to reduce stress relaxation in laryngeal tissues.

    Directory of Open Access Journals (Sweden)

    Eric J Hunter

    Full Text Available Vocal fold tissues in animal and human species undergo deformation processes at several types of loading rates: a slow strain involved in vocal fold posturing (on the order of 1 Hz or so, cyclic and faster posturing often found in speech tasks or vocal embellishment (1-10 Hz, and shear strain associated with vocal fold vibration during phonation (100 Hz and higher. Relevant to these deformation patterns are the viscous properties of laryngeal tissues, which exhibit non-linear stress relaxation and recovery. In the current study, a large strain time-dependent constitutive model of human vocal fold tissue is used to investigate effects of phonatory posturing cyclic strain in the range of 1 Hz to 10 Hz. Tissue data for two subjects are considered and used to contrast the potential effects of age. Results suggest that modulation frequency and extent (amplitude, as well as the amount of vocal fold overall strain, all affect the change in stress relaxation with modulation added. Generally, the vocal fold cover reduces the rate of relaxation while the opposite is true for the vocal ligament. Further, higher modulation frequencies appear to reduce the rate of relaxation, primarily affecting the ligament. The potential benefits of cyclic strain, often found in vibrato (around 5 Hz modulation and intonational inflection, are discussed in terms of vocal effort and vocal pitch maintenance. Additionally, elderly tissue appears to not exhibit these benefits to modulation. The exacerbating effect such modulations may have on certain voice disorders, such as muscle tension dysphonia, are explored.

  9. Comparing Methods for Cardiac Output: Intraoperatively Doppler-Derived Cardiac Output Measured With 3-Dimensional Echocardiography Is Not Interchangeable With Cardiac Output by Pulmonary Catheter Thermodilution.

    Science.gov (United States)

    Graeser, Karin; Zemtsovski, Mikhail; Kofoed, Klaus F; Winther-Jensen, Matilde; Nilsson, Jens C; Kjaergaard, Jesper; Møller-Sørensen, Hasse

    2018-01-09

    Estimation of cardiac output (CO) is essential in the treatment of circulatory unstable patients. CO measured by pulmonary artery catheter thermodilution is considered the gold standard but carries a small risk of severe complications. Stroke volume and CO can be measured by transesophageal echocardiography (TEE), which is widely used during cardiac surgery. We hypothesized that Doppler-derived CO by 3-dimensional (3D) TEE would agree well with CO measured with pulmonary artery catheter thermodilution as a reference method based on accurate measurements of the cross-sectional area of the left ventricular outflow tract. The primary aim was a systematic comparison of CO with Doppler-derived 3D TEE and CO by thermodilution in a broad population of patients undergoing cardiac surgery. A subanalysis was performed comparing cross-sectional area by TEE with cardiac computed tomography (CT) angiography. Sixty-two patients, scheduled for elective heart surgery, were included; 1 was subsequently excluded for logistic reasons. Inclusion criteria were coronary artery bypass surgery (N = 42) and aortic valve replacement (N = 19). Exclusion criteria were chronic atrial fibrillation, left ventricular ejection fraction below 0.40 and intracardiac shunts. Nineteen randomly selected patients had a cardiac CT the day before surgery. All images were stored for blinded post hoc analyses, and Bland-Altman plots were used to assess agreement between measurement methods, defined as the bias (mean difference between methods), limits of agreement (equal to bias ± 2 standard deviations of the bias), and percentage error (limits of agreement divided by the mean of the 2 methods). Precision was determined for the individual methods (equal to 2 standard deviations of the bias between replicate measurements) to determine the acceptable limits of agreement. We found a good precision for Doppler-derived CO measured by 3D TEE, but although the bias for Doppler-derived CO by 3D compared to

  10. 3D non-affine finite strains measured in isolated bovine annulus fibrosus tissue samples

    NARCIS (Netherlands)

    Huyghe, J.M.R.J.; Talen-Jongeneelen, C.J.M.

    2012-01-01

    Understanding of the mechanics of disc tissue calls for measurement of strains in physiological conditions. Because the intervertebral disc is gripped between two vertebrae, the swelling is constrained in vivo, resulting in a intradiscal pressure of 0.1–0.2 MPa in supine position. The excision of

  11. Electrical conductivity and ion diffusion in porcine meniscus: effects of strain, anisotropy, and tissue region.

    Science.gov (United States)

    Kleinhans, Kelsey L; McMahan, Jeffrey B; Jackson, Alicia R

    2016-09-06

    The purpose of the present study was to investigate the effects of mechanical strain, anisotropy, and tissue region on electrical conductivity and ion diffusivity in meniscus fibrocartilage. A one-dimensional, 4-wire conductivity experiment was employed to measure the electrical conductivity in porcine meniscus tissues from two tissue regions (horn and central), for two tissue orientations (axial and circumferential), and for three levels of compressive strain (0%, 10%, and 20%). Conductivity values were then used to estimate the relative ion diffusivity in meniscus. The water volume fraction of tissue specimens was determined using a buoyancy method. A total of 135 meniscus samples were measured; electrical conductivity values ranged from 2.47mS/cm to 4.84mS/cm, while relative ion diffusivity was in the range of 0.235 to 0.409. Results show that electrical conductivity and ion diffusion are significantly anisotropic (pmeniscus fibrocartilage, which is essential in developing new strategies to treat and/or prevent tissue degeneration. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. An experimental study on the mechanical properties of rat brain tissue using different stress-strain definitions.

    Science.gov (United States)

    Karimi, Alireza; Navidbakhsh, Mahdi

    2014-07-01

    There are different stress-strain definitions to measure the mechanical properties of the brain tissue. However, there is no agreement as to which stress-strain definition should be employed to measure the mechanical properties of the brain tissue at both the longitudinal and circumferential directions. It is worth knowing that an optimize stress-strain definition of the brain tissue at different loading directions may have implications for neuronavigation and surgery simulation through haptic devices. This study is aimed to conduct a comparative study on different results are given by the various definitions of stress-strain and to recommend a specific definition when testing brain tissues. Prepared cylindrical samples are excised from the parietal lobes of rats' brains and experimentally tested by applying load on both the longitudinal and circumferential directions. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are used to determine the elastic modulus, maximum stress and strain. The highest non-linear stress-strain relation is observed for the Almansi-Hamel strain definition and it may overestimate the elastic modulus at different stress definitions at both the longitudinal and circumferential directions. The Green-St. Venant strain definition fails to address the non-linear stress-strain relation using different definitions of stress and triggers an underestimation of the elastic modulus. The results suggest the application of the true stress-true strain definition for characterization of the brain tissues mechanics since it gives more accurate measurements of the tissue's response using the instantaneous values.

  13. A new nonlinear parameter in the developed strain-to-applied strain of the soft tissues and its application in ultrasound elasticity imaging.

    Science.gov (United States)

    Xu, Jingping; Tripathy, Sakya; Rubin, Jonathan M; Stidham, Ryan W; Johnson, Laura A; Higgins, Peter D R; Kim, Kang

    2012-03-01

    Strain developed under quasi-static deformation has been mostly used in ultrasound elasticity imaging (UEI) to determine the stiffness change of tissues. However, the strain measure in UEI is often less sensitive to a subtle change of stiffness. This is particularly true for Crohn's disease where we have applied strain imaging to the differentiation of acutely inflamed bowel from chronically fibrotic bowel. In this study, a new nonlinear elastic parameter of the soft tissues is proposed to overcome this limit. The purpose of this study is to evaluate the newly proposed method and demonstrate its feasibility in the UEI. A nonlinear characteristic of soft tissues over a relatively large dynamic range of strain was investigated. A simplified tissue model based on a finite element (FE) analysis was integrated with a laboratory developed ultrasound radio-frequency (RF) signal synthesis program. Two-dimensional speckle tracking was applied to this model to simulate the nonlinear behavior of the strain developed in a target inclusion over the applied average strain to the surrounding tissues. A nonlinear empirical equation was formulated and optimized to best match the developed strain-to-applied strain relation obtained from the FE simulation. The proposed nonlinear equation was applied to in vivo measurements and nonlinear parameters were further empirically optimized. For an animal model, acute and chronic inflammatory bowel disease was induced in Lewis rats with trinitrobenzene sulfonic acid (TNBS)-ethanol treatments. After UEI, histopathology and direct mechanical measurements were performed on the excised tissues. The extracted nonlinear parameter from the developed strain-to-applied strain relation differentiated the three different tissue types with 1.96 ± 0.12 for normal, 1.50 ± 0.09 for the acutely inflamed and 1.03 ± 0.08 for the chronically fibrotic tissue. T-tests determined that the nonlinear parameters between normal, acutely inflamed and fibrotic tissue

  14. Stress-sensitive tissue regeneration in viscoelastic biomaterials subjected to modulated tensile strain.

    Science.gov (United States)

    Belfiore, Laurence A; Floren, Michael L; Paulino, Alexandre T; Belfiore, Carol J

    2011-09-01

    This research contribution addresses the mechanochemistry of intra-tissue mass transfer for nutrients, oxygen, growth factors, and other essential ingredients that anchorage-dependent cells require for successful proliferation on biocompatible surfaces. The unsteady state reaction-diffusion equation (i.e., modified diffusion equation) is solved according to the von Kármán-Pohlhausen integral method of boundary layer analysis when nutrient consumption and tissue regeneration are stimulated by harmonically imposed stress. The mass balance with diffusion and stress-sensitive kinetics represents a rare example where the Damköhler and Deborah numbers appear together in an effort to simulate the development of mass transfer boundary layers in porous viscoelastic biomaterials. The Boltzmann superposition integral is employed to calculate time-dependent strain in terms of the real and imaginary components of dynamic compliance for viscoelastic solids that transmit harmonic excitation to anchorage-dependent cells. Rates of nutrient consumption under stress-free conditions are described by third-order kinetics which include local mass densities of nutrients, oxygen, and attached cells that maintain dynamic equilibrium with active protein sites in the porous matrix. Thinner nutrient mass transfer boundary layers are stabilized at shorter dimensionless diffusion times when the stress-free intra-tissue Damköhler number increases above its initial-condition-sensitive critical value. The critical stress-sensitive intra-tissue Damköhler number, above which it is necessary to consider the effect of harmonic strain on nutrient consumption and tissue regeneration, is proportional to the Deborah number and corresponds to a larger fraction of the stress-free intra-tissue Damköhler number in rigid biomaterials. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Strain-specific helper T cell profile in the gut-associated lymphoid tissue.

    Science.gov (United States)

    Stanisavljević, Suzana; Đedović, Neda; Vujičić, Milica; Saksida, Tamara; Jevtić, Bojan; Milovanović, Boško; Momčilović, Miljana; Miljković, Đorđe; Stojanović, Ivana

    2017-10-01

    C57BL/6, BALB/c and NOD mice are among the most frequently used strains in autoimmunity research. NOD mice spontaneously develop type 1 diabetes (T1D) and they are prone to induction of experimental autoimmune encephalomyelitis (EAE). Both diseases can be routinely induced in C57BL/6 mice, but not in BALB/c mice. Also, C57BL/6 mice are generally considered T helper (Th)1-biased and BALB/c Th2-biased mice. Having in mind increasingly appreciated role of gut associated lymphoid tissue (GALT) cells in autoimmunity, especially in relation to gut Th17 and regulatory T (Treg) cells, our aim was to determine if there are differences in proportion of CD4 + T cell populations in mesenteric lymph nodes and Peyer's patches of these mouse strains. Lower proportion of Treg was observed in NOD PP, Th2 cells dominated in BALB/c mice in mesenteric lymph nodes (MLN) and Peyer's patches (PP), while Th1 cells prevailed in C57BL/6 MLN. Intradermal immunization of mice with complete Freund's adjuvant resulted in significant difference in Th cell distribution in GALT of NOD mice. Differences were less pronounced in C57BL/6 mice, while GALT of BALB/c mice was almost unresponsive to the immunization. The observed strain- and tissue-dependent changes in Treg proportion after the immunization was probably a consequence of different CCR2 or CCR6-related migration patterns and/or in situ Treg proliferation. In conclusion, NOD, a highly autoimmunity-prone mouse strain, exhibits more profound GALT-related immune response upon immunization compared to the strains that are less prone to autoimmunity. Copyright © 2017 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

  16. Prediction of Local Ultimate Strain and Toughness of Trabecular Bone Tissue by Raman Material Composition Analysis

    Directory of Open Access Journals (Sweden)

    Roberto Carretta

    2015-01-01

    Full Text Available Clinical studies indicate that bone mineral density correlates with fracture risk at the population level but does not correlate with individual fracture risk well. Current research aims to better understand the failure mechanism of bone and to identify key determinants of bone quality, thus improving fracture risk prediction. To get a better understanding of bone strength, it is important to analyze tissue-level properties not influenced by macro- or microarchitectural factors. The aim of this pilot study was to identify whether and to what extent material properties are correlated with mechanical properties at the tissue level. The influence of macro- or microarchitectural factors was excluded by testing individual trabeculae. Previously reported data of mechanical parameters measured in single trabeculae under tension and bending and its compositional properties measured by Raman spectroscopy was evaluated. Linear and multivariate regressions show that bone matrix quality but not quantity was significantly and independently correlated with the tissue-level ultimate strain and postyield work (r=0.65–0.94. Principal component analysis extracted three independent components explaining 86% of the total variance, representing elastic, yield, and ultimate components according to the included mechanical parameters. Some matrix parameters were both included in the ultimate component, indicating that the variation in ultimate strain and postyield work could be largely explained by Raman-derived compositional parameters.

  17. Tissue tropisms in group A Streptococcus: what virulence factors distinguish pharyngitis from impetigo strains?

    Science.gov (United States)

    Bessen, Debra E

    2016-06-01

    Group A streptococci (GAS) are a common cause of pharyngitis and impetigo, and distinct throat strains and skin strains have been long recognized. This review aims to describe recent advances in molecular differences between throat and skin strains, and the pathogenic mechanisms used by virulence factors that may distinguish between these two groups. Recent findings include a new typing scheme for GAS strains based on sequence clusters of genes encoding the entire surface-exposed portion of M protein; correlations between emm-based typing schemes, clinical disease and surface adhesins; covalent bond formation mediated by GAS pili and other adhesins in binding to host ligands; a key role for superantigens in oropharyngeal infection via binding major histocompatibility complex class II antigen; and migration of GAS-specific Th17 cells from the upper respiratory tract to the brain, which may be relevant to autoimmune sequelae. The gap between molecular markers of disease (correlation) and virulence mechanisms (causation) in the establishment of tissue tropisms for GAS infection currently remains wide, but the gap also continues to narrow. Whole genome sequencing combined with mutant construction and improvements in animal models for oropharyngeal infection by GAS may help pave the way for new discoveries.

  18. Quantified Facial Soft-tissue Strain in Animation Measured by Real-time Dynamic 3-Dimensional Imaging

    Directory of Open Access Journals (Sweden)

    Vivian M. Hsu, MD

    2014-09-01

    Conclusions: This pilot study illustrates that the face can be objectively and quantitatively evaluated using dynamic major strain analysis. The technology of 3-dimensional optical imaging can be used to advance our understanding of facial soft-tissue dynamics and the effects of animation on facial strain over time.

  19. Three-dimensional development of tensile pre-strained annulus fibrosus cells for tissue regeneration: An in-vitro study

    Energy Technology Data Exchange (ETDEWEB)

    Chuah, Yon Jin [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Lee, Wu Chean [University Hospital Conventry & Warwickshire NHS Trust, Clifford Bridge Road, West Midlands CV2, 2DX (United Kingdom); Wong, Hee Kit [Department of Orthopedic Surgery, National University Health System, NUHS Tower Block Level 11, 1E Kent Ridge Road, Singapore 119228 (Singapore); Kang, Yuejun, E-mail: yuejun.kang@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Hee, Hwan Tak, E-mail: HTHee@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Pinnacle Spine & Scoliosis Centre, 3 Mount Elizabeth, Mount Elizabeth Medical Centre, #04-07, Singapore 228510 (Singapore); School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637459 (Singapore)

    2015-02-01

    Prior research has investigated the immediate response after application of tensile strain on annulus fibrosus (AF) cells for the past decade. Although mechanical strain can produce either catabolic or anabolic consequences to the cell monolayer, little is known on how to translate these findings into further tissue engineering applications. Till to date, the application and effect of tensile pre-strained cells to construct a three-dimensional (3D) AF tissue remains unknown. This study aims to investigate the effect of tensile pre-strained exposure of 1 to 24 h on the development of AF pellet culture for 3 weeks. Equibiaxial cyclic tensile strain was applied on AF monolayer cells over a period of 24 h, which was subsequently developed into a cell pellet. Investigation on cellular proliferation, phenotypic gene expression, and histological changes revealed that tensile pre-strain for 24 h had significant and lasting effect on the AF tissue development, with enhanced cell proliferation, and up-regulation of collagen type I, II, and aggrecan expression. Our results demonstrated the regenerative ability of AF cell pellets subjected to 24 h tensile pre-straining. Knowledge on the effects of tensile pre-strain exposure is necessary to optimize AF development for tissue reconstruction. Moreover, the tensile pre-strained cells may further be utilized in either cell therapy to treat mild disc degeneration disease, or the development of a disc construct for total disc replacement. - Highlights: • Establishment of tensile pre-strained cell line population for annulus development. • Tensile strain limits collagen gene expression declination in monolayer culture. • Tensile pre-strained cells up-regulate their matrix protein in 3D pellet culture.

  20. Value of the Strain Ratio on Ultrasonic Elastography for Differentiation of Benign and Malignant Soft Tissue Tumors.

    Science.gov (United States)

    Hahn, Seok; Lee, Young Han; Lee, Seung Hyun; Suh, Jin-Suck

    2017-01-01

    The purpose of this study was to evaluate whether the strain ratio provides additional value to conventional visual elasticity scores in the differentiation of benign and malignant soft tissue tumors by ultrasonic elastography. The Institutional Review Board approved the protocol of this retrospective review. Seventy-three patients who underwent elastography and had a soft tissue mass pathologically confirmed by ultrasound-guided core biopsy or surgical excision were enrolled from April 2012 through October 2014. On elastography, elasticity scores were determined with a 5-point visual scale, and the strain ratio to adjacent soft tissue at the same depth was calculated. Tumors were divided into benign and malignant groups according to the pathologic diagnoses. Elasticity scores and strain ratios were compared between benign and malignant groups, and diagnostic performance was evaluated by receiver operating characteristic curves. Of the 73 patients, 40 had benign tumors, and 33 had malignant tumors. Strain ratios (P = .003) and elasticity scores (P = .048) were significantly different between pathologic results. The areas under the receiver operating characteristic curves were 0.700 (95% confidence interval, 0.581-0.802) for the strain ratio and 0.623 (95% confidence interval, 0.515-0.746) for elastography. The strain ratios of malignant soft tissue tumors were lower than those of benign tumors and showed better diagnostic performance than did elasticity scores. The strain ratio can be used as a diagnostic indicator to predict the malignant potential of soft tissue tumors. © 2016 by the American Institute of Ultrasound in Medicine.

  1. Exploring the mechanical behavior of degrading swine neural tissue at low strain rates via the fractional Zener constitutive model.

    Science.gov (United States)

    Bentil, Sarah A; Dupaix, Rebecca B

    2014-02-01

    The ability of the fractional Zener constitutive model to predict the behavior of postmortem swine brain tissue was examined in this work. Understanding tissue behavior attributed to degradation is invaluable in many fields such as the forensic sciences or cases where only cadaveric tissue is available. To understand how material properties change with postmortem age, the fractional Zener model was considered as it includes parameters to describe brain stiffness and also the parameter α, which quantifies the viscoelasticity of a material. The relationship between the viscoelasticity described by α and tissue degradation was examined by fitting the model to data collected in a previous study (Bentil, 2013). This previous study subjected swine neural tissue to in vitro unconfined compression tests using four postmortem age groups (week). All samples were compressed to a strain level of 10% using two compressive rates: 1mm/min and 5mm/min. Statistical analysis was used as a tool to study the influence of the fractional Zener constants on factors such as tissue degradation and compressive rate. Application of the fractional Zener constitutive model to the experimental data showed that swine neural tissue becomes less stiff with increased postmortem age. The fractional Zener model was also able to capture the nonlinear viscoelastic features of the brain tissue at low strain rates. The results showed that the parameter α was better correlated with compressive rate than with postmortem age. © 2013 Published by Elsevier Ltd.

  2. Assessment of strain and strain rate by two-dimensional speckle tracking in mice: comparison with tissue Doppler echocardiography and conductance catheter measurements.

    Science.gov (United States)

    Ferferieva, V; Van den Bergh, A; Claus, P; Jasaityte, R; La Gerche, A; Rademakers, F; Herijgers, P; D'hooge, J

    2013-08-01

    This study was designed in order to compare the strain and strain rate deformation parameters assessed by speckle tracking imaging (STI) with those of tissue Doppler imaging (TDI) and conductance catheter measurements in chronic murine models of left ventricular (LV) dysfunction. Twenty-four male C57BL/6J mice were assigned to wild-type (n = 8), myocardial infarction (n = 8) and transaortic constriction (n = 8) groups. Echocardiographic and conductance measurements were simultaneously performed at rest and during dobutamine infusion (5 µg/kg/min) in all animals 10 weeks post-surgery. The LV circumferential strain (Scirc) and the strain rate (SRcirc) were derived from grey scale and tissue Doppler data at frame rates of 224 and 375 Hz, respectively. Scirc and SRcirc by TDI/STI correlated well with the preload recruitable stroke work (PRSW) (r = -0.64 and -0.71 for TDI; r = -0.46 and -0.50 for STI, P < 0.05). Both modalities showed a good agreement with respect to Scirc and SRcirc (r = 0.60 and r = 0.63, P < 0.05). During stress, however, TDI-estimated Scirc and SRcirc values were predominantly higher than those measured by STI (P < 0.05). The similarity of Scirc and SRcirc measurements with respect to the STI/TDI data was examined by the Bland-Altman analysis. In mice, the STI- and TDI-derived strain and strain rate deformation parameters relate closely to intrinsic myocardial function. At low heart rate-to-frame rate ratios (HR/FR), both STI and TDI are equally acceptable for assessing the LV function non-invasively in these animals. At HR/FR (e.g. dobutamine challenge), however, these methods cannot be used interchangeably as STI underestimates S and SR at high values.

  3. Draft Genome Sequence of the Biocontrol Strain Serratia plymuthica A30, Isolated from Rotting Potato Tuber Tissue

    NARCIS (Netherlands)

    Czajkowski, R.L.; Van der Wolf, J.M.

    2012-01-01

    Serratia plymuthica A30 is a Gram-negative bacterium expressing antagonistic activity toward blackleg- and soft rot-causing Dickeya sp. biovar 3 ("Dickeya solani"). Here, we present the draft genome sequence of strain A30, which has been isolated from rotten potato tuber tissue. [KEYWORDS: biovar 3

  4. Draft Genome Sequence of the Biocontrol Strain Serratia plymuthica A30, Isolated from Rotting Potato Tuber Tissue

    NARCIS (Netherlands)

    Czajkowski, R.L.; Wolf, van der J.M.

    2012-01-01

    Serratia plymuthica A30 is a Gram-negative bacterium expressing antagonistic activity toward blackleg- and soft rot-causing Dickeya sp. biovar 3 (“Dickeya solani”). Here, we present the draft genome sequence of strain A30, which has been isolated from rotten potato tuber tissue

  5. Vaccination reduces macrophage infiltration in bronchus-associated lymphoid tissue in pigs infected with a highly virulent Mycoplasma hyopneumoniae strain

    Directory of Open Access Journals (Sweden)

    Vranckx Katleen

    2012-03-01

    Full Text Available Abstract Background Mycoplasma hyopneumoniae is the causative agent of enzootic pneumonia and is responsible for significant economic losses to the pig industry. To better understand the mode of action of a commercial, adjuvanted, inactivated whole cell vaccine and the influence of diversity on the efficacy of vaccination, we investigated samples from vaccinated and non-vaccinated pigs experimentally infected with either a low (LV or a highly virulent (HV M. hyopneumoniae strain. Non-vaccinated and sham-infected control groups were included. Lung tissue samples collected at 4 and 8 weeks post infection (PI were immunohistochemically tested for the presence of T-lymphocytes, B-lymphocytes and macrophages in the bronchus-associated lymphoid tissue (BALT. The number of M. hyopneumoniae organisms in bronchoalveolar lavage (BAL fluid was determined using quantitative PCR at 4 and 8 weeks PI. Serum antibodies against M. hyopneumoniae were determined at 0, 2, 4, 6 and 8 weeks PI. Results The immunostaining revealed a lower density of macrophages in the BALT of the vaccinated groups compared to the non-vaccinated groups. The highest number of M. hyopneumoniae organisms in the BAL fluid was measured at 4 weeks PI for the HV strain and at 8 weeks PI for the LV strain. Vaccination reduced the number of organisms non-significantly, though for the HV strain the reduction was clinically more relevant than for the LV strain. At the level of the individual pigs, a higher lung lesion score was associated with more M. hyopneumoniae organisms in the lungs and a higher density of the investigated immune cells in the BALT. Conclusions In conclusion, the infiltration of macrophages after infection with M. hyopneumoniae is reduced by vaccination. The M. hyopneumoniae replication in the lungs is also reduced in vaccinated pigs, though the HV strain is inhibited more than the LV strain.

  6. Normal and Fibrotic Rat Livers Demonstrate Shear Strain Softening and Compression Stiffening: A Model for Soft Tissue Mechanics.

    Directory of Open Access Journals (Sweden)

    Maryna Perepelyuk

    Full Text Available Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G' and G" and the apparent Young's moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver.

  7. On the Rule of Mixtures for Predicting Stress-Softening and Residual Strain Effects in Biological Tissues and Biocompatible Materials

    Directory of Open Access Journals (Sweden)

    Alex Elías-Zúñiga

    2014-01-01

    Full Text Available In this work, we use the rule of mixtures to develop an equivalent material model in which the total strain energy density is split into the isotropic part related to the matrix component and the anisotropic energy contribution related to the fiber effects. For the isotropic energy part, we select the amended non-Gaussian strain energy density model, while the energy fiber effects are added by considering the equivalent anisotropic volumetric fraction contribution, as well as the isotropized representation form of the eight-chain energy model that accounts for the material anisotropic effects. Furthermore, our proposed material model uses a phenomenological non-monotonous softening function that predicts stress softening effects and has an energy term, derived from the pseudo-elasticity theory, that accounts for residual strain deformations. The model’s theoretical predictions are compared with experimental data collected from human vaginal tissues, mice skin, poly(glycolide-co-caprolactone (PGC25 3-0 and polypropylene suture materials and tracheal and brain human tissues. In all cases examined here, our equivalent material model closely follows stress-softening and residual strain effects exhibited by experimental data.

  8. On the Rule of Mixtures for Predicting Stress-Softening and Residual Strain Effects in Biological Tissues and Biocompatible Materials

    Science.gov (United States)

    Elías-Zúñiga, Alex; Baylón, Karen; Ferrer, Inés; Serenó, Lídia; Garcia-Romeu, Maria Luisa; Bagudanch, Isabel; Grabalosa, Jordi; Pérez-Recio, Tania; Martínez-Romero, Oscar; Ortega-Lara, Wendy; Elizalde, Luis Ernesto

    2014-01-01

    In this work, we use the rule of mixtures to develop an equivalent material model in which the total strain energy density is split into the isotropic part related to the matrix component and the anisotropic energy contribution related to the fiber effects. For the isotropic energy part, we select the amended non-Gaussian strain energy density model, while the energy fiber effects are added by considering the equivalent anisotropic volumetric fraction contribution, as well as the isotropized representation form of the eight-chain energy model that accounts for the material anisotropic effects. Furthermore, our proposed material model uses a phenomenological non-monotonous softening function that predicts stress softening effects and has an energy term, derived from the pseudo-elasticity theory, that accounts for residual strain deformations. The model’s theoretical predictions are compared with experimental data collected from human vaginal tissues, mice skin, poly(glycolide-co-caprolactone) (PGC25 3-0) and polypropylene suture materials and tracheal and brain human tissues. In all cases examined here, our equivalent material model closely follows stress-softening and residual strain effects exhibited by experimental data. PMID:28788466

  9. Quantified Facial Soft-tissue Strain in Animation Measured by Real-time Dynamic 3-Dimensional Imaging.

    Science.gov (United States)

    Hsu, Vivian M; Wes, Ari M; Tahiri, Youssef; Cornman-Homonoff, Joshua; Percec, Ivona

    2014-09-01

    The aim of this study is to evaluate and quantify dynamic soft-tissue strain in the human face using real-time 3-dimensional imaging technology. Thirteen subjects (8 women, 5 men) between the ages of 18 and 70 were imaged using a dual-camera system and 3-dimensional optical analysis (ARAMIS, Trilion Quality Systems, Pa.). Each subject was imaged at rest and with the following facial expressions: (1) smile, (2) laughter, (3) surprise, (4) anger, (5) grimace, and (6) pursed lips. The facial strains defining stretch and compression were computed for each subject and compared. The areas of greatest strain were localized to the midface and lower face for all expressions. Subjects over the age of 40 had a statistically significant increase in stretch in the perioral region while lip pursing compared with subjects under the age of 40 (58.4% vs 33.8%, P = 0.015). When specific components of lip pursing were analyzed, there was a significantly greater degree of stretch in the nasolabial fold region in subjects over 40 compared with those under 40 (61.6% vs 32.9%, P = 0.007). Furthermore, we observed a greater degree of asymmetry of strain in the nasolabial fold region in the older age group (18.4% vs 5.4%, P = 0.03). This pilot study illustrates that the face can be objectively and quantitatively evaluated using dynamic major strain analysis. The technology of 3-dimensional optical imaging can be used to advance our understanding of facial soft-tissue dynamics and the effects of animation on facial strain over time.

  10. Correlation between the tissue Doppler, strain rate, strain imaging during the dobutamine infusion and coronary fractional flow reserve during catheterization: a comparative study.

    Science.gov (United States)

    Dagdelen, Sinan; Yuce, Murat; Emiroglu, Yunus; Ergelen, Mehmet; Pala, Selcuk; Tanalp, Ali Cevat; Izgi, Akin; Kirma, Cevat

    2005-06-22

    Coronary fractional flow reserve (FFR) as an invasive, and dobutamine stress echocardiography (DSE) as a noninvasive technique were used to detect critical coronary stenosis. This study was undertaken to assess correlation between these two techniques by using tissue Doppler, strain rate (SR), and strain imaging (S). In 17 patients (aged 54.9+/-12.6, 4 F), a total of 22 vessels were studied. On dobutamine stress echocardiography, baseline and peak systolic (Sm), early (Em) and late (Am) diastolic myocardial velocities, SR and S were recorded from parasternal view (mid-posterior segment) for radial and apical view (mid-septum) for longitudinal deformation. Then coronary FFR was performed by using intracoronary adenosine infusion, and the value of system were analyzed for longitudinal SR and S values, it had a mild correlation with SR (r = 0.47, p = 0.044) and a good correlation with S (r = 0.66, p = 0.002). The quantification of regional myocardial deformation by using DSE rather than the motion would be more appropriate in detecting the ischemic dysfunctional segment supplied by the critical coronary stenosis. Strain measurement during the dobutamine infusion may provide an information on the FFR results of the culprit vessel.

  11. A deep learning approach to estimate chemically-treated collagenous tissue nonlinear anisotropic stress-strain responses from microscopy images.

    Science.gov (United States)

    Liang, Liang; Liu, Minliang; Sun, Wei

    2017-11-01

    Biological collagenous tissues comprised of networks of collagen fibers are suitable for a broad spectrum of medical applications owing to their attractive mechanical properties. In this study, we developed a noninvasive approach to estimate collagenous tissue elastic properties directly from microscopy images using Machine Learning (ML) techniques. Glutaraldehyde-treated bovine pericardium (GLBP) tissue, widely used in the fabrication of bioprosthetic heart valves and vascular patches, was chosen to develop a representative application. A Deep Learning model was designed and trained to process second harmonic generation (SHG) images of collagen networks in GLBP tissue samples, and directly predict the tissue elastic mechanical properties. The trained model is capable of identifying the overall tissue stiffness with a classification accuracy of 84%, and predicting the nonlinear anisotropic stress-strain curves with average regression errors of 0.021 and 0.031. Thus, this study demonstrates the feasibility and great potential of using the Deep Learning approach for fast and noninvasive assessment of collagenous tissue elastic properties from microstructural images. In this study, we developed, to our best knowledge, the first Deep Learning-based approach to estimate the elastic properties of collagenous tissues directly from noninvasive second harmonic generation images. The success of this study holds promise for the use of Machine Learning techniques to noninvasively and efficiently estimate the mechanical properties of many structure-based biological materials, and it also enables many potential applications such as serving as a quality control tool to select tissue for the manufacturing of medical devices (e.g. bioprosthetic heart valves). Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Experimental Toxoplasmosis in Rats Induced Orally with Eleven Strains of Toxoplasma gondii of Seven Genotypes: Tissue Tropism, Tissue Cyst Size, Neural Lesions, Tissue Cyst Rupture without Reactivation, and Ocular Lesions.

    Directory of Open Access Journals (Sweden)

    Jitender P Dubey

    Full Text Available The protozoan parasite Toxoplasma gondii is one of the most widely distributed and successful parasites. Toxoplasma gondii alters rodent behavior such that infected rodents reverse their fear of cat odor, and indeed are attracted rather than repelled by feline urine. The location of the parasite encysted in the brain may influence this behavior. However, most studies are based on the highly susceptible rodent, the mouse.Latent toxoplasmosis was induced in rats (10 rats per T. gondii strains of the same age, strain, and sex, after oral inoculation with oocysts (natural route and natural stage of infection of 11 T. gondii strains of seven genotypes. Rats were euthanized at two months post inoculation (p.i. to investigate whether the parasite genotype affects the distribution, location, tissue cyst size, or lesions. Tissue cysts were enumerated in different regions of the brains, both in histological sections as well in saline homogenates. Tissue cysts were found in all regions of the brain. The tissue cyst density in different brain regions varied extensively between rats with many regions highly infected in some animals. Overall, the colliculus was most highly infected although there was a large amount of variability. The cerebral cortex, thalamus, and cerebellum had higher tissue cyst densities and two strains exhibited tropism for the colliculus and olfactory bulb. Histologically, lesions were confined to the brain and eyes. Tissue cyst rupture was frequent with no clear evidence for reactivation of tachyzoites. Ocular lesions were found in 23 (25% of 92 rat eyes at two months p.i. The predominant lesion was focal inflammation in the retina. Tissue cysts were seen in the sclera of one and in the optic nerve of two rats. The choroid was not affected. Only tissue cysts, not active tachyzoite infections, were detected. Tissue cysts were seen in histological sections of tongue of 20 rats but not in myocardium and leg muscle.This study reevaluated

  13. Vaccine-induced rabies case in a cow (Bos taurus): Molecular characterisation of vaccine strain in brain tissue.

    Science.gov (United States)

    Vuta, Vlad; Picard-Meyer, Evelyne; Robardet, Emmanuelle; Barboi, Gheorghe; Motiu, Razvan; Barbuceanu, Florica; Vlagioiu, Constantin; Cliquet, Florence

    2016-09-22

    Rabies is a fatal neuropathogenic zoonosis caused by the rabies virus of the Lyssavirus genus, Rhabdoviridae family. The oral vaccination of foxes - the main reservoir of rabies in Europe - using a live attenuated rabies virus vaccine was successfully conducted in many Western European countries. In July 2015, a rabies vaccine strain was isolated from the brain tissues of a clinically suspect cow (Bos taurus) in Romania. The nucleotide analysis of both N and G gene sequences showed 100% identity between the rabid animal, the GenBank reference SAD B19 strain and five rabies vaccine batches used for the national oral vaccination campaign targeting foxes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. [Effect of elastic strain rate ratio method and virtual touch tissue quantification on the diagnosis of breast masses].

    Science.gov (United States)

    Gong, LiJie; He, Yan; Tian, Peng; Yan, Yan

    2016-07-01

    To determine the effect of elastic strain rate ratio method and virtual touch tissue quantification (VTQ) on the diagnosis of breast masses.
 Sixty female patients with breast cancer, who received surgical treatment in Daqing Oilfield General Hospital, were enrolled. All patients signed the informed consent paperwork and they were treated by routine ultrasound examination, compression elastography (CE) examination, and VTQ examination in turn. Strain ratio (SR) was checked by CE and shear wave velocity (SWV) value was measured by VTQ. The diagnostic values of different methods were evaluated by receiver operating characteristic (ROC) curves in the diagnosis of benign and malignant breast tumors.
 The maximum diameter and SWV value of the benign tumors were lower than those of the malignant tumors, and the SR ratio of benign masses was higher than that of malignant tumors (Pbreast mass than that used alone.

  15. About the inevitable compromise between spatial resolution and accuracy of strain measurement for bone tissue: a 3D zero-strain study.

    Science.gov (United States)

    Dall'Ara, E; Barber, D; Viceconti, M

    2014-09-22

    The accurate measurement of local strain is necessary to study bone mechanics and to validate micro computed tomography (µCT) based finite element (FE) models at the tissue scale. Digital volume correlation (DVC) has been used to provide a volumetric estimation of local strain in trabecular bone sample with a reasonable accuracy. However, nothing has been reported so far for µCT based analysis of cortical bone. The goal of this study was to evaluate accuracy and precision of a deformable registration method for prediction of local zero-strains in bovine cortical and trabecular bone samples. The accuracy and precision were analyzed by comparing scans virtually displaced, repeated scans without any repositioning of the sample in the scanner and repeated scans with repositioning of the samples. The analysis showed that both precision and accuracy errors decrease with increasing the size of the region analyzed, by following power laws. The main source of error was found to be the intrinsic noise of the images compared to the others investigated. The results, once extrapolated for larger regions of interest that are typically used in the literature, were in most cases better than the ones previously reported. For a nodal spacing equal to 50 voxels (498 µm), the accuracy and precision ranges were 425-692 µε and 202-394 µε, respectively. In conclusion, it was shown that the proposed method can be used to study the local deformation of cortical and trabecular bone loaded beyond yield, if a sufficiently high nodal spacing is used. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Mapping of Mechanical Strains and Stresses around Quiescent Engineered Three-Dimensional Epithelial Tissues

    Science.gov (United States)

    Gjorevski, Nikolce; Nelson, Celeste M.

    2012-01-01

    Understanding how physical signals guide biological processes requires qualitative and quantitative knowledge of the mechanical forces generated and sensed by cells in a physiologically realistic three-dimensional (3D) context. Here, we used computational modeling and engineered epithelial tissues of precise geometry to define the experimental parameters that are required to measure directly the mechanical stress profile of 3D tissues embedded within native type I collagen. We found that to calculate the stresses accurately in these settings, we had to account for mechanical heterogeneities within the matrix, which we visualized and quantified using confocal reflectance and atomic force microscopy. Using this technique, we were able to obtain traction forces at the epithelium-matrix interface, and to resolve and quantify patterns of mechanical stress throughout the surrounding matrix. We discovered that whereas single cells generate tension by contracting and pulling on the matrix, the contraction of multicellular tissues can also push against the matrix, causing emergent compression. Furthermore, tissue geometry defines the spatial distribution of mechanical stress across the epithelium, which communicates mechanically over distances spanning hundreds of micrometers. Spatially resolved mechanical maps can provide insight into the types and magnitudes of physical parameters that are sensed and interpreted by multicellular tissues during normal and pathological processes. PMID:22828342

  17. Elements determination of clinical relevance in biological tissues Dmdmdx/J dystrophic mice strains investigated by NAA

    International Nuclear Information System (INIS)

    Metairon, Sabrina

    2012-01-01

    In this work the determination of chemistry elements in biological tissues (whole blood, bones and organs) of dystrophic mice, used as animal model of Duchenne Muscular Dystrophy (DMD), was performed using analytical nuclear technique. The aim of this work was to determine reference values of elements of clinical (Ca, Cl, K, Mg, Na) and nutritional (Br and S) relevance in whole blood, tibia, quadriceps and hearts from Dmdmdx/J (10 males and 10 females) dystrophic mice and C57BL/6J (10 males) control group mice, using Neutron Activation Analysis technique (NAA). To show in more details the alterations that this disease may cause in these biological tissues, correlations matrixes of the DMD mdx /J mouse strain were generated and compared with C57BL/6J control group. For this study 119 samples of biological tissue were irradiated in the IEA-R1 nuclear reactor at IPEN (Sao Paulo, Brazil). The concentrations of these elements in biological tissues of Dmd mdx /J and C57B/6J mice are the first indicative interval for reference values. Moreover, the alteration in some correlation coefficients data among the elements in the health status and in the diseased status indicates a connection between these elements in whole blood, tibia, quadriceps and heart. These results may help the researchers to evaluate the efficiency of new treatments and to compare the advantages of different treatment approaches before performing tests in patients with muscular dystrophy. (author)

  18. Infection studies with two highly pathogenic avian influenza strains (Vietnamese and Indonesian) in Pekin ducks (Anas platyrhynchos), with particular reference to clinical disease, tissue tropism and viral shedding.

    Science.gov (United States)

    Bingham, John; Green, Diane J; Lowther, Sue; Klippel, Jessica; Burggraaf, Simon; Anderson, Danielle E; Wibawa, Hendra; Hoa, Dong Manh; Long, Ngo Thanh; Vu, Pham Phong; Middleton, Deborah J; Daniels, Peter W

    2009-08-01

    Pekin ducks were infected by the mucosal route (oral, nasal, ocular) with one of two strains of Eurasian lineage H5N1 highly pathogenic avian influenza virus: A/Muscovy duck/Vietnam/453/2004 and A/duck/Indramayu/BBVW/109/2006 (from Indonesia). Ducks were killed humanely on days 1, 2, 3, 5 and 7 after challenge, or whenever morbidity was severe enough to justify euthanasia. Morbidity was recorded by observation of clinical signs and cloacal temperatures; the disease was characterized by histopathology; tissue tropism was studied by immunohistochemistry and virus titration on tissue samples; and viral shedding patterns were determined by virus isolation and titration of oral and cloacal swabs. The Vietnamese strain caused severe morbidity with fever and depression; the Indonesian strain caused only transient fever. Both viruses had a predilection for a similar range of tissue types, but the quantity of tissue antigen and tissue virus titres were considerably higher with the Vietnamese strain. The Vietnamese strain caused severe myocarditis and skeletal myositis; both strains caused non-suppurative encephalitis and a range of other inflammatory reactions of varying severity. The principal epithelial tissue infected was that of the air sacs, but antigen was not abundant. Epithelium of the turbinates, trachea and bronchi had only rare infection with virus. Virus was shed from both the oral and cloacal routes; it was first detected 24 h after challenge and persisted until day 5 after challenge. The higher prevalence of virus from swabs from ducks infected with the Vietnamese strain indicates that this strain may be more adapted to ducks than the Indonesia strain.

  19. Murine strain differences and the effects of zinc on cadmium concentrations in tissues after acute cadmium exposure

    Energy Technology Data Exchange (ETDEWEB)

    King, L.M. [ARS USDA, Germplasm and Gamete Physiology Lab., Beltsville, MD (United States); Anderson, M.B. [Dept. of Anatomy, Tulane Univ. School of Medicine, New Orleans, LA (United States); Sikka, S.C. [Dept. of Urology, Tulane Univ. School of Medicine, New Orleans, LA (United States); George, W.J. [Dept. of Pharmacology, Tulane Univ. School of Medicine, New Orleans, LA (United States)

    1998-10-01

    The role of strain differences in cadmium tissue distribution was studied using sensitive (129/J) and resistant (A/J) mice. These murine strains have previously been shown to differ in their susceptibility to cadmium-induced testicular toxicity. Cadmium concentration was measured in testis, epididymis, seminal vesicle, liver, and kidney at 24 h after cadmium chloride exposure (4, 10, and 20 {mu}mol/kg CdCl{sub 2}). The 129/J mice exhibited a significant increase in cadmium concentration in testis, epididymis, and seminal vesicle at all cadmium doses used, compared to A/J mice. However, cadmium concentrations in liver and kidney were not different between the strains, at any dose, indicating that cadmium uptake is similar in these organs at 24 h. These murine strains demonstrate similar hepatic and renal cadmium uptake but significantly different cadmium accumulation in the reproductive organs at 24 h. The mechanism of the protective effect of zinc on cadmium toxicity was studied by assessing the impact of zinc acetate (ZnAc) treatment on cadmium concentrations in 129/J mice after 24 h. Zinc pretreatment (250 {mu}mol/kg ZnAc), given 24 h prior to 20 {mu}mol/kg CdCl{sub 2} administration, significantly decreased the amount of cadmium in the testis, epididymis, and seminal vesicle of 129/J mice, and significantly increased the cadmium content of the liver after 24 h. Cadmium levels in the kidney were unaffected at this time. Zinc pretreatment also prevented the cadmium-induced decrease in testicular sperm concentration and epididymal sperm motility seen in 129/J mice. These findings suggest that the differences in the two murine strains may be attributed partly to the differential accumulation of cadmium in murine gonads. This may be caused by strain differences in the specificity of cadmium transport mechanisms. The protective role of zinc in cadmium-induced testicular toxicity in the sensitive strain may be due to an interference in the cadmium uptake by susceptible

  20. Biomimetic fetal rotation bioreactor for engineering bone tissues-Effect of cyclic strains on upregulation of osteogenic gene expression.

    Science.gov (United States)

    Ravichandran, Akhilandeshwari; Wen, Feng; Lim, Jing; Chong, Mark Seow Khoon; Chan, Jerry K Y; Teoh, Swee-Hin

    2018-04-01

    Cells respond to physiological mechanical stresses especially during early fetal development. Adopting a biomimetic approach, it is necessary to develop bioreactor systems to explore the effects of physiologically relevant mechanical strains and shear stresses for functional tissue growth and development. This study introduces a multimodal bioreactor system that allows application of cyclic compressive strains on premature bone grafts that are cultured under biaxial rotation (chamber rotation about 2 axes) conditions for bone tissue engineering. The bioreactor is integrated with sensors for dissolved oxygen levels and pH that allow real-time, non-invasive monitoring of the culture parameters. Mesenchymal stem cells-seeded polycaprolactone-β-tricalcium phosphate scaffolds were cultured in this bioreactor over 2 weeks in 4 different modes-static, cyclic compression, biaxial rotation, and multimodal (combination of cyclic compression and biaxial rotation). The multimodal culture resulted in 1.8-fold higher cellular proliferation in comparison with the static controls within the first week. Two weeks of culture in the multimodal bioreactor utilizing the combined effects of optimal fluid flow conditions and cyclic compression led to the upregulation of osteogenic genes alkaline phosphatase (3.2-fold), osteonectin (2.4-fold), osteocalcin (10-fold), and collagen type 1 α1 (2-fold) in comparison with static cultures. We report for the first time, the independent and combined effects of mechanical stimulation and biaxial rotation for bone tissue engineering using a bioreactor platform with non-invasive sensing modalities. The demonstrated results show leaning towards the futuristic vision of using a physiologically relevant bioreactor system for generation of autologous bone grafts for clinical implantation. Copyright © 2018 John Wiley & Sons, Ltd.

  1. A tissue adaptation model based on strain-dependent collagen degradation and contact-guided cell traction.

    Science.gov (United States)

    Heck, T A M; Wilson, W; Foolen, J; Cilingir, A C; Ito, K; van Donkelaar, C C

    2015-03-18

    Soft biological tissues adapt their collagen network to the mechanical environment. Collagen remodeling and cell traction are both involved in this process. The present study presents a collagen adaptation model which includes strain-dependent collagen degradation and contact-guided cell traction. Cell traction is determined by the prevailing collagen structure and is assumed to strive for tensional homeostasis. In addition, collagen is assumed to mechanically fail if it is over-strained. Care is taken to use principally measurable and physiologically meaningful relationships. This model is implemented in a fibril-reinforced biphasic finite element model for soft hydrated tissues. The versatility and limitations of the model are demonstrated by corroborating the predicted transient and equilibrium collagen adaptation under distinct mechanical constraints against experimental observations from the literature. These experiments include overloading of pericardium explants until failure, static uniaxial and biaxial loading of cell-seeded gels in vitro and shortening of periosteum explants. In addition, remodeling under hypothetical conditions is explored to demonstrate how collagen might adapt to small differences in constraints. Typical aspects of all essentially different experimental conditions are captured quantitatively or qualitatively. Differences between predictions and experiments as well as new insights that emerge from the present simulations are discussed. This model is anticipated to evolve into a mechanistic description of collagen adaptation, which may assist in developing load-regimes for functional tissue engineered constructs, or may be employed to improve our understanding of the mechanisms behind physiological and pathological collagen remodeling. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. The Effect of the Elimination of Micromotion and Tissue Strain on Intracortical Device Performance

    Science.gov (United States)

    2017-10-01

    evoked by short term and chronic implantation of non-softening, moderately softening, and softening shape memory polymer (SMP)-based intracortical...Does probe softening improve the surrounding tissue response and recording performance of the device? The short term impact will be on the scientific...community through publications and presentations. Over the long term , the core technology has exceptional promise for translation into the clinic. SMP

  3. Increasing Accuracy of Tissue Shear Modulus Reconstruction Using Ultrasonic Strain Tensor Measurement

    Science.gov (United States)

    Sumi, C.

    Previously, we developed three displacement vector measurement methods, i.e., the multidimensional cross-spectrum phase gradient method (MCSPGM), the multidimensional autocorrelation method (MAM), and the multidimensional Doppler method (MDM). To increase the accuracies and stabilities of lateral and elevational displacement measurements, we also developed spatially variant, displacement component-dependent regularization. In particular, the regularization of only the lateral/elevational displacements is advantageous for the lateral unmodulated case. The demonstrated measurements of the displacement vector distributions in experiments using an inhomogeneous shear modulus agar phantom confirm that displacement-component-dependent regularization enables more stable shear modulus reconstruction. In this report, we also review our developed lateral modulation methods that use Parabolic functions, Hanning windows, and Gaussian functions in the apodization function and the optimized apodization function that realizes the designed point spread function (PSF). The modulations significantly increase the accuracy of the strain tensor measurement and shear modulus reconstruction (demonstrated using an agar phantom).

  4. Assessment of regional systolic and diastolic myocardial function using tissue Doppler and strain imaging in dogs with dilated cardiomyopathy.

    Science.gov (United States)

    Chetboul, Valérie; Gouni, Vassiliki; Sampedrano, Carolina Carlos; Tissier, Renaud; Serres, François; Pouchelon, Jean-Louis

    2007-01-01

    Tissue Doppler Imaging (TDI) or strain (St) imaging could provide sensitive indices for early detection and treatment follow-up of canine dilated cardiomyopathy (DCM). Analysis of TDI and St features in dogs with overt DCM is a prerequisite before using these new criteria in prospective screenings of predisposed families or in clinical trials. Radial and longitudinal right and left myocardial motion, assessed by TDI and St variables, is altered in dogs with DCM. Case records for 26 dogs; 14 with DCM and 12 healthy controls of comparable age and weight were reviewed. A retrospective analysis was conducted of conventional echocardiography, 2-dimensional color TDI, and St imaging data. The DCM group was characterized by decreases in radial and longitudinal systolic velocity gradients of the left ventricular free wall (LVFW), radial and longitudinal absolute values of peak systolic St of the LVFW, and longitudinal systolic right ventricular (RV) velocities (all P canine DCM.

  5. Rhizospheric bacterial strain Brevibacterium casei MH8a colonizes plant tissues and enhances Cd, Zn, Cu phytoextraction by white mustard

    Directory of Open Access Journals (Sweden)

    Tomasz ePłociniczak

    2016-02-01

    Full Text Available Environmental pollution by heavy metals has become a serious problem in the world. Phytoextraction, which is one of the plant-based technologies, has attracted the most attention for the bioremediation of soils polluted with these contaminants.The aim of this study was to determine whether the multiple-tolerant bacterium, Brevibacterium casei MH8a isolated from the heavy metal-contaminated rhizosphere soil of Sinapis alba L., is able to promote plant growth and enhance Cd, Zn and Cu uptake by white mustard under laboratory conditions. Additionally, the ability of the rifampicin-resistant spontaneous mutant of MH8a to colonize plant tissues and its mechanisms of plant growth promotion were also examined. In order to assess the ecological consequences of bioaugmentation on autochthonous bacteria, the phospholipid fatty acid (PLFA analysis was used. The MH8a strain exhibited the ability to produce ammonia, 1-amino-cyclopropane-1-carboxylic acid deaminase, indole 3-acetic acid and HCN but was not able to solubilize inorganic phosphate and produce siderophores. Introduction of MH8a into soil significantly increased S. alba biomass and the accumulation of Cd (208%, Zn (86% and Cu (39% in plant shoots in comparison with those grown in non-inoculated soil. Introduced into the soil, MH8a was able to enter the plant and was found in the roots and leaves of inoculated plants thus indicating its endophytic features. PLFA analysis revealed that the MH8a that was introduced into soil had a temporary influence on the structure of the autochthonous bacterial communities. The plant growth-promoting features of the MH8a strain and its ability to enhance the metal uptake by white mustard and its long-term survival in soil as well as its temporary impact on autochthonous microorganisms make the strain a suitable candidate for the promotion of plant growth and the efficiency of phytoextraction.

  6. Rhizospheric Bacterial Strain Brevibacterium casei MH8a Colonizes Plant Tissues and Enhances Cd, Zn, Cu Phytoextraction by White Mustard.

    Science.gov (United States)

    Płociniczak, Tomasz; Sinkkonen, Aki; Romantschuk, Martin; Sułowicz, Sławomir; Piotrowska-Seget, Zofia

    2016-01-01

    Environmental pollution by heavy metals has become a serious problem in the world. Phytoextraction, which is one of the plant-based technologies, has attracted the most attention for the bioremediation of soils polluted with these contaminants. The aim of this study was to determine whether the multiple-tolerant bacterium, Brevibacterium casei MH8a isolated from the heavy metal-contaminated rhizosphere soil of Sinapis alba L., is able to promote plant growth and enhance Cd, Zn, and Cu uptake by white mustard under laboratory conditions. Additionally, the ability of the rifampicin-resistant spontaneous mutant of MH8a to colonize plant tissues and its mechanisms of plant growth promotion were also examined. In order to assess the ecological consequences of bioaugmentation on autochthonous bacteria, the phospholipid fatty acid (PLFA) analysis was used. The MH8a strain exhibited the ability to produce ammonia, 1-amino-cyclopropane-1-carboxylic acid deaminase, indole 3-acetic acid and HCN but was not able to solubilize inorganic phosphate and produce siderophores. Introduction of MH8a into soil significantly increased S. alba biomass and the accumulation of Cd (208%), Zn (86%), and Cu (39%) in plant shoots in comparison with those grown in non-inoculated soil. Introduced into the soil, MH8a was able to enter the plant and was found in the roots and leaves of inoculated plants thus indicating its endophytic features. PLFA analysis revealed that the MH8a that was introduced into soil had a temporary influence on the structure of the autochthonous bacterial communities. The plant growth-promoting features of the MH8a strain and its ability to enhance the metal uptake by white mustard and its long-term survival in soil as well as its temporary impact on autochthonous microorganisms make the strain a suitable candidate for the promotion of plant growth and the efficiency of phytoextraction.

  7. Evaluation of PCR methods for detection of Brucella strains from culture and tissues.

    Science.gov (United States)

    Çiftci, Alper; İça, Tuba; Savaşan, Serap; Sareyyüpoğlu, Barış; Akan, Mehmet; Diker, Kadir Serdar

    2017-04-01

    The genus Brucella causes significant economic losses due to infertility, abortion, stillbirth or weak calves, and neonatal mortality in livestock. Brucellosis is still a zoonosis of public health importance worldwide. The study was aimed to optimize and evaluate PCR assays used for the diagnosis of Brucella infections. For this aim, several primers and PCR protocols were performed and compared with Brucella cultures and biological material inoculated with Brucella. In PCR assays, genus- or species-specific oligonucleotide primers derived from 16S rRNA sequences (F4/R2, Ba148/928, IS711, BruP6-P7) and OMPs (JPF/JPR, 31ter/sd) of Brucella were used. All primers except for BruP6-P7 detected the DNA from reference Brucella strains and field isolates. In spiked blood, milk, and semen samples, F4-R2 primer-oriented PCR assays detected minimal numbers of Brucella. In spiked serum and fetal stomach content, Ba148/928 primer-oriented PCR assays detected minimal numbers of Brucella. Field samples collected from sheep and cattle were examined by bacteriological methods and optimized PCR assays. Overall, sensitivity of PCR assays was found superior to conventional bacteriological isolation. Brucella DNA was detected in 35.1, 1.1, 24.8, 5.0, and 8.0% of aborted fetus, blood, milk, semen, and serum samples by PCR assays, respectively. In conclusion, PCR assay in optimized conditions was found to be valuable in sensitive and specific detection of Brucella infections of animals.

  8. Mechanical Stimulation of Adipose-Derived Stem Cells for Functional Tissue Engineering of the Musculoskeletal System via Cyclic Hydrostatic Pressure, Simulated Microgravity, and Cyclic Tensile Strain.

    Science.gov (United States)

    Nordberg, Rachel C; Bodle, Josie C; Loboa, Elizabeth G

    2018-01-01

    It is critical that human adipose stem cell (hASC) tissue-engineering therapies possess appropriate mechanical properties in order to restore function of the load bearing tissues of the musculoskeletal system. In an effort to elucidate the hASC response to mechanical stimulation and develop mechanically robust tissue engineered constructs, recent research has utilized a variety of mechanical loading paradigms including cyclic tensile strain, cyclic hydrostatic pressure, and mechanical unloading in simulated microgravity. This chapter describes methods for applying these mechanical stimuli to hASC to direct differentiation for functional tissue engineering of the musculoskeletal system.

  9. Brain tissue strains vary with head impact location: A possible explanation for increased concussion risk in struck versus striking football players.

    Science.gov (United States)

    Elkin, Benjamin S; Gabler, Lee F; Panzer, Matthew B; Siegmund, Gunter P

    2018-03-29

    On-field football helmet impacts over a large range of severities have caused concussions in some players but not in other players. One possible explanation for this variability is the struck player's helmet impact location. We examined the effect of impact location on regional brain tissue strain when input energy was held constant. Laboratory impacts were performed at 12 locations distributed over the helmet and the resulting head kinematics were simulated in two finite element models of the brain: the Simulated Injury Monitor and the Global Human Body Model Consortium brain model. Peak kinematics, injury metrics and brain strain varied significantly with impact location. Differences in impact location explained 33 to 37% of the total variance in brain strain for the whole brain and cerebrum, considerably more than the variance explained by impact location for the peak resultant head kinematics (8 to 23%) and slightly more than half of the variance explained by the difference in closing speed (57 to 61%). Both finite element models generated similar strain results, with minor variations for impacts that generated multi-axial rotations, larger variations in brainstem strains for some impact locations and a small bias for the cerebellum. Based on this experimental and computational simulation study, impact location on the football helmet has a large effect on regional brain tissue strain. We also found that the lowest strains consistently occurred in impacts to the crown and forehead, helmet locations commonly associated with the striking player. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Tissue

    Directory of Open Access Journals (Sweden)

    David Morrissey

    2012-01-01

    Full Text Available Purpose. In vivo gene therapy directed at tissues of mesenchymal origin could potentially augment healing. We aimed to assess the duration and magnitude of transene expression in vivo in mice and ex vivo in human tissues. Methods. Using bioluminescence imaging, plasmid and adenoviral vector-based transgene expression in murine quadriceps in vivo was examined. Temporal control was assessed using a doxycycline-inducible system. An ex vivo model was developed and optimised using murine tissue, and applied in ex vivo human tissue. Results. In vivo plasmid-based transgene expression did not silence in murine muscle, unlike in liver. Although maximum luciferase expression was higher in muscle with adenoviral delivery compared with plasmid, expression reduced over time. The inducible promoter cassette successfully regulated gene expression with maximum levels a factor of 11 greater than baseline. Expression was re-induced to a similar level on a temporal basis. Luciferase expression was readily detected ex vivo in human muscle and tendon. Conclusions. Plasmid constructs resulted in long-term in vivo gene expression in skeletal muscle, in a controllable fashion utilising an inducible promoter in combination with oral agents. Successful plasmid gene transfection in human ex vivo mesenchymal tissue was demonstrated for the first time.

  11. Acute, massive pulmonary embolism with right heart strain and hypoxia requiring emergent tissue plasminogen activator (TPA infusion

    Directory of Open Access Journals (Sweden)

    Jonathan Patane

    2017-04-01

    Full Text Available History of present illness: A 63-year-old male presented to the emergency department with shortness of breath. He had a history of prostate cancer and two previous pulmonary embolisms, but was not currently on blood thinners. He had no associated chest pain at the time of presentation, but endorsed hemoptysis. Vital signs were significant for a heart rate of 88, blood pressure 145/89, oxygen saturation in the mid-70’s on room air which increased to mid-80’s on 15L facemask. His exam was significant for clear lung sounds bilaterally. He immediately underwent chest x-ray which showed no acute abnormalities. A bedside ultrasound was performed which showed evidence of right ventricular and atrial dilation, consistent with right heart strain. Given that the patient’s oxygen saturations improved to 88% on 15L facemask, the patient was felt to be stable enough for CT angiography. Significant findings: CT angiogram showed multiple large acute pulmonary emboli, most significantly in the distal right main pulmonary artery (image 1 and 2. Additional pulmonary emboli were noted in the bilateral lobar, segmental, and subsegmental levels of all lobes. There was a peripheral, wedge-shaped consolidation surrounded by groundglass changes in the posterolateral basal right lower lobe that was consistent with a small lung infarction (image 3. Discussion: The patient underwent in the Emergency Department a tissue plasminogen activator (TPA infusion of alteplase 100 mg over 2 hours for his massive acute pulmonary embolisms. Throughout his TPA infusion his oxygen saturations became improved to mid-90’s and his shortness of breath symptoms began improving. His troponin returned at 0.15 ng/mL, suggesting right heart strain. He was admitted to the ICU for continued monitoring and treatment. An acute, massive pulmonary embolism is described as having more than 50% occlusion of pulmonary blood flow.1 The main causes of hypoxia includes ventilation

  12. Hamp1 mRNA and plasma hepcidin levels are influenced by sex and strain but do not predict tissue iron levels in inbred mice.

    Science.gov (United States)

    McLachlan, Stela; Page, Kathryn E; Lee, Seung-Min; Loguinov, Alex; Valore, Erika; Hui, Simon T; Jung, Grace; Zhou, Jie; Lusis, Aldons J; Fuqua, Brie; Ganz, Tomas; Nemeth, Elizabeta; Vulpe, Chris D

    2017-11-01

    Iron homeostasis is tightly regulated, and the peptide hormone hepcidin is considered to be a principal regulator of iron metabolism. Previous studies in a limited number of mouse strains found equivocal sex- and strain-dependent differences in mRNA and serum levels of hepcidin and reported conflicting data on the relationship between hepcidin ( Hamp1 ) mRNA levels and iron status. Our aim was to clarify the relationships between strain, sex, and hepcidin expression by examining multiple tissues and the effects of different dietary conditions in multiple inbred strains. Two studies were done: first, Hamp1 mRNA, liver iron, and plasma diferric transferrin levels were measured in 14 inbred strains on a control diet; and second, Hamp1 mRNA and plasma hepcidin levels in both sexes and iron levels in the heart, kidneys, liver, pancreas, and spleen in males were measured in nine inbred/recombinant inbred strains raised on an iron-sufficient or high-iron diet. Both sex and strain have a significant effect on both hepcidin mRNA (primarily a sex effect) and plasma hepcidin levels (primarily a strain effect). However, liver iron and diferric transferrin levels are not predictors of Hamp1 mRNA levels in mice fed iron-sufficient or high-iron diets, nor are the Hamp1 mRNA and plasma hepcidin levels good predictors of tissue iron levels, at least in males. We also measured plasma erythroferrone, performed RNA-sequencing analysis of liver samples from six inbred strains fed the iron-sufficient, low-iron, or high-iron diets, and explored differences in gene expression between the strains with the highest and lowest hepcidin levels. NEW & NOTEWORTHY Both sex and strain have a significant effect on both hepcidin mRNA (primarily a sex effect) and plasma hepcidin levels (primarily a strain effect). Liver iron and diferric transferrin levels are not predictors of Hamp1 mRNA levels in mice, nor are the Hamp1 mRNA and plasma hepcidin levels good predictors of tissue iron levels, at least

  13. The mechanical heterogeneity of the hard callus influences local tissue strains during bone healing: a finite element study based on sheep experiments.

    Science.gov (United States)

    Vetter, A; Liu, Y; Witt, F; Manjubala, I; Sander, O; Epari, D R; Fratzl, P; Duda, G N; Weinkamer, R

    2011-02-03

    During secondary fracture healing, various tissue types including new bone are formed. The local mechanical strains play an important role in tissue proliferation and differentiation. To further our mechanobiological understanding of fracture healing, a precise assessment of local strains is mandatory. Until now, static analyses using Finite Elements (FE) have assumed homogenous material properties. With the recent quantification of both the spatial tissue patterns (Vetter et al., 2010) and the development of elastic modulus of newly formed bone during healing (Manjubala et al., 2009), it is now possible to incorporate this heterogeneity. Therefore, the aim of this study is to investigate the effect of this heterogeneity on the strain patterns at six successive healing stages. The input data of the present work stemmed from a comprehensive cross-sectional study of sheep with a tibial osteotomy (Epari et al., 2006). In our FE model, each element containing bone was described by a bulk elastic modulus, which depended on both the local area fraction and the local elastic modulus of the bone material. The obtained strains were compared with the results of hypothetical FE models assuming homogeneous material properties. The differences in the spatial distributions of the strains between the heterogeneous and homogeneous FE models were interpreted using a current mechanobiological theory (Isakson et al., 2006). This interpretation showed that considering the heterogeneity of the hard callus is most important at the intermediate stages of healing, when cartilage transforms to bone via endochondral ossification. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Evaluation of left ventricular function by tissue Doppler and speckle-derived strain rate echocardiography after percutaneous ductus closure.

    Science.gov (United States)

    Amoogzar, Hamid; Shakiba, Ali Mohammad; Derakhshan, Dorna; Ajami, Gholamhossein; Cheriki, Sirous; Borzouee, Mohammad; Edraki, Mohammad Reza; Mehdizadegan, Nima

    2015-01-01

    The aim of this study was to evaluate the left ventricular systolic and diastolic function before and after transcatheter percutaneous patent ductus arteriosus (PDA) closure. 21 children (age >6 months old) diagnosed with hemodynamically significant PDA underwent percutaneous PDA closure. Conventional, Doppler and tissue Doppler imaging and speckled-derived strain rate echocardiography were done at pre-closure, 1 day (early) and 1 month (late) post-closure. Mean age of the patients (female/male: 1.3) was 17.54 ± 24.7 months with the mean PDA diameter of 3.6 ± 0.8 mm. Systolic measures (ejection fraction, shortening fraction) reduced significantly early after PDA closure (P closure status. Early and late diastolic flow velocities of mitral (E M and A M) reduced considerably in early and late post-closure time (P closure. After 1 month, E'M increased considerably. (P = 0.01) but E'M/A'M had an insignificant rise (P > 0.05). E M/E'M ratio did not change in early post-closure but it had a considerable reduction in the subsequent month compared with the pre- and early post-closure (P closure (P closure causes a significant decrease in left ventricular performance early after PDA closure which recovers completely within 1 month. Also PDA size can affect post-closure left ventricular function.

  15. Transrectal real-time tissue elastography targeted biopsy coupled with peak strain index improves the detection of clinically important prostate cancer.

    Science.gov (United States)

    Ma, Qi; Yang, Dong-Rong; Xue, Bo-Xin; Wang, Cheng; Chen, Han-Bin; Dong, Yun; Wang, Cai-Shan; Shan, Yu-Xi

    2017-07-01

    The focus of the present study was to evaluate transrectal real-time tissue elastography (RTE)-targeted two-core biopsy coupled with peak strain index for the detection of prostate cancer (PCa) and to compare this method with 10-core systematic biopsy. A total of 141 patients were enrolled for evaluation. The diagnostic value of peak strain index was assessed using a receiver operating characteristic curve. The cancer detection rates of the two approaches and corresponding positive cores and Gleason score were compared. The cancer detection rate per core in the RTE-targeted biopsy (44%) was higher compared with that in systematic biopsy (30%). The peak strain index value of PCa was higher compared with that of the benign lesion. PCa was detected with the highest sensitivity (87.5%) and specificity (85.5%) using the threshold value of a peak strain index of ≥5.97 with an area under the curve value of 0.95. When the Gleason score was ≥7, RTE-targeted biopsy coupled with peak strain index detected 95.6% of PCa cases, but 84.4% were detected using systematic biopsy. Peak strain index as a quantitative parameter may improve the differentiation of PCa from benign lesions in the prostate peripheral zone. Transrectal RTE-targeted biopsy coupled with peak strain index may enhance the detection of clinically significant PCa, particularly when combined with systematic biopsy.

  16. Myocardial left ventricular dysfunction in patients with systemic lupus erythematosus: new insights from tissue Doppler and strain imaging.

    Science.gov (United States)

    Buss, Sebastian J; Wolf, David; Korosoglou, Grigorios; Max, Regina; Weiss, Celine S; Fischer, Christian; Schellberg, Dieter; Zugck, Christian; Kuecherer, Helmut F; Lorenz, Hanns-Martin; Katus, Hugo A; Hardt, Stefan E; Hansen, Alexander

    2010-01-01

    Systemic lupus erythematosus (SLE) is associated with high cardiovascular morbidity and mortality. Cardiovascular involvement is frequently underestimated by routine imaging techniques. Our aim was to determine if new echocardiographic imaging modalities like tissue Doppler (TDI), strain rate (SRR), and strain (SRI) imaging detect abnormalities in left ventricular (LV) function in asymptomatic patients with SLE. Sixty-seven young patients with SLE (mean age 42 +/- 10 yrs) without typical symptoms or signs of heart failure or angina, and a matched healthy control group (n = 40), underwent standard transthoracic echocardiography, TDI, SRR, and SRI imaging of the LV as well as assessment of disease characteristics. Despite findings within the normal range on routine standard 2-dimensional echocardiography, SLE was associated with significantly impaired systolic and diastolic myocardial velocities of the LV measured by TDI [mean global TDI: systolic (s): 2.9 +/- 0.9 vs 3.9 +/- 0.7 cm/s, p < 0.05; early (e): 4.3 +/- 1.5 vs 6.3 +/- 1.3 cm/s, p < 0.05; late (a): 2.9 +/- 0.8 vs 3.4 +/- 0.8 cm/s, p < 0.05; values +/- SD); SRR (s: -0.8 +/- 0.1 vs -1.1 +/- 0.1 s(-1); e: 1.1 +/- 0.2 vs 1.6 +/- 0.3 s(-1); a: 0.7 +/- 0.1 vs 1.0 +/- 0.2 s(-1); all p < 0.05); and SR (-15.11 +/- 2.2% vs -19.7 +/- 1.9%; p < 0.05) compared to the control group. Further, elevated disease activity, measured with the ECLAM and the SLEDAI score, resulted in significantly lower values for LV longitudinal function measured by SRR and SR, but not by TDI. SLE is associated with a significant impairment of systolic and diastolic LV longitudinal function in patients without cardiac symptoms. New imaging modalities provide earlier insight into cardiovascular involvement in SLE and seem to be superior to standard echocardiography to detect subclinical myocardial disease.

  17. Characterization of inter-tissue and inter-strain variability of TCE glutathione conjugation metabolites DCVG, DCVC, and NAcDCVC in the mouse.

    Science.gov (United States)

    Luo, Yu-Syuan; Furuya, Shinji; Chiu, Weihsueh; Rusyn, Ivan

    2018-01-01

    Trichloroethylene (TCE) is a ubiquitous environmental toxicant that is a liver and kidney carcinogen. Conjugation of TCE with glutathione (GSH) leads to formation of nepthrotoxic and mutagenic metabolites postulated to be critical for kidney cancerdevelopment; however, relatively little is known regarding their tissue levels as previous analytical methods for their detection lacked sensitivity. Here, an LC-MS/MS-based method for simultaneous detection of S-(1,2-dichlorovinyl)-glutathione (DCVG), S-(1,2-dichlorovinyl)-L-cysteine (DCVC), and N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine (NAcDCVC) in multiple mouse tissues was developed. This analytical method is rapid, sensitive (limits of detection (LOD) 3-30 fmol across metabolites and tissues), and robust to quantify all three metabolites in liver, kidneys, and serum. The method was used to characterize inter-tissue and inter-strain variability in formation of conjugative metabolites of TCE. Single oral dose of TCE (24, 240 or 800 mg/kg) was administered to male mice from 20 inbred strains of Collaborative Cross. Inter-strain variability in the levels of DCVG, DCVC, and NAcDCVC (GSD = 1.6-2.9) was observed. Whereas NAcDCVC was distributed equally among analyzed tissues, highest levels of DCVG were detected in liver and DCVC in kidneys. Evidence indicated that inter-strain variability in conjugative metabolite formation of TCE might affect susceptibility to adverse health effects and that this method might aid in filling data gaps in human health assessment of TCE.

  18. Tissue tropisms, infection kinetics, histologic lesions, and antibody response of the MR766 strain of Zika virus in a murine model.

    Science.gov (United States)

    Kawiecki, Anna B; Mayton, E Handly; Dutuze, M Fausta; Goupil, Brad A; Langohr, Ingeborg M; Del Piero, Fabio; Christofferson, Rebecca C

    2017-04-18

    The appearance of severe Zika virus (ZIKV) disease in the most recent outbreak has prompted researchers to respond through the development of tools to quickly characterize transmission and pathology. We describe here another such tool, a mouse model of ZIKV infection and pathogenesis using the MR766 strain of virus that adds to the growing body of knowledge regarding ZIKV kinetics in small animal models. We infected mice with the MR766 strain of ZIKV to determine infection kinetics via serum viremia. We further evaluated infection-induced lesions via histopathology and visualized viral antigen via immunohistochemical labeling. We also investigated the antibody response of recovered animals to both the MR766 and a strain from the current outbreak (PRVABC59). We demonstrate that the IRF3/7 DKO mouse is a susceptible, mostly non-lethal model well suited for the study of infection kinetics, pathological progression, and antibody response. Infected mice presented lesions in tissues that have been associated with ZIKV infection in the human population, such as the eyes, male gonads, and central nervous system. In addition, we demonstrate that infection with the MR766 strain produces cross-neutralizing antibodies to the PRVABC59 strain of the Asian lineage. This model provides an additional tool for future studies into the transmission routes of ZIKV, as well as for the development of antivirals and other therapeutics, and should be included in the growing list of available tools for investigations of ZIKV infection and pathogenesis.

  19. Comparative Analysis of the Relationship between Trichloroethylene Metabolism and Tissue-Specific Toxicity among Inbred Mouse Strains: Kidney Effects

    Science.gov (United States)

    Yoo, Hong Sik; Bradford, Blair U.; Kosyk, Oksana; Uehara, Takeki; Shymonyak, Svitlana; Collins, Leonard B.; Bodnar, Wanda M.; Ball, Louise M.; Gold, Avram; Rusyn, Ivan

    2014-01-01

    Trichloroethylene (TCE) is a well-known environmental and occupational toxicant that is classified as carcinogenic to humans based on the epidemiological evidence of an association with higher risk of renal cell carcinoma. A number of scientific issues critical for assessing human health risks from TCE remain unresolved, such as the amount of kidney-toxic glutathione conjugation metabolites formed, inter-species and -individual differences, and the mode of action for kidney carcinogenicity. We hypothesized that TCE metabolite levels in the kidney are associated with kidney-specific toxicity. Oral dosing with TCE was conducted in sub-acute (600 mg/kg/d; 5 days; 7 inbred mouse strains) and sub-chronic (100 or 400 mg/kg/d; 1, 2, or 4 weeks; 2 inbred mouse strains) designs. We evaluated the quantitative relationship between strain-, dose-, and time-dependent formation of TCE metabolites from cytochrome P450-mediated oxidation [trichloroacetic acid (TCA), dichloroacetic acid (DCA), and trichloroethanol] and glutathione conjugation [S-(1,2-dichlorovinyl)-L-cysteine and S-(1,2-dichlorovinyl)glutathione], and various kidney toxicity phenotypes. In sub-acute study, we observed inter-strain differences in TCE metabolite levels in the kidney. In addition, we found that in several strains kidney-specific effects of TCE included induction of peroxisome proliferator-marker genes Cyp4a10 and Acox1, increased cell proliferation, and expression of KIM-1, a marker of tubular damage and regeneration. In sub-chronic study, peroxisome proliferator-marker gene induction and kidney toxicity diminished while cell proliferative response was elevated in a dose-dependent manner in NZW/LacJ, but not C57BL/6J mice. Overall, we show that TCE metabolite levels in the kidney are associated with kidney-specific toxicity and that these effects are strain-dependent. PMID:25424545

  20. Phytohormone Involvement in the Ustilago maydis- Zea mays Pathosystem: Relationships between Abscisic Acid and Cytokinin Levels and Strain Virulence in Infected Cob Tissue.

    Directory of Open Access Journals (Sweden)

    Erin N Morrison

    Full Text Available Ustilago maydis is the causative agent of common smut of corn. Early studies noted its ability to synthesize phytohormones and, more recently these growth promoting substances were confirmed as cytokinins (CKs. Cytokinins comprise a group of phytohormones commonly associated with actively dividing tissues. Lab analyses identified variation in virulence between U. maydis dikaryon and solopathogen infections of corn cob tissue. Samples from infected cob tissue were taken at sequential time points post infection and biochemical profiling was performed using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS. This hormone profiling revealed that there were altered levels of ABA and major CKs, with a marked reduction in CK glucosides, increases in methylthiol CKs and a particularly dramatic increase in cisZ CK forms, in U. maydis infected tissue. These changes were more pronounced in the more virulent dikaryon relative to the solopathogenic strain suggesting a role for cytokinins in moderating virulence during biotrophic infection. These findings highlight the fact that U. maydis does not simply mimic a fertilized seed but instead reprograms the host tissue. Results underscore the suitability of the Ustilago maydis- Zea mays model as a basis for investigating the control of phytohormone dynamics during biotrophic infection of plants.

  1. Tissue expression of Toll-like receptors 2, 3, 4 and 7 in swine in response to the Shimen strain of classical swine fever virus

    Science.gov (United States)

    Cao, Zhi; Zheng, Minping; Lv, Huifang; Guo, Kangkang; Zhang, Yanming

    2018-01-01

    The Toll-like receptors (TLRs) of the innate immune system provide the host with the ability to detect and respond to viral infections. The present study aimed to investigate the mRNA and protein expression levels of TLR2, 3, 4 and 7 in porcine tissues upon infection with the highly virulent Shimen strain of classical swine fever virus (CSFV). Reverse transcription-quantitative polymerase chain reaction was used to detect the mRNA expression levels of CSFV and TLR, whereas western blotting was used to detect the expression levels of TLR proteins. In addition, tissues underwent histological examination and immunohistochemistry to reveal the histopathological alterations associated with highly virulent CSFV infection and to detect TLR antigens. Furthermore, porcine monocyte-derived macrophages (pMDMs) were prestimulated with peptidoglycan from Staphylococcus aureus (PGN-SA), polyinosinic-polycytidylic acid [poly (I:C)], lipopolysaccharide from Escherichia coli 055:B5 (LPS-B5) or imiquimod (R837) in order to analyze the association between TLR expression and CSFV replication. Following stimulation for 12 h (with TLR-specific ligands), cells were infected with CSFV Shimen strain. The results revealed that the expression levels of TLR2 and TLR4 were increased in the lung and kidney, but were decreased in the spleen and lymph nodes in response to CSFV. TLR3 was strongly expressed in the heart and slightly upregulated in the spleen in response to CSFV Shimen strain infection, and TLR7 was increased in all examined tissues in the presence of CSFV. Furthermore, R837 and LPS-B5 exerted inhibitory effects on CSFV replication in pMDMs, whereas PGN-SA and poly(I:C) had no significant effect. These findings highlight the potential role of TLR expression in the context of CSFV infection. PMID:29568891

  2. Release of tensile strain on engineered human tendon tissue disturbs cell adhesions, changes matrix architecture, and induces an inflammatory phenotype

    DEFF Research Database (Denmark)

    Bayer, Monika L; Schjerling, Peter; Herchenhan, Andreas

    2014-01-01

    Mechanical loading of tendon cells results in an upregulation of mechanotransduction signaling pathways, cell-matrix adhesion and collagen synthesis, but whether unloading removes these responses is unclear. We investigated the response to tension release, with regard to matrix proteins, pro......-inflammatory mediators and tendon phenotypic specific molecules, in an in vitro model where tendon-like tissue was engineered from human tendon cells. Tissue sampling was performed 1, 2, 4 and 6 days after surgical de-tensioning of the tendon construct. When tensile stimulus was removed, integrin type collagen receptors...... were upregulated. Stimulation with the cytokine TGF-β1 had distinct effects on some tendon-related genes in both tensioned and de-tensioned tissue. These findings indicate an important role of mechanical loading for cellular and matrix responses in tendon, including that loss of tension leads...

  3. Comparative Analysis of the Relationship between Trichloroethylene Metabolism and Tissue-Specific Toxicity among Inbred Mouse Strains: Liver Effects

    Science.gov (United States)

    Yoo, Hong Sik; Bradford, Blair U.; Kosyk, Oksana; Shymonyak, Svitlana; Uehara, Takeki; Collins, Leonard B.; Bodnar, Wanda M.; Ball, Louise M.; Gold, Avram; Rusyn, Ivan

    2014-01-01

    Trichloroethylene (TCE) is a widely used organic solvent. Although TCE is classified as carcinogenic to humans, substantial gaps remain in our understanding of inter-individual variability in TCE metabolism and toxicity, especially in the liver. We tested a hypothesis that amounts of oxidative metabolites of TCE in mouse liver are associated with liver-specific toxicity. Oral dosing with TCE was conducted in sub-acute (600 mg/kg/d; 5 days; 7 inbred mouse strains) and sub-chronic (100 or 400 mg/kg/d; 1, 2, or 4 weeks; 2 inbred mouse strains) designs. We evaluated the quantitative relationship between strain-, dose-, and time-dependent formation of TCE metabolites from cytochrome P450-mediated oxidation [trichloroacetic acid (TCA), dichloroacetic acid (DCA), and trichloroethanol] and glutathione conjugation [S-(1,2-dichlorovinyl)-L-cysteine and S-(1,2-dichlorovinyl)glutathione] in serum and liver, and various liver toxicity phenotypes. In sub-acute study, inter-strain variability in TCE metabolite amounts was observed in serum and liver. No induction of Cyp2e1 protein levels in liver was detected. Serum and liver levels of TCA and DCA were correlated with increased transcription of peroxisome proliferator-marker genes Cyp4a10 and Acox1, but not with degree of induction in hepatocellular proliferation. In sub-chronic study, serum and liver levels of oxidative metabolites gradually decreased over time despite continuous dosing. Liver protein levels of Cyp2e1, Adh and Aldh2 were unaffected by treatment with TCE. While the magnitude of induction of peroxisome proliferator-marker genes also declined, hepatocellular proliferation increased. This study offers a unique opportunity to provide a scientific data-driven rationale for some of the major assumptions in human health assessment of TCE. PMID:25424544

  4. Variability of antibiotic susceptibility and toxin production of Staphylococcus aureus strains isolated from skin, soft tissue, and bone related infections

    NARCIS (Netherlands)

    Sina, Haziz; Ahoyo, Theodora A.; Moussaoui, Wardi; Keller, Daniel; Bankole, Honore S.; Barogui, Yves; Stienstra, Ymkje; Kotchoni, Simeon O.; Prevost, Gilles; Baba-Moussa, Lamine

    2013-01-01

    Background: Staphylococcus aureus is an opportunistic commensal bacterium that mostly colonizes the skin and soft tissues. The pathogenicity of S. aureus is due to both its ability to resist antibiotics, and the production of toxins. Here, we characterize a group of genes responsible for toxin

  5. Molecular cloning of a Bangladeshi strain of very virulent infectious bursal disease virus of chickens and its adaptation in tissue culture by site-directed mutagenesis

    International Nuclear Information System (INIS)

    Islam, M.R.; Raue, R.; Mueller, H.

    2005-01-01

    Full-length cDNA of both genome segments of a Bangladeshi strain of very virulent infectious bursal disease virus (BD 3/99) were cloned in plasmid vectors along with the T7 promoter tagged to the 5'-ends. Mutations were introduced in the cloned cDNA to bring about two amino acid exchanges (Q253H and A284T) in the capsid protein VP2. Transfection of primary chicken embryo fibroblast cells with RNA transcribed in vitro from the full-length cDNA resulted in the formation of mutant infectious virus particles that grow in tissue culture. The pathogenicity of this molecularly-cloned, tissue-culture- adapted virus (BD-3tc) was tested in commercial chickens. The parental wild-type strain, BD 3/99, was included for comparison. The subclinical course of the disease and delayed bursal atrophy in BD-3tc-inoculated birds suggested that these amino acid substitutions made BD-3tc partially attenuated. (author)

  6. Immunobiotic Lactobacillus strains augment NLRP3 expression in newborn and adult porcine gut-associated lymphoid tissues.

    Science.gov (United States)

    Tohno, Masanori; Shimosato, Takeshi; Aso, Hisashi; Kitazawa, Haruki

    2011-12-15

    We isolated cDNA encoding porcine nucleotide-binding domain-like receptor family, pryin domain containing 3 (NLRP3) from Peyer's patches. The complete nucleotide open reading frame of porcine NLRP3 contains 3108-bp encoding a deduced polypeptide of 1036-amino acid residues. The porcine NLRP3 amino acid sequence is more similar to the longest isoform of human than the mouse counterpart. The predicted amino acid sequence of porcine NLRP3 presented nine C-terminal leucine-rich repeat domains. In newborn swine, the expression of NLRP3 was detected at higher levels in spleen and mesenteric lymph nodes, while lower levels were observed in intestinal tissues. In adult swine, NLRP3 was strongly expressed in Peyer's patches and the mesenteric lymph nodes, and the expression level in the lower intestinal tissues was comparable to that in spleen. Toll-like receptor and nucleotide-binding domain ligands, as well as Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus gasseri, enhanced NLRP3 expression in gut-associated lymphoid tissues (GALT) of newborn and adult swine. Our results should aid in understanding the intestinal immunoregulatory mechanisms underlying NLRP3 activation and the priming ability of immunobiotic lactic acid bacteria in porcine GALT. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Endogenous IL-33 is highly expressed in mouse epithelial barrier tissues, lymphoid organs, brain, embryos, and inflamed tissues: in situ analysis using a novel Il-33-LacZ gene trap reporter strain.

    Science.gov (United States)

    Pichery, Mélanie; Mirey, Emilie; Mercier, Pascale; Lefrancais, Emma; Dujardin, Arnaud; Ortega, Nathalie; Girard, Jean-Philippe

    2012-04-01

    IL-33 (previously known as NF from high endothelial venules) is an IL-1 family cytokine that signals through the ST2 receptor and drives cytokine production in mast cells, basophils, eosinophils, invariant NKT and NK cells, Th2 lymphocytes, and type 2 innate immune cells (natural helper cells, nuocytes, and innate helper 2 cells). Little is known about endogenous IL-33; for instance, the cellular sources of IL-33 in mouse tissues have not yet been defined. In this study, we generated an Il-33-LacZ gene trap reporter strain (Il-33(Gt/Gt)) and used this novel tool to analyze expression of endogenous IL-33 in vivo. We found that the Il-33 promoter exhibits constitutive activity in mouse lymphoid organs, epithelial barrier tissues, brain, and embryos. Immunostaining with anti-IL-33 Abs, using Il-33(Gt/Gt) (Il-33-deficient) mice as control, revealed that endogenous IL-33 protein is highly expressed in mouse epithelial barrier tissues, including stratified squamous epithelia from vagina and skin, as well as cuboidal epithelium from lung, stomach, and salivary gland. Constitutive expression of IL-33 was not detected in blood vessels, revealing the existence of species-specific differences between humans and mice. Importantly, IL-33 protein was always localized in the nucleus of producing cells with no evidence for cytoplasmic localization. Finally, strong expression of the Il-33-LacZ reporter was also observed in inflamed tissues, in the liver during LPS-induced endotoxin shock, and in the lung alveoli during papain-induced allergic airway inflammation. Together, our findings support the possibility that IL-33 may function as a nuclear alarmin to alert the innate immune system after injury or infection in epithelial barrier tissues.

  8. Mimicking mechanical response of natural tissues. Strain hardening induced by transient reticulation in lactose-modified chitosan (chitlac).

    Science.gov (United States)

    Cok, Michela; Sacco, Pasquale; Porrelli, Davide; Travan, Andrea; Borgogna, Massimiliano; Marsich, Eleonora; Paoletti, Sergio; Donati, Ivan

    2018-01-01

    The effect of transient cross-links has been explored on a lactose-modified chitosan, which previously had shown interesting biological features. The presence of galactose side chains and of the polyol spacer resulted particularly appealing for the reticulation by borate ions. The interaction between chitlac and borax was investigated by means of 11 B NMR while rheology pointed to a marked non-linear behavior depending on the amount of borax added to the system. The presence of limited amount of cross-linking ion led to dilatant behavior when the steady flow curve was measured. In addition, strain stiffening was noticed on elastic response upon exceeding a critical stress, indicating a transient nature in the formation of the cross-links. The non-linear response of chitlac in the presence of borax compared surprisingly well with the one showed by proteins composing the natural ECM pointing at a possible role of mechanotransduction in the biological significance of the modified chitosan. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Exopolysaccharide-producing Bifidobacterium animalis subsp. lactis strains and their polymers elicit different responses on immune cells from blood and gut associated lymphoid tissue.

    Science.gov (United States)

    Hidalgo-Cantabrana, Claudio; Nikolic, Milica; López, Patricia; Suárez, Ana; Miljkovic, Marija; Kojic, Milan; Margolles, Abelardo; Golic, Natasa; Ruas-Madiedo, Patricia

    2014-04-01

    The effect of exopolysaccharide (EPS) producing bifidobacteria, and the EPS derived thereof, on the modulation of immune response was evaluated. Cells isolated from gut associated lymphoid tissue (GALT) and from peripheral blood mononuclear cells (PBMC) of naïve rats were used. The proliferation and cytokine production of these immune cells in the presence of the three isogenic Bifidobacterium animalis subsp. lactis strains (A1, A1dOx and A1dOxR), as well as their purified polymers, were in vitro analysed. The cytokine pattern produced by immune cells isolated from GALT showed that most levels remained stable in the presence of the three strains or their corresponding polymers. However, in PBMC the UV-inactivated bacteria induced higher levels of the ratios IFNγ/IL-17, TNFα/IL-10 and TNFα/TGFβ, and no variation in the ratio IFNγ/IL-4. Thus, B. animalis subsp. lactis strains were able to activate blood monocytes as well as T lymphocytes towards a mild inflammatory Th1 response. Furthermore, only the EPS-A1dOxR was able to stimulate a response in a similar way than its EPS-producing bacterium. Our work supports the notion that some bifidobacterial EPS could play a role in mediating the dialog of these microorganisms with the immune system. In addition, this study emphasizes the effect that the origin of the immune cells has in results obtained; this could explain the great amount of contradiction found in literature about the immunomodulation capability of EPS from probiotic bacteria. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Elemental analysis of biological tissues of Dmdmdx/J and C57BL/6J mice strains investigated by neutron activation analysis

    International Nuclear Information System (INIS)

    Sabrina Metairon; Zamboni, C.B.; Suzuki, M.F.; Bueno Junior, C.R.; Sant'Anna, O.A.

    2013-01-01

    In order to understand in more details the alterations that Duchenne muscular dystrophy disease may cause in biological tissues (blood, tibia, quadriceps and heart), correlations matrixes of the Dmd mdx /J dystrophic mice as well as C57BL/6J (control group) were generated. These mice were obtained from Jackson Laboratory (Maine, USA) and bred at IPEN (Dmd mdx /J), and at Centro de Estudos do Genoma Humano (C57BL/6J), both research centers at Sao Paulo city. Elements of clinical and nutritional relevance (Br, Ca, Cl, K, Mg, Na and S) were investigated by neutron activation analysis. These measurements were performed using the nuclear reactor IEA-R1 (3.5-4.5 MW, pool type) at IPEN. Comparisons between concentrations and correlations in these biological tissues, of these strains, showed that a Ca and Mg in blood are altered for the dystrophic mice. A significant change in the heart of dystrophic mice was also observed suggesting that a constant monitoring is required. Moreover, these results may help the researchers to evaluate the efficiency of new treatments and to compare the advantages of different treatment approaches before performing tests in patients with muscular dystrophy. (author)

  11. The tissue velocity imaging and strain rate imaging in the assessment of interatrial electromechanical conduction in patients with sick sinus syndrome before and after pacemaker implantation

    Directory of Open Access Journals (Sweden)

    Xiaozhi Zheng

    2011-05-01

    Full Text Available Tissue velocity imaging (TVI and strain rate imaging (SRI were recently introduced to quantify myocardial mechanical activity in patients receiving cardiac resynchronization therapy. To clear whether atrial-demand-based (AAI (R atrial pacing can fully simulate the electromechanical conduction of physiological state and to clarify which one is more appropriate for the assessment of electromechanical activity of the heart between TVI and SRI, 30 normal subjects and 31 patients with sick sinus syndrome (SSS before and after AAI(R pacemaker implantation (PI were investigated in this study. The results showed that the time intervals (ms, P-SRa assessed by SRI (not P-Va assessed by TVI prolonged step by step from the lateral wall of the right atrium (RA, the interatrial septum (IAS and the left atrium (LA in normal subjects(5.01±0.62, 17.05±3.54 and 45.09±12.26, p<0.01. P-Va and P-SRa did not differ at the RA, IAS and LA in patients with SSS before PI (p>0.05, and they were significant longer than those of normal subjects (p<0.01. However, they shortened to normal levels in patients with SSS after PI and P-SRa showed again the trend of gradually prolonging from the RA, IAS to LA. At the same time, the peak velocities and the peak strain rates during atrial contraction also returned to normal values from lower levels. These data suggested that AAI(R atrial pacing can successfully reverse the abnormal interatrial electromechanical conduction in patients with SSS, and SRI is more appropriate for the assessment of the electromechanical activity of atrial wall than TVI.

  12. Effects of mechanical strain on human mesenchymal stem cells and ligament fibroblasts in a textured poly(L-lactide) scaffold for ligament tissue engineering.

    Science.gov (United States)

    Kreja, Ludwika; Liedert, Astrid; Schlenker, Heiter; Brenner, Rolf E; Fiedler, Jörg; Friemert, Benedikt; Dürselen, Lutz; Ignatius, Anita

    2012-10-01

    The purpose of this study was to prove the effect of cyclic uniaxial intermittent strain on the mRNA expression of ligament-specific marker genes in human mesenchymal stem cells (MSC) and anterior cruciate ligament-derived fibroblasts (ACL-fibroblasts) seeded onto a novel textured poly(L-lactide) scaffold (PLA scaffold). Cell-seeded scaffolds were mechanically stimulated by cyclic uniaxial stretching. The expression of ligament matrix gene markers: collagen types I and III, fibronectin, tenascin C and decorin, as well as the proteolytic enzymes matrix metalloproteinase MMP-1 and MMP-2 and their tissue specific inhibitors TIMP-1 and TIMP-2 was investigated by analysing the mRNA expression using reverse transcriptase polymerase chain reaction and related to the static control. In ACL-fibroblasts seeded on PLA, mechanical load induced up-regulation of collagen types I and III, fibronectin and tenascin C. No effect of mechanical stimulation on the expression of ligament marker genes was found in undifferentiated MSC seeded on PLA. The results indicated that the new textured PLA scaffold could transfer the mechanical load to the ACL-fibroblasts and improved their ligament phenotype. This scaffold might be suitable as a cell-carrying component of ACL prostheses.

  13. Evaluation of healthy muscle tissue by strain and shear wave elastography – Dependency on depth and ROI position in relation to underlying bone

    DEFF Research Database (Denmark)

    Ewertsen, Caroline; Carlsen, Jonathan Frederik; Christiansen, Iben Riishede

    2016-01-01

    and methods: Ten healthy volunteers (five males and five females) had their biceps brachii, gastrocnemius, and quadriceps muscle examined with strain- and shear wave elastography at three different depths and in regions located above bone and beside bone. Strain ratios were averaged from cine-loops of 10 s...

  14. A pilot study of the characterization of hepatic tissue strain in children with cystic-fibrosis-associated liver disease (CFLD) by acoustic radiation force impulse imaging

    International Nuclear Information System (INIS)

    Behrens, Christopher B.; Langholz, Juliane H.; Eiler, Jessika; Jenewein, Raphael; Fuchs, Konstantin; Alzen, Gerhard F.P.; Naehrlich, Lutz; Harth, Sebastian; Krombach, Gabriele A.

    2013-01-01

    Progressive fibrotic alterations of liver tissue represent a major complication in children with cystic fibrosis. Correct assessment of cystic-fibrosis-associated liver disease (CFLD) in clinical routine is a challenging issue. Sonographic elastography based on acoustic radiation force impulse imaging (ARFI) is a new noninvasive approach for quantitatively assessing in vivo elasticity of biological tissues in many organs. To characterize ARFI elastography as a diagnostic tool to assess alteration of liver tissue elasticity related to cystic fibrosis in children. ARFI elastography and B-mode US imaging were performed in 36 children with cystic fibrosis. The children's clinical history and laboratory parameters were documented. According to the findings on conventional US, children were assigned to distinct groups indicating severity of hepatic tissue alterations. The relationship between US findings and respective elastography values was assessed. Additionally, differences between ARFI elastography values of each US group were statistically tested. Children with sonomorphologic characteristics of fibrotic tissue remodeling presented significantly increased values for tissue elasticity. Children with normal B-mode US or discrete signs of hepatic tissue alterations showed a tendency toward increased tissue stiffness indicating early tissue remodeling. Assessment of children with CFLD by means of ARFI elastography yields adequate results when compared to conventional US. For detection of early stages of liver disease with mild fibrotic reactions of hepatic tissue, ARFI elastography might offer diagnostic advantages over conventional US. Thus, liver stiffness measured by means of elastography might represent a valuable biological parameter for evaluation and follow-up of CFLD. (orig.)

  15. A pilot study of the characterization of hepatic tissue strain in children with cystic-fibrosis-associated liver disease (CFLD) by acoustic radiation force impulse imaging

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, Christopher B.; Langholz, Juliane H.; Eiler, Jessika; Jenewein, Raphael; Fuchs, Konstantin; Alzen, Gerhard F.P. [University Hospital Giessen, Department of Pediatric Radiology, Giessen (Germany); Naehrlich, Lutz [University Hospital Giessen, Department of Pediatrics, Giessen (Germany); Harth, Sebastian; Krombach, Gabriele A. [University Hospital Giessen, Department of Radiology, Giessen (Germany)

    2013-03-15

    Progressive fibrotic alterations of liver tissue represent a major complication in children with cystic fibrosis. Correct assessment of cystic-fibrosis-associated liver disease (CFLD) in clinical routine is a challenging issue. Sonographic elastography based on acoustic radiation force impulse imaging (ARFI) is a new noninvasive approach for quantitatively assessing in vivo elasticity of biological tissues in many organs. To characterize ARFI elastography as a diagnostic tool to assess alteration of liver tissue elasticity related to cystic fibrosis in children. ARFI elastography and B-mode US imaging were performed in 36 children with cystic fibrosis. The children's clinical history and laboratory parameters were documented. According to the findings on conventional US, children were assigned to distinct groups indicating severity of hepatic tissue alterations. The relationship between US findings and respective elastography values was assessed. Additionally, differences between ARFI elastography values of each US group were statistically tested. Children with sonomorphologic characteristics of fibrotic tissue remodeling presented significantly increased values for tissue elasticity. Children with normal B-mode US or discrete signs of hepatic tissue alterations showed a tendency toward increased tissue stiffness indicating early tissue remodeling. Assessment of children with CFLD by means of ARFI elastography yields adequate results when compared to conventional US. For detection of early stages of liver disease with mild fibrotic reactions of hepatic tissue, ARFI elastography might offer diagnostic advantages over conventional US. Thus, liver stiffness measured by means of elastography might represent a valuable biological parameter for evaluation and follow-up of CFLD. (orig.)

  16. Genome Sequence of African Swine Fever Virus BA71, the Virulent Parental Strain of the Nonpathogenic and Tissue-Culture Adapted BA71V.

    Science.gov (United States)

    Rodríguez, Javier M; Moreno, Leticia Tais; Alejo, Alí; Lacasta, Anna; Rodríguez, Fernando; Salas, María L

    2015-01-01

    The strain BA71V has played a key role in African swine fever virus (ASFV) research. It was the first genome sequenced, and remains the only genome completely determined. A large part of the studies on the function of ASFV genes, viral transcription, replication, DNA repair and morphogenesis, has been performed using this model. This avirulent strain was obtained by adaptation to grow in Vero cells of the highly virulent BA71 strain. We report here the analysis of the genome sequence of BA71 in comparison with that of BA71V. They possess the smallest genomes for a virulent or an attenuated ASFV, and are essentially identical except for a relatively small number of changes. We discuss the possible contribution of these changes to virulence. Analysis of the BA71 sequence allowed us to identify new similarities among ASFV proteins, and with database proteins including two ASFV proteins that could function as a two-component signaling network.

  17. Concordance and reproducibility between M-mode, tissue Doppler imaging, and two-dimensional strain imaging in the assessment of mitral annular displacement and velocity in patients with various heart conditions

    DEFF Research Database (Denmark)

    de Knegt, Martina Chantal; Biering-Sorensen, Tor; Sogaard, Peter

    2014-01-01

    AIMS: Mitral annular (MA) displacement reflects longitudinal left ventricular (LV) deformation and systolic velocity measurements reflect the rate of contraction; both are valuable in the diagnosis and prognosis of cardiac disease. The aim of this study was to test the agreement and reproducibility...... between motion mode (M-mode), colour tissue Doppler imaging (TDI), and two-dimensional strain imaging (2DSI) when measuring MA displacement and systolic velocity. METHODS AND RESULTS: Using GE Healthcare Vivid 7 and E9 and Echopac BT11 software, MA displacement and velocity measurements by 2DSI, TDI...

  18. Natural hybrid of Leishmania infantum/L. donovani: development in Phlebotomus tobbi, P. perniciosus and Lutzomyia longipalpis and comparison with non-hybrid strains differing in tissue tropism.

    Science.gov (United States)

    Seblova, Veronika; Myskova, Jitka; Hlavacova, Jana; Votypka, Jan; Antoniou, Maria; Volf, Petr

    2015-11-25

    Infection caused by parasites from L. donovani complex can manifest as a serious visceral disease or a self-healing milder cutaneous form. The different tropism and pathology in humans is caused by the interaction between parasites, host and vector determinants but the mechanisms are not well understood. In Cukurova region in Turkey we previously identified a major focus of cutaneous leishmaniasis caused by L. donovani/infantum hybrids (CUK strain) and isolated this parasite from the locally abundant sand fly, Phlebotomus tobbi. Here, we present the first experimental study with P. tobbi. We tested the susceptibility of this species to various Leishmania under laboratory conditions, characterized glycoproteins in the P. tobbi midgut putatively involved in parasite-vector interaction and compared the development of the CUK strain in the sand fly with one other dermotropic and three viscerotropic strains belonging to the L. donovani complex. Females of laboratory reared P. tobbi, P. perniciosus and Lutzomyia longipalpis were infected using membrane feeding on rabbit blood containing promastigotes of various Leishmania species with different tropisms. The individual guts were checked microscopically for presence and localization of Leishmania parasites; the number of parasites was assessed more precisely by qPCR. In addition, glycosylation of midgut proteins of P. tobbi was studied by lectin blotting of midgut lysate with lectins specific for terminal sugars of N-type and O-type glycans. High infection rates, heavy parasite loads and late-stage infection with colonization of the stomodeal valve were observed in P. tobbi infected by Leishmania major or L. infantum CUK hybrid. In parallel, lectin blotting revealed the presence of O-glycosylated proteins in the P. tobbi midgut. In P. perniciosus and L. longipalpis all five Leishmania strains tested developed well. In both vectors, significantly higher parasite numbers were detected by qPCR for dermotropic L. donovani

  19. Elements determination of clinical relevance in biological tissues Dmd{sup mdx}/J dystrophic mice strains investigated by NAA; Determinacao de elementos de relevancia clinica em tecidos biologicos de camundongos distroficos Dmd{sup mdx}/J por AAN

    Energy Technology Data Exchange (ETDEWEB)

    Metairon, Sabrina

    2012-07-01

    In this work the determination of chemistry elements in biological tissues (whole blood, bones and organs) of dystrophic mice, used as animal model of Duchenne Muscular Dystrophy (DMD), was performed using analytical nuclear technique. The aim of this work was to determine reference values of elements of clinical (Ca, Cl, K, Mg, Na) and nutritional (Br and S) relevance in whole blood, tibia, quadriceps and hearts from Dmdmdx/J (10 males and 10 females) dystrophic mice and C57BL/6J (10 males) control group mice, using Neutron Activation Analysis technique (NAA). To show in more details the alterations that this disease may cause in these biological tissues, correlations matrixes of the DMD{sup mdx}/J mouse strain were generated and compared with C57BL/6J control group. For this study 119 samples of biological tissue were irradiated in the IEA-R1 nuclear reactor at IPEN (Sao Paulo, Brazil). The concentrations of these elements in biological tissues of Dmd{sup mdx}/J and C57B/6J mice are the first indicative interval for reference values. Moreover, the alteration in some correlation coefficients data among the elements in the health status and in the diseased status indicates a connection between these elements in whole blood, tibia, quadriceps and heart. These results may help the researchers to evaluate the efficiency of new treatments and to compare the advantages of different treatment approaches before performing tests in patients with muscular dystrophy. (author)

  20. Evaluation of three PCR assays for the identification of the sheep strain (genotype 1) of Echinococcus granulosus in canid feces and parasite tissues

    NARCIS (Netherlands)

    Boufana, Belgees S; Campos-Ponce, Maiza; Naidich, Ariel; Buishi, Imad; Lahmar, Selma; Zeyhle, Eberhard; Jenkins, David J; Combes, Benoit; Wen, Hao; Xiao, Ning; Nakao, Minoru; Ito, Akira; Qiu, Jiamin; Craig, Philip S

    2008-01-01

    The performance of 3 PCR assays for the identification of the G1 sheep genotype of Echinococcus granulosus was evaluated using tissue and canid fecal samples. The "Dinkel" and "Stefanić" primers were the most sensitive in detecting E. granulosus DNA in feces of necropsied dogs (73.7% and 100%,

  1. Pathological lesions in the central nervous system and peripheral tissues of ddY mice with street rabies virus (1088 strain).

    Science.gov (United States)

    Kimitsuki, Kazunori; Yamada, Kentaro; Shiwa, Nozomi; Inoue, Satoshi; Nishizono, Akira; Park, Chun-Ho

    2017-06-10

    Most studies on rabies virus pathogenesis in animal models have employed fixed rabies viruses, and the results of those employing street rabies viruses have been inconsistent. Therefore, to clarify the pathogenesis of street rabies virus (1088 strain) in mice, 10 6 focus forming units were inoculated into the right hindlimb of ddY mice (6 weeks, female). At 3 days postinoculation (DPI), mild inflammation was observed in the hindlimb muscle. At 5 DPI, ganglion cells in the right lumbosacral spinal dorsal root ganglia showed chromatolysis. Axonal degeneration and inflammatory cells increased with infection progress in the spinal dorsal horn and dorsal root ganglia. Right hindlimb paralysis was observed from 7 DPI, which progressed to quadriparalysis. However, no pathological changes were observed in the ventral horn and root fibers of the spinal cord. Viral antigen was first detected in the right hindlimb muscle at 3 DPI, followed by the right lumbosacral dorsal root ganglia, dorsal horn of spinal cord, left red nuclei, medulla oblongata and cerebral cortex (M1 area) at 5 DPI. These results suggested that the 1088 virus ascended the lumbosacral spinal cord via mainly afferent fibers at early stage of infection and moved to cerebral cortex (M1 area) using descending spinal tract. Additionally, we concluded that significant pathological changes in mice infected with 1088 strain occur in the sensory tract of the spinal cord; this selective susceptibility results in clinical features of the disease.

  2. Engineering Musculoskeletal Tissue Interfaces

    Directory of Open Access Journals (Sweden)

    Ece Bayrak

    2018-04-01

    Full Text Available Tissue engineering aims to bring together biomaterials, cells, and signaling molecules within properly designed microenvironments in order to create viable treatment options for the lost or malfunctioning tissues. Design and production of scaffolds and cell-laden grafts that mimic the complex structural and functional features of tissues are among the most important elements of tissue engineering strategy. Although all tissues have their own complex structure, an even more complex case in terms of engineering a proper carrier material is encountered at the tissue interfaces, where two distinct tissues come together. The interfaces in the body can be examined in four categories; cartilage-bone and ligament-bone interfaces at the knee and the spine, tendon-bone interfaces at the shoulder and the feet, and muscle-tendon interface at the skeletal system. These interfaces are seen mainly at the soft-to-hard tissue transitions and they are especially susceptible to injury and tear due to the biomechanical inconsistency between these tissues where high strain fields are present. Therefore, engineering the musculoskeletal tissue interfaces remain a challenge. This review focuses on recent advancements in strategies for musculoskeletal interface engineering using different biomaterial-based platforms and surface modification techniques.

  3. Early detection of left ventricular dysfunction in asymptomatic diabetic patient using strain and strain rate echocardiographic imaging

    Directory of Open Access Journals (Sweden)

    Rania Gaber

    2014-03-01

    Conclusion: Type 2 diabetes mellitus deteriorate both LV systolic and diastolic performance. Strain and strain rate by tissue Doppler Imaging is superior to conventional Doppler in early detection and evaluation of systolic and diastolic dysfunction in type 2 diabetic patients.

  4. Tissue engineering

    CERN Document Server

    Fisher, John P; Bronzino, Joseph D

    2007-01-01

    Increasingly viewed as the future of medicine, the field of tissue engineering is still in its infancy. As evidenced in both the scientific and popular press, there exists considerable excitement surrounding the strategy of regenerative medicine. To achieve its highest potential, a series of technological advances must be made. Putting the numerous breakthroughs made in this field into a broad context, Tissue Engineering disseminates current thinking on the development of engineered tissues. Divided into three sections, the book covers the fundamentals of tissue engineering, enabling technologies, and tissue engineering applications. It examines the properties of stem cells, primary cells, growth factors, and extracellular matrix as well as their impact on the development of tissue engineered devices. Contributions focus on those strategies typically incorporated into tissue engineered devices or utilized in their development, including scaffolds, nanocomposites, bioreactors, drug delivery systems, and gene t...

  5. Tissue types (image)

    Science.gov (United States)

    ... are 4 basic types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue. Connective tissue supports ... binds them together (bone, blood, and lymph tissues). Epithelial tissue provides a covering (skin, the linings of the ...

  6. Tissue Classification

    DEFF Research Database (Denmark)

    Van Leemput, Koen; Puonti, Oula

    2015-01-01

    Computational methods for automatically segmenting magnetic resonance images of the brain have seen tremendous advances in recent years. So-called tissue classification techniques, aimed at extracting the three main brain tissue classes (white matter, gray matter, and cerebrospinal fluid), are now...... well established. In their simplest form, these methods classify voxels independently based on their intensity alone, although much more sophisticated models are typically used in practice. This article aims to give an overview of often-used computational techniques for brain tissue classification...

  7. Taxonomy of oxalotrophic Methylobacterium strains

    Science.gov (United States)

    Sahin, Nurettin; Kato, Yuko; Yilmaz, Ferah

    2008-10-01

    Most of the oxalotrophic bacteria are facultative methylotrophs and play important ecological roles in soil fertility and cycling of elements. This study gives a detailed picture of the taxonomy and diversity of these bacteria and provides new information about the taxonomical variability within the genus Methylobacterium. Twelve mesophilic, pink-pigmented, and facultatively methylotrophic oxalate-oxidizing strains were included in this work that had been previously isolated from the soil and some plant tissues by the potassium oxalate enrichment method. The isolates were characterized using biochemical tests, cellular lipid profiles, spectral characteristics of carotenoid pigments, G+C content of the DNA, and 16S rDNA sequencing. The taxonomic similarities among the strains were analyzed using the simple matching ( S SM) and Jaccard ( S J) coefficients, and the UPGMA clustering algorithm. The phylogenetic position of the strains was inferred by the neighbor-joining method on the basis of the 16S rDNA sequences. All isolates were Gram-negative, facultatively methylotrophic, oxidase and catalase positive, and required no growth factors. Based on the results of numerical taxonomy, the strains formed four closely related clusters sharing ≥85% similarity. Analysis of the 16S rDNA sequences demonstrated that oxalotrophic, pink-pigmented, and facultatively methylotrophic strains could be identified as members of the genus Methylobacterium. Except for M. variabile and M. aquaticum, all of the Methylobacterium type strains tested had the ability of oxalate utilization. Our results indicate that the capability of oxalate utilization seems to be an uncommon trait and could be used as a valuable taxonomic criterion for differentiation of Methylobacterium species.

  8. Rehabilitation effect of exercise with soft tissue manipulation in ...

    African Journals Online (AJOL)

    Rehabilitation effect of exercise with soft tissue manipulation in patients with lumbar muscle strain. H Li, H Zhang, S Liu, Y Wang, D Gai, Q Lu, H Gan, Y Shi, W Qi. Abstract. Objective: To study the rehabilitation effect of exercise with soft tissue manipulation therapy for patients with lumbar muscle strain. Methods: Patients with ...

  9. Connective tissue activation. XVII

    International Nuclear Information System (INIS)

    Weiss, J.J.; Donakowski, C.; Anderson, B.; Meyers, S.; Castor, C.W.

    1980-01-01

    The platelet-derived connective tissue activating peptide (CTAP-III) has been shown to be an important factor stimulating the metabolism and proliferation of human connective tissue cell strains, including synovial tissue cells. The quantities of CTAP-III affecting the cellular changes and the amounts in various biologic fluids and tissues are small. The objectives of this study were to develop a radioimmunoassay (RIA) for CTAP-III and to ascertain the specificities of the anti-CTAP-III sera reagents. The antisera were shown not to cross-react with a number of polypeptide hormones. However, two other platelet proteins β-thromboglobulin and low affinity platelet factor-4, competed equally as well as CTAP-III for anti-CTAP-III antibodies in the RIA system. Thus, the three platelet proteins are similar or identical with respect to those portions of the molecules constituting the reactive antigenic determinants. The levels of material in normal human platelet-free plasma that inhibited anti-CTAP-III- 125 I-CTAP-III complex formation were determined to be 34+-13 (S.D.) ng/ml. (Auth.)

  10. Strain-Modulated Epitaxy

    National Research Council Canada - National Science Library

    Brown, April

    1999-01-01

    Strain-Modulated Epitaxy (SME) is a novel approach, invented at Georgia Tech, to utilize subsurface stressors to control strain and therefore material properties and growth kinetics in the material above the stressors...

  11. Hamstring strain - aftercare

    Science.gov (United States)

    Pulled hamstring muscle; Sprain - hamstring ... There are 3 levels of hamstring strains: Grade 1 -- mild muscle strain or pull Grade 2 -- partial muscle tear Grade 3 -- complete muscle tear Recovery time depends ...

  12. TL transgenic mouse strains

    International Nuclear Information System (INIS)

    Obata, Y.; Matsudaira, Y.; Hasegawa, H.; Tamaki, H.; Takahashi, T.; Morita, A.; Kasai, K.

    1993-01-01

    As a result of abnormal development of the thymus of these mice, TCR αβ lineage of the T cell differentiation is disturbed and cells belonging to the TCR γδ CD4 - CD8 - double negative (DN) lineage become preponderant. The γδ DN cells migrate into peripheral lymphoid organs and constitute nearly 50% of peripheral T cells. Immune function of the transgenic mice is severely impaired, indicating that the γδ cells are incapable of participating in these reactions. Molecular and serological analyses of T-cell lymphomas reveal that they belong to the γδ lineage. Tg.Tla a -3-1 mice should be useful in defining the role of TL in normal and abnormal T cell differentiation as well as in the development of T-cell lymphomas, and further they should facilitate studies on the differentiation and function of γδ T cells. We isolated T3 b -TL gene from B6 mice and constructed a chimeric gene in which T3 b -TL is driven by the promoter of H-2K b . With the chimeric gene, two transgenic mouse strains, Tg. Con.3-1 and -2 have been derived in C3H background. Both strains express TL antigen in various tissues including skin. The skin graft of transgenic mice on C3H and (B6 X C3H)F 1 mice were rejected. In the mice which rejected the grafts, CD8 + TCRαβ cytotoxic T cells (CTL) against TL antigens were recognized. The recognition of TL by CTL did not require the antigen presentation by H-2 molecules. The results indicated that TL antigen in the skin becomes a transplantation antigen and behaves like a typical allogeneic MHC class I antigen. The facts that (B6 X C3H)F 1 mice rejected the skin expressing T3 b -TL antigen and induced CTL that killed TL + lymphomas of B6 origin revealed that TL antigen encoded by T3 b -TL is recognized as non-self in B6 mice. Experiments are now extended to analyze immune responses to TL antigen expressed on autochthonous T cell lymphomas. (J.P.N.)

  13. A strain gauge

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid positioned on the carrier layer, wherein the strain gauge comprises two reinforcement members positioned on the carrier layer at opposite ends of the measurement grid in the axial direction....... The reinforcement members are each placed within a certain axial distance to the measurement grid with the axial distance being equal to or smaller than a factor times the grid spacing. The invention further relates to a multi-axial strain gauge such as a bi-axial strain gauge or a strain gauge rosette where each...... of the strain gauges comprises reinforcement members. The invention further relates to a method for manufacturing a strain gauge as mentioned above....

  14. The Methodology of Doppler-Derived Central Blood Flow Measurements in Newborn Infants

    Directory of Open Access Journals (Sweden)

    Koert A. de Waal

    2012-01-01

    Full Text Available Central blood flow (CBF measurements are measurements in and around the heart. It incorporates cardiac output, but also measurements of cardiac input and assessment of intra- and extracardiac shunts. CBF can be measured in the central circulation as right or left ventricular output (RVO or LVO and/or as cardiac input measured at the superior vena cava (SVC flow. Assessment of shunts incorporates evaluation of the ductus arteriosus and the foramen ovale. This paper describes the methodology of CBF measurements in newborn infants. It provides a brief overview of the evolution of Doppler ultrasound blood flow measurements, basic principles of Doppler ultrasound, and an overview of all used methodology in the literature. A general guide for interpretation and normal values with suggested cutoffs of CBFs are provided for clinical use.

  15. Three dimensional strained semiconductors

    Science.gov (United States)

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

    2016-11-08

    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  16. Taxonomy of Streptomyces strains isolated from rhizospheres of ...

    African Journals Online (AJOL)

    Taxonomy of Streptomyces strains isolated from rhizospheres of various plant species grown in Taif region, KSA, having antagonistic activities against some microbial tissue ... African Journal of Biotechnology ... Keywords: Taxonomy, Streptomyces, microbial tissue culture contaminants, antagonistic activities, 16S rRNA

  17. Strain measurement technique

    International Nuclear Information System (INIS)

    1987-01-01

    The 10 contributions are concerned with selected areas of application, such as strain measurements in wood, rubber/metal compounds, sets of strain measurements on buildings, reinforced concrete structures without gaps, pipes buried in the ground and measurements of pressure fluctuations. To increase the availability and safety of plant, stress analyses were made on gas turbine rotors with HT-DMS or capacitive HT-DMS (high temperature strain measurements). (DG) [de

  18. Strained Silicon Photonics

    Directory of Open Access Journals (Sweden)

    Ralf B. Wehrspohn

    2012-05-01

    Full Text Available A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.

  19. Tissue irradiator

    International Nuclear Information System (INIS)

    Hungate, F.P.; Riemath, W.F.; Bunnell, L.R.

    1975-01-01

    A tissue irradiator is provided for the in-vivo irradiation of body tissue. The irradiator comprises a radiation source material contained and completely encapsulated within vitreous carbon. An embodiment for use as an in-vivo blood irradiator comprises a cylindrical body having an axial bore therethrough. A radioisotope is contained within a first portion of vitreous carbon cylindrically surrounding the axial bore, and a containment portion of vitreous carbon surrounds the radioisotope containing portion, the two portions of vitreous carbon being integrally formed as a single unit. Connecting means are provided at each end of the cylindrical body to permit connections to blood-carrying vessels and to provide for passage of blood through the bore. In a preferred embodiment, the radioisotope is thulium-170 which is present in the irradiator in the form of thulium oxide. A method of producing the preferred blood irradiator is also provided, whereby nonradioactive thulium-169 is dispersed within a polyfurfuryl alcohol resin which is carbonized and fired to form the integral vitreous carbon body and the device is activated by neutron bombardment of the thulium-169 to produce the beta-emitting thulium-170

  20. Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients.

    Science.gov (United States)

    Zhan, Xiao-Yong; Hu, Chao-Hui; Zhu, Qing-Yi

    2016-04-01

    Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains, respectively. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Distribution frequencies of these genes in reference L. pneumophila strains were similar to those in environmental L. pneumophila strains. In contrast, environmental non-L. pneumophila maintained higher frequencies of these genes compared to those found in reference non-L. pneumophila strains. This study illustrates the association of virulence genes with Legionella pathogenicity and reveals the possible virulence evolution of non-L. pneumophia strains isolated from environmental water.

  1. Multimodality instrument for tissue characterization

    Science.gov (United States)

    Mah, Robert W. (Inventor); Andrews, Russell J. (Inventor)

    2004-01-01

    A system with multimodality instrument for tissue identification includes a computer-controlled motor driven heuristic probe with a multisensory tip. For neurosurgical applications, the instrument is mounted on a stereotactic frame for the probe to penetrate the brain in a precisely controlled fashion. The resistance of the brain tissue being penetrated is continually monitored by a miniaturized strain gauge attached to the probe tip. Other modality sensors may be mounted near the probe tip to provide real-time tissue characterizations and the ability to detect the proximity of blood vessels, thus eliminating errors normally associated with registration of pre-operative scans, tissue swelling, elastic tissue deformation, human judgement, etc., and rendering surgical procedures safer, more accurate, and efficient. A neural network program adaptively learns the information on resistance and other characteristic features of normal brain tissue during the surgery and provides near real-time modeling. A fuzzy logic interface to the neural network program incorporates expert medical knowledge in the learning process. Identification of abnormal brain tissue is determined by the detection of change and comparison with previously learned models of abnormal brain tissues. The operation of the instrument is controlled through a user friendly graphical interface. Patient data is presented in a 3D stereographics display. Acoustic feedback of selected information may optionally be provided. Upon detection of the close proximity to blood vessels or abnormal brain tissue, the computer-controlled motor immediately stops probe penetration. The use of this system will make surgical procedures safer, more accurate, and more efficient. Other applications of this system include the detection, prognosis and treatment of breast cancer, prostate cancer, spinal diseases, and use in general exploratory surgery.

  2. A strain gauge

    DEFF Research Database (Denmark)

    2017-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid (101) positioned on the carrier layer, wherein the measurement grid comprises a number of measurement grid sections placed side by side with gaps in between, and a number of end loops (106) interconnecting...... relates to a method for manufacturing a strain gauge as mentioned above....

  3. Mastication and the Postorbital Ligament: Dynamic Strain in Soft Tissues

    Science.gov (United States)

    Herring, Susan W.; Rafferty, Katherine L.; Liu, Zi Jun; Lemme, Michael

    2011-01-01

    Although the FEED database focuses on muscle activity patterns, it is equally suitable for other physiological recording and especially for synthesizing different types of information. The present contribution addresses the interaction between muscle activity and ligamentary stretch during mastication. The postorbital ligament is the thickened edge of a septum dividing the orbital contents from the temporal fossa and is continuous with the temporal fascia. As a tensile element, this fascial complex could support the zygomatic arch against the pull of the masseter muscle. An ossified postorbital bar has evolved repeatedly in mammals, enabling resistance to compression and shear in addition to tension. Although such ossification clearly reinforces the skull against muscle pull, the most accepted explanation is that it helps isolate the orbital contents from contractions of the temporalis muscle. However, it has never been demonstrated that the contraction of jaw muscles deforms the unossified ligament. We examined linear deformation of the postorbital ligament in minipigs, Sus scrofa, along with electromyography of the jaw muscles and an assessment of changes in pressure and shape in the temporalis. During chewing, the ligament elongated (average 0.9%, maximum 2.8%) in synchrony with the contraction of the elevator muscles of the jaw. Although the temporalis bulged outward and created substantial pressure against the braincase, the superficial fibers usually retracted caudally, away from the postorbital ligament. In anesthetized animals, stimulating either the temporalis or the masseter muscle in isolation usually elongated the ligament (average 0.4–0.7%). These results confirm that contraction of the masticatory muscles can potentially distort the orbital contents and further suggest that the postorbital ligament does function as a tension member resisting the pull of the masseter on the zygomatic arch. PMID:21593142

  4. Lung tissue mechanics as an emergent phenomenon.

    Science.gov (United States)

    Suki, Béla; Bates, Jason H T

    2011-04-01

    The mechanical properties of lung parenchymal tissue are both elastic and dissipative, as well as being highly nonlinear. These properties cannot be fully understood, however, in terms of the individual constituents of the tissue. Rather, the mechanical behavior of lung tissue emerges as a macroscopic phenomenon from the interactions of its microscopic components in a way that is neither intuitive nor easily understood. In this review, we first consider the quasi-static mechanical behavior of lung tissue and discuss computational models that show how smooth nonlinear stress-strain behavior can arise through a percolation-like process in which the sequential recruitment of collagen fibers with increasing strain causes them to progressively take over the load-bearing role from elastin. We also show how the concept of percolation can be used to link the pathologic progression of parenchymal disease at the micro scale to physiological symptoms at the macro scale. We then examine the dynamic mechanical behavior of lung tissue, which invokes the notion of tissue resistance. Although usually modeled phenomenologically in terms of collections of springs and dashpots, lung tissue viscoelasticity again can be seen to reflect various types of complex dynamic interactions at the molecular level. Finally, we discuss the inevitability of why lung tissue mechanics need to be complex.

  5. Laser-induced photo-thermal strain imaging

    Science.gov (United States)

    Choi, Changhoon; Ahn, Joongho; Jeon, Seungwan; Kim, Chulhong

    2018-02-01

    Vulnerable plaque is the one of the leading causes of cardiovascular disease occurrence. However, conventional intravascular imaging techniques suffer from difficulty in finding vulnerable plaque due to limitation such as lack of physiological information, imaging depth, and depth sensitivity. Therefore, new techniques are needed to help determine the vulnerability of plaque, Thermal strain imaging (TSI) is an imaging technique based on ultrasound (US) wave propagation speed that varies with temperature of medium. During temperature increase, strain occurs in the medium and its variation tendency is depending on the type of tissue, which makes it possible to use for tissue differentiation. Here, we demonstrate laser-induced photo-thermal strain imaging (pTSI) to differentiate tissue using an intravascular ultrasound (IVUS) catheter and a 1210-nm continuous-wave laser for heating lipids intensively. During heating, consecutive US images were obtained from a custom-made phantom made of porcine fat and gelatin. A cross correlation-based speckle-tracking algorithm was then applied to calculate the strain of US images. In the strain images, the positive strain produced in lipids (porcine fat) was clearly differentiated from water-bearing tissue (gelatin). This result shows that laser-induced pTSI could be a new method to distinguish lipids in the plaque and can help to differentiate vulnerability of plaque.

  6. Internally Mounting Strain Gages

    Science.gov (United States)

    Jett, J. R., Jr.

    1984-01-01

    Technique for mounting strain gages inside bolt or cylinder simultaneously inserts gage, attached dowel segment, and length of expandable tubing. Expandable tubing holds gage in place while adhesive cures, assuring even distribution of pressure on gage and area gaged.

  7. Running Title: Strained Yoghurts

    African Journals Online (AJOL)

    USER

    2012-09-27

    Sep 27, 2012 ... ever, the traditional method of producing strained yoghurt ... Food market studies have the essential function of providing ..... Communication No: 2001/21. ... fermented foods and beverages of Turkey. Crit. Rev. Food. Sci. Nutr.

  8. Flexible piezotronic strain sensor.

    Science.gov (United States)

    Zhou, Jun; Gu, Yudong; Fei, Peng; Mai, Wenjie; Gao, Yifan; Yang, Rusen; Bao, Gang; Wang, Zhong Lin

    2008-09-01

    Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I- V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

  9. Early pathogenesis of classical swine fever virus (CSFV) strains in Danish pigs

    DEFF Research Database (Denmark)

    Lohse, Louise; Nielsen, Jens; Uttenthal, Åse

    2012-01-01

    between strains, however, lymphoid atrophy and growth retardation represented a consistent finding for all 4 strains. Virus distribution, viral load and in particular virus persistence differed, but supported present practice that recommends lymphoid tissue, most optimal tonsil and lymph nodes, as target...... material to be applied for early laboratory diagnosis. The present study demonstrated constraints associated with early detection of infections with CSFV strains of low virulence. Since neither clinical symptoms nor pathological lesions observed with these strains constituted characteristic signs of CSF...

  10. Mechanotransduction mechanisms in growing spherically structured tissues

    Science.gov (United States)

    Littlejohns, Euan; Dunlop, Carina M.

    2018-04-01

    There is increasing experimental interest in mechanotransduction in multi-cellular tissues as opposed to single cells. This is driven by a growing awareness of the importance of physiologically relevant three-dimensional culture and of cell–cell and cell–gel interactions in directing growth and development. The paradigm biophysical technique for investigating tissue level mechanobiology in this context is to grow model tissues in artificial gels with well-defined mechanical properties. These studies often indicate that the stiffness of the encapsulating gel can significantly alter cellular behaviours. We demonstrate here potential mechanisms linking tissue growth with stiffness-mediated mechanotransduction. We show how tissue growth in gel systems generates points at which there is a significant qualitative change in the cellular stress and strain experienced. We show analytically how these potential switching points depend on the mechanical properties of the constraining gel and predict when they will occur. Significantly, we identify distinct mechanisms that act separately in each of the stress and strain fields at different times. These observations suggest growth as a potential physical mechanism coupling gel stiffness with cellular mechanotransduction in three-dimensional tissues. We additionally show that non-proliferating areas, in the case that the constraining gel is soft compared with the tissue, will expand and contract passively as a result of growth. Central compartment size is thus seen to not be a reliable indicator on its own for growth initiation or active behaviour.

  11. Musculoskeletal Application of Ultrasound Elastography: Soft Tissue Lipoma

    International Nuclear Information System (INIS)

    Choi, Ja Young; Hong, Sung Hwan; Yoo, Hye Jin; Kim, Su Jin

    2010-01-01

    Real-time freehand elastography. Conventional ultrasonography (US) and real-time freehand US elastography were performed in nine patients (M:F = 4:5: mean age, 53 years: 29-64 years) with soft-tissue lipoma confirmed by surgical resection. The elastogram was color-coded by 256 scales according to the degree of strain induced by light compression. The relative strains for lipoma and surrounding soft tissue were measured and mean strains were examined by using a Wilcoxon signed rank test. The elastograms showed red to sky-blue color in all lipomas and predominantly black in surrounding soft tissue. The mean relative strain (±standard deviation) was 67.9±28.5, 77.1±25.3, 63.3±31.2, and 15.7±18.3 for total, intramuscular, and subcutaneous lipoma, and surrounding soft tissue, respectively. The mean strain of the lipoma was significantly higher than one of surrounding soft tissue (p = .008, Wilcoxon signed rank test). Real-time elastography yields characteristic elastographic features of soft tissue lipoma distinguishing from those of adjacent soft tissues

  12. Elliptical posts allow for detailed control of non-equibiaxial straining of cell cultures

    DEFF Research Database (Denmark)

    Olesen, Christian Gammelgaard; Pennisi, Cristian Pablo; de Zee, Mark

    2013-01-01

    tissue cells in vivo are subjected to a range of mechanical deformations including shear strain caused by activities of daily living. Shear strains are suspected to play an important role in tissue necrosis. Method The Flexcell system was redesigned using a finite element model in order to obtain large...... areas of the membrane in a controlled, uniform non-equibiaxial strain state. Results The redesign was manufactured and the resulting strains were experimentally validated by means of image analysis methods. The results showed that the system could be used for experiments varying the shear strain....... Conclusion The result allows scientists and experimentalists to apply detailed control of the strain tensor applied to tissue samples in two dimensions....

  13. Localized strain measurements of the intervertebral disc annulus during biaxial tensile testing.

    Science.gov (United States)

    Karakolis, Thomas; Callaghan, Jack P

    2015-01-01

    Both inter-lamellar and intra-lamellar failures of the annulus have been described as potential modes of disc herniation. Attempts to characterize initial lamellar failure of the annulus have involved tensile testing of small tissue samples. The purpose of this study was to evaluate a method of measuring local surface strains through image analysis of a tensile test conducted on an isolated sample of annular tissue in order to enhance future studies of intervertebral disc failure. An annulus tissue sample was biaxial strained to 10%. High-resolution images captured the tissue surface throughout testing. Three test conditions were evaluated: submerged, non-submerged and marker. Surface strains were calculated for the two non-marker conditions based on motion of virtual tracking points. Tracking algorithm parameters (grid resolution and template size) were varied to determine the effect on estimated strains. Accuracy of point tracking was assessed through a comparison of the non-marker conditions to a condition involving markers placed on tissue surface. Grid resolution had a larger effect on local strain than template size. Average local strain error ranged from 3% to 9.25% and 0.1% to 2.0%, for the non-submerged and submerged conditions, respectively. Local strain estimation has a relatively high potential for error. Submerging the tissue provided superior strain estimates.

  14. Comparison of contrast in brightness mode and strain ultrasonography of glial brain tumours

    International Nuclear Information System (INIS)

    Selbekk, Tormod; Brekken, Reidar; Indergaard, Marit; Solheim, Ole; Unsgård, Geirmund

    2012-01-01

    Image contrast between normal tissue and brain tumours may sometimes appear to be low in intraoperative ultrasound. Ultrasound imaging of strain is an image modality that has been recently explored for intraoperative imaging of the brain. This study aims to investigate differences in image contrast between ultrasound brightness mode (B-mode) images and ultrasound strain magnitude images of brain tumours. Ultrasound radiofrequency (RF) data was acquired during surgery in 15 patients with glial tumours. The data were subsequently processed to provide strain magnitude images. The contrast in the B-mode images and the strain images was determined in assumed normal brain tissue and tumour tissue at selected regions of interest (ROI). Three measurements of contrast were done in the ultrasound data for each patient. The B-mode and strain contrasts measurements were compared using the paired samples t- test. The statistical analysis of a total of 45 measurements shows that the contrasts in the strain magnitude images are significantly higher than in the conventional ultrasound B-mode images (P < 0.0001). The results indicate that ultrasound strain imaging provides better discrimination between normal brain tissue and glial tumour tissue than conventional ultrasound B-mode imaging. Ultrasound imaging of tissue strain therefore holds the potential of becoming a valuable adjunct to conventional intraoperative ultrasound imaging in brain tumour surgery

  15. Measurement of the uniaxial mechanical properties of rat skin using different stress-strain definitions.

    Science.gov (United States)

    Karimi, A; Navidbakhsh, M

    2015-05-01

    The mechanical properties of skin tissue may vary according to the anatomical locations of a body. There are different stress-strain definitions to measure the mechanical properties of skin tissue. However, there is no agreement as to which stress-strain definition should be implemented to measure the mechanical properties of skin at different anatomical locations. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are employed to determine the mechanical properties of skin tissue at back and abdomen locations of a rat body. The back and abdomen skins of eight rats are excised and subjected to a series of tensile tests. The elastic modulus, maximum stress, and strain of skin tissues are measured using three stress definitions and four strain definitions. The results show that the effect of varying the stress definition on the maximum stress measurements of the back skin is significant but not when calculating the elastic modulus and maximum strain. No significant effects are observed on the elastic modulus, maximum stress, and strain measurements of abdomen skin by varying the stress definition. In the true stress-strain diagram, the maximum stress (20%), and elastic modulus (35%) of back skin are significantly higher than that of abdomen skin. The true stress-strain definition is favored to measure the mechanical properties of skin tissue since it gives more accurate measurements of the skin's response using the instantaneous values. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Real-Time Implementation of Medical Ultrasound Strain Imaging System

    International Nuclear Information System (INIS)

    Jeong, Mok Kun; Kwon, Sung Jae; Bae, Moo Ho

    2008-01-01

    Strain imaging in a medical ultrasound imaging system can differentiate the cancer or tumor in a lesion that is stiffer than the surrounding tissue. In this paper, a strain imaging technique using quasistatic compression is implemented that estimates the displacement between pre- and postcompression ultrasound echoes and obtains strain by differentiating it in the spatial direction. Displacements are computed from the phase difference of complex baseband signals obtained using their autocorrelation, and errors associated with converting the phase difference into time or distance are compensated for by taking into the center frequency variation. Also, to reduce the effect of operator's hand motion, the displacements of all scanlines are normalized with the result that satisfactory strain image quality has been obtained. These techniques have been incorporated into implementing a medical ultrasound strain imaging system that operates in real time.

  17. Ultrasound strain imaging using Barker code

    Science.gov (United States)

    Peng, Hui; Tie, Juhong; Guo, Dequan

    2017-01-01

    Ultrasound strain imaging is showing promise as a new way of imaging soft tissue elasticity in order to help clinicians detect lesions or cancers in tissues. In this paper, Barker code is applied to strain imaging to improve its quality. Barker code as a coded excitation signal can be used to improve the echo signal-to-noise ratio (eSNR) in ultrasound imaging system. For the Baker code of length 13, the sidelobe level of the matched filter output is -22dB, which is unacceptable for ultrasound strain imaging, because high sidelobe level will cause high decorrelation noise. Instead of using the conventional matched filter, we use the Wiener filter to decode the Barker-coded echo signal to suppress the range sidelobes. We also compare the performance of Barker code and the conventional short pulse in simulation method. The simulation results demonstrate that the performance of the Wiener filter is much better than the matched filter, and Baker code achieves higher elastographic signal-to-noise ratio (SNRe) than the short pulse in low eSNR or great depth conditions due to the increased eSNR with it.

  18. Mixed Connective Tissue Disease

    Science.gov (United States)

    Mixed connective tissue disease Overview Mixed connective tissue disease has signs and symptoms of a combination of disorders — primarily lupus, scleroderma and polymyositis. For this reason, mixed connective tissue disease ...

  19. Undifferentiated Connective Tissue Disease

    Science.gov (United States)

    ... Home Conditions Undifferentiated Connective Tissue Disease (UCTD) Undifferentiated Connective Tissue Disease (UCTD) Make an Appointment Find a Doctor ... by Barbara Goldstein, MD (February 01, 2016) Undifferentiated connective tissue disease (UCTD) is a systemic autoimmune disease. This ...

  20. Soft Tissue Sarcoma

    Science.gov (United States)

    ... muscles, tendons, fat, and blood vessels. Soft tissue sarcoma is a cancer of these soft tissues. There ... have certain genetic diseases. Doctors diagnose soft tissue sarcomas with a biopsy. Treatments include surgery to remove ...

  1. Strains and Sprains

    Science.gov (United States)

    ... lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains may be more likely to happen if you haven't warmed up first to get blood circulating to the muscles. They're also common for someone returning to a sport after the off-season. That first time playing ...

  2. Bacillus cereus strain MCN as a debriding agent

    Science.gov (United States)

    Dalton, H. P.; Haynes, B. W.; Stone, L. L.

    1978-01-01

    Biologically active means are effective for rapidly removing scar tissue caused by burns or corrosive agents. Specially selected strain of bacteria applied to injury site releases enzymes which are active against eschar. These bacteria tend to locate between eschar and unburned tissue, thus providing optimal cell surface area arrangement for enzyme dispersal. Procedure may prove especially useful in treatment of disaster casualties under relatively primitive conditions.

  3. Viscoelastic Properties of Human Tracheal Tissues.

    Science.gov (United States)

    Safshekan, Farzaneh; Tafazzoli-Shadpour, Mohammad; Abdouss, Majid; Shadmehr, Mohammad B

    2017-01-01

    The physiological performance of trachea is highly dependent on its mechanical behavior, and therefore, the mechanical properties of its components. Mechanical characterization of trachea is key to succeed in new treatments such as tissue engineering, which requires the utilization of scaffolds which are mechanically compatible with the native human trachea. In this study, after isolating human trachea samples from brain-dead cases and proper storage, we assessed the viscoelastic properties of tracheal cartilage, smooth muscle, and connective tissue based on stress relaxation tests (at 5% and 10% strains for cartilage and 20%, 30%, and 40% for smooth muscle and connective tissue). After investigation of viscoelastic linearity, constitutive models including Prony series for linear viscoelasticity and quasi-linear viscoelastic, modified superposition, and Schapery models for nonlinear viscoelasticity were fitted to the experimental data to find the best model for each tissue. We also investigated the effect of age on the viscoelastic behavior of tracheal tissues. Based on the results, all three tissues exhibited a (nonsignificant) decrease in relaxation rate with increasing the strain, indicating viscoelastic nonlinearity which was most evident for cartilage and with the least effect for connective tissue. The three-term Prony model was selected for describing the linear viscoelasticity. Among different models, the modified superposition model was best able to capture the relaxation behavior of the three tracheal components. We observed a general (but not significant) stiffening of tracheal cartilage and connective tissue with aging. No change in the stress relaxation percentage with aging was observed. The results of this study may be useful in the design and fabrication of tracheal tissue engineering scaffolds.

  4. Added clinical value of applying myocardial deformation imaging to assess right ventricular function.

    Science.gov (United States)

    Sokalskis, Vladislavs; Peluso, Diletta; Jagodzinski, Annika; Sinning, Christoph

    2017-06-01

    Right heart dysfunction has been found to be a strong prognostic factor predicting adverse outcome in various cardiopulmonary diseases. Conventional echocardiographic measurements can be limited by geometrical assumptions and impaired reproducibility. Speckle tracking-derived strain provides a robust quantification of right ventricular function. It explicitly evaluates myocardial deformation, as opposed to tissue Doppler-derived strain, which is computed from tissue velocity gradients. Right ventricular longitudinal strain provides a sensitive tool for detecting right ventricular dysfunction, even at subclinical levels. Moreover, the longitudinal strain can be applied for prognostic stratification of patients with pulmonary hypertension, pulmonary embolism, and congestive heart failure. Speckle tracking-derived right atrial strain, right ventricular longitudinal strain-derived mechanical dyssynchrony, and three-dimensional echocardiography-derived strain are emerging imaging parameters and methods. Their application in research is paving the way for their clinical use. © 2017, Wiley Periodicals, Inc.

  5. X-ray strain tensor imaging: FEM simulation and experiments with a micro-CT.

    Science.gov (United States)

    Kim, Jae G; Park, So E; Lee, Soo Y

    2014-01-01

    In tissue elasticity imaging, measuring the strain tensor components is necessary to solve the inverse problem. However, it is impractical to measure all the tensor components in ultrasound or MRI elastography because of their anisotropic spatial resolution. The objective of this study is to compute 3D strain tensor maps from the 3D CT images of a tissue-mimicking phantom. We took 3D micro-CT images of the phantom twice with applying two different mechanical compressions to it. Applying the 3D image correlation technique to the CT images under different compression, we computed 3D displacement vectors and strain tensors at every pixel. To evaluate the accuracy of the strain tensor maps, we made a 3D FEM model of the phantom, and we computed strain tensor maps through FEM simulation. Experimentally obtained strain tensor maps showed similar patterns to the FEM-simulated ones in visual inspection. The correlation between the strain tensor maps obtained from the experiment and the FEM simulation ranges from 0.03 to 0.93. Even though the strain tensor maps suffer from high level noise, we expect the x-ray strain tensor imaging may find some biomedical applications such as malignant tissue characterization and stress analysis inside the tissues.

  6. Methodology for dynamic biaxial tension testing of pregnant uterine tissue.

    Science.gov (United States)

    Manoogian, Sarah; Mcnally, Craig; Calloway, Britt; Duma, Stefan

    2007-01-01

    Placental abruption accounts for 50% to 70% of fetal losses in motor vehicle crashes. Since automobile crashes are the leading cause of traumatic fetal injury mortality in the United States, research of this injury mechanism is important. Before research can adequately evaluate current and future restraint designs, a detailed model of the pregnant uterine tissues is necessary. The purpose of this study is to develop a methodology for testing the pregnant uterus in biaxial tension at a rate normally seen in a motor vehicle crash. Since the majority of previous biaxial work has established methods for quasi-static testing, this paper combines previous research and new methods to develop a custom designed system to strain the tissue at a dynamic rate. Load cells and optical markers are used for calculating stress strain curves of the perpendicular loading axes. Results for this methodology show images of a tissue specimen loaded and a finite verification of the optical strain measurement. The biaxial test system dynamically pulls the tissue to failure with synchronous motion of four tissue grips that are rigidly coupled to the tissue specimen. The test device models in situ loading conditions of the pregnant uterus and overcomes previous limitations of biaxial testing. A non-contact method of measuring strains combined with data reduction to resolve the stresses in two directions provides the information necessary to develop a three dimensional constitutive model of the material. Moreover, future research can apply this method to other soft tissues with similar in situ loading conditions.

  7. Strains in general relativity

    International Nuclear Information System (INIS)

    Bini, Donato; Felice, Fernando de; Geralico, Andrea

    2006-01-01

    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a 'fiducial observer'. We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations

  8. Tissue bionics: examples in biomimetic tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Green, David W [Bone and Joint Research Group, Developmental Origins of Health and Disease, General Hospital, University of Southampton, SO16 6YD (United Kingdom)], E-mail: Hindoostuart@googlemail.com

    2008-09-01

    Many important lessons can be learnt from the study of biological form and the functional design of organisms as design criteria for the development of tissue engineering products. This merging of biomimetics and regenerative medicine is termed 'tissue bionics'. Clinically useful analogues can be generated by appropriating, modifying and mimicking structures from a diversity of natural biomatrices ranging from marine plankton shells to sea urchin spines. Methods in biomimetic materials chemistry can also be used to fabricate tissue engineering scaffolds with added functional utility that promise human tissues fit for the clinic.

  9. Tissue bionics: examples in biomimetic tissue engineering

    International Nuclear Information System (INIS)

    Green, David W

    2008-01-01

    Many important lessons can be learnt from the study of biological form and the functional design of organisms as design criteria for the development of tissue engineering products. This merging of biomimetics and regenerative medicine is termed 'tissue bionics'. Clinically useful analogues can be generated by appropriating, modifying and mimicking structures from a diversity of natural biomatrices ranging from marine plankton shells to sea urchin spines. Methods in biomimetic materials chemistry can also be used to fabricate tissue engineering scaffolds with added functional utility that promise human tissues fit for the clinic

  10. Strain Induced Adatom Correlations

    OpenAIRE

    Kappus, Wolfgang

    2012-01-01

    A Born-Green-Yvon type model for adatom density correlations is combined with a model for adatom interactions mediated by the strain in elastic anisotropic substrates. The resulting nonlinear integral equation is solved numerically for coverages from zero to a limit given by stability constraints. W, Nb, Ta and Au surfaces are taken as examples to show the effects of different elastic anisotropy regions. Results of the calculation are shown by appropriate plots and discussed. A mapping to sup...

  11. Ratchetting strain prediction

    International Nuclear Information System (INIS)

    Noban, Mohammad; Jahed, Hamid

    2007-01-01

    A time-efficient method for predicting ratchetting strain is proposed. The ratchetting strain at any cycle is determined by finding the ratchetting rate at only a few cycles. This determination is done by first defining the trajectory of the origin of stress in the deviatoric stress space and then incorporating this moving origin into a cyclic plasticity model. It is shown that at the beginning of the loading, the starting point of this trajectory coincides with the initial stress origin and approaches the mean stress, displaying a power-law relationship with the number of loading cycles. The method of obtaining this trajectory from a standard uniaxial asymmetric cyclic loading is presented. Ratchetting rates are calculated with the help of this trajectory and through the use of a constitutive cyclic plasticity model which incorporates deviatoric stresses and back stresses that are measured with respect to this moving frame. The proposed model is used to predict the ratchetting strain of two types of steels under single- and multi-step loadings. Results obtained agree well with the available experimental measurements

  12. Strain measurement based battery testing

    Science.gov (United States)

    Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

    2017-05-23

    A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

  13. Cardiac biplane strain imaging: initial in vivo experience

    Science.gov (United States)

    Lopata, R. G. P.; Nillesen, M. M.; Verrijp, C. N.; Singh, S. K.; Lammens, M. M. Y.; van der Laak, J. A. W. M.; van Wetten, H. B.; Thijssen, J. M.; Kapusta, L.; de Korte, C. L.

    2010-02-01

    In this study, first we propose a biplane strain imaging method using a commercial ultrasound system, yielding estimation of the strain in three orthogonal directions. Secondly, an animal model of a child's heart was introduced that is suitable to simulate congenital heart disease and was used to test the method in vivo. The proposed approach can serve as a framework to monitor the development of cardiac hypertrophy and fibrosis. A 2D strain estimation technique using radio frequency (RF) ultrasound data was applied. Biplane image acquisition was performed at a relatively low frame rate (dogs with an aortic stenosis. Initial results reveal the feasibility of measuring large radial, circumferential and longitudinal cumulative strain (up to 70%) at a frame rate of 100 Hz. Mean radial strain curves of a manually segmented region-of-interest in the infero-lateral wall show excellent correlation between the measured strain curves acquired in two perpendicular planes. Furthermore, the results show the feasibility and reproducibility of assessing radial, circumferential and longitudinal strains simultaneously. In this preliminary study, three beagles developed an elevated pressure gradient over the aortic valve (Δp: 100-200 mmHg) and myocardial hypertrophy. One dog did not develop any sign of hypertrophy (Δp = 20 mmHg). Initial strain (rate) results showed that the maximum strain (rate) decreased with increasing valvular stenosis (-50%), which is in accordance with previous studies. Histological findings corroborated these results and showed an increase in fibrotic tissue for the hearts with larger pressure gradients (100, 200 mmHg), as well as lower strain and strain rate values.

  14. Cardiac biplane strain imaging: initial in vivo experience

    Energy Technology Data Exchange (ETDEWEB)

    Lopata, R G P; Nillesen, M M; Thijssen, J M; De Korte, C L [Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Verrijp, C N; Lammens, M M Y; Van der Laak, J A W M [Department of Pathology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Singh, S K; Van Wetten, H B [Department of Cardiothoracic Surgery, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Kapusta, L [Pediatric Cardiology, Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)], E-mail: R.Lopata@cukz.umcn.nl

    2010-02-21

    In this study, first we propose a biplane strain imaging method using a commercial ultrasound system, yielding estimation of the strain in three orthogonal directions. Secondly, an animal model of a child's heart was introduced that is suitable to simulate congenital heart disease and was used to test the method in vivo. The proposed approach can serve as a framework to monitor the development of cardiac hypertrophy and fibrosis. A 2D strain estimation technique using radio frequency (RF) ultrasound data was applied. Biplane image acquisition was performed at a relatively low frame rate (<100 Hz) using a commercial platform with an RF interface. For testing the method in vivo, biplane image sequences of the heart were recorded during the cardiac cycle in four dogs with an aortic stenosis. Initial results reveal the feasibility of measuring large radial, circumferential and longitudinal cumulative strain (up to 70%) at a frame rate of 100 Hz. Mean radial strain curves of a manually segmented region-of-interest in the infero-lateral wall show excellent correlation between the measured strain curves acquired in two perpendicular planes. Furthermore, the results show the feasibility and reproducibility of assessing radial, circumferential and longitudinal strains simultaneously. In this preliminary study, three beagles developed an elevated pressure gradient over the aortic valve ({delta}p: 100-200 mmHg) and myocardial hypertrophy. One dog did not develop any sign of hypertrophy ({delta}p = 20 mmHg). Initial strain (rate) results showed that the maximum strain (rate) decreased with increasing valvular stenosis (-50%), which is in accordance with previous studies. Histological findings corroborated these results and showed an increase in fibrotic tissue for the hearts with larger pressure gradients (100, 200 mmHg), as well as lower strain and strain rate values.

  15. Cardiac biplane strain imaging: initial in vivo experience

    International Nuclear Information System (INIS)

    Lopata, R G P; Nillesen, M M; Thijssen, J M; De Korte, C L; Verrijp, C N; Lammens, M M Y; Van der Laak, J A W M; Singh, S K; Van Wetten, H B; Kapusta, L

    2010-01-01

    In this study, first we propose a biplane strain imaging method using a commercial ultrasound system, yielding estimation of the strain in three orthogonal directions. Secondly, an animal model of a child's heart was introduced that is suitable to simulate congenital heart disease and was used to test the method in vivo. The proposed approach can serve as a framework to monitor the development of cardiac hypertrophy and fibrosis. A 2D strain estimation technique using radio frequency (RF) ultrasound data was applied. Biplane image acquisition was performed at a relatively low frame rate (<100 Hz) using a commercial platform with an RF interface. For testing the method in vivo, biplane image sequences of the heart were recorded during the cardiac cycle in four dogs with an aortic stenosis. Initial results reveal the feasibility of measuring large radial, circumferential and longitudinal cumulative strain (up to 70%) at a frame rate of 100 Hz. Mean radial strain curves of a manually segmented region-of-interest in the infero-lateral wall show excellent correlation between the measured strain curves acquired in two perpendicular planes. Furthermore, the results show the feasibility and reproducibility of assessing radial, circumferential and longitudinal strains simultaneously. In this preliminary study, three beagles developed an elevated pressure gradient over the aortic valve (Δp: 100-200 mmHg) and myocardial hypertrophy. One dog did not develop any sign of hypertrophy (Δp = 20 mmHg). Initial strain (rate) results showed that the maximum strain (rate) decreased with increasing valvular stenosis (-50%), which is in accordance with previous studies. Histological findings corroborated these results and showed an increase in fibrotic tissue for the hearts with larger pressure gradients (100, 200 mmHg), as well as lower strain and strain rate values.

  16. Studies on Drosophila radiosensitive strains

    International Nuclear Information System (INIS)

    Varentsova, E.P.; Zakharov, I.A.

    1976-01-01

    45 of radiosensitive strains of Drosophila melanogaster were isolated by Curly/Lobe technique after EMS treatment of Livadia population males. The lethality of non-Curly late larvae after gamma-irradiation (4000r) characterized radiosensitivity strains. Most of them exhibited higher frequency of the spontaneous dominant lethals (up to 69%). The males of 6 strains were semi-sterile. 5 of these strains exhibited higher frequency of X-chromosome non-disjunction

  17. Mimicking biological stress-strain behaviour with synthetic elastomers

    Science.gov (United States)

    Vatankhah-Varnosfaderani, Mohammad; Daniel, William F. M.; Everhart, Matthew H.; Pandya, Ashish A.; Liang, Heyi; Matyjaszewski, Krzysztof; Dobrynin, Andrey V.; Sheiko, Sergei S.

    2017-09-01

    Despite the versatility of synthetic chemistry, certain combinations of mechanical softness, strength, and toughness can be difficult to achieve in a single material. These combinations are, however, commonplace in biological tissues, and are therefore needed for applications such as medical implants, tissue engineering, soft robotics, and wearable electronics. Present materials synthesis strategies are predominantly Edisonian, involving the empirical mixing of assorted monomers, crosslinking schemes, and occluded swelling agents, but this approach yields limited property control. Here we present a general strategy for mimicking the mechanical behaviour of biological materials by precisely encoding their stress-strain curves in solvent-free brush- and comb-like polymer networks (elastomers). The code consists of three independent architectural parameters—network strand length, side-chain length and grafting density. Using prototypical poly(dimethylsiloxane) elastomers, we illustrate how this parametric triplet enables the replication of the strain-stiffening characteristics of jellyfish, lung, and arterial tissues.

  18. Strain induced adatom correlations

    Science.gov (United States)

    Kappus, Wolfgang

    2012-12-01

    A Born-Green-Yvon type model for adatom density correlations is combined with a model for adatom interactions mediated by the strain in elastic anisotropic substrates. The resulting nonlinear integral equation is solved numerically for coverages from zero to a limit given by stability constraints. W, Nb, Ta and Au surfaces are taken as examples to show the effects of different elastic anisotropy regions. Results of the calculation are shown by appropriate plots and discussed. A mapping to superstructures is tried. Corresponding adatom configurations from Monte Carlo simulations are shown.

  19. Strain actuated aeroelastic control

    Science.gov (United States)

    Lazarus, Kenneth B.

    1992-01-01

    Viewgraphs on strain actuated aeroelastic control are presented. Topics covered include: structural and aerodynamic modeling; control law design methodology; system block diagram; adaptive wing test article; bench-top experiments; bench-top disturbance rejection: open and closed loop response; bench-top disturbance rejection: state cost versus control cost; wind tunnel experiments; wind tunnel gust alleviation: open and closed loop response at 60 mph; wind tunnel gust alleviation: state cost versus control cost at 60 mph; wind tunnel command following: open and closed loop error at 60 mph; wind tunnel flutter suppression: open loop flutter speed; and wind tunnel flutter suppression: closed loop state cost curves.

  20. Neuromuscular Strain Increases Symptom Intensity in Chronic Fatigue Syndrome.

    Directory of Open Access Journals (Sweden)

    Peter C Rowe

    Full Text Available Chronic fatigue syndrome (CFS is a complex, multisystem disorder that can be disabling. CFS symptoms can be provoked by increased physical or cognitive activity, and by orthostatic stress. In preliminary work, we noted that CFS symptoms also could be provoked by application of longitudinal neural and soft tissue strain to the limbs and spine of affected individuals. In this study we measured the responses to a straight leg raise neuromuscular strain maneuver in individuals with CFS and healthy controls. We randomly assigned 60 individuals with CFS and 20 healthy controls to either a 15 minute period of passive supine straight leg raise (true neuromuscular strain or a sham straight leg raise. The primary outcome measure was the symptom intensity difference between the scores during and 24 hours after the study maneuver compared to baseline. Fatigue, body pain, lightheadedness, concentration difficulties, and headache scores were measured individually on a 0-10 scale, and summed to create a composite symptom score. Compared to individuals with CFS in the sham strain group, those with CFS in the true strain group reported significantly increased body pain (P = 0.04 and concentration difficulties (P = 0.02 as well as increased composite symptom scores (all P = 0.03 during the maneuver. After 24 hours, the symptom intensity differences were significantly greater for the CFS true strain group for the individual symptom of lightheadedness (P = 0.001 and for the composite symptom score (P = 0.005. During and 24 hours after the exposure to the true strain maneuver, those with CFS had significantly higher individual and composite symptom intensity changes compared to the healthy controls. We conclude that a longitudinal strain applied to the nerves and soft tissues of the lower limb is capable of increasing symptom intensity in individuals with CFS for up to 24 hours. These findings support our preliminary observations that increased mechanical

  1. Antimicrobial resistance of bacterial strains isolated from avian cellulitis

    Directory of Open Access Journals (Sweden)

    MM Santos

    2014-03-01

    Full Text Available Avian cellulitis is an inflammatory process in the subcutaneous tissue, mainly located in the abdomen and thighs. This problem is commonly observed in poultry at slaughter and it is considered one of the major causes of condemnation of carcasses in Brazil. The aim of this study was to perform the microbial isolation of lesions of avian cellulitis from a processing plant located in the State of Goiás in order to analyze antimicrobial resistance by antibiogram test and to detect resistance genes by polymerase chain reaction. A total of 25 samples of avian cellulitis lesions were analyzed, from which 30 bacterial strains were isolated. There were eleven (44% strains of Escherichia coli, nine (36% strains of Staphylococcus epidermidis, seven (28% strains of Proteus mirabilis and three (12% strains of Manheimiahaemolytica. The antibiogram test showed that all strains were resistant to at least one antimicrobial. The gene of antimicrobial resistance tetB was detected in E. coli, S. epidermidis and P. mirabilis strains, and was the most frequently observed gene. The gene of antimicrobial resistance Sul1 was detected in all bacterial species, while tetA was found in E. coli and S. epidermidis strains, SHV in E. coli strains, S. epidermidis and P. mirabilis,and cat1 in one P. mirabilis strain. The results suggest a potential public health hazard due to the ability of these microorganisms to transmit antimicrobial resistancegenes to other microorganisms present in the intestinal tract of humans and animals, which may affect clinical-medical usage of these drugs.

  2. Differential growth of Mycobacterium leprae strains (SNP genotypes) in armadillos.

    Science.gov (United States)

    Sharma, Rahul; Singh, Pushpendra; Pena, Maria; Subramanian, Ramesh; Chouljenko, Vladmir; Kim, Joohyun; Kim, Nayong; Caskey, John; Baudena, Marie A; Adams, Linda B; Truman, Richard W

    2018-04-14

    Leprosy (Hansen's Disease) has occurred throughout human history, and persists today at a low prevalence in most populations. Caused by Mycobacterium leprae, the infection primarily involves the skin, mucosa and peripheral nerves. The susceptible host range for Mycobacterium leprae is quite narrow. Besides humans, nine banded armadillos (Dasypus novemcinctus) and red squirrels (Sciurus vulgaris) are the only other natural hosts for M. leprae, but only armadillos recapitulate the disease as seen in humans. Armadillos across the Southern United States harbor a single predominant genotypic strain (SNP Type-3I) of M. leprae, which is also implicated in the zoonotic transmission of leprosy. We investigated, whether the zoonotic strain (3I) has any notable growth advantages in armadillos over another genetically distant strain-type (SNP Type-4P) of M. leprae, and if M. leprae strains manifest any notably different pathology among armadillos. We co-infected armadillos (n = 6) with 2 × 10 9 highly viable M. leprae of both strains and assessed the relative growth and dissemination of each strain in the animals. We also analyzed 12 additional armadillos, 6 each individually infected with the same quantity of either strain. The infections were allowed to fulminate and the clinical manifestations of the disease were noted. Animals were humanely sacrificed at the terminal stage of infection and the number of bacilli per gram of liver, spleen and lymph node tissue were enumerated by Q-PCR assay. The growth of M. leprae strain 4P was significantly higher (P leprae strains within armadillos suggest there are notable pathological variations between M. leprae strain-types. Copyright © 2018. Published by Elsevier B.V.

  3. Strain and Vibration in Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Brooke McClarren

    2018-01-01

    Full Text Available Mesenchymal stem cells (MSCs are multipotent cells capable of differentiating into any mesenchymal tissue, including bone, cartilage, muscle, and fat. MSC differentiation can be influenced by a variety of stimuli, including environmental and mechanical stimulation, scaffold physical properties, or applied loads. Numerous studies have evaluated the effects of vibration or cyclic tensile strain on MSCs towards developing a mechanically based method of differentiation, but there is no consensus between studies and each investigation uses different culture conditions, which also influence MSC fate. Here we present an overview of the response of MSCs to vibration and cyclic tension, focusing on the effect of various culture conditions and strain or vibration parameters. Our review reveals that scaffold type (e.g., natural versus synthetic; 2D versus 3D can influence cell response to vibration and strain to the same degree as loading parameters. Hence, in the efforts to use mechanical loading as a reliable method to differentiate cells, scaffold selection is as important as method of loading.

  4. Plant tissue culture techniques

    Directory of Open Access Journals (Sweden)

    Rolf Dieter Illg

    1991-01-01

    Full Text Available Plant cell and tissue culture in a simple fashion refers to techniques which utilize either single plant cells, groups of unorganized cells (callus or organized tissues or organs put in culture, under controlled sterile conditions.

  5. Plant Tissue Culture

    Indian Academy of Sciences (India)

    Admin

    Plant tissue culture is a technique of culturing plant cells, tissues and organs on ... working methods (Box 2) and discovery of the need for B vita- mins and auxins for ... Kotte (Germany) reported some success with growing isolated root tips.

  6. Breast reconstruction - natural tissue

    Science.gov (United States)

    ... flap; TRAM; Latissimus muscle flap with a breast implant; DIEP flap; DIEAP flap; Gluteal free flap; Transverse upper gracilis flap; TUG; Mastectomy - breast reconstruction with natural tissue; Breast cancer - breast reconstruction with natural tissue

  7. FRD tissue archive

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The fishery genetics tissue collection has over 80,000 tissues stored in 95% ethanol representing fishes and invertebrates collected globally but with a focus on the...

  8. Tissue banking in australia.

    Science.gov (United States)

    Ireland, Lynette; McKelvie, Helen

    2003-01-01

    The legal structure for the regulation of tissue banking has existed for many years. In Australia, the donation of human tissue is regulated by legislation in each of the eight States and Territories. These substantially uniform Acts were passed in the late 1970's and early 1980's, based on model legislation and underpinned by the concept of consensual giving. However, it was not until the early 1990's that tissue banking came under the notice of regulatory authorities. Since then the Australian Government has moved quickly to oversee the tissue banking sector in Australia. Banked human tissue has been deemed to be a therapeutic good under the Therapeutic Goods Act 1989, and tissue banks are required to be licensed by the Therapeutic Goods Administration and are audited for compliance with the Code of Good Manufacturing Practice- Human Blood and Tissues. In addition, tissue banks must comply with a myriad of other standards, guidelines and recommendations.

  9. Breast Cancer Tissue Repository

    National Research Council Canada - National Science Library

    Iglehart, J

    1997-01-01

    The Breast Tissue Repository at Duke enters its fourth year of finding. The purpose of the Repository at Duke is to provide substantial quantities of frozen tissue for explorative molecular studies...

  10. Coronaviruses in brain tissue from patients with multiple sclerosis

    DEFF Research Database (Denmark)

    Dessau, R B; Lisby, G; Frederiksen, J L

    2001-01-01

    Brain tissue from 25 patients with clinically definite multiple sclerosis (MS) and as controls brain tissue from 36 patients without neurological disease was tested for the presence of human coronaviral RNA. Four PCR assays with primers specific for N-protein of human coronavirus strain 229E...... and three PCR assays with primers specific for the nucleocapsid protein of human coronavirus strain OC43 were performed. Sporadic positive PCR assays were observed in both patients and controls in some of the PCR assays. However, these results were not reproducible and there was no difference...... in the proportion of positive signals from the MS patients compared to controls. Evidence for a chronic infection with the human coronaviruses strain 229E or OC43 in brain tissue from patients with MS or controls has not been found in this study....

  11. Visual Measurement of Suture Strain for Robotic Surgery

    Directory of Open Access Journals (Sweden)

    John Martell

    2011-01-01

    Full Text Available Minimally invasive surgical procedures offer advantages of smaller incisions, decreased hospital length of stay, and rapid postoperative recovery to the patient. Surgical robots improve access and visualization intraoperatively and have expanded the indications for minimally invasive procedures. A limitation of the DaVinci surgical robot is a lack of sensory feedback to the operative surgeon. Experienced robotic surgeons use visual interpretation of tissue and suture deformation as a surrogate for tactile feedback. A difficulty encountered during robotic surgery is maintaining adequate suture tension while tying knots or following a running anastomotic suture. Displaying suture strain in real time has potential to decrease the learning curve and improve the performance and safety of robotic surgical procedures. Conventional strain measurement methods involve installation of complex sensors on the robotic instruments. This paper presents a noninvasive video processing-based method to determine strain in surgical sutures. The method accurately calculates strain in suture by processing video from the existing surgical camera, making implementation uncomplicated. The video analysis method was developed and validated using video of suture strain standards on a servohydraulic testing system. The video-based suture strain algorithm is shown capable of measuring suture strains of 0.2% with subpixel resolution and proven reliability under various conditions.

  12. Development of tissue bank

    Directory of Open Access Journals (Sweden)

    R P Narayan

    2012-01-01

    Full Text Available The history of tissue banking is as old as the use of skin grafting for resurfacing of burn wounds. Beneficial effects of tissue grafts led to wide spread use of auto and allograft for management of varied clinical conditions like skin wounds, bone defects following trauma or tumor ablation. Availability of adequate amount of tissues at the time of requirement was the biggest challenge that forced clinicians to find out techniques to preserve the living tissue for prolonged period of time for later use and thus the foundation of tissue banking was started in early twentieth century. Harvesting, processing, storage and transportation of human tissues for clinical use is the major activity of tissue banks. Low temperature storage of processed tissue is the best preservation technique at present. Tissue banking organization is a very complex system and needs high technical expertise and skilled personnel for proper functioning in a dedicated facility. A small lapse/deviation from the established protocol leads to loss of precious tissues and or harm to recipients as well as the risk of transmission of deadly diseases and tumors. Strict tissue transplant acts and stringent regulations help to streamline the whole process of tissue banking safe for recipients and to community as whole.

  13. Connective Tissue Disorders

    Science.gov (United States)

    ... of connective tissue. Over 200 disorders that impact connective tissue. There are different types: Genetic disorders, such as Ehlers-Danlos syndrome, Marfan syndrome, and osteogenesis imperfecta Autoimmune disorders, such as lupus and scleroderma Cancers, like some types of soft tissue sarcoma Each ...

  14. Colony Dimorphism in Bradyrhizobium Strains

    Science.gov (United States)

    Sylvester-Bradley, Rosemary; Thornton, Philip; Jones, Peter

    1988-01-01

    Ten isolates of Bradyrhizobium spp. which form two colony types were studied; the isolates originated from a range of legume species. The two colony types differed in the amount of gum formed or size or both, depending on the strain. Whole 7-day-old colonies of each type were subcultured to determine the proportion of cells which had changed to the other type. An iterative computerized procedure was used to determine the rate of switching per generation between the two types and to predict proportions reached at equilibrium for each strain. The predicted proportions of the wetter (more gummy) or larger colony type at equilibrium differed significantly between strains, ranging from 0.9999 (strain CIAT 2383) to 0.0216 (strain CIAT 2469), because some strains switched faster from dry to wet (or small to large) and others switched faster from wet to dry (or large to small). Predicted equilibrium was reached after about 140 generations in strain USDA 76. In all but one strain (CIAT 3030) the growth rate of the wetter colony type was greater than or similar to that of the drier type. The mean difference in generation time between the two colony types was 0.37 h. Doubling times calculated for either colony type after 7 days of growth on the agar surface ranged from 6.0 to 7.3 h. The formation of two persistent colony types by one strain (clonal or colony dimorphism) may be a common phenomenon among Bradyrhizobium strains. Images PMID:16347599

  15. Viscoelastic properties of bovine orbital connective tissue and fat: constitutive models.

    Science.gov (United States)

    Yoo, Lawrence; Gupta, Vijay; Lee, Choongyeop; Kavehpore, Pirouz; Demer, Joseph L

    2011-12-01

    Reported mechanical properties of orbital connective tissue and fat have been too sparse to model strain-stress relationships underlying biomechanical interactions in strabismus. We performed rheological tests to develop a multi-mode upper convected Maxwell (UCM) model of these tissues under shear loading. From 20 fresh bovine orbits, 30 samples of connective tissue were taken from rectus pulley regions and 30 samples of fatty tissues from the posterior orbit. Additional samples were defatted to determine connective tissue weight proportion, which was verified histologically. Mechanical testing in shear employed a triborheometer to perform: strain sweeps at 0.5-2.0 Hz; shear stress relaxation with 1% strain; viscometry at 0.01-0.5 s(-1) strain rate; and shear oscillation at 1% strain. Average connective tissue weight proportion was 98% for predominantly connective tissue and 76% for fatty tissue. Connective tissue specimens reached a long-term relaxation modulus of 668 Pa after 1,500 s, while corresponding values for fatty tissue specimens were 290 Pa and 1,100 s. Shear stress magnitude for connective tissue exceeded that of fatty tissue by five-fold. Based on these data, we developed a multi-mode UCM model with variable viscosities and time constants, and a damped hyperelastic response that accurately described measured properties of both connective and fatty tissues. Model parameters differed significantly between the two tissues. Viscoelastic properties of predominantly connective orbital tissues under shear loading differ markedly from properties of orbital fat, but both are accurately reflected using UCM models. These viscoelastic models will facilitate realistic global modeling of EOM behavior in binocular alignment and strabismus.

  16. Evaluation of Brucella abortus strain RB51 and strain 19 in pronghorn antelope

    Science.gov (United States)

    Elzer, P.H.; Smith, J.; Roffe, T.; Kreeger, T.; Edwards, J.; Davis, D.

    2002-01-01

    Free-roaming elk and bison in the Greater Yellowstone Area remain the only wildlife reservoirs for Brucella abortus in the United States, and the large number of animals and a lack of holding facilities make it unreasonable to individually vaccinate each animal. Therefore, oral delivery is being proposed as a possible option to vaccinate these wild ungulates. One of the main problems associated with oral vaccination is the potential exposure of nontarget species to the vaccines. The purpose of this study was to determine the effects of two Brucella vaccines, strain 19 (S19) and the rough strain RB51 (SRB51), in pregnant pronghorn antelope. We conclude that S19 and SRB51 rarely colonize maternal and fetal tissues of pregnant pronghorn and were not associated with fetal death. Oral delivery of either vaccine at this dose appears to be nonhazardous to pregnant pronghorn.

  17. Emergent material properties of developing epithelial tissues.

    Science.gov (United States)

    Machado, Pedro F; Duque, Julia; Étienne, Jocelyn; Martinez-Arias, Alfonso; Blanchard, Guy B; Gorfinkiel, Nicole

    2015-11-23

    Force generation and the material properties of cells and tissues are central to morphogenesis but remain difficult to measure in vivo. Insight is often limited to the ratios of mechanical properties obtained through disruptive manipulation, and the appropriate models relating stress and strain are unknown. The Drosophila amnioserosa epithelium progressively contracts over 3 hours of dorsal closure, during which cell apices exhibit area fluctuations driven by medial myosin pulses with periods of 1.5-6 min. Linking these two timescales and understanding how pulsatile contractions drive morphogenetic movements is an urgent challenge. We present a novel framework to measure in a continuous manner the mechanical properties of epithelial cells in the natural context of a tissue undergoing morphogenesis. We show that the relationship between apicomedial myosin fluorescence intensity and strain during fluctuations is consistent with a linear behaviour, although with a lag. We thus used myosin fluorescence intensity as a proxy for active force generation and treated cells as natural experiments of mechanical response under cyclic loading, revealing unambiguous mechanical properties from the hysteresis loop relating stress to strain. Amnioserosa cells can be described as a contractile viscoelastic fluid. We show that their emergent mechanical behaviour can be described by a linear viscoelastic rheology at timescales relevant for tissue morphogenesis. For the first time, we establish relative changes in separate effective mechanical properties in vivo. Over the course of dorsal closure, the tissue solidifies and effective stiffness doubles as net contraction of the tissue commences. Combining our findings with those from previous laser ablation experiments, we show that both apicomedial and junctional stress also increase over time, with the relative increase in apicomedial stress approximately twice that of other obtained measures. Our results show that in an epithelial

  18. Morphogenesis and Biomechanics of Engineered Skin Cultured Under Uniaxial Strain.

    Science.gov (United States)

    Blackstone, Britani N; Powell, Heather M

    2012-04-01

    Split-thickness autograft is the standard wound treatment for full-thickness burns. In large burns, sparse availability of uninjured skin prevents rapid closure of the wound, resulting in increased scar tissue formation or mortality. Tissue-engineered skin (ES) offers promise when autografts are not available. ES, constructed from a polymeric scaffold and skin cells, has been shown to reduce donor site area required to permanently close wounds, mortality, and morbidity from scarring but cannot restore all skin functions. Current generations of ES are orders of magnitude weaker than normal human skin, leading to difficulty in surgical application, greater susceptibility to mechanical damage during fabrication and application, and less elasticity and strength once engrafted. Previous studies to improve ES biomechanics focus on altering the scaffolding material, which resulted in modest improvements but often inhibited proper skin development. As the skin is naturally under static strain, adding these mechanical cues to the culture environment is hypothesized to improve ES biomechanics. ES was cultured under applied static strains ranging from 0% to 40% strain for a total of 10 days. Strain magnitudes of 10% and 20% strain resulted in significantly stronger ES than unstrained controls, showed upregulation of many genes encoding structural extracellular matrix proteins, and exhibited increased epidermal cell proliferation and differentiation. Enhanced biomechanical properties of ES can allow for facile surgical application and less damage during dressing changes. These findings suggest that mechanical cues play a significant role in skin development and should be further explored.

  19. Strain Pattern in Supercooled Liquids

    Science.gov (United States)

    Illing, Bernd; Fritschi, Sebastian; Hajnal, David; Klix, Christian; Keim, Peter; Fuchs, Matthias

    2016-11-01

    Investigations of strain correlations at the glass transition reveal unexpected phenomena. The shear strain fluctuations show an Eshelby-strain pattern [˜cos (4 θ ) /r2 ], characteristic of elastic response, even in liquids, at long times. We address this using a mode-coupling theory for the strain fluctuations in supercooled liquids and data from both video microscopy of a two-dimensional colloidal glass former and simulations of Brownian hard disks. We show that the long-ranged and long-lived strain signatures follow a scaling law valid close to the glass transition. For large enough viscosities, the Eshelby-strain pattern is visible even on time scales longer than the structural relaxation time τ and after the shear modulus has relaxed to zero.

  20. Cell and Tissue Engineering

    CERN Document Server

    2012-01-01

    “Cell and Tissue Engineering” introduces the principles and new approaches in cell and tissue engineering. It includes both the fundamentals and the current trends in cell and tissue engineering, in a way useful both to a novice and an expert in the field. The book is composed of 13 chapters all of which are written by the leading experts. It is organized to gradually assemble an insight in cell and tissue function starting form a molecular nano-level, extending to a cellular micro-level and finishing at the tissue macro-level. In specific, biological, physiological, biophysical, biochemical, medical, and engineering aspects are covered from the standpoint of the development of functional substitutes of biological tissues for potential clinical use. Topics in the area of cell engineering include cell membrane biophysics, structure and function of the cytoskeleton, cell-extracellular matrix interactions, and mechanotransduction. In the area of tissue engineering the focus is on the in vitro cultivation of ...

  1. Engineering Complex Tissues

    Science.gov (United States)

    MIKOS, ANTONIOS G.; HERRING, SUSAN W.; OCHAREON, PANNEE; ELISSEEFF, JENNIFER; LU, HELEN H.; KANDEL, RITA; SCHOEN, FREDERICK J.; TONER, MEHMET; MOONEY, DAVID; ATALA, ANTHONY; VAN DYKE, MARK E.; KAPLAN, DAVID; VUNJAK-NOVAKOVIC, GORDANA

    2010-01-01

    This article summarizes the views expressed at the third session of the workshop “Tissue Engineering—The Next Generation,” which was devoted to the engineering of complex tissue structures. Antonios Mikos described the engineering of complex oral and craniofacial tissues as a “guided interplay” between biomaterial scaffolds, growth factors, and local cell populations toward the restoration of the original architecture and function of complex tissues. Susan Herring, reviewing osteogenesis and vasculogenesis, explained that the vascular arrangement precedes and dictates the architecture of the new bone, and proposed that engineering of osseous tissues might benefit from preconstruction of an appropriate vasculature. Jennifer Elisseeff explored the formation of complex tissue structures based on the example of stratified cartilage engineered using stem cells and hydrogels. Helen Lu discussed engineering of tissue interfaces, a problem critical for biological fixation of tendons and ligaments, and the development of a new generation of fixation devices. Rita Kandel discussed the challenges related to the re-creation of the cartilage-bone interface, in the context of tissue engineered joint repair. Frederick Schoen emphasized, in the context of heart valve engineering, the need for including the requirements derived from “adult biology” of tissue remodeling and establishing reliable early predictors of success or failure of tissue engineered implants. Mehmet Toner presented a review of biopreservation techniques and stressed that a new breakthrough in this field may be necessary to meet all the needs of tissue engineering. David Mooney described systems providing temporal and spatial regulation of growth factor availability, which may find utility in virtually all tissue engineering and regeneration applications, including directed in vitro and in vivo vascularization of tissues. Anthony Atala offered a clinician’s perspective for functional tissue

  2. Hydrogen production from microbial strains

    Science.gov (United States)

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  3. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast...... to uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...

  4. Small RNA expression and strain specificity in the rat

    Directory of Open Access Journals (Sweden)

    de Bruijn Ewart

    2010-04-01

    Full Text Available Abstract Background Digital gene expression (DGE profiling has become an established tool to study RNA expression. Here, we provide an in-depth analysis of small RNA DGE profiles from two different rat strains (BN-Lx and SHR from six different rat tissues (spleen, liver, brain, testis, heart, kidney. We describe the expression patterns of known and novel micro (miRNAs and piwi-interacting (piRNAs. Results We confirmed the expression of 588 known miRNAs (54 in antisense orientation and identified 56 miRNAs homologous to known human or mouse miRNAs, as well as 45 new rat miRNAs. Furthermore, we confirmed specific A to I editing in brain for mir-376a/b/c and identified mir-377 as a novel editing target. In accordance with earlier findings, we observed a highly tissue-specific expression pattern for all tissues analyzed. The brain was found to express the highest number of tissue-specific miRNAs, followed by testis. Notably, our experiments also revealed robust strain-specific differential miRNA expression in the liver that is caused by genetic variation between the strains. Finally, we identified two types of germline-specific piRNAs in testis, mapping either to transposons or in strand-specific clusters. Conclusions Taken together, the small RNA compendium described here advances the annotation of small RNAs in the rat genome. Strain and tissue-specific expression patterns furthermore provide a strong basis for studying the role of small RNAs in regulatory networks as well as biological process like physiology and neurobiology that are extensively studied in this model system.

  5. Stochastic precision analysis of 2D cardiac strain estimation in vivo

    International Nuclear Information System (INIS)

    Bunting, E A; Provost, J; Konofagou, E E

    2014-01-01

    Ultrasonic strain imaging has been applied to echocardiography and carries great potential to be used as a tool in the clinical setting. Two-dimensional (2D) strain estimation may be useful when studying the heart due to the complex, 3D deformation of the cardiac tissue. Increasing the framerate used for motion estimation, i.e. motion estimation rate (MER), has been shown to improve the precision of the strain estimation, although maintaining the spatial resolution necessary to view the entire heart structure in a single heartbeat remains challenging at high MERs. Two previously developed methods, the temporally unequispaced acquisition sequence (TUAS) and the diverging beam sequence (DBS), have been used in the past to successfully estimate in vivo axial strain at high MERs without compromising spatial resolution. In this study, a stochastic assessment of 2D strain estimation precision is performed in vivo for both sequences at varying MERs (65, 272, 544, 815 Hz for TUAS; 250, 500, 1000, 2000 Hz for DBS). 2D incremental strains were estimated during left ventricular contraction in five healthy volunteers using a normalized cross-correlation function and a least-squares strain estimator. Both sequences were shown capable of estimating 2D incremental strains in vivo. The conditional expected value of the elastographic signal-to-noise ratio (E(SNRe|ε)) was used to compare strain estimation precision of both sequences at multiple MERs over a wide range of clinical strain values. The results here indicate that axial strain estimation precision is much more dependent on MER than lateral strain estimation, while lateral estimation is more affected by strain magnitude. MER should be increased at least above 544 Hz to avoid suboptimal axial strain estimation. Radial and circumferential strain estimations were influenced by the axial and lateral strain in different ways. Furthermore, the TUAS and DBS were found to be of comparable precision at similar MERs. (paper)

  6. DNA from keratinous tissue

    DEFF Research Database (Denmark)

    Bengtsson, Camilla F.; Olsen, Maja E.; Brandt, Luise Ørsted

    2011-01-01

    Keratinous tissues such as nail, hair, horn, scales and feather have been used as a source of DNA for over 20 years. Particular benefits of such tissues include the ease with which they can be sampled, the relative stability of DNA in such tissues once sampled, and, in the context of ancient...... genetic analyses, the fact that sampling generally causes minimal visual damage to valuable specimens. Even when freshly sampled, however, the DNA quantity and quality in the fully keratinized parts of such tissues is extremely poor in comparison to other tissues such as blood and muscle – although little...... systematic research has been undertaken to characterize how such degradation may relate to sample source. In this review paper we present the current understanding of the quality and limitations of DNA in two key keratinous tissues, nail and hair. The findings indicate that although some fragments of nuclear...

  7. Tissue engineering in dentistry.

    Science.gov (United States)

    Abou Neel, Ensanya Ali; Chrzanowski, Wojciech; Salih, Vehid M; Kim, Hae-Won; Knowles, Jonathan C

    2014-08-01

    of this review is to inform practitioners with the most updated information on tissue engineering and its potential applications in dentistry. The authors used "PUBMED" to find relevant literature written in English and published from the beginning of tissue engineering until today. A combination of keywords was used as the search terms e.g., "tissue engineering", "approaches", "strategies" "dentistry", "dental stem cells", "dentino-pulp complex", "guided tissue regeneration", "whole tooth", "TMJ", "condyle", "salivary glands", and "oral mucosa". Abstracts and full text articles were used to identify causes of craniofacial tissue loss, different approaches for craniofacial reconstructions, how the tissue engineering emerges, different strategies of tissue engineering, biomaterials employed for this purpose, the major attempts to engineer different dental structures, finally challenges and future of tissue engineering in dentistry. Only those articles that dealt with the tissue engineering in dentistry were selected. There have been a recent surge in guided tissue engineering methods to manage periodontal diseases beyond the traditional approaches. However, the predictable reconstruction of the innate organisation and function of whole teeth as well as their periodontal structures remains challenging. Despite some limited progress and minor successes, there remain distinct and important challenges in the development of reproducible and clinically safe approaches for oral tissue repair and regeneration. Clearly, there is a convincing body of evidence which confirms the need for this type of treatment, and public health data worldwide indicates a more than adequate patient resource. The future of these therapies involving more biological approaches and the use of dental tissue stem cells is promising and advancing. Also there may be a significant interest of their application and wider potential to treat disorders beyond the craniofacial region. Considering the

  8. Biomaterials for Tissue Engineering

    Science.gov (United States)

    Lee, Esther J.; Kasper, F. Kurtis; Mikos, Antonios G.

    2013-01-01

    Biomaterials serve as an integral component of tissue engineering. They are designed to provide architectural framework reminiscent of native extracellular matrix in order to encourage cell growth and eventual tissue regeneration. Bone and cartilage represent two distinct tissues with varying compositional and mechanical properties. Despite these differences, both meet at the osteochondral interface. This article presents an overview of current biomaterials employed in bone and cartilage applications, discusses some design considerations, and alludes to future prospects within this field of research. PMID:23820768

  9. Nutritionally fastidious Ruminococct $ flovefociens : strains

    African Journals Online (AJOL)

    than those obtained in a medium containing rumen fluid. Growth of all strains was remarkably uniform. Where the same inoculum was used, differences in the qualitative com- position of the medium usually had little effect on growth. In contrast, the R. f/avefaciens strains were much more variable in their growth responses.

  10. Haldane model under nonuniform strain

    Science.gov (United States)

    Ho, Yen-Hung; Castro, Eduardo V.; Cazalilla, Miguel A.

    2017-10-01

    We study the Haldane model under strain using a tight-binding approach, and compare the obtained results with the continuum-limit approximation. As in graphene, nonuniform strain leads to a time-reversal preserving pseudomagnetic field that induces (pseudo-)Landau levels. Unlike a real magnetic field, strain lifts the degeneracy of the zeroth pseudo-Landau levels at different valleys. Moreover, for the zigzag edge under uniaxial strain, strain removes the degeneracy within the pseudo-Landau levels by inducing a tilt in their energy dispersion. The latter arises from next-to-leading order corrections to the continuum-limit Hamiltonian, which are absent for a real magnetic field. We show that, for the lowest pseudo-Landau levels in the Haldane model, the dominant contribution to the tilt is different from graphene. In addition, although strain does not strongly modify the dispersion of the edge states, their interplay with the pseudo-Landau levels is different for the armchair and zigzag ribbons. Finally, we study the effect of strain in the band structure of the Haldane model at the critical point of the topological transition, thus shedding light on the interplay between nontrivial topology and strain in quantum anomalous Hall systems.

  11. Multiphase poroelastic finite element models for soft tissue structures

    International Nuclear Information System (INIS)

    Simon, B.R.

    1992-01-01

    During the last two decades, biological structures with soft tissue components have been modeled using poroelastic or mixture-based constitutive laws, i.e., the material is viewed as a deformable (porous) solid matrix that is saturated by mobile tissue fluid. These structures exhibit a highly nonlinear, history-dependent material behavior; undergo finite strains; and may swell or shrink when tissue ionic concentrations are altered. Give the geometric and material complexity of soft tissue structures and that they are subjected to complicated initial and boundary conditions, finite element models (FEMs) have been very useful for quantitative structural analyses. This paper surveys recent applications of poroelastic and mixture-based theories and the associated FEMs for the study of the biomechanics of soft tissues, and indicates future directions for research in this area. Equivalent finite-strain poroelastic and mixture continuum biomechanical models are presented. Special attention is given to the identification of material properties using a porohyperelastic constitutive law ans a total Lagrangian view for the formulation. The associated FEMs are then formulated to include this porohyperelastic material response and finite strains. Extensions of the theory are suggested in order to include inherent viscoelasticity, transport phenomena, and swelling in soft tissue structures. A number of biomechanical research areas are identified, and possible applications of the porohyperelastic and mixture-based FEMs are suggested. 62 refs., 11 figs., 3 tabs

  12. Pin clad strains in Phenix

    International Nuclear Information System (INIS)

    Languille, A.

    1979-07-01

    The Phenix reactor has operated for 4 years in a satisfactory manner. The first 2 sub-assembly loadings contained pins clad in solution treated 316. The principal pin strains are: diametral strain (swelling and irradiation creep), ovality and spiral bending of the pin (interaction of wire and pin cluster and wrapper). A pin cluster irradiated to a dose of 80 dpa F reached a pin diameter strain of 5%. This strain is principally due to swelling (low fission gas pressure). The principal parameters governing the swelling are instantaneous dose, time and temperature for a given type of pin cladding. Other types of steel are or will be irradiated in Phenix. In particular, cold-worked titanium stabilised 316 steel should contribute towards a reduction in the pin clad strains and increase the target burn-up in this reactor. (author)

  13. Optical coherence elastography assesses tissue modifications in laser reshaping of cornea and cartilages

    Science.gov (United States)

    Zaitsev, V. Y.; Matveyev, A. L.; Matveev, L. A.; Gelikonov, G. V.; Omelchenko, A. I.; Shabanov, D. V.; Sovetsky, A. A.; Baum, O. I.; Vitkin, A.; Sobol, E. N.

    2018-02-01

    Non-surgical thermo-mechanical reshaping of avascular collagenous tissues (cartilages and cornea) using moderate heating by IR-laser irradiation is an emerging technology that can find important applications in visioncorrection problems and preparation of cartilaginous implants in otolaryngology. To estimate both transient interframe strains and cumulative resultant strains produced by the laser irradiation of the tissue we use and improved version of strain mapping developed in our previous work related to compressional phase-sensitive optical coherence tomography. To reveal microstructural changes in the tissue regions where irradiation-produced strains do not disappear after temperature equilibration, we apply compressional optical coherence elastography in order to visualize the resultant variations in the tissue stiffness. The so-found regions of the stiffness reduction are attributed to formation of microscopic pores, existence of which agree with independent data obtained using methods of high-resolution microscopy.

  14. Mouse genetic approaches applied to the normal tissue radiation response

    International Nuclear Information System (INIS)

    Haston, Christina K.

    2012-01-01

    The varying responses of inbred mouse models to radiation exposure present a unique opportunity to dissect the genetic basis of radiation sensitivity and tissue injury. Such studies are complementary to human association studies as they permit both the analysis of clinical features of disease, and of specific variants associated with its presentation, in a controlled environment. Herein I review how animal models are studied to identify specific genetic variants influencing predisposition to radiation-induced traits. Among these radiation-induced responses are documented strain differences in repair of DNA damage and in extent of tissue injury (in the lung, skin, and intestine) which form the base for genetic investigations. For example, radiation-induced DNA damage is consistently greater in tissues from BALB/cJ mice, than the levels in C57BL/6J mice, suggesting there may be an inherent DNA damage level per strain. Regarding tissue injury, strain specific inflammatory and fibrotic phenotypes have been documented for principally, C57BL/6 C3H and A/J mice but a correlation among responses such that knowledge of the radiation injury in one tissue informs of the response in another is not evident. Strategies to identify genetic differences contributing to a trait based on inbred strain differences, which include linkage analysis and the evaluation of recombinant congenic (RC) strains, are presented, with a focus on the lung response to irradiation which is the only radiation-induced tissue injury mapped to date. Such approaches are needed to reveal genetic differences in susceptibility to radiation injury, and also to provide a context for the effects of specific genetic variation uncovered in anticipated clinical association studies. In summary, mouse models can be studied to uncover heritable variation predisposing to specific radiation responses, and such variations may point to pathways of importance to phenotype development in the clinic.

  15. Strain expansion-reduction approach

    Science.gov (United States)

    Baqersad, Javad; Bharadwaj, Kedar

    2018-02-01

    Validating numerical models are one of the main aspects of engineering design. However, correlating million degrees of freedom of numerical models to the few degrees of freedom of test models is challenging. Reduction/expansion approaches have been traditionally used to match these degrees of freedom. However, the conventional reduction/expansion approaches are only limited to displacement, velocity or acceleration data. While in many cases only strain data are accessible (e.g. when a structure is monitored using strain-gages), the conventional approaches are not capable of expanding strain data. To bridge this gap, the current paper outlines a reduction/expansion technique to reduce/expand strain data. In the proposed approach, strain mode shapes of a structure are extracted using the finite element method or the digital image correlation technique. The strain mode shapes are used to generate a transformation matrix that can expand the limited set of measurement data. The proposed approach can be used to correlate experimental and analytical strain data. Furthermore, the proposed technique can be used to expand real-time operating data for structural health monitoring (SHM). In order to verify the accuracy of the approach, the proposed technique was used to expand the limited set of real-time operating data in a numerical model of a cantilever beam subjected to various types of excitations. The proposed technique was also applied to expand real-time operating data measured using a few strain gages mounted to an aluminum beam. It was shown that the proposed approach can effectively expand the strain data at limited locations to accurately predict the strain at locations where no sensors were placed.

  16. Experimental Evaluation of the Pathogenicity of Different Strains of Schistosoma mansoni

    Directory of Open Access Journals (Sweden)

    Antônio Aurélio Euzébio

    2012-01-01

    Full Text Available The pathogenesis of three different Schistosoma mansoni strains from the Brazilian states of Minas Gerais (BH strain and São Paulo (SJ and SD strains was evaluated in experimentally infected mice. Observations of the most severe clinical cases among local patients treated (SD strain in the city of Campinas (São Paulo, Brazil formed the basis of this study. Mice were used as definitive hosts and were infected with cercariae from Biomphalaria tenagophila (SJ and SD strains and Biomphalaria glabrata (BH strains. The parameters analyzed were as follows: number of S. mansoni eggs in mice feces; number of granulomas per tissue area in liver, spleen, lungs, pancreas, and ascending colon; measurements of hepatic and intestinal granulomas; number of adult worms; and measurements of trematode eggs. The comparison among the three strains indicated that the SD strain, isolated in Campinas, presented a higher worm recovery relative to the number of penetrating cercariae. In addition, when compared to the SJ and BH strains, the SD strain demonstrated similar pathogenicity to the BH strain, with a greater quantity of granulomas in the viscera, as well as larger granulomas and eggs. Furthermore, a greater quantity of trematode eggs was also shed in the feces.

  17. Can tissues be owned?

    African Journals Online (AJOL)

    2013-06-17

    Jun 17, 2013 ... Regulations Regarding Rendering of Clinical Forensic Medicine ... 1 Special Interest Research Group on Biotechnology and Medical Law of the College of Law, University of ... persons for the following medical and dental purposes: ... tissue to the international market were taking tissue without consent.

  18. Neural tissue-spheres

    DEFF Research Database (Denmark)

    Andersen, Rikke K; Johansen, Mathias; Blaabjerg, Morten

    2007-01-01

    By combining new and established protocols we have developed a procedure for isolation and propagation of neural precursor cells from the forebrain subventricular zone (SVZ) of newborn rats. Small tissue blocks of the SVZ were dissected and propagated en bloc as free-floating neural tissue...... content, thus allowing experimental studies of neural precursor cells and their niche...

  19. Determination of friction coefficient in unconfined compression of brain tissue.

    Science.gov (United States)

    Rashid, Badar; Destrade, Michel; Gilchrist, Michael D

    2012-10-01

    Unconfined compression tests are more convenient to perform on cylindrical samples of brain tissue than tensile tests in order to estimate mechanical properties of the brain tissue because they allow homogeneous deformations. The reliability of these tests depends significantly on the amount of friction generated at the specimen/platen interface. Thus, there is a crucial need to find an approximate value of the friction coefficient in order to predict a possible overestimation of stresses during unconfined compression tests. In this study, a combined experimental-computational approach was adopted to estimate the dynamic friction coefficient μ of porcine brain matter against metal platens in compressive tests. Cylindrical samples of porcine brain tissue were tested up to 30% strain at variable strain rates, both under bonded and lubricated conditions in the same controlled environment. It was established that μ was equal to 0.09±0.03, 0.18±0.04, 0.18±0.04 and 0.20±0.02 at strain rates of 1, 30, 60 and 90/s, respectively. Additional tests were also performed to analyze brain tissue under lubricated and bonded conditions, with and without initial contact of the top platen with the brain tissue, with different specimen aspect ratios and with different lubricants (Phosphate Buffer Saline (PBS), Polytetrafluoroethylene (PTFE) and Silicone). The test conditions (lubricant used, biological tissue, loading velocity) adopted in this study were similar to the studies conducted by other research groups. This study will help to understand the amount of friction generated during unconfined compression of brain tissue for strain rates of up to 90/s. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Ultrasound elastography assessment of bone/soft tissue interface

    International Nuclear Information System (INIS)

    Parmar, Biren J; Yang, Xu; Chaudhry, Anuj; Shajudeen, Peer Shafeeq; Nair, Sanjay P; Righetti, Raffaella; Weiner, Bradley K; Tasciotti, Ennio; Krouskop, Thomas A

    2016-01-01

    We report on the use of elastographic imaging techniques to assess the bone/soft tissue interface, a region that has not been previously investigated but may provide important information about fracture and bone healing. The performance of axial strain elastograms and axial shear strain elastograms at the bone/soft tissue interface was studied ex vivo on intact and fractured canine and ovine tibias. Selected ex vivo results were corroborated on intact sheep tibias in vivo. The elastography results were statistically analyzed using elastographic image quality tools. The results of this study demonstrate distinct patterns in the distribution of the normalized local axial strains and axial shear strains at the bone/soft tissue interface with respect to the background soft tissue. They also show that the relative strength and distribution of the elastographic parameters change in the presence of a fracture and depend on the degree of misalignment between the fracture fragments. Thus, elastographic imaging modalities might be used in the future to obtain information regarding the integrity of bones and to assess the severity of fractures, alignment of bone fragments as well as to follow bone healing. (paper)

  1. Ultrasound elastography assessment of bone/soft tissue interface

    Science.gov (United States)

    Parmar, Biren J.; Yang, Xu; Chaudhry, Anuj; Shafeeq Shajudeen, Peer; Nair, Sanjay P.; Weiner, Bradley K.; Tasciotti, Ennio; Krouskop, Thomas A.; Righetti, Raffaella

    2016-01-01

    We report on the use of elastographic imaging techniques to assess the bone/soft tissue interface, a region that has not been previously investigated but may provide important information about fracture and bone healing. The performance of axial strain elastograms and axial shear strain elastograms at the bone/soft tissue interface was studied ex vivo on intact and fractured canine and ovine tibias. Selected ex vivo results were corroborated on intact sheep tibias in vivo. The elastography results were statistically analyzed using elastographic image quality tools. The results of this study demonstrate distinct patterns in the distribution of the normalized local axial strains and axial shear strains at the bone/soft tissue interface with respect to the background soft tissue. They also show that the relative strength and distribution of the elastographic parameters change in the presence of a fracture and depend on the degree of misalignment between the fracture fragments. Thus, elastographic imaging modalities might be used in the future to obtain information regarding the integrity of bones and to assess the severity of fractures, alignment of bone fragments as well as to follow bone healing.

  2. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... of the cross rolled volume fraction is found. To further asses this effect, and the anisotropy, it is necessary to acquire knowledge about both texture and microstructure, e.g. by TEM. Roll bonding of pre-strained aluminium is found to be a possible alternative to ARB in the quest for ultra-fine grained...

  3. Strain fluctuations and elastic constants

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, M.; Rahman, A.

    1982-03-01

    It is shown that the elastic strain fluctuations are a direct measure of elastic compliances in a general anisotropic medium; depending on the ensemble in which the fluctuation is measured either the isothermal or the adiabatic compliances are obtained. These fluctuations can now be calculated in a constant enthalpy and pressure, and hence, constant entropy, ensemble due to recent develpments in the molecular dynamics techniques. A calculation for a Ni single crystal under uniform uniaxial 100 tensile or compressive load is presented as an illustration of the relationships derived between various strain fluctuations and the elastic modulii. The Born stability criteria and the behavior of strain fluctuations are shown to be related.

  4. Strain accumulation in quasicrystalline solids

    International Nuclear Information System (INIS)

    Nori, F.; Ronchetti, M.; Elser, V.

    1988-01-01

    We study the relaxation of 2D quasicrystalline elastic networks when their constituent bonds are perturbed homogeneously. Whereas ideal, quasiperiodic networks are stable against such perturbations, we find significant accumulations of strain in a class of disordered networks generated by a growth process. The grown networks are characterized by root mean square phason fluctuations which grow linearly with system size. The strain accumulation we observe in these networks also grows linearly with system size. Finally, we find a dependence of strain accumulation on cooling rate

  5. Serum protein changes in immune and nonimmune pigeons infected with various strains of Trichomonas gallinae

    Science.gov (United States)

    Kocan, R.M.; Herman, C.M.

    1970-01-01

    Serum protein changes were studied in immune and nonimmune pigeons infected with three different strains of Trichomonas gallinae. Strain I (nonvirulent) produced no change in the relative concentration of serum components. Strains II (oral canker) and III (Jones' Barn) produced decreases in albumin and alpha globulins, and increases in beta and gamma globulins between the 7th and 20th days post infection. Birds infected with strain II began to return to normal by the 20th day, while all those infected with strain III were dead between 10 and 14 days post infection. Two serum protein patterns resulted from infection of immune birds with the Jones' Barn strain. One showed no change in relative protein concentrations and no tissue invasion by the parasite while the other was similar to that seen in nonimmune birds infected with a strain producing oral canker. These also showed evidence of tissue invasion by the parasite. It was concluded that tissue invasion was necessary to evoke a quantitative change in serum protein concentrations.

  6. Micromechanics and constitutive modeling of connective soft tissues.

    Science.gov (United States)

    Fallah, A; Ahmadian, M T; Firozbakhsh, K; Aghdam, M M

    2016-07-01

    In this paper, a micromechanical model for connective soft tissues based on the available histological evidences is developed. The proposed model constituents i.e. collagen fibers and ground matrix are considered as hyperelastic materials. The matrix material is assumed to be isotropic Neo-Hookean while the collagen fibers are considered to be transversely isotropic hyperelastic. In order to take into account the effects of tissue structure in lower scales on the macroscopic behavior of tissue, a strain energy density function (SEDF) is developed for collagen fibers based on tissue hierarchical structure. Macroscopic response and properties of tissue are obtained using the numerical homogenization method with the help of ABAQUS software. The periodic boundary conditions and the proposed constitutive models are implemented into ABAQUS using the DISP and the UMAT subroutines, respectively. The existence of the solution and stable material behavior of proposed constitutive model for collagen fibers are investigated based on the poly-convexity condition. Results of the presented micromechanics model for connective tissues are compared and validated with available experimental data. Effects of geometrical and material parameters variation at microscale on macroscopic mechanical behavior of tissues are investigated. The results show that decrease in collagen content of the connective tissues like the tendon due to diseases leads 20% more stretch than healthy tissue under the same load which can results in connective tissue malfunction and hypermobility in joints. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Dynamic impact indentation of hydrated biological tissues and tissue surrogate gels

    Science.gov (United States)

    Ilke Kalcioglu, Z.; Qu, Meng; Strawhecker, Kenneth E.; Shazly, Tarek; Edelman, Elazer; VanLandingham, Mark R.; Smith, James F.; Van Vliet, Krystyn J.

    2011-03-01

    For both materials engineering research and applied biomedicine, a growing need exists to quantify mechanical behaviour of tissues under defined hydration and loading conditions. In particular, characterisation under dynamic contact-loading conditions can enable quantitative predictions of deformation due to high rate 'impact' events typical of industrial accidents and ballistic insults. The impact indentation responses were examined of both hydrated tissues and candidate tissue surrogate materials. The goals of this work were to determine the mechanical response of fully hydrated soft tissues under defined dynamic loading conditions, and to identify design principles by which synthetic, air-stable polymers could mimic those responses. Soft tissues from two organs (liver and heart), a commercially available tissue surrogate gel (Perma-Gel™) and three styrenic block copolymer gels were investigated. Impact indentation enabled quantification of resistance to penetration and energy dissipative constants under the rates and energy densities of interest for tissue surrogate applications. These analyses indicated that the energy dissipation capacity under dynamic impact increased with increasing diblock concentration in the styrenic gels. Under the impact rates employed (2 mm/s to 20 mm/s, corresponding to approximate strain energy densities from 0.4 kJ/m3 to 20 kJ/m3), the energy dissipation capacities of fully hydrated soft tissues were ultimately well matched by a 50/50 triblock/diblock composition that is stable in ambient environments. More generally, the methodologies detailed here facilitate further optimisation of impact energy dissipation capacity of polymer-based tissue surrogate materials, either in air or in fluids.

  8. Strain localisation in granular media

    OpenAIRE

    Desrues , Jacques

    1984-01-01

    This study is devoted to strain localisation in Granular materials. Both experimental and theoretical results have been obtained.The first part of the thesis is a review of the methods and theories about rupture in sols mechanics and more generally, in solid mechanics. The classical framework of Shear Band analysis is presented, and the main results available for different classes of materials are discussed.The second part describes an experimental study of strain localisation in sand specime...

  9. Tattoo-Like Strain Gauges Based on Silicon Nano-Membranes

    Science.gov (United States)

    Lu, Nanshu

    2012-02-01

    This talk reports the in vivo measurement of tissue deformation through adhesive-free, conformable lamination of a tattoo-like elastic strain gauge consisted of piezoresistive silicon nano-membranes strategically integrated with tissue-like elastomeric substrates. The mechanical deformation in soft tissues cannot yet be directly quantified due to the lack of enabling tools. While stiff strain gauges for structural health monitoring have long existed, biological tissues are soft, curvilinear and highly deformable in contrast to civil or aerospace structures. An ultra-thin, ultra-soft, tattoo-like strain gauge that can conform to the convoluted surface of human body and stay attached during locomotion will be able to directly quantify tissue deformation without affecting the mechanical behavior of the tissue. While single crystalline silicon is known to have the highest gauge factor and best elastic response, it is intrinsically stiff and brittle. To achieve strain gauges with high compliance, high stretchability and reasonable sensitivity, single crystalline silicon nano-membranes will be transfer-printed onto polymeric support through carefully engineered stamps. The thickness and length of the Si strip will be chosen according to theoretical and numerical mechanics analysis which takes into account for the tradeoff between stretchability and sensitivity.

  10. Soft Tissue Biomechanical Modeling for Computer Assisted Surgery

    CERN Document Server

    2012-01-01

      This volume focuses on the biomechanical modeling of biological tissues in the context of Computer Assisted Surgery (CAS). More specifically, deformable soft tissues are addressed since they are the subject of the most recent developments in this field. The pioneering works on this CAS topic date from the 1980's, with applications in orthopaedics and biomechanical models of bones. More recently, however, biomechanical models of soft tissues have been proposed since most of the human body is made of soft organs that can be deformed by the surgical gesture. Such models are much more complicated to handle since the tissues can be subject to large deformations (non-linear geometrical framework) as well as complex stress/strain relationships (non-linear mechanical framework). Part 1 of the volume presents biomechanical models that have been developed in a CAS context and used during surgery. This is particularly new since most of the soft tissues models already proposed concern Computer Assisted Planning, with ...

  11. Insulin action in adipose tissue and muscle in hypothyroidism.

    Science.gov (United States)

    Dimitriadis, George; Mitrou, Panayota; Lambadiari, Vaia; Boutati, Eleni; Maratou, Eirini; Panagiotakos, Demosthenes B; Koukkou, Efi; Tzanela, Marinela; Thalassinos, Nikos; Raptis, Sotirios A

    2006-12-01

    Although insulin resistance in thyroid hormone excess is well documented, information on insulin action in hypothyroidism is limited. To investigate this, a meal was given to 11 hypothyroid (HO; aged 45 +/- 3 yr) and 10 euthyroid subjects (EU; aged 42 +/- 4 yr). Blood was withdrawn for 360 min from veins (V) draining the anterior abdominal sc adipose tissue and the forearm and from the radial artery (A). Blood flow (BF) in adipose tissue was measured with 133Xe and in forearm with strain-gauge plethysmography. Tissue glucose uptake was calculated as (A-V)glucose(BF), lipoprotein lipase as (A-V)Triglycerides(BF), and lipolysis as [(V-A)glycerol(BF)]-lipoprotein lipase. The HO group had higher glucose and insulin levels than the EU group (P hypothyroidism: 1) glucose uptake in muscle and adipose tissue is resistant to insulin; 2) suppression of lipolysis by insulin is not impaired; and 3) hypertriglyceridemia is due to decreased clearance by the adipose tissue.

  12. Synovial tissue research

    DEFF Research Database (Denmark)

    Orr, Carl; Sousa, Elsa; Boyle, David L

    2017-01-01

    The synovium is the major target tissue of inflammatory arthritides such as rheumatoid arthritis. The study of synovial tissue has advanced considerably throughout the past few decades from arthroplasty and blind needle biopsy to the use of arthroscopic and ultrasonographic technologies that enable...... easier visualization and improve the reliability of synovial biopsies. Rapid progress has been made in using synovial tissue to study disease pathogenesis, to stratify patients, to discover biomarkers and novel targets, and to validate therapies, and this progress has been facilitated by increasingly...... diverse and sophisticated analytical and technological approaches. In this Review, we describe these approaches, and summarize how their use in synovial tissue research has improved our understanding of rheumatoid arthritis and identified candidate biomarkers that could be used in disease diagnosis...

  13. Optical tomography of tissues

    International Nuclear Information System (INIS)

    Zimnyakov, D A; Tuchin, Valerii V

    2002-01-01

    Methods of optical tomography of biological tissues are considered, which include pulse-modulation and frequency-modulation tomography, diffusion tomography with the use of cw radiation sources, optical coherent tomography, speckle-correlation tomography of nonstationary media, and optoacoustic tomography. The method for controlling the optical properties of tissues is studied from the point of view of increasing a probing depth in optical coherent tomography. The modern state and prospects of the development of optical tomography are discussed. (review)

  14. Determination of a tissue-level failure evaluation standard for rat femoral cortical bone utilizing a hybrid computational-experimental method.

    Science.gov (United States)

    Fan, Ruoxun; Liu, Jie; Jia, Zhengbin; Deng, Ying; Liu, Jun

    2018-01-01

    Macro-level failure in bone structure could be diagnosed by pain or physical examination. However, diagnosing tissue-level failure in a timely manner is challenging due to the difficulty in observing the interior mechanical environment of bone tissue. Because most fractures begin with tissue-level failure in bone tissue caused by continually applied loading, people attempt to monitor the tissue-level failure of bone and provide corresponding measures to prevent fracture. Many tissue-level mechanical parameters of bone could be predicted or measured; however, the value of the parameter may vary among different specimens belonging to a kind of bone structure even at the same age and anatomical site. These variations cause difficulty in representing tissue-level bone failure. Therefore, determining an appropriate tissue-level failure evaluation standard is necessary to represent tissue-level bone failure. In this study, the yield and failure processes of rat femoral cortical bones were primarily simulated through a hybrid computational-experimental method. Subsequently, the tissue-level strains and the ratio between tissue-level failure and yield strains in cortical bones were predicted. The results indicated that certain differences existed in tissue-level strains; however, slight variations in the ratio were observed among different cortical bones. Therefore, the ratio between tissue-level failure and yield strains for a kind of bone structure could be determined. This ratio may then be regarded as an appropriate tissue-level failure evaluation standard to represent the mechanical status of bone tissue.

  15. Nondestructive and noninvasive assessment of mechanical properties in heart valve tissue engineering

    NARCIS (Netherlands)

    Kortsmit, J.; Driessen, N.J.B.; Rutten, M.C.M.; Baaijens, F.P.T.

    2009-01-01

    Despite recent progress, mechanical behavior of tissue-engineered heart valves still needs improvement when native aortic valves are considered as a benchmark. Although it is known that cyclic straining enhances tissue formation, optimal loading protocols have not been defined yet. To obtain a

  16. Design and Validation of a Cyclic Strain Bioreactor to Condition Spatially-Selective Scaffolds in Dual Strain Regimes

    Directory of Open Access Journals (Sweden)

    J. Matthew Goodhart

    2014-03-01

    Full Text Available The objective of this study was to design and validate a unique bioreactor design for applying spatially selective, linear, cyclic strain to degradable and non-degradable polymeric fabric scaffolds. This system uses a novel three-clamp design to apply cyclic strain via a computer controlled linear actuator to a specified zone of a scaffold while isolating the remainder of the scaffold from strain. Image analysis of polyethylene terephthalate (PET woven scaffolds subjected to a 3% mechanical stretch demonstrated that the stretched portion of the scaffold experienced 2.97% ± 0.13% strain (mean ± standard deviation while the unstretched portion experienced 0.02% ± 0.18% strain. NIH-3T3 fibroblast cells were cultured on the PET scaffolds and half of each scaffold was stretched 5% at 0.5 Hz for one hour per day for 14 days in the bioreactor. Cells were checked for viability and proliferation at the end of the 14 day period and levels of glycosaminoglycan (GAG and collagen (hydroxyproline were measured as indicators of extracellular matrix production. Scaffolds in the bioreactor showed a seven-fold increase in cell number over scaffolds cultured statically in tissue culture plastic petri dishes (control. Bioreactor scaffolds showed a lower concentration of GAG deposition per cell as compared to the control scaffolds largely due to the great increase in cell number. A 75% increase in hydroxyproline concentration per cell was seen in the bioreactor stretched scaffolds as compared to the control scaffolds. Surprisingly, little differences were experienced between the stretched and unstretched portions of the scaffolds for this study. This was largely attributed to the conditioned and shared media effect. Results indicate that the bioreactor system is capable of applying spatially-selective, linear, cyclic strain to cells growing on polymeric fabric scaffolds and evaluating the cellular and matrix responses to the applied strains.

  17. Multi-axial mechanical stimulation of tissue engineered cartilage: Review

    Directory of Open Access Journals (Sweden)

    S D Waldman

    2007-04-01

    Full Text Available The development of tissue engineered cartilage is a promising new approach for the repair of damaged or diseased tissue. Since it has proven difficult to generate cartilaginous tissue with properties similar to that of native articular cartilage, several studies have used mechanical stimuli as a means to improve the quantity and quality of the developed tissue. In this study, we have investigated the effect of multi-axial loading applied during in vitro tissue formation to better reflect the physiological forces that chondrocytes are subjected to in vivo. Dynamic combined compression-shear stimulation (5% compression and 5% shear strain amplitudes increased both collagen and proteoglycan synthesis (76 ± 8% and 73 ± 5%, respectively over the static (unstimulated controls. When this multi-axial loading condition was applied to the chondrocyte cultures over a four week period, there were significant improvements in both extracellular matrix (ECM accumulation and the mechanical properties of the in vitro-formed tissue (3-fold increase in compressive modulus and 1.75-fold increase in shear modulus. Stimulated tissues were also significantly thinner than the static controls (19% reduction suggesting that there was a degree of ECM consolidation as a result of long-term multi-axial loading. This study demonstrated that stimulation by multi-axial forces can improve the quality of the in vitro-formed tissue, but additional studies are required to further optimize the conditions to favour improved biochemical and mechanical properties of the developed tissue.

  18. Preliminary Evaluation of Probiotic Properties of Lactobacillus Strains Isolated from Sardinian Dairy Products

    OpenAIRE

    Pisano, Maria Barbara; Viale, Silvia; Conti, Stefania; Fadda, Maria Elisabetta; Deplano, Maura; Melis, Maria Paola; Deiana, Monica; Cosentino, Sofia

    2014-01-01

    Twenty-three Lactobacillus strains of dairy origin were evaluated for some functional properties relevant to their use as probiotics. A preliminary subtractive screening based on the abilities to inhibit the growth of microbial pathogens and hydrolyze conjugated bile salts was applied, and six strains were selected for further characterization including survival under gastrointestinal environmental conditions, adhesion to gut epithelial tissue, enzymatic activity, and some safety properties. ...

  19. Job strain and male fertility.

    Science.gov (United States)

    Hjollund, Niels Henrik I; Bonde, Jens Peter E; Henriksen, Tine Brink; Giwercman, Aleksander; Olsen, Jørn

    2004-01-01

    Job strain, defined as high job demands and low job control, has not previously been explored as a possible determinant of male fertility. We collected prospective data on job strain among men, and describe the associations with semen quality and probability of conceiving a clinical pregnancy during a menstrual cycle. Danish couples (N = 399) who were trying to become pregnant for the first time were followed for up to 6 menstrual periods. All men collected semen samples, and a blood sample was drawn from both partners. Job demand and job control were measured by a self-administered questionnaire at entry, and in each cycle the participants recorded changes in job control or job demand during the previous 30 days. In adjusted analyses, no associations were found between any semen characteristic or sexual hormones and any job strain variable. The odds for pregnancy were not associated with job strain. Psychologic job strain encountered in normal jobs in Denmark does not seem to affect male reproductive function.

  20. Planar strain analysis of liver undergoing microwave thermal ablation using x-ray CT.

    Science.gov (United States)

    Weiss, Noam; Goldberg, S Nahum; Nissenbaum, Yitzhak; Sosna, Jacob; Azhari, Haim

    2015-01-01

    To study the planar strain effects in liver during microwave (MW) thermal ablation as a means for tracking tissue expansion and contraction as a method for improving ablation monitoring. 1.4 mm circular metallic markers were inserted into 16 ex-vivo bovine fresh liver specimens, that were subsequently ablated (with the markers inside the specimen) by 40 W of microwave energy, for 1, 2, 3, 6, and 10 min. The markers were tracked during the ablation using an x-ray CT scanner. Images were acquired every 5-10 s enabling determination of the markers' coordinates over time. The 2D principal strains were calculated for triangles formed by subgroups of three markers, and their planar strain index, Ω, was plotted vs time. In addition, the radial distance of the markers from the antenna was measured at the end of each ablation. Subsequently, the tissue was sliced parallel to the imaged planes and the ablation zone was traced and digitized. The average ablation radius was then computed and compared to the radial distance. The planar strain, Ω(t), profile demonstrated an ascending pattern until reaching a maximum at about 180 s, with a mean peak value (Ω = 1.31 ± 0.04) indicating tissue expansion. Thereafter, Ω progressively declined over the remaining duration of the ablation treatment, indicating tissue contraction. Furthermore, when plotting the ablation size vs time and the markers' mean radial distance vs time, it was found that the two curves intercepted at a time corresponding to the time of peak planar strain. By detecting the point of maximal planar strain in tissues during MW application, it is possible to noninvasively identify the location of the ablation zone front. The fact that the liver tissue proximal to the ablated zone expands during the first part of the treatment and then contracts when the ablation front reaches it, may serve as an index for monitoring the thermal treatment.

  1. Mechanical cues in orofacial tissue engineering and regenerative medicine.

    Science.gov (United States)

    Brouwer, Katrien M; Lundvig, Ditte M S; Middelkoop, Esther; Wagener, Frank A D T G; Von den Hoff, Johannes W

    2015-01-01

    Cleft lip and palate patients suffer from functional, aesthetical, and psychosocial problems due to suboptimal regeneration of skin, mucosa, and skeletal muscle after restorative cleft surgery. The field of tissue engineering and regenerative medicine (TE/RM) aims to restore the normal physiology of tissues and organs in conditions such as birth defects or after injury. A crucial factor in cell differentiation, tissue formation, and tissue function is mechanical strain. Regardless of this, mechanical cues are not yet widely used in TE/RM. The effects of mechanical stimulation on cells are not straight-forward in vitro as cellular responses may differ with cell type and loading regime, complicating the translation to a therapeutic protocol. We here give an overview of the different types of mechanical strain that act on cells and tissues and discuss the effects on muscle, and skin and mucosa. We conclude that presently, sufficient knowledge is lacking to reproducibly implement external mechanical loading in TE/RM approaches. Mechanical cues can be applied in TE/RM by fine-tuning the stiffness and architecture of the constructs to guide the differentiation of the seeded cells or the invading surrounding cells. This may already improve the treatment of orofacial clefts and other disorders affecting soft tissues. © 2015 by the Wound Healing Society.

  2. [Connective tissue and inflammation].

    Science.gov (United States)

    Jakab, Lajos

    2014-03-23

    The author summarizes the structure of the connective tissues, the increasing motion of the constituents, which determine the role in establishing the structure and function of that. The structure and function of the connective tissue are related to each other in the resting as well as inflammatory states. It is emphasized that cellular events in the connective tissue are part of the defence of the organism, the localisation of the damage and, if possible, the maintenance of restitutio ad integrum. The organism responds to damage with inflammation, the non specific immune response, as well as specific, adaptive immunity. These processes are located in the connective tissue. Sterile and pathogenic inflammation are relatively similar processes, but inevitable differences are present, too. Sialic acids and glycoproteins containing sialic acids have important roles, and the role of Siglecs is also highlighted. Also, similarities and differences in damages caused by pathogens and sterile agents are briefly summarized. In addition, the roles of adhesion molecules linked to each other, and the whole event of inflammatory processes are presented. When considering practical consequences it is stressed that the structure (building up) of the organism and the defending function of inflammation both have fundamental importance. Inflammation has a crucial role in maintaining the integrity and the unimpaired somato-psychological state of the organism. Thus, inflammation serves as a tool of organism identical with the natural immune response, inseparably connected with the specific, adaptive immune response. The main events of the inflammatory processes take place in the connective tissue.

  3. Autopsy Tissue Program

    International Nuclear Information System (INIS)

    Fox, T.; Tietjen, G.

    1979-01-01

    The Autopsy Tissue Program was begun in 1960. To date, tissues on 900 or more persons in 7 geographic regions have been collected and analyzed for plutonium content. The tissues generally consist of lung, liver, kidney, lymph, bone, and gonadal tissue for each individual. The original objective of the program was to determine the level of plutonium in human tissues due solely to fall-out from weapons testing. The baseline thus established was to be used to evaluate future changes. From the first, this program was beset with chemical and statistical difficulties. Many factors whose effects were not recognized and not planned for were found later to be important. Privacy and ethical considerations hindered the gathering of adequate data. Since the chemists were looking for amounts of plutonium very close to background, possible contamination was a very real problem. Widely used chemical techniques introduced a host of statistical problems. The difficulties encountered touch on areas common to large data sets, unusual outlier detection methods, minimum detection limits, problems with Aliquot sizes, and time-trends in the data. The conclusions point out areas to which the biologists will have to devote much more careful attention than was believed

  4. Morphology of urethral tissues

    Science.gov (United States)

    Müller, Bert; Schulz, Georg; Herzen, Julia; Mushkolaj, Shpend; Bormann, Therese; Beckmann, Felix; Püschel, Klaus

    2010-09-01

    Micro computed tomography has been developed to a powerful technique for the characterization of hard and soft human and animal tissues. Soft tissues including the urethra, however, are difficult to be analyzed, since the microstructures of interest exhibit X-ray absorption values very similar to the surroundings. Selective staining using highly absorbing species is a widely used approach, but associated with significant tissue modification. Alternatively, one can suitably embed the soft tissue, which requires the exchange of water. Therefore, the more recently developed phase contrast modes providing much better contrast of low X-ray absorbing species are especially accommodating in soft tissue characterization. The present communication deals with the morphological characterization of sheep, pig and human urethras on the micrometer scale taking advantage of micro computed tomography in absorption and phase contrast modes. The performance of grating-based tomography is demonstrated for freshly explanted male and female urethras in saline solution. The micro-morphology of the urethra is important to understand how the muscles close the urethra to reach continence. As the number of incontinent patients is steadily increasing, the function under static and, more important, under stress conditions has to be uncovered for the realization of artificial urinary sphincters, which needs sophisticated, biologically inspired concepts to become nature analogue.

  5. A duplex PCR assay for the detection of Ralstonia solanacearum phylotype II strains in Musa spp.

    Directory of Open Access Journals (Sweden)

    Gilles Cellier

    Full Text Available Banana wilt outbreaks that are attributable to Moko disease-causing strains of the pathogen Ralstonia solanacearum (Rs remain a social and economic burden for both multinational corporations and subsistence farmers. All known Moko strains belong to the phylotype II lineage, which has been previously recognized for its broad genetic basis. Moko strains are paraphyletic and are distributed among seven related but distinct phylogenetic clusters (sequevars that are potentially major threats to Musaceae, Solanaceae, and ornamental crops in many countries. Although clustered within the Moko IIB-4 sequevar, strains of the epidemiologically variant IIB-4NPB do not cause wilt on Cavendish or plantain bananas; instead, they establish a latent infection in the vascular tissues of plantains and demonstrate an expanded host range and high aggressiveness toward Solanaceae and Cucurbitaceae. Although most molecular diagnostic methods focus on strains that wilt Solanaceae (particularly potato, no relevant protocol has been described that universally detects strains of the Musaceae-infecting Rs phylotype II. Thus, a duplex PCR assay targeting Moko and IIB-4NPB variant strains was developed, and its performance was assessed using an extensive collection of 111 strains representing the known diversity of Rs Moko-related strains and IIB-4NPB variant strains along with certain related strains and families. The proposed diagnostic protocol demonstrated both high accuracy (inclusivity and exclusivity and high repeatability, detected targets on either pure culture or spiked plant extracts. Although they did not belong to the Moko clusters described at the time of the study, recently discovered banana-infecting strains from Brazil were also detected. According to our comprehensive evaluation, this duplex PCR assay appears suitable for both research and diagnostic laboratories and provides reliable detection of phylotype II Rs strains that infect Musaceae.

  6. Crack tip stress and strain

    International Nuclear Information System (INIS)

    Francois, D.

    1975-01-01

    The study of potential energy variations in a loaded elastic solid containing a crack leads to determination of the crack driving force G. Generalization of this concept to cases other than linear elasticity leads to definition of the integral J. In a linear solid, the crack tip stress field is characterized by a single parameter: the stress-intensity factor K. When the crack tip plastic zone size is confined to the elastic singularity J=G, it is possible to establish relationship between these parameters and plastic strain (and in particular the crack tip opening displacement delta). The stress increases because of the triaxiality effect. This overload rises with increasing strain hardening. When the plastic zone size expands, using certain hypotheses, delta can be calculated. The plastic strain intensity is exclusively dependent on parameter J [fr

  7. Management of digital eye strain.

    Science.gov (United States)

    Coles-Brennan, Chantal; Sulley, Anna; Young, Graeme

    2018-05-23

    Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5 Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer

  8. Tissue Engineering Initiative

    Science.gov (United States)

    2000-08-01

    forefoot with the foot in the neutral position, and (b) similar to (a) but with heel landing. Although the authors reported no absolute strain values...diameter of sensors (or, in the case of a rectangular sensor, width as measured along pin axis). Worst case : Strike line from inside edges of sensors...potoroo it is just prior to "toe strike ". The locomotion of the potoroo is described as digitigrade, unlike humans, who walk in a plantigrade manner

  9. Skeletal muscle connective tissue

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline

    in the structure of fibrous collagen and myofibers at high-resolution. The results demonstrate that the collagen composition in the extra cellular matrix of Gadus morhua fish muscle is much more complex than previously anticipated, as it contains type III, IV, V  and VI collagen in addition to type I. The vascular....... Consequently, functional structures, ensuring "tissue maintenance" must form a major role of connective tissue, in addition that is to the force transmitting structures one typically finds in muscle. Vascular structures have also been shown to change their mechanical properties with age and it has been shown...

  10. Noncontacting-optical-strain device

    Science.gov (United States)

    Silver, R. H.

    1970-01-01

    Noncontacting-strain-measuring gauge and extensometer remotely measures the mechanical displacement along the entire length of a test specimen. Measurement is accomplished by continuous scanning of a reflected light from reflective bench markings or stripes previously affixed to the specimen.

  11. Job strain and tobacco smoking

    DEFF Research Database (Denmark)

    Heikkilä, Katriina; Nyberg, Solja T; Fransson, Eleonor I

    2012-01-01

    Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job...... strain, is associated with tobacco smoking in working adults....

  12. Strain effects in oxide superconductors

    International Nuclear Information System (INIS)

    Wada, H.; Kuroda, T.; Sekine, H.; Yuyama, M.; Itoh, K.

    1991-01-01

    Strain sensitivities of superconducting properties are critical to high magnetic field applications of superconductors, since critical temperature, T c , upper critical field, H c2 , and critical current (density), I c (J c ), are all degraded under strains. Oxide superconductors so far known are all very fragile, thus requiring to be fabricated in the form of composite. In the case of practical metallic superconductors, such as Nb 3 Sn and V 3 Ga, the so-called bronze method has been developed where these superconducting intermetallics are enveloped in a ductile metallic sheath. Recently, a fabrication method similar to the bronze method has been developed for the Bi 2 Sr 2 Ca 2 Cu 3 O x superconductors using Ag tubes as sheath. In the present study mono- and multicore BiPbSrCaCuO tape conductors were prepared by means of this Ag-sheath composite method, and examined in terms of strain sensitivity by measuring their T c and I c (J c ) under bending or tensile strains. (orig.)

  13. Failure in cartilaginous tissues

    NARCIS (Netherlands)

    Huyghe, J.M.R.J.; Talen-Jongeneelen, C.J.M.; Schroeder, Y.; Kraaijeveld, F.; Borst, de R.; Baaijens, F.P.T.

    2007-01-01

    Cartilaginous tissues high load bearing capacity is explained by osmotic prestressing putting the collagen fiber reinforcement under tension and the proteoglycan gel under compression. The osmotic forces are boosted by a further 50 % by the affinity of the collagen with the aquous solution. The high

  14. Soft Tissue Extramedullary Plasmacytoma

    Directory of Open Access Journals (Sweden)

    Fernando Ruiz Santiago

    2010-01-01

    Full Text Available We present the uncommon case of a subcutaneous fascia-based extramedullary plasmacytoma in the leg, which was confirmed by the pathology report and followed up until its remission. We report the differential diagnosis with other more common soft tissue masses. Imaging findings are nonspecific but are important to determine the tumour extension and to plan the biopsy.

  15. Neoproteoglycans in tissue engineering

    Science.gov (United States)

    Weyers, Amanda; Linhardt, Robert J.

    2014-01-01

    Proteoglycans, comprised of a core protein to which glycosaminoglycan chains are covalently linked, are an important structural and functional family of macromolecules found in the extracellular matrix. Advances in our understanding of biological interactions have lead to a greater appreciation for the need to design tissue engineering scaffolds that incorporate mimetics of key extracellular matrix components. A variety of synthetic and semisynthetic molecules and polymers have been examined by tissue engineers that serve as structural, chemical and biological replacements for proteoglycans. These proteoglycan mimetics have been referred to as neoproteoglycans and serve as functional and therapeutic replacements for natural proteoglycans that are often unavailable for tissue engineering studies. Although neoproteoglycans have important limitations, such as limited signaling ability and biocompatibility, they have shown promise in replacing the natural activity of proteoglycans through cell and protein binding interactions. This review focuses on the recent in vivo and in vitro tissue engineering applications of three basic types of neoproteoglycan structures, protein–glycosaminoglycan conjugates, nano-glycosaminoglycan composites and polymer–glycosaminoglycan complexes. PMID:23399318

  16. Sensing in tissue bioreactors

    Science.gov (United States)

    Rolfe, P.

    2006-03-01

    Specialized sensing and measurement instruments are under development to aid the controlled culture of cells in bioreactors for the fabrication of biological tissues. Precisely defined physical and chemical conditions are needed for the correct culture of the many cell-tissue types now being studied, including chondrocytes (cartilage), vascular endothelial cells and smooth muscle cells (blood vessels), fibroblasts, hepatocytes (liver) and receptor neurones. Cell and tissue culture processes are dynamic and therefore, optimal control requires monitoring of the key process variables. Chemical and physical sensing is approached in this paper with the aim of enabling automatic optimal control, based on classical cell growth models, to be achieved. Non-invasive sensing is performed via the bioreactor wall, invasive sensing with probes placed inside the cell culture chamber and indirect monitoring using analysis within a shunt or a sampling chamber. Electroanalytical and photonics-based systems are described. Chemical sensing for gases, ions, metabolites, certain hormones and proteins, is under development. Spectroscopic analysis of the culture medium is used for measurement of glucose and for proteins that are markers of cell biosynthetic behaviour. Optical interrogation of cells and tissues is also investigated for structural analysis based on scatter.

  17. A Novel bioreactor with mechanical stimulation for skeletal tissue engineering

    Directory of Open Access Journals (Sweden)

    M. Petrović

    2009-01-01

    Full Text Available The provision of mechanical stimulation is believed to be necessary for the functional assembly of skeletal tissues, which are normally exposed to a variety of biomechanical signals in vivo. In this paper, we present a development and validation of a novel bioreactor aimed for skeletal tissue engineering that provides dynamic compression and perfusion of cultivated tissues. Dynamic compression can be applied at frequencies up to 67.5 Hz and displacements down to 5 m thus suitable for the simulation of physiological conditions in a native cartilage tissue (0.1-1 Hz, 5-10 % strain. The bioreactor also includes a load sensor that was calibrated so to measure average loads imposed on tissue samples. Regimes of the mechanical stimulation and acquisition of load sensor outputs are directed by an automatic control system using applications developed within the LabView platform. In addition, perfusion of tissue samples at physiological velocities (10–100 m/s provides efficient mass transfer, as well as the possibilities to expose the cells to hydrodynamic shear and simulate the conditions in a native bone tissue. Thus, the novel bioreactor is suited for studies of the effects of different biomechanical signals on in vitro regeneration of skeletal tissues, as well as for the studies of newly formulated biomaterials and cell biomaterial interactions under in vivo-like settings.

  18. Mechanical analysis of the strains generated by water tension in plant stems. Part II: strains in wood and bark and apparent compliance.

    Science.gov (United States)

    Alméras, Tancrède

    2008-10-01

    Tree stems shrink in diameter during the day and swell during the night in response to changes in water tension in the xylem. Stem shrinkage can easily be measured in a nondestructive way, to derive continuous information about tree water status. The relationship between the strain and the change in water tension can be evaluated by empirical calibrations, or can be related to the structure of the plant. A mechanical analysis was performed to make this relationship explicit. The stem is modeled as a cylinder made of multiple layers of tissues, including heartwood, sapwood, and inner and outer bark. The effect of changes in water tension on the apparent strain at the surface of a tissue is quantified as a function of parameters defining stem anatomy and the mechanical properties of the tissues. Various possible applications in the context of tree physiology are suggested.

  19. Mobilomics in Saccharomyces cerevisiae strains.

    Science.gov (United States)

    Menconi, Giulia; Battaglia, Giovanni; Grossi, Roberto; Pisanti, Nadia; Marangoni, Roberto

    2013-03-20

    Mobile Genetic Elements (MGEs) are selfish DNA integrated in the genomes. Their detection is mainly based on consensus-like searches by scanning the investigated genome against the sequence of an already identified MGE. Mobilomics aims at discovering all the MGEs in a genome and understanding their dynamic behavior: The data for this kind of investigation can be provided by comparative genomics of closely related organisms. The amount of data thus involved requires a strong computational effort, which should be alleviated. Our approach proposes to exploit the high similarity among homologous chromosomes of different strains of the same species, following a progressive comparative genomics philosophy. We introduce a software tool based on our new fast algorithm, called regender, which is able to identify the conserved regions between chromosomes. Our case study is represented by a unique recently available dataset of 39 different strains of S.cerevisiae, which regender is able to compare in few minutes. By exploring the non-conserved regions, where MGEs are mainly retrotransposons called Tys, and marking the candidate Tys based on their length, we are able to locate a priori and automatically all the already known Tys and map all the putative Tys in all the strains. The remaining putative mobile elements (PMEs) emerging from this intra-specific comparison are sharp markers of inter-specific evolution: indeed, many events of non-conservation among different yeast strains correspond to PMEs. A clustering based on the presence/absence of the candidate Tys in the strains suggests an evolutionary interconnection that is very similar to classic phylogenetic trees based on SNPs analysis, even though it is computed without using phylogenetic information. The case study indicates that the proposed methodology brings two major advantages: (a) it does not require any template sequence for the wanted MGEs and (b) it can be applied to infer MGEs also for low coverage genomes

  20. Mobilomics in Saccharomyces cerevisiae strains

    Science.gov (United States)

    2013-01-01

    Background Mobile Genetic Elements (MGEs) are selfish DNA integrated in the genomes. Their detection is mainly based on consensus–like searches by scanning the investigated genome against the sequence of an already identified MGE. Mobilomics aims at discovering all the MGEs in a genome and understanding their dynamic behavior: The data for this kind of investigation can be provided by comparative genomics of closely related organisms. The amount of data thus involved requires a strong computational effort, which should be alleviated. Results Our approach proposes to exploit the high similarity among homologous chromosomes of different strains of the same species, following a progressive comparative genomics philosophy. We introduce a software tool based on our new fast algorithm, called regender, which is able to identify the conserved regions between chromosomes. Our case study is represented by a unique recently available dataset of 39 different strains of S.cerevisiae, which regender is able to compare in few minutes. By exploring the non–conserved regions, where MGEs are mainly retrotransposons called Tys, and marking the candidate Tys based on their length, we are able to locate a priori and automatically all the already known Tys and map all the putative Tys in all the strains. The remaining putative mobile elements (PMEs) emerging from this intra–specific comparison are sharp markers of inter–specific evolution: indeed, many events of non–conservation among different yeast strains correspond to PMEs. A clustering based on the presence/absence of the candidate Tys in the strains suggests an evolutionary interconnection that is very similar to classic phylogenetic trees based on SNPs analysis, even though it is computed without using phylogenetic information. Conclusions The case study indicates that the proposed methodology brings two major advantages: (a) it does not require any template sequence for the wanted MGEs and (b) it can be applied to

  1. Degradable polymers for tissue engineering

    NARCIS (Netherlands)

    van Dijkhuizen-Radersma, Riemke; Moroni, Lorenzo; van Apeldoorn, Aart A.; Zhang, Zheng; Grijpma, Dirk W.; van Blitterswijk, Clemens A.

    2008-01-01

    This chapter elaborates the degradable polymers for tissue engineering and their required scaffold material in tissue engineering. It recognizes the examples of degradable polymers broadly used in tissue engineering. Tissue engineering is the persuasion of the body to heal itself through the

  2. In vitro infection of salmonid epidermal tissues by infectious hematopoietic necrosis virus and viral hemorrhagic septicemia virus

    Science.gov (United States)

    Yamamoto, T.; Batts, W.N.; Winton, J.R.

    1992-01-01

    The ability of two rhabdoviruses, infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV), to infect fish skin was investigated by in vitro infection of excised tissues. Virus replication was determined by plaque assay of homogenized tissue extracts, and the virus antigen was detected by immunohistology of tissue sections. Gill, fin, and ventral abdominal skin tissues of rainbow trout Oncorhynchus mykiss that had been infected in vitro with a virulent strain of IHNV (193–110) produced substantial increases in virus titer within 24 h. Titers continued to increase up until day 3 of incubation; by this time, virus had increased 1,000-fold or more. This increase in IHNV titer occurred in epidermal tissues of fingerlings and of older fish. In another experiment, IHNV replicated in excised rainbow trout tissues whether the fish had been subject to prior infection with a virulent strain of IHNV (Western Regional Aquaculture Consortium isolate) or whether the fish had been infected previously with an attenuated strain of the virus (Nan Scott Lake, with 100 passes in culture). A virulent strain of VHSV (23/75) replicated effectively in excised gill tissues and epidermal tissues of rainbow trout and chinook salmon O. tshawytscha; however, the avirulent North American strain of VHSV (Makah) replicated poorly or not at all.

  3. Micromechanical modeling of rate-dependent behavior of Connective tissues.

    Science.gov (United States)

    Fallah, A; Ahmadian, M T; Firozbakhsh, K; Aghdam, M M

    2017-03-07

    In this paper, a constitutive and micromechanical model for prediction of rate-dependent behavior of connective tissues (CTs) is presented. Connective tissues are considered as nonlinear viscoelastic material. The rate-dependent behavior of CTs is incorporated into model using the well-known quasi-linear viscoelasticity (QLV) theory. A planar wavy representative volume element (RVE) is considered based on the tissue microstructure histological evidences. The presented model parameters are identified based on the available experiments in the literature. The presented constitutive model introduced to ABAQUS by means of UMAT subroutine. Results show that, monotonic uniaxial test predictions of the presented model at different strain rates for rat tail tendon (RTT) and human patellar tendon (HPT) are in good agreement with experimental data. Results of incremental stress-relaxation test are also presented to investigate both instantaneous and viscoelastic behavior of connective tissues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. In vitro quantification of strain patterns in the craniofacial skeleton due to masseter and temporalis activities.

    Science.gov (United States)

    Maloul, Asmaa; Regev, Eran; Whyne, Cari M; Beek, Marteen; Fialkov, Jeffrey A

    2012-09-01

    Many complications in craniofacial surgery can be attributed to a lack of characterization of facial skeletal strain patterns. This study aimed to delineate human midfacial strain patterns under uniform muscle loading. The left sides of 5 fresh-frozen human cadaveric heads were dissected of all soft tissues except the temporalis and masseter muscles. Tensile forces were applied to the free mandibular ends of the muscles. Maxillary alveolar arches were used to restrain the skulls. Eight strain gauges were bonded to the surface of the midface to measure the strain under single muscle loading conditions (100 N). Maxillary strain gauges revealed a biaxial load state for both muscles. Thin antral bone experienced high maximum principal tensile strains (maximum of 685.5 με) and high minimum principal compressive strains (maximum of -722.44 με). Similar biaxial patterns of lower magnitude were measured on the zygoma (maximum of 208.59 με for maximum principal strains and -78.11 με for minimum principal strains). Results, consistent for all specimens and counter to previously accepted concepts of biomechanical behavior of the midface under masticatory muscle loading, included high strain in the thin maxillary antral wall, rotational bending through the maxilla and zygoma, and a previously underestimated contribution of the temporalis muscle. This experimental model produced repeatable strain patterns quantifying the mechanics of the facial skeleton. These new counterintuitive findings underscore the need for accurate characterization of craniofacial strain patterns to address problems in the current treatment methods and develop robust design criteria.

  5. A NEW STRAIN OF TRANSMISSIBLE LEUCEMIA IN FOWLS (STRAIN H).

    Science.gov (United States)

    Ellermann, V

    1921-03-31

    1. A new strain of fowl leucosis has been transmitted through twelve generations of fowls. 2. An increase in virulence was observed during its passage. This was shown in a shortening of the interval between inoculation and death. The increase in virulence does not affect the number of successful inoculations, which remains approximately constant in from 20 to 40 per cent of the birds employed. 3. As with former strains, the disease manifests itself in various forms; i.e., myeloid and intravascular lymphoid types. A single lymphatic case was observed. 4. In several intravascular cases a diminution in the hemolytic power of the serum was established. This phenomenon was absent in a number of myeloid cases. 5. Active immunization cannot be produced by means of the subcutaneous injection of virulent material. 6. The finding of previous experiments that the virus is filterable has been confirmed. 7. The inoculation of human leucemic material into fowls gave negative results.

  6. Design of triaxial test with controlled suction: measure of strain

    International Nuclear Information System (INIS)

    Gasc-Barbier, M.; Cosenza, Ph.; Ghoreychi, M.; Chanchole, S.; Cosenza, Ph.; Tessier, D.

    2000-01-01

    Experimental study of mechanical behavior of clayey materials under hygrometric condition is usually performed either on unloaded samples or by means of classical odometer tests used in soil mechanics. Such methods are not well adapted to hard deep clayey rocks with little deformability, porosity and permeability. Moreover, stress and strain tensors having a significant effect on hygro-mechanical behaviour and properties cannot be measured and investigated appropriately by classical tests. This is why a specific triaxial test was designed in which the sample is surrounded by a fiber glass tissue allowing air circulation and then by silicon on which confining pressure is applied. Thus, equilibrium between air and sample was reduced. Stress and strain tensors were also measured in time on the sample subjected to a mechanical loading and to a controlled suction. After presentation of the test, preliminary results are given. (authors)

  7. Reptile Soft Tissue Surgery.

    Science.gov (United States)

    Di Girolamo, Nicola; Mans, Christoph

    2016-01-01

    The surgical approach to reptiles can be challenging. Reptiles have unique physiologic, anatomic, and pathologic differences. This may result in frustrating surgical experiences. However, recent investigations provided novel, less invasive, surgical techniques. The purpose of this review was to describe the technical aspects behind soft tissue surgical techniques that have been used in reptiles, so as to provide a general guideline for veterinarians working with reptiles. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Ligament Tissue Engineering

    OpenAIRE

    Khan, Wasim Sardar

    2016-01-01

    Ligaments are commonly injured in the knee joint, and have a poor capacity for healing due to their relative avascularity. Ligament reconstruction is well established for injuries such as anterior cruciate ligament rupture, however the use of autografts and allografts for ligament reconstruction are associated with complications, and outcomes are variable. Ligament tissue engineering using stem cells, growth factors and scaffolds is a novel technique that has the potential to provide an unlim...

  9. Subcutaneous adipose tissue classification

    Directory of Open Access Journals (Sweden)

    A. Sbarbati

    2010-11-01

    Full Text Available The developments in the technologies based on the use of autologous adipose tissue attracted attention to minor depots as possible sampling areas. Some of those depots have never been studied in detail. The present study was performed on subcutaneous adipose depots sampled in different areas with the aim of explaining their morphology, particularly as far as regards stem niches. The results demonstrated that three different types of white adipose tissue (WAT can be differentiated on the basis of structural and ultrastructural features: deposit WAT (dWAT, structural WAT (sWAT and fibrous WAT (fWAT. dWAT can be found essentially in large fatty depots in the abdominal area (periumbilical. In the dWAT, cells are tightly packed and linked by a weak net of isolated collagen fibers. Collagenic components are very poor, cells are large and few blood vessels are present. The deep portion appears more fibrous then the superficial one. The microcirculation is formed by thin walled capillaries with rare stem niches. Reinforcement pericyte elements are rarely evident. The sWAT is more stromal; it is located in some areas in the limbs and in the hips. The stroma is fairly well represented, with a good vascularity and adequate staminality. Cells are wrapped by a basket of collagen fibers. The fatty depots of the knees and of the trochanteric areas have quite loose meshes. The fWAT has a noteworthy fibrous component and can be found in areas where a severe mechanic stress occurs. Adipocytes have an individual thick fibrous shell. In conclusion, the present study demonstrates evident differences among subcutaneous WAT deposits, thus suggesting that in regenerative procedures based on autologous adipose tissues the sampling area should not be randomly chosen, but it should be oriented by evidence based evaluations. The structural peculiarities of the sWAT, and particularly of its microcirculation, suggest that it could represent a privileged source for

  10. Reduction of /sup 51/Cr-permeability of tissue culture cells by infection with herpes simplex virus type 1

    Energy Technology Data Exchange (ETDEWEB)

    Schlehofer, J.R.; Habermehl, K.O.; Diefenthal, W.; Hampl, H.

    1979-01-01

    Infection of different strains of tissue culture cells with herpes simplex virus type 1(HSV-1) resulted in a reduced /sup 51/Cr-permeability. A stability of the cellular membrane to Triton X-100, toxic sera and HSV-specific complement-mediated immune-cytolysis could be observed simultaneously. The results differed with respect to the cell strain used in the experiments.

  11. The plant tissue culture

    International Nuclear Information System (INIS)

    Crocomo, O.J.; Sharp, W.R.

    1973-01-01

    Progress in the field of plant tissue culture at the Plant Biochemistry Sector, Centro de Energia na Agricultura (CENA), Piracicaba, S.P., Brazil, pertains to the simplification of development in 'Phaseolus vulgaris' by dividing the organism into its component organs, tissues, and cells and the maintenance of these components on defined culture media 'in vitro'. This achievement has set the stage for probing the basis for the stability of the differentiated states and/or the reentry of mature differentiated cells into the mitotic cell cycle and their subsequent redifferentiation. Data from such studies at the cytological and biochemical level have been invaluable in the elucidation of the control mechanisms responsible for expression of the cellular phenotype. Unlimited possibilities exist for the application of tissue culture in the vegetative propagation of 'Phaseolus' and other important cultivars in providing genocopies or a large scale and/or readily obtaining plantlets from haploid cell lines or from protoplast (wall-less cells) hybridization products following genetic manipulation. These tools are being applied in this laboratory for the development and selection of high protein synthesizing 'Phaseolus' cultivars

  12. Cardiac tissue engineering

    Directory of Open Access Journals (Sweden)

    MILICA RADISIC

    2005-03-01

    Full Text Available We hypothesized that clinically sized (1-5 mm thick,compact cardiac constructs containing physiologically high density of viable cells (~108 cells/cm3 can be engineered in vitro by using biomimetic culture systems capable of providing oxygen transport and electrical stimulation, designed to mimic those in native heart. This hypothesis was tested by culturing rat heart cells on polymer scaffolds, either with perfusion of culture medium (physiologic interstitial velocity, supplementation of perfluorocarbons, or with electrical stimulation (continuous application of biphasic pulses, 2 ms, 5 V, 1 Hz. Tissue constructs cultured without perfusion or electrical stimulation served as controls. Medium perfusion and addition of perfluorocarbons resulted in compact, thick constructs containing physiologic density of viable, electromechanically coupled cells, in contrast to control constructs which had only a ~100 mm thick peripheral region with functionally connected cells. Electrical stimulation of cultured constructs resulted in markedly improved contractile properties, increased amounts of cardiac proteins, and remarkably well developed ultrastructure (similar to that of native heart as compared to non-stimulated controls. We discuss here the state of the art of cardiac tissue engineering, in light of the biomimetic approach that reproduces in vitro some of the conditions present during normal tissue development.

  13. Atomically resolved tissue integration.

    Science.gov (United States)

    Karlsson, Johan; Sundell, Gustav; Thuvander, Mattias; Andersson, Martin

    2014-08-13

    In the field of biomedical technology, a critical aspect is the ability to control and understand the integration of an implantable device in living tissue. Despite the technical advances in the development of biomaterials, the elaborate interplay encompassing materials science and biology on the atomic level is not very well understood. Within implantology, anchoring a biomaterial device into bone tissue is termed osseointegration. In the most accepted theory, osseointegration is defined as an interfacial bonding between implant and bone; however, there is lack of experimental evidence to confirm this. Here we show that atom probe tomography can be used to study the implant-tissue interaction, allowing for three-dimensional atomic mapping of the interface region. Interestingly, our analyses demonstrated that direct contact between Ca atoms and the implanted titanium oxide surface is formed without the presence of a protein interlayer, which means that a pure inorganic interface is created, hence giving experimental support to the current theory of osseointegration. We foresee that this result will be of importance in the development of future biomaterials as well as in the design of in vitro evaluation techniques.

  14. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  15. Strain-Detecting Composite Materials

    Science.gov (United States)

    Wallace, Terryl A. (Inventor); Smith, Stephen W. (Inventor); Piascik, Robert S. (Inventor); Horne, Michael R. (Inventor); Messick, Peter L. (Inventor); Alexa, Joel A. (Inventor); Glaessgen, Edward H. (Inventor); Hailer, Benjamin T. (Inventor)

    2016-01-01

    A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700.degree. C. to form the composite material.

  16. Estimation of left ventricular end diastolic pressure by tissue doppler imaging in patients with acute myocardial infarction

    International Nuclear Information System (INIS)

    Ali, M.; Abid, A.R.; Rehman, T.A.; Masood, A.; Sohail, S.

    2010-01-01

    Objective: To evaluate sensitivity and specificity of E / Ea > 10 for prediction of LVEDP > 15 mmHg in patients with coronary artery disease undergoing left heart catheterization. Materials and Methods: Sixty patients of acute transmural myocardial infarction at Jinnah Hospital Lahore were enrolled in study from December 2008 to December 2009. Patients with sinus rhythm were included in the study. Patients with valvular heart disease, complete right/left bundle branch block, Pacemaker dependence, Atrial fibrillation and Post mitral valve replacement were excluded. All patients were examined by performing trans thoracic Doppler echocardiography. The trans-mitral LV filling signal was traced manually and the following variables were obtained: peak early (E) and late (A) trans-mitral velocities, and E/A ratio. Tissue - Doppler derived indices were recorded at the lateral mitral annulus. These indices included systolic velocities (S'), early diastolic (Ea) velocities and late diastolic (Aa) velocities. Finally, the dimensionless index of E/Ea was calculated. All were averaged from at least three beats. Cardiac catheterization was performed via trans-femoral / trasradial route using six French (6F) sheaths. Left ventricular diastolic pressure was directly measured by fluid filled pigtail catheter attached to a pressure transducer. Results: Mean age of the study population was 56.8 +- 12.7 years. There were 47 (78.3%) males and 13 (21.7%) females. Diabetes mellitus was present in 12(20%), hypertension in 32 (53.3%), smoking in 35 (58.3%), dyslipidemia in 24 (40%). Anterior wall myocardial infarction occurred in 44 (73.3%) and inferior wall MI in 16 (26.7%). Grade I diastolic dysfunction was present in 22 (36.7%), Grade II in 31 (51.7%) and Grade III in 7 (11.7%) patients. E/E 15 in 9 (15%). Overall 21 patients were true positive, 6 were false positive, 25 were true negative and 8 were false negative. By applying 2 X 2 table sensitivity was 77.7%, specificity was 80

  17. Estimation of left ventricular end diastolic pressure by tissue doppler imaging in patients with acute myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Ali, M; Abid, A R; Rehman, T A; Masood, A; Sohail, S [Allama Iqbal Medical College/Jinnah Hospital, Lahore(Pakistan)

    2010-10-15

    Objective: To evaluate sensitivity and specificity of E / Ea > 10 for prediction of LVEDP > 15 mmHg in patients with coronary artery disease undergoing left heart catheterization. Materials and Methods: Sixty patients of acute transmural myocardial infarction at Jinnah Hospital Lahore were enrolled in study from December 2008 to December 2009. Patients with sinus rhythm were included in the study. Patients with valvular heart disease, complete right/left bundle branch block, Pacemaker dependence, Atrial fibrillation and Post mitral valve replacement were excluded. All patients were examined by performing trans thoracic Doppler echocardiography. The trans-mitral LV filling signal was traced manually and the following variables were obtained: peak early (E) and late (A) trans-mitral velocities, and E/A ratio. Tissue - Doppler derived indices were recorded at the lateral mitral annulus. These indices included systolic velocities (S'), early diastolic (Ea) velocities and late diastolic (Aa) velocities. Finally, the dimensionless index of E/Ea was calculated. All were averaged from at least three beats. Cardiac catheterization was performed via trans-femoral / trasradial route using six French (6F) sheaths. Left ventricular diastolic pressure was directly measured by fluid filled pigtail catheter attached to a pressure transducer. Results: Mean age of the study population was 56.8 +- 12.7 years. There were 47 (78.3%) males and 13 (21.7%) females. Diabetes mellitus was present in 12(20%), hypertension in 32 (53.3%), smoking in 35 (58.3%), dyslipidemia in 24 (40%). Anterior wall myocardial infarction occurred in 44 (73.3%) and inferior wall MI in 16 (26.7%). Grade I diastolic dysfunction was present in 22 (36.7%), Grade II in 31 (51.7%) and Grade III in 7 (11.7%) patients. E/E < 10 was observed in 31 (51.7%), 11 - 15 in 20 (33.3%) and > 15 in 9 (15%). Overall 21 patients were true positive, 6 were false positive, 25 were true negative and 8 were false negative. By

  18. Biomechanical study of the bone tissue with dental implants interaction

    Directory of Open Access Journals (Sweden)

    Navrátil P.

    2011-12-01

    Full Text Available The article deals with the stress-strain analysis of human mandible in the physiological state and after the dental implant application. The evaluation is focused on assessing of the cancellous bone tissue modeling-level. Three cancellous bone model-types are assessed: Non-trabecular model with homogenous isotropic material, nontrabecular model with inhomogeneous material obtained from computer tomography data using CT Data Analysis software, and trabecular model built from mandible section image. Computational modeling was chosen as the most suitable solution method and the solution on two-dimensional level was carried out. The results show that strain is more preferable value than stress in case of evaluation of mechanical response in cancellous bone. The non-trabecular model with CT-obtained material model is not acceptable for stress-strain analysis of the cancellous bone for singularities occurring on interfaces of regions with different values of modulus of elasticity.

  19. Necrotizing Soft Tissue Infection

    Directory of Open Access Journals (Sweden)

    Sahil Aggarwal, BS

    2018-04-01

    Full Text Available History of present illness: A 71-year-old woman with a history of metastatic ovarian cancer presented with sudden onset, rapidly progressing painful rash in the genital region and lower abdominal wall. She was febrile to 103°F, heart rate was 114 beats per minute, and respiratory rate was 24 per minute. Her exam was notable for a toxic-appearing female with extensive areas of erythema, tenderness, and induration to her lower abdomen, intertriginous areas, and perineum with intermittent segments of crepitus without hemorrhagic bullae or skin breakdown. Significant findings: Computed tomography (CT of the abdominal and pelvis with intravenous (IV contrast revealed inflammatory changes, including gas and fluid collections within the ventral abdominal wall extending to the vulva, consistent with a necrotizing soft tissue infection. Discussion: Necrotizing fasciitis is a serious infection of the skin and soft tissues that requires an early diagnosis to reduce morbidity and mortality. Classified into several subtypes based on the type of microbial infection, necrotizing fasciitis can rapidly progress to septic shock or death if left untreated.1 Diagnosing necrotizing fasciitis requires a high index of suspicion based on patient risk factors, presentation, and exam findings. Definitive treatment involves prompt surgical exploration and debridement coupled with IV antibiotics.2,3 Clinical characteristics such as swelling, disproportionate pain, erythema, crepitus, and necrotic tissue should be a guide to further diagnostic tests.4 Unfortunately, lab values such as white blood cell count and lactate imaging studies have high sensitivity but low specificity, making the diagnosis of necrotizing fasciitis still largely a clinical one.4,5 CT is a reliable method to exclude the diagnosis of necrotizing soft tissue infections (sensitivity of 100%, but is only moderately reliable in correctly identifying such infections (specificity of 81%.5 Given the emergent

  20. Systems genetic analysis of brown adipose tissue function

    Czech Academy of Sciences Publication Activity Database

    Pravenec, Michal; Saba, L. M.; Zídek, Václav; Landa, Vladimír; Mlejnek, Petr; Šilhavý, Jan; Šimáková, Miroslava; Strnad, Hynek; Trnovská, J.; Škop, V.; Hüttl, M.; Marková, I.; Oliyarnyk, O.; Malínská, H.; Kazdová, L.; Smith, H.; Tabakoff, B.

    2018-01-01

    Roč. 50, č. 1 (2018), s. 52-66 ISSN 1094-8341 R&D Projects: GA ČR(CZ) GA13-04420S Institutional support: RVO:67985823 Keywords : brown adipose tissue * coexpression modules * quantitative trait locus * recombinant inbred strains * spontaneously hypertensive rat Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Human genetics Impact factor: 3.044, year: 2016

  1. Draft Genome Sequence of a Kale (Brassica oleracea L.) Root Endophyte, Pseudomonas sp. Strain C9.

    Science.gov (United States)

    Laugraud, Aurelie; Young, Sandra; Gerard, Emily; O'Callaghan, Maureen; Wakelin, Steven

    2017-04-13

    Pseudomonas sp. strain C9 is a plant growth-promoting bacterium isolated from the root tissue of Brassica oleracea L. grown in soil from Marlborough, New Zealand. Its draft genome of 6,350,161 bp contains genes associated with plant growth promotion and biological control. Copyright © 2017 Laugraud et al.

  2. A fully implantable telemetry system for the long-term measurement of habitual bone strain

    NARCIS (Netherlands)

    de Jong, W. C.; Koolstra, J. H.; van Ruijven, L. J.; Korfage, J. A. M.; Langenbach, G. E. J.

    2010-01-01

    Long-term in-vivo recordings of habitual bone strain in freely moving animals are needed to better understand the everyday mechanical loading environment responsible for bone-tissue maintenance. However, wireless methods to make such recordings are scarce. We report on the successful customisation

  3. Fatal necrotizing fasciitis due to necrotic toxin-producing Escherichia coli strain

    Directory of Open Access Journals (Sweden)

    C. Gallois

    2015-11-01

    Full Text Available We report a fatal case of necrotizing soft tissues infection caused by an Escherichia coli strain belonging to phylogenetic group C and harbouring numerous virulence factors reported to be part of a pathogenicity island (PAI such as PAI IIJ96 and conserved virulence plasmidic region.

  4. Biomaterials for tissue engineering applications.

    Science.gov (United States)

    Keane, Timothy J; Badylak, Stephen F

    2014-06-01

    With advancements in biological and engineering sciences, the definition of an ideal biomaterial has evolved over the past 50 years from a substance that is inert to one that has select bioinductive properties and integrates well with adjacent host tissue. Biomaterials are a fundamental component of tissue engineering, which aims to replace diseased, damaged, or missing tissue with reconstructed functional tissue. Most biomaterials are less than satisfactory for pediatric patients because the scaffold must adapt to the growth and development of the surrounding tissues and organs over time. The pediatric community, therefore, provides a distinct challenge for the tissue engineering community. Copyright © 2014. Published by Elsevier Inc.

  5. Nutrient content of sorghum beer strainings

    African Journals Online (AJOL)

    Sorghum beer strainings were analysed for starch, protein, fat, crude fibre, ash, minerals and ... The importance of minerals in animal nutrition has been recognized for many ..... strainings is probably due to yeast activity during fermentation ...

  6. Three-dimensional assessment of brain tissue morphology

    Science.gov (United States)

    Müller, Bert; Germann, Marco; Jeanmonod, Daniel; Morel, Anne

    2006-08-01

    The microstructure of brain tissues becomes visible using different types of optical microscopy after the tissue sectioning. This preparation procedure introduces stress and strain in the anisotropic and inhomogeneous soft tissue slices, which are several 10 μm thick. Consequently, the three-dimensional dataset, generated out of the two-dimensional images with lateral submicrometer resolution, needs algorithms to correct the deformations, which can be significant for mellow tissue such as brain segments. The spatial resolution perpendicular to the slices is much worse with respect to the lateral sub-micrometer resolution. Therefore, we propose as complementary method the synchrotron-radiation-based micro computed tomography (SRμCT), which avoids any kind of preparation artifacts due to sectioning and histological processing and yields true micrometer resolution in the three orthogonal directions. The visualization of soft matter by the use of SRμCT, however, is often based on elaborate staining protocols, since the tissue exhibits (almost) the same x-ray absorption as the surrounding medium. Therefore, it is unexpected that human tissue from the pons and the medulla oblongata in phosphate buffer show several features such as the blood vessels and the inferior olivary nucleus without staining. The value of these tomograms lies especially in the precise non-rigid registration of the different sets of histological slices. Applications of this method to larger pieces of brain tissue, such as the human thalamus are planned in the context of stereotactic functional neurosurgery.

  7. Comparative proteome analysis of two Streptococcus agalactiae strains from cultured tilapia with different virulence.

    Science.gov (United States)

    Li, Wei; Su, You-Lu; Mai, Yong-Zhan; Li, Yan-Wei; Mo, Ze-Quan; Li, An-Xing

    2014-05-14

    Streptococcus agalactiae is a major piscine pathogen, which causes significant morbidity and mortality among numerous fish species, and results in huge economic losses to aquaculture. Many S. agalactiae strains showing different virulence characteristics have been isolated from infected tilapia in different geographical regions throughout South China in the recent years, including natural attenuated S. agalactiae strain TFJ0901 and virulent S. agalactiae strain THN0901. In the present study, survival of tilapia challenged with S. agalactiae strain TFJ0901 and THN0901 (10(7)CFU/fish) were 93.3% and 13.3%, respectively. Moreover, there are severe lesions of the examined tissues in tilapia infected with strain THN0901, but no significant histopathological changes were observed in tilapia infected with the strain TFJ0901. In order to elucidate the factors responsible for the invasive potential of S. agalactiae between two strains TFJ0901 and THN0901, a comparative proteome analysis was applied to identify the different protein expression profiles between the two strains. 506 and 508 cellular protein spots of S. agalactiae TFJ0901 and THN0901 were separated by two dimensional electrophoresis, respectively. And 34 strain-specific spots, corresponding to 27 proteins, were identified successfully by MALDI-TOF mass spectrometry. Among them, 23 proteins presented exclusively in S. agalactiae TFJ0901 or THN0901, and the other 4 proteins presented in different isomeric forms between TFJ0901 and THN0901. Most of the strain-specific proteins were just involved in metabolic pathways, while 7 of them were presumed to be responsible for the virulence differences of S. agalactiae strain TFJ0901 and THN0901, including molecular chaperone DnaJ, dihydrolipoamide dehydrogenase, thioredoxin, manganese-dependent inorganic pyrophosphatase, elongation factor Tu, bleomycin resistance protein and cell division protein DivIVA. These virulence-associated proteins may contribute to identify new

  8. Visualization of bonding at an inclusion boundary using axial-shear strain elastography: a feasibility study

    International Nuclear Information System (INIS)

    Thitaikumar, Arun; Krouskop, Thomas A; Garra, Brian S; Ophir, Jonathan

    2007-01-01

    Ultrasound elastography produces strain images of compliant tissues under quasi-static compression. In axial-shear strain elastography, the local axial-shear strain resulting from application of quasi-static axial compression to an inhomogeneous material is imaged. The overall hypothesis of this work is that the pattern of axial-shear strain distribution around the inclusion/background interface is completely determined by the bonding at the interface after normalization for inclusion size and applied strain levels, and that it is feasible to extract certain features from the axial-shear strain elastograms to quantify this pattern. The mechanical model used in this study consisted of a single stiff circular inclusion embedded in a homogeneous softer background. First, we performed a parametric study using finite-element analysis (FEA) (no ultrasound involved) to identify possible features that quantify the pattern of axial-shear strain distribution around an inclusion/background interface. Next, the ability to extract these features from axial-shear strain elastograms, estimated from simulated pre- and post-compression noisy RF data, was investigated. Further, the feasibility of extracting these features from in vivo breast data of benign and malignant tumors was also investigated. It is shown using the FEA study that the pattern of axial-shear strain distribution is determined by the degree of bonding at the inclusion/background interface. The results suggest the feasibility of using normalized features that capture the region of positive and negative axial-shear strain area to quantify the pattern of the axial-shear strain distribution. The simulation results showed that it was feasible to extract the features, as identified in the FEA study, from axial-shear strain elastograms. However, an effort must be made to obtain axial-shear strain elastograms with the highest signal-to-noise ratio (SNR asse ) possible, without compromising the resolution. The in vivo

  9. Strain sonoelastographic evaluation of biceps muscle intrinsic stiffness after botulinum toxin-A injection.

    Science.gov (United States)

    Aşkın, Ayhan; Kalaycı, Özlem Tuğçe; Bayram, Korhan Barış; Tosun, Aliye; Demirdal, Ümit Seçil; Atar, Emel; İnci, Mehmet Fatih

    2017-01-01

    The most commonly used clinical tools for measuring spasticity are modified Ashworth scale (MAS) and Tardieu scale but both yield subjective rather than objective results. Ultrasound elastography (EUS) provides information on tissue stiffness and allows the qualitative or quantitative measurements of the mechanical properties of tissues. To assess the stiffness of biceps brachialis muscles in stroke patients by strain EUS and to investigate the sonoelastographic changes and its correlations with clinical evaluation parameters after botulinum toxin-A (BTA) injections. This is a prospective study. A total of 48 chronic stroke patients requiring BTA injections to biceps brachialis muscles were included in the study. All patients received injections with BTA to biceps brachialis muscles under ultrasound guidance. MAS, goniometric measurements, and strain EUS assessments were performed at preintervention and at 4-week postintervention. Strain index values of biceps muscle on the affected side were significantly increased compared with those on the unaffected side (p < 0.01). At 4 weeks after BTA injection, significant improvements were observed in MAS grades and goniometric measurements (p < 0.05). Statistically significant differences were also found between the MAS grades and strain index values in both pre-/postintervention period (p < 0.01). No significant correlations were observed between clinical parameters and strain EUS findings. Strain EUS is a promising diagnostic tool for assessing stiffness in spastic muscles, in establishing the treatment plan and monitoring the effectiveness of the therapeutic modality.

  10. Yeast strains and methods of use thereof

    OpenAIRE

    Goddard, Matthew Robert; Gardner, Richard Clague; Anfang, Nicole

    2013-01-01

    The present invention relates to yeast strains and, in particular, to yeast stains for use in fermentation processes. The invention also relates to methods of fermentation using the yeast strains of the invention either alone or in combination with other yeast strains. The invention thither relates to methods for the selection of yeast strains suitable for fermentation cultures by screening for various metabolic products and the use of specific nutrient sources.

  11. Development of Industrial Yeast Platform Strains

    DEFF Research Database (Denmark)

    Bergdahl, Basti; Dato, Laura; Förster, Jochen

    2014-01-01

    Most of the current metabolic engineering projects are carried out using laboratory strains as the starting host. Although such strains are easily manipulated genetically, their robustness does not always meet the requirements set by industrial fermentation conditions. In such conditions, the cells...... screening of the 36 industrial and laboratory yeast strains. In addition, progress in the development of molecular biology methods for generating the new strains will be presented....

  12. STRAINED OFF BREAST MILK: PRO AND CONTRA

    Directory of Open Access Journals (Sweden)

    O.L. Lukoyanova

    2010-01-01

    Full Text Available The questions of feeding of children with strained off breast milk are discussed in this article. Author presents medical indications to such type of feeding, peculiarities and rules of storage of strained off milk. There is a brief literature review on the influence of different factors on the composition of strained off breast milk.Key words: strained milk, breast feeding, pasteurization, freezing.(Voprosy sovremennoi pediatrii — Current Pediatrics. 2010;9(2:70-73

  13. Poisson's ratio of collagen fibrils measured by small angle X-ray scattering of strained bovine pericardium

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Hannah C.; Sizeland, Katie H.; Kayed, Hanan R.; Haverkamp, Richard G., E-mail: r.haverkamp@massey.ac.nz [School of Engineering and Advanced Technology, Massey University, Private Bag 11222, Palmerston North 4442 (New Zealand); Kirby, Nigel; Hawley, Adrian; Mudie, Stephen T. [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia)

    2015-01-28

    Type I collagen is the main structural component of skin, tendons, and skin products, such as leather. Understanding the mechanical performance of collagen fibrils is important for understanding the mechanical performance of the tissues that they make up, while the mechanical properties of bulk tissue are well characterized, less is known about the mechanical behavior of individual collagen fibrils. In this study, bovine pericardium is subjected to strain while small angle X-ray scattering (SAXS) patterns are recorded using synchrotron radiation. The change in d-spacing, which is a measure of fibril extension, and the change in fibril diameter are determined from SAXS. The tissue is strained 0.25 (25%) with a corresponding strain in the collagen fibrils of 0.045 observed. The ratio of collagen fibril width contraction to length extension, or the Poisson's ratio, is 2.1 ± 0.7 for a tissue strain from 0 to 0.25. This Poisson's ratio indicates that the volume of individual collagen fibrils decreases with increasing strain, which is quite unlike most engineering materials. This high Poisson's ratio of individual fibrils may contribute to high Poisson's ratio observed for tissues, contributing to some of the remarkable properties of collagen-based materials.

  14. Fibre-Matrix Interaction in Soft Tissue

    International Nuclear Information System (INIS)

    Guo, Zaoyang

    2010-01-01

    Although the mechanical behaviour of soft tissue has been extensively studied, the interaction between the collagen fibres and the ground matrix has not been well understood and is therefore ignored by most constitutive models of soft tissue. In this paper, the human annulus fibrosus is used as an example and the potential fibre-matrix interaction is identified by careful investigation of the experimental results of biaxial and uniaxial testing of the human annulus fibrosus. First, the uniaxial testing result of the HAF along the axial direction is analysed and it is shown that the mechanical behaviour of the ground matrix can be well simulated by the incompressible neo-Hookean model when the collagen fibres are all under contraction. If the collagen fibres are stretched, the response of the ground matrix can still be described by the incompressible neo-Hookean model, but the effective stiffness of the matrix depends on the fibre stretch ratio. This stiffness can be more than 10 times larger than the one obtained with collagen fibres under contraction. This phenomenon can only be explained by the fibre-matrix interaction. Furthermore, we find that the physical interpretation of this interaction includes the inhomogeneity of the soft tissue and the fibre orientation dispersion. The dependence of the tangent stiffness of the matrix on the first invariant of the deformation tensor can also be explained by the fibre orientation dispersion. The significant effect of the fibre-matrix interaction strain energy on mechanical behaviour of the soft tissue is also illustrated by comparing some simulation results.

  15. Infection dynamics of western equine encephalomyelitis virus (Togaviridae: Alphavirus) in four strains of Culex tarsalis (Diptera: Culicidae): an immunocytochemical study.

    Science.gov (United States)

    Oviedo, Marco V Neira; Romoser, William S; James, Calvin Bl; Mahmood, Farida; Reisen, William K

    2011-04-18

    BACKGROUND: Vector competence describes the efficiency with which vector arthropods become infected with and transmit pathogens and depends on interactions between pathogen and arthropod genetics as well as environmental factors. For arbovirus transmission, the female mosquito ingests viremic blood, the virus infects and replicates in midgut cells, escapes from the midgut, and disseminates to other tissues, including the salivary glands. Virus-laden saliva is then injected into a new host. For transmission to occur, the virus must overcome several "barriers", including barriers to midgut infection and/or escape and salivary infection and/or escape. By examining the spatial/temporal infection dynamics of Culex tarsalis strains infected with western equine encephalomyelitis virus (WEEV), we identified tissue tropisms and potential tissue barriers, and evaluated the effects of viral dose and time postingestion. METHODS: Using immunostained paraffin sections, WEEV antigens were tracked in four Cx. tarsalis strains: two recently colonized California field strains - Coachella Valley, Riverside County (COAV) and Kern National Wildlife Refuge (KNWR); and two laboratory strains selected for WEEV susceptibility (high viremia producer, HVP), and WEEV resistance (WR). RESULTS AND CONCLUSIONS: Tissues susceptible to WEEV infection included midgut epithelium, neural ganglia, trachea, chorionated eggs, and salivary glands. Neuroendocrine cells in the retrocerebral complex were occasionally infected, indicating the potential for behavioral effects. The HVP and COAV strains vigorously supported viral growth, whereas the WR and KNWR strains were less competent. Consistent with earlier studies, WEEV resistance appeared to be related to a dose-dependent midgut infection barrier, and a midgut escape barrier. The midgut escape barrier was not dependent upon the ingested viral dose. Consistent with midgut infection modulation, disseminated infections were less common in the WR and KNWR

  16. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains.

    Directory of Open Access Journals (Sweden)

    Dharanesh Gangaiah

    Full Text Available Although cutaneous ulcers (CU in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin?To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin.These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions.

  17. Strain gradient effects in surface roughening

    DEFF Research Database (Denmark)

    Borg, Ulrik; Fleck, N.A.

    2007-01-01

    evidence for strain gradient effects. Numerical analyses of a bicrystal undergoing in-plane tensile deformation are also studied using a strain gradient crystal plasticity theory and also by using a strain gradient plasticity theory for an isotropic solid. Both theories include an internal material length...

  18. Engineering piezoresistivity using biaxially strained silicon

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Richter, Jacob; Brandbyge, Mads

    2008-01-01

    of the piezocoefficient on temperature and dopant density is altered qualitatively for strained silicon. In particular, we find that a vanishing temperature coefficient may result for silicon with grown-in biaxial tensile strain. These results suggest that strained silicon may be used to engineer the iezoresistivity...

  19. drug resistant strains of Salmonella enterica

    African Journals Online (AJOL)

    Conclusions: The aqueous extract of Thonningia sanguinea can provide an alternative therapy for the treatment of salmonellosis, mainly for typhoid fever caused by MDR strains of S. Typhi.The extract also inhibits S.Hadar a MDR emerging strain in Ivory Coast. Keywords: Thonningia sanguinea; Salmonella, MDR strains, ...

  20. Development of high temperature strain gage, (5)

    International Nuclear Information System (INIS)

    Yuuki, Hiroshi; Kobayashi, Yukio; Kanai, Kenji; Yamaura, Yoshio

    1976-01-01

    Development and improvement of resistance wire type strain gages usable for experimental measurement of thermal strains generated at high temperature in various structures and equipments that consist of a Fast Breeder Reactor have been carried out, and various characteristics of the strain gages have been investigated. Based on the results obtained up to now, development and research of this time mainly aim to improve strain and fatigue characteristics. As the results, characteristics of strain gages with sensing elements of nichrome V are improved, specifically mechanical hysteresis is decreased, strain limit is increased, etc. Also, improvement is recognized in thermal output, and it becomes clear that dummy gages work effectively. However, a filling method of MgO and an inserting method of active-dummy elements are selected as primary objects to improve strain characteristics, and many hours are taken for these objects, so confirmations of characteristics of platinum-tungsten strain gages, strain sensing elements of which are troublesome to produce, have not been completely done, though the performance of the gages has been improved in several points. As to nichrome V strain gages, there is a fair prospect of obtaining ones, specifications of which are quite close to the goal, though problems in manufacturing technics remain for future. As to platinum-tungsten strain gages, it is expected that similar strain gages to nichrome V are obtainable by improvement in manufacturing of sensing elements. (auth.)

  1. Strain path dependency in metal plasticity

    NARCIS (Netherlands)

    Viatkina, E.M.; Brekelmans, W.A.M.; Geers, M.G.D.

    2003-01-01

    A change in strain path has a significant effect on the mechanical response of metals. Strain path change effects physically originate from a complex microstructure evolution. This paper deals with the contribution of cell structure evolution to the strain path change effect. The material with cells

  2. Stress and strain measurements in solids

    International Nuclear Information System (INIS)

    Askegaard, V.

    1978-01-01

    A design basis is given for stress- and strain cells to be used in a solid either externally loaded or with a stressfree strain field (for example shrinkage). A stress- and a strain cell has been designed for use in granular materials. Calibration tests show either good or reasonably good correspondance with calculated values. (orig.) [de

  3. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjollund, N H; Jensen, Tina Kold; Bonde, Jens Peter

    2000-01-01

    pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  4. Strain engineering of van der Waals heterostructures

    NARCIS (Netherlands)

    Vermeulen, Paul A.; Mulder, Jefta; Momand, Jamo; Kooi, Bart J.

    2018-01-01

    Modifying the strain state of solids allows control over a plethora of functional properties. The weak interlayer bonding in van der Waals (vdWaals) materials such as graphene, hBN, MoS2, and Bi2Te3 might seem to exclude strain engineering, since strain would immediately relax at the vdWaals

  5. Comparative pathogenicity of Coxsackievirus A16 circulating and noncirculating strains in vitro and in a neonatal mouse model

    International Nuclear Information System (INIS)

    Huang, L.; Liu, X.; Li, J.L.; Chang, J.L.; Liu, G.C.; Yu, X.F.; Zhang, W.Y.

    2015-01-01

    An enterovirus 71 (EV71) vaccine for the prevention of hand, foot, and mouth disease (HMFD) is available, but it is not known whether the EV71 vaccine cross-protects against Coxsackievirus (CV) infection. Furthermore, although an inactivated circulating CVA16 Changchun 024 (CC024) strain vaccine candidate is effective in newborn mice, the CC024 strain causes severe lesions in muscle and lung tissues. Therefore, an effective CV vaccine with improved pathogenic safety is needed. The aim of this study was to evaluate the in vivo safety and in vitro replication capability of a noncirculating CVA16 SHZH05 strain. The replication capacity of circulating CVA16 strains CC024, CC045, CC090 and CC163 and the noncirculating SHZH05 strain was evaluated by cytopathic effect in different cell lines. The replication capacity and pathogenicity of the CC024 and SHZH05 strains were also evaluated in a neonatal mouse model. Histopathological and viral load analyses demonstrated that the SHZH05 strain had an in vitro replication capacity comparable to the four CC strains. The CC024, but not the SHZH05 strain, became distributed in a variety of tissues and caused severe lesions and mortality in neonatal mice. The differences in replication capacity and in vivo pathogenicity of the CC024 and SHZH05 strains may result from differences in the nucleotide and amino acid sequences of viral functional polyproteins P1, P2 and P3. Our findings suggest that the noncirculating SHZH05 strain may be a safer CV vaccine candidate than the CC024 strain

  6. Comparative pathogenicity of Coxsackievirus A16 circulating and noncirculating strains in vitro and in a neonatal mouse model

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L. [Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun (China); The 208th Hospital of PLA, Changchun (China); Liu, X.; Li, J.L.; Chang, J.L.; Liu, G.C. [Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun (China); Yu, X.F. [Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun (China); Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD (United States); Zhang, W.Y. [Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun (China)

    2015-03-27

    An enterovirus 71 (EV71) vaccine for the prevention of hand, foot, and mouth disease (HMFD) is available, but it is not known whether the EV71 vaccine cross-protects against Coxsackievirus (CV) infection. Furthermore, although an inactivated circulating CVA16 Changchun 024 (CC024) strain vaccine candidate is effective in newborn mice, the CC024 strain causes severe lesions in muscle and lung tissues. Therefore, an effective CV vaccine with improved pathogenic safety is needed. The aim of this study was to evaluate the in vivo safety and in vitro replication capability of a noncirculating CVA16 SHZH05 strain. The replication capacity of circulating CVA16 strains CC024, CC045, CC090 and CC163 and the noncirculating SHZH05 strain was evaluated by cytopathic effect in different cell lines. The replication capacity and pathogenicity of the CC024 and SHZH05 strains were also evaluated in a neonatal mouse model. Histopathological and viral load analyses demonstrated that the SHZH05 strain had an in vitro replication capacity comparable to the four CC strains. The CC024, but not the SHZH05 strain, became distributed in a variety of tissues and caused severe lesions and mortality in neonatal mice. The differences in replication capacity and in vivo pathogenicity of the CC024 and SHZH05 strains may result from differences in the nucleotide and amino acid sequences of viral functional polyproteins P1, P2 and P3. Our findings suggest that the noncirculating SHZH05 strain may be a safer CV vaccine candidate than the CC024 strain.

  7. Soft tissue sparganosis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ki Soon; Lee, Yul; Chung, Soo Young; Park, Choong Ki; Lee, Kwan Sup [Hallym University College of Medicine, Seoul (Korea, Republic of); Cho, In Hwan; Suh, Hyoung Sim [Daelin S. Mary' s Hospital, Seoul (Korea, Republic of)

    1993-11-15

    Sparganosis is a rare tissue-parasitic infestation caused by a plerocercoid tapeworm larva(sparganum), genus Spirometra. The most common clinical presentation of sparganosis is a palpable subcutaneous mass or masses. Fifteen simple radiographs and 10 ultrasosnograms of 17 patients with operatively verified subcutaneous sparganosis were retrospectively analyzed to find its radiologic characteristics for preoperative diagnosis of sparganosis. The location of the subcutaneous sparganosis were lower extremity, abdominal wall, breast, inguinal region and scrotum in order of frequency. The simple radiographs showed linear or elongated calcification with or without nodular elongated shaped soft tissue mass shadows in 8 patients, soft tissue mass shadow only in 2 patients and lateral abdominal wall thickening in 1 patient. But no specific findings was noted in 4 patients with small abdominal and inguinal masses. We could classify the subcutaneous sparganosis by ultrasound into 2 types: one is long band-like hypoechoic structures, corresponding to the subcutaneous tunnel-like tracks formed by migration of sparganum larva and the order is elongated or ovoid hyperechoic nodules, representing granulomas. Long band-like hypoechoic structures within or associated with mixed echoic granulomatous masses were noted in 6 patients and elongated or ovoid hypoechoic mass or masses were noted in 4 patients. In conclusion, sparganosis should be considered when these radiologic findings-irregular linear calcifications on simple radiograph and long band-like hypoechoic structures on ultrasonography, corresponding to the subcutaneous tunnel-like tracks formed by migration of sparganum larva are noted in the patients who have subcutaneous palpable mass or masses. And radiologic examination especially ultrasonography is very helpful to diagnose sparganosis.

  8. Real-time contrast-enhanced ultrasound determination of microvascular blood volume in abdominal subcutaneous adipose tissue in man. Evidence for adipose tissue capillary recruitment

    DEFF Research Database (Denmark)

    Tobin, L; Simonsen, L; Bülow, J

    2010-01-01

    The adipose tissue metabolism is dependent on its blood perfusion. During lipid mobilization e.g. during exercise and during lipid deposition e.g. postprandial, adipose tissue blood flow is increased. This increase in blood flow may involve capillary recruitment in the tissue. We investigated...... of ultrasound contrast agent to establish the reproducibility of the technique. In nine subjects, the effect of an oral glucose load on blood flow and microvascular volume was measured in abdominal subcutaneous adipose tissue and forearm skeletal muscle. ¹³³Xe washout and venous occlusion strain......-gauge plethysmography was used to measure the adipose tissue and forearm blood flow, respectively. Ultrasound signal intensity of the first plateau phases was 27 ± dB in the abdominal subcutaneous adipose tissue and 18 ± 2 dB (P

  9. [Human brown adipose tissue].

    Science.gov (United States)

    Virtanen, Kirsi A; Nuutila, Pirjo

    2015-01-01

    Adult humans have heat-producing and energy-consuming brown adipose tissue in the clavicular region of the neck. There are two types of brown adipose cells, the so-called classic and beige adipose cells. Brown adipose cells produce heat by means of uncoupler protein 1 (UCP1) from fatty acids and sugar. By applying positron emission tomography (PET) measuring the utilization of sugar, the metabolism of brown fat has been shown to multiply in the cold, presumably influencing energy consumption. Active brown fat is most likely present in young adults, persons of normal weight and women, least likely in obese persons.

  10. Microsurgical Composite Tissue Transplantation

    Science.gov (United States)

    Serafin, Donald; Georgiade, Nicholas G.

    1978-01-01

    Since 1974, 69 patients with extensive defects have undergone reconstruction by microsurgical composite tissue transplantation. Using this method, donor composite tissue is isolated on its blood supply, removed to a distant recipient site, and the continuity of blood flow re-established by microvascular anastomoses. In this series, 56 patients (81%) were completely successful. There have been eight (12%) failures, primarily in the extremities. There have been five (7%) partial successes, (i.e., a microvascular flap in which a portion was lost requiring a secondary procedure such as a split thickness graft). In those patients with a severely injured lower extremity, the failure rate was the greatest. Most of these were arterial (six of seven). These failures occurred early in the series and were thought to be related to a severely damaged recipient vasculature. This problem has been circumvented by an autogenous interpositional vein graft, permitting more mobility of flap placement. In the upper extremity, all but one case were successful. Early motion was permitted, preventing joint capsular contractures and loss of function. Twenty-three cases in the head and neck region were successful (one partial success). This included two composite rib grafts to the mandible. Prolonged delays in reconstruction following extirpation of a malignancy were avoided. A rapid return to society following complete reconstruction was ensured. Nine patients presented for reconstruction of the breast and thorax following radical mastectomy. All were successfully reconstructed with this new technique except one patient. Its many advantages include immediate reconstruction without delayed procedures and no secondary deformity of the donor site. Healthy, well vascularized tissue can now be transferred to a previously irradiated area with no tissue loss. This new method offers many advantages to older methods of reconstruction. Length of hospital stay and immobilization are reduced. The

  11. Butyltin Compounds in Tissues.

    Science.gov (United States)

    1986-01-01

    accumulate tin in their tissues (Dooley & Homer. 1983). Whether the toxic tributyltin (Bu 3 Sn) is accumulated as such or whether the various marine organisms...did not appear to have reached an equilibrium after 60 days of exposure: while fish appeared to be able to deal with tributyltin fairly efficiently...Depuration of tributyltin in oysters occurred at 5 percent/day to give a calculated half-life of about 2 weeks. AcO51.on. For I;, + I - INSPECTED~ is

  12. Soft tissue anchor systems.

    Science.gov (United States)

    Yu, G V; Chang, T; White, J M

    1994-04-01

    The concept of soft tissue attachment and reattachment has been addressed over the years through a variety of surgical techniques. This includes tendons and ligaments that have been detached both surgically and traumatically from their osseous origins or insertions. This study is designed to provide the reader with a comprehensive overview of current commercially available devices. Detailed descriptions of the various devices are provided along with a discussion of the advantages and disadvantages of each. Their application and use in reconstructive foot and ankle surgery are also discussed.

  13. Tissue bank: Sri Lanka

    International Nuclear Information System (INIS)

    2003-01-01

    Human degenerative diseases and congenital defects are common throughout the world. Many people suffer also from burns, fractures and nerve damage resulting from traumatic accidents and outbreaks of violence which occur all too frequently, especially in poorer countries. Far too many people are impaired for life because they have no access to treatment or simply cannot afford it. The Department of Technical Co-operation is sponsoring a programme, with technical support from the Division of Nuclear Medicine, to improve facilities at the Sri Lanka Tissue Bank. (IAEA)

  14. Heritable Disorders of Connective Tissue

    Science.gov (United States)

    ... Home Health Topics English Español Heritable Disorders of Connective Tissue Basics In-Depth Download Download EPUB Download PDF ... they? Points To Remember About Heritable Disorders of Connective Tissue There are more than 200 heritable disorders that ...

  15. Random lasing in human tissues

    International Nuclear Information System (INIS)

    Polson, Randal C.; Vardeny, Z. Valy

    2004-01-01

    A random collection of scatterers in a gain medium can produce coherent laser emission lines dubbed 'random lasing'. We show that biological tissues, including human tissues, can support coherent random lasing when infiltrated with a concentrated laser dye solution. To extract a typical random resonator size within the tissue we average the power Fourier transform of random laser spectra collected from many excitation locations in the tissue; we verified this procedure by a computer simulation. Surprisingly, we found that malignant tissues show many more laser lines compared to healthy tissues taken from the same organ. Consequently, the obtained typical random resonator was found to be different for healthy and cancerous tissues, and this may lead to a technique for separating malignant from healthy tissues for diagnostic imaging

  16. Neutron RBE for normal tissues

    International Nuclear Information System (INIS)

    Field, S.B.; Hornsey, S.

    1979-01-01

    RBE for various normal tissues is considered as a function of neutron dose per fraction. Results from a variety of centres are reviewed. It is shown that RBE is dependent on neutron energy and is tissue dependent, but is not specially high for the more critical tissues or for damage occurring late after irradiation. (author)

  17. Repair kinetics in tissues

    International Nuclear Information System (INIS)

    Thames, H.D.

    1989-01-01

    Monoexponential repair kinetics is based on the assumption of a single, dose-independent rate of repair of sublethal injury in the target cells for tissue injury after exposure to ionizing radiation. Descriptions of the available data based on this assumption have proved fairly successful for both acutely responding (skin, lip mucosa, gut) and late-responding (lung, spinal cord) normal tissues. There are indications of biphasic exponential repair in both categories, however. Unfortunately, the data usually lack sufficient resolution to permit unambiguous determination of the repair rates. There are also indications that repair kinetics may depend on the size of the dose. The data are conflicting on this account, however, with suggestions of both faster and slower repair after larger doses. Indeed, experiments that have been explicitly designed to test this hypothesis show either no effect (gut, spinal cord), faster repair after higher doses (lung, kidney), or slower repair after higher doses (skin). Monoexponential repair appears to be a fairly accurate description that provides an approximation to a more complicated picture, the elucidation of whose details will, however, require very careful and extensive experimental study. (author). 30 refs.; 1 fig

  18. Peripheral tissue oximetry

    DEFF Research Database (Denmark)

    Hyttel-Sorensen, Simon; Hessel, Trine Witzner; Greisen, Gorm

    2014-01-01

    Estimation of regional tissue oxygenation (rStO2) by near infrared spectroscopy enables non-invasive end-organ oxygen balance monitoring and could be a valuable tool in intensive care. However, the diverse absolute values and dynamics of different devices, and overall poor repeatability of measur......Estimation of regional tissue oxygenation (rStO2) by near infrared spectroscopy enables non-invasive end-organ oxygen balance monitoring and could be a valuable tool in intensive care. However, the diverse absolute values and dynamics of different devices, and overall poor repeatability......, and response to changing oxygenation by the down slope of rStO2 during vascular occlusion in the respective arm. 10 healthy adults, 21-29 years old, with double skinfolds on the forearm less than 10 mm participated. The median rStO2 was 70.7% (interquartile range (IQR) 7.7%), 68.4% (IQR 8.4%), and 64.6% (IQR 4...

  19. Localization of IAA transporting tissue by tissue printing and autoradiography

    International Nuclear Information System (INIS)

    Mee-Rye Cha; Evans, M.L.; Hangarter, R.P.

    1991-01-01

    Tissue printing on nitrocellulose membranes provides a useful technique for visualizing anatomical details of tissue morphology of cut ends of stem segments. Basal ends of Coleus stem and corn coleoptile segments that were transporting 14 C-IAA were gently blotted onto DEAE-nitrocellulose for several minutes to allow 14 C-IAA to efflux from the tissue. Because of the anion exchange properties of DEAE-nitrocellulose the 14 C-IAA remains on the membrane at the point it leaves the transporting tissue. Autoradiography of the DEAE membrane allowed indirect visualization of the tissues preferentially involved in auxin transport. The authors observed that polar transport through the stem segments occurred primarily through or in association with vascular tissues. However, in Coleus stems, substantial amounts of the label appeared to move through the tissue by diffusion as well as by active transport

  20. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...... the tangent moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that is at odds with what is expected from a strain gradient theory....... The findings raise questions about the physical acceptability of this class of strain gradient theories....

  1. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjøllund, Niels Henrik Ingvar; Jensen, T.K.; Bonde, J.P.

    2000-01-01

    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  2. Local strains in waste tank deflagration analysis

    International Nuclear Information System (INIS)

    Bryan, B.J.; Flanders, H.E. Jr.

    1993-01-01

    In recent years extensive effort has been expended to qualify buried nuclear waste storage tanks under accident conditions. One of these conditions is deflagration of the combustible gases which may build up over time. While much work has been done to calculate the general strain state, less effort has been made to address the local strains at structural discontinuities. An analytical method is presented for calculating these local strains and combining them with the general strain state. A closed form solution of the local strains is compared to a finite element solution

  3. Sensibility of different wheat varieties (strains) to Ar+ implantation

    International Nuclear Information System (INIS)

    Cui Huanhu; Jing Hua; Ma Aiping; Kang Xiuli; Yang Liping; Huang Mingjing; Ma Buzhou; Shanxi Academy of Agricultural Sciences, Taiyuan

    2005-01-01

    The sensibility of different wheat varieties (strains) to Ar + implantation was studied. The results showed that the survival rate of 21 wheat varieties (strains) at the dose of 6 x 10 16 Ar + /cm 2 could be divided into five groups: surplus sensitive varieties (strains), sensitive varieties (strains), transitional varieties (strains), obtuse varieties (strains) and surplus obtuse varieties (strains). The sensibility of wheat varieties (strains) to Ar + injection is high-moisture-fertility wheat varieties (strains) > medium-moisture-fertility wheat varieties (strains) > dry land wheat varieties (strains). The study has provided theoretical basis in induced mutation medial lethal dose of different wheat varieties (strains) to Ar + implantation. (authors)

  4. Strain-typical patterns of pregnancy-induced nestbuilding in mice: maternal and experiential influences.

    Science.gov (United States)

    Broida, J; Svare, B

    1982-07-01

    Pregnant C57BL/6J mice incorporate less material into maternal nests and build fewer fully enclosed nests than do pregnant DBA/2J mice. These strain differences are not ameliorated by additional reproductive experience since multiparous animals also exhibit a similar pattern. Reciprocally-crossed hybrid females exhibit DBA-like levels of pregnancy-induced nestbuilding and cross-fostered C57BL and DBA females retain the phenotype of their strain. Experiential and maternal environmental factors apparently are not responsible for strain differences in pregnancy-induced nestbuilding. Differences in ovarian function and/or central neural tissue sensitivity to ovarian hormones may modulate strain differences in pregnancy-induced nestbuilding.

  5. Stress-strain properties of railway steel at strain rates of upto 105 per second

    International Nuclear Information System (INIS)

    Hashmi, M.S.J.; Islam, M.N.

    1985-01-01

    This paper presents the stress-strain characteristics of railway steel at strain rates of up to 10 5 /s at room temperature determined by a new technique. In determining the results, account has been taken of the strain-rate variation, the total strain and the strain rate history. The effect of friction, material inertia and temperature rise is also assessed and an empirical constitutive equation describing the strain-rate and strain sensitive flow stress for this type of steel is proposed. (orig.)

  6. Strain quantification in epitaxial thin films

    International Nuclear Information System (INIS)

    Cushley, M

    2008-01-01

    Strain arising in epitaxial thin films can be beneficial in some cases but devastating in others. By altering the lattice parameters, strain may give a thin film properties hitherto unseen in the bulk material. On the other hand, heavily strained systems are prone to develop lattice defects in order to relieve the strain, which can cause device failure or, at least, a decrease in functionality. Using convergent beam electron diffraction (CBED) and high-resolution transmission electron microscopy (HRTEM), it is possible to determine local strains within a material. By comparing the results from CBED and HRTEM experiments, it is possible to gain a complete view of a material, including the strain and any lattice defects present. As well as looking at how the two experimental techniques differ from each other, I will also look at how results from different image analysis algorithms compare. Strain in Si/SiGe samples and BST/SRO/MgO capacitor structures will be discussed.

  7. Reduced thoracolumbar fascia shear strain in human chronic low back pain

    Directory of Open Access Journals (Sweden)

    Konofagou Elisa E

    2011-09-01

    Full Text Available Abstract Background The role played by the thoracolumbar fascia in chronic low back pain (LBP is poorly understood. The thoracolumbar fascia is composed of dense connective tissue layers separated by layers of loose connective tissue that normally allow the dense layers to glide past one another during trunk motion. The goal of this study was to quantify shear plane motion within the thoracolumbar fascia using ultrasound elasticity imaging in human subjects with and without chronic low back pain (LBP. Methods We tested 121 human subjects, 50 without LBP and 71 with LBP of greater than 12 months duration. In each subject, an ultrasound cine-recording was acquired on the right and left sides of the back during passive trunk flexion using a motorized articulated table with the hinge point of the table at L4-5 and the ultrasound probe located longitudinally 2 cm lateral to the midline at the level of the L2-3 interspace. Tissue displacement within the thoracolumbar fascia was calculated using cross correlation techniques and shear strain was derived from this displacement data. Additional measures included standard range of motion and physical performance evaluations as well as ultrasound measurement of perimuscular connective tissue thickness and echogenicity. Results Thoracolumbar fascia shear strain was reduced in the LBP group compared with the No-LBP group (56.4% ± 3.1% vs. 70.2% ± 3.6% respectively, p Conclusion Thoracolumbar fascia shear strain was ~20% lower in human subjects with chronic low back pain. This reduction of shear plane motion may be due to abnormal trunk movement patterns and/or intrinsic connective tissue pathology. There appears to be some sex-related differences in thoracolumbar fascia shear strain that may also play a role in altered connective tissue function.

  8. High strain-rate soft material characterization via inertial cavitation

    Science.gov (United States)

    Estrada, Jonathan B.; Barajas, Carlos; Henann, David L.; Johnsen, Eric; Franck, Christian

    2018-03-01

    Mechanical characterization of soft materials at high strain-rates is challenging due to their high compliance, slow wave speeds, and non-linear viscoelasticity. Yet, knowledge of their material behavior is paramount across a spectrum of biological and engineering applications from minimizing tissue damage in ultrasound and laser surgeries to diagnosing and mitigating impact injuries. To address this significant experimental hurdle and the need to accurately measure the viscoelastic properties of soft materials at high strain-rates (103-108 s-1), we present a minimally invasive, local 3D microrheology technique based on inertial microcavitation. By combining high-speed time-lapse imaging with an appropriate theoretical cavitation framework, we demonstrate that this technique has the capability to accurately determine the general viscoelastic material properties of soft matter as compliant as a few kilopascals. Similar to commercial characterization algorithms, we provide the user with significant flexibility in evaluating several constitutive laws to determine the most appropriate physical model for the material under investigation. Given its straightforward implementation into most current microscopy setups, we anticipate that this technique can be easily adopted by anyone interested in characterizing soft material properties at high loading rates including hydrogels, tissues and various polymeric specimens.

  9. Mechanical Characterization of Immature Porcine Brainstem in Tension at Dynamic Strain Rates.

    Science.gov (United States)

    Zhao, Hui; Yin, Zhiyong; Li, Kui; Liao, Zhikang; Xiang, Hongyi; Zhu, Feng

    2016-01-21

    Many brain injury cases involve pediatric road traffic accidents, and among these, brainstem injury causes disastrous outcomes. A thorough understanding of the tensile characterization of immature brainstem tissue is crucial in modeling traumatic brain injury sustained by children, but limited experimental data in tension is available for the immature brain tissue at dynamic strain rates. We harvested brainstem tissue from immature pigs (about 4 weeks old, and at a developmental stage similar to that of human toddlers) as a byproduct from a local slaughter house and very carefully prepared the samples. Tensile tests were performed on specimens at dynamic strain rates of 2/s, 20/s, and 100/s using a biological material instrument. The constitutive models, Fung, Ogden, Gent, and exponential function, for immature brainstem tissue material property were developed for the recorded experimental data using OriginPro 8.0 software. The t test was performed for infinitesimal shear modules. The curves of stress-versus-stretch ratio were convex in shape, and inflection points were found in all the test groups at the strain of about 2.5%. The average Lagrange stress of the immature brainstem specimen at the 30% strain at the strain rates of 2, 20, and 100/s was 273±114, 515±107, and 1121±197 Pa, respectively. The adjusted R-Square (R2) of Fung, Ogden, Gent, and exponential model was 0.820≤R2≤0.933, 0.774≤R2≤0.940, 0.650≤R2≤0.922, and 0.852≤R2≤0.981, respectively. The infinitesimal shear modulus of the strain energy functions showed a significant association with the strain rate (pmaterial in dynamic tensile tests, and the tissue becomes stiffer with increased strain rate. The reported results may be useful in the study of brain injuries in children who sustain injuries in road traffic accidents. Further research in more detail should be performed in the future.

  10. Plasmid-dependent attachment of Agrobacterium tumefaciens to plant tissue culture cells.

    Science.gov (United States)

    Matthysse, A G; Wyman, P M; Holmes, K V

    1978-11-01

    Kinetic, microscopic, and biochemical studies show that virulent Ti (tumor inducing)-plasmid-containing strains of Agrobacterium attach to normal tobacco and carrot tissue culture cells. Kinetic studies showed that virulent strains of A. tumefaciens attach to the plant tissue culture cells in increasing numbers during the first 1 to 2 h of incubation of the bacteria with the plant cells. Five Ti-plasmid-containing virulent Agrobacterium strains showed greater attachment to tobacco cells than did five avirulent strains. Light and scanning electron microscopic observations confirmed that virulent strains showed little attachment. Bacterial attachment was blocked by prior incubation of the plant cells with lipopolysaccharide extracted from A. tumefaciens, but not from A. radiobacter, suggesting that bacterial lipopolysaccharide is one of the components involved in the attachment process. At least one other bacterial product may be required for attachment in tissue culture because the virulent A. tumefaciens NT1, which lacks the Ti plasmid, does not itself attach to tobacco cells, but its lipopolysaccharide does inhibit the attachment of virulent strains.

  11. Studies on Drosophila radiosensitivity strains

    International Nuclear Information System (INIS)

    Varentsova, E.R.; Sharygin, V.I.; Khromykh, Yu.U.

    1985-01-01

    Fertility of radiosensitive mutant drosophila female strain rad (2) 201 61 after irradiation and frequency of dominant lethal mutations (DLM), induced by γ-radiation for 0-5 h and 5-7 days, are investigated. It is shown, that oocytes of the mutant strain are more radiosensitive as compared with cells of mongrel flies as to criterion of DLM appearance over the period of maturing. Early oocytes of stages 2-7 are the most sensitive, i.e. at the stages, corresponding to the manifestation of previously established recombination-defective properties of mutations rad (2) 201 61 . It is also sown, that doses of γ-rays, exceeding 10 Gy produce a strong sterilizing effect on mutant females due to destruction and resorption of egg chambers, irradiated at the stages of previtellogenetic growth of oocytes. In females, carrying mutation of radiosensitivity there is no direct correlation betwen sensitivity of oocytes proper to DLM induction and sensitivity of egg folleicles to resorbing effect of γ-rays. The ways of possible involvement of mutant locus studied into genetic processes in various specialized cells of drosophila

  12. Four-point bending protocols to study the effects of dynamic strain in osteoblastic cells in vitro.

    Science.gov (United States)

    Galea, Gabriel L; Price, Joanna S

    2015-01-01

    Strain engendered within bone tissue by mechanical loading of the skeleton is a major influence on the processes of bone modeling and remodeling and so a critical determinant of bone mass and architecture. The cells best placed to respond to strain in bone tissue are the resident osteocytes and osteoblasts. To address the mechanisms of strain-related responses in osteoblast-like cells, our group uses both in vivo and in vitro approaches, including a system of four-point bending of the substrate on which cells are cultured. A range of cell lines can be studied using this system but we routinely compare their responses to those in primary cultures of osteoblast-like cells derived from explants of mouse long bones. These cells show a range of well-characterized responses to physiological levels of strain, including increased proliferation, which in vivo is a feature of the osteogenic response.

  13. Tissue engineered tumor models.

    Science.gov (United States)

    Ingram, M; Techy, G B; Ward, B R; Imam, S A; Atkinson, R; Ho, H; Taylor, C R

    2010-08-01

    Many research programs use well-characterized tumor cell lines as tumor models for in vitro studies. Because tumor cells grown as three-dimensional (3-D) structures have been shown to behave more like tumors in vivo than do cells growing in monolayer culture, a growing number of investigators now use tumor cell spheroids as models. Single cell type spheroids, however, do not model the stromal-epithelial interactions that have an important role in controlling tumor growth and development in vivo. We describe here a method for generating, reproducibly, more realistic 3-D tumor models that contain both stromal and malignant epithelial cells with an architecture that closely resembles that of tumor microlesions in vivo. Because they are so tissue-like we refer to them as tumor histoids. They can be generated reproducibly in substantial quantities. The bioreactor developed to generate histoid constructs is described and illustrated. It accommodates disposable culture chambers that have filled volumes of either 10 or 64 ml, each culture yielding on the order of 100 or 600 histoid particles, respectively. Each particle is a few tenths of a millimeter in diameter. Examples of histological sections of tumor histoids representing cancers of breast, prostate, colon, pancreas and urinary bladder are presented. Potential applications of tumor histoids include, but are not limited to, use as surrogate tumors for pre-screening anti-solid tumor pharmaceutical agents, as reference specimens for immunostaining in the surgical pathology laboratory and use in studies of invasive properties of cells or other aspects of tumor development and progression. Histoids containing nonmalignant cells also may have potential as "seeds" in tissue engineering. For drug testing, histoids probably will have to meet certain criteria of size and tumor cell content. Using a COPAS Plus flow cytometer, histoids containing fluorescent tumor cells were analyzed successfully and sorted using such criteria.

  14. Rhizobium Strain Effects on Yield and Bleeding Sap Amino Compounds in Pisum sativum

    DEFF Research Database (Denmark)

    Rosendahl, Lis

    1984-01-01

    Bleeding sap composition, dry matter production and N distribution in pea (P. sativum L. cv. Bodil) grown with and without nitrate and nodulated with either R. leguminosarum strain 128c53 or strain 1044 were compared. Nitrate increased the total dry matter production of both symbioses, but decrea......Bleeding sap composition, dry matter production and N distribution in pea (P. sativum L. cv. Bodil) grown with and without nitrate and nodulated with either R. leguminosarum strain 128c53 or strain 1044 were compared. Nitrate increased the total dry matter production of both symbioses...... relative to the total N-accumulation was greater with strain 128c53 due to a higher production of nodule tissue. The root bleeding sap of the symbiosis with the greater yield (strain 1044) contained high levels of asparagine and aspartic acid. In the 128c53 symbiosis, glutamine plus homoserine accounted...... for a higher percentage of the organic solutes transporting newly assimilated N from the root system than in the association with 1044. The Rhizobium strain effect on amino compound composition of the bleeding sap may indicate an influence of the bacteroids on either the N-assimilatory enzyme system...

  15. High-resolution analysis of the mechanical behavior of tissue

    Science.gov (United States)

    Hudnut, Alexa W.; Armani, Andrea M.

    2017-06-01

    The mechanical behavior and properties of biomaterials, such as tissue, have been directly and indirectly connected to numerous malignant physiological states. For example, an increase in the Young's Modulus of tissue can be indicative of cancer. Due to the heterogeneity of biomaterials, it is extremely important to perform these measurements using whole or unprocessed tissue because the tissue matrix contains important information about the intercellular interactions and the structure. Thus, developing high-resolution approaches that can accurately measure the elasticity of unprocessed tissue samples is of great interest. Unfortunately, conventional elastography methods such as atomic force microscopy, compression testing, and ultrasound elastography either require sample processing or have poor resolution. In the present work, we demonstrate the characterization of unprocessed salmon muscle using an optical polarimetric elastography system. We compare the results of compression testing within different samples of salmon skeletal muscle with different numbers of collagen membranes to characterize differences in heterogeneity. Using the intrinsic collagen membranes as markers, we determine the resolution of the system when testing biomaterials. The device reproducibly measures the stiffness of the tissues at variable strains. By analyzing the amount of energy lost by the sample during compression, collagen membranes that are 500 μm in size are detected.

  16. Detection of Flavobacterium psychrophilum from fish tissue and water samples by PCR amplification

    DEFF Research Database (Denmark)

    Wiklund, T.; Madsen, Lone; Bruun, Morten Sichlau

    2000-01-01

    investigation, the possible detection of Fl. psychrophilum from fish tissue and water samples was examined using nested PCR with DNA probes against a sequence of the 16S rRNA genes. The DNA was extracted using Chelex(R) 100 chelating resin. The primers, which were tested against strains isolated from diseased...... fish, healthy fish, fish farm environments and reference strains, proved to be specific for Fl. psychrophilum. The obtained detection limit of Fl. psychrophilum seeded into rainbow trout brain tissue was 0.4 cfu in the PCR tube, corresponding to 17 cfu mg(-1) brain tissue. The PCR-assay proved...... to be more sensitive than agar cultivation of tissue samples from the brain of rainbow trout injected with Fl. psychrophilum. In non-sterile fresh water seeded with Fl. psychrophilum the detection limit of the PCR- assay was 1.7 cfu in the PCR tube, corresponding to 110 cfu ml(-1) water. The PCR...

  17. Noninvasive characterization of carotid plaque strain.

    Science.gov (United States)

    Khan, Amir A; Sikdar, Siddhartha; Hatsukami, Thomas; Cebral, Juan; Jones, Michael; Huston, John; Howard, George; Lal, Brajesh K

    2017-06-01

    Current risk stratification of internal carotid artery plaques based on diameter-reducing percentage stenosis may be unreliable because ischemic stroke results from plaque disruption with atheroembolization. Biomechanical forces acting on the plaque may render it vulnerable to rupture. The feasibility of ultrasound-based quantification of plaque displacement and strain induced by hemodynamic forces and their relationship to high-risk plaques have not been determined. We studied the feasibility and reliability of carotid plaque strain measurement from clinical B-mode ultrasound images and the relationship of strain to high-risk plaque morphology. We analyzed carotid ultrasound B-mode cine loops obtained in patients with asymptomatic ≥50% stenosis during routine clinical scanning. Optical flow methods were used to quantify plaque motion and shear strain during the cardiac cycle. The magnitude (maximum absolute shear strain rate [MASSR]) and variability (entropy of shear strain rate [ESSR] and variance of shear strain rate [VSSR]) of strain were combined into a composite shear strain index (SSI), which was assessed for interscan repeatability and correlated with plaque echolucency. Nineteen patients (mean age, 70 years) constituting 36 plaques underwent imaging; 37% of patients (n = 7) showed high strain (SSI ≥0.5; MASSR, 2.2; ESSR, 39.7; VSSR, 0.03) in their plaques; the remaining clustered into a low-strain group (SSI routine B-mode imaging using clinical ultrasound machines. High plaque strain correlates with known high-risk echolucent morphology. Strain measurement can complement identification of patients at high risk for plaque disruption and stroke. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  18. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  19. Evaluation of the endophytic nature of Bacillus amyloliquefaciens strain GYL4 and its efficacy in the control of anthracnose.

    Science.gov (United States)

    Kim, Jeong Do; Jeon, Byeong Jun; Han, Jae Woo; Park, Min Young; Kang, Sin Ae; Kim, Beom Seok

    2016-08-01

    Endophytic bacteria are viewed as a potential new source of biofungicides because they have beneficial characteristics as control agents for plant disease. This study was performed to examine the endophytic feature and disease control efficacy of Bacillus amyloliquefaciens strain GYL4 and to identify the antifungal compounds produced by this strain. B. amyloliquefaciens strain GYL4 was isolated from leaf tissue of pepper plants (Capsicum annuum L.). Anthracnose symptoms were markedly reduced in the leaves of pepper plants colonised by GYL4. An egfp-expressing strain of GYL4 (GYL4-egfp) was constructed and reintroduced into pepper plants, which confirmed its ability to colonise the internal tissues of pepper plants. GYL4-egfp was observed in the root and stem tissues 4 days after treatment and abundantly found in the internal leaf tissue 9 days after treatment. Bacillomycin derivatives purified from the culture extract of GYL4 displayed control efficacy on anthracnose development in cucumber (Cucumis sativus L. cv. Chunsim). The present study is the first report on evaluation of the endophytic and systemic nature of B. amyloliquefaciens strain GYL4 and its potential as a biocontrol agent for anthracnose management. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  20. Porous titanium bases for osteochondral tissue engineering

    Science.gov (United States)

    Nover, Adam B.; Lee, Stephanie L.; Georgescu, Maria S.; Howard, Daniel R.; Saunders, Reuben A.; Yu, William T.; Klein, Robert W.; Napolitano, Anthony P.; Ateshian, Gerard A.

    2015-01-01

    Tissue engineering of osteochondral grafts may offer a cell-based alternative to native allografts, which are in short supply. Previous studies promote the fabrication of grafts consisting of a viable cell-seeded hydrogel integrated atop a porous, bone-like metal. Advantages of the manufacturing process have led to the evaluation of porous titanium as the bone-like base material. Here, porous titanium was shown to support the growth of cartilage to produce native levels of Young’s modulus, using a clinically relevant cell source. Mechanical and biochemical properties were similar or higher for the osteochondral constructs compared to chondral-only controls. Further investigation into the mechanical influence of the base on the composite material suggests that underlying pores may decrease interstitial fluid pressurization and applied strains, which may be overcome by alterations to the base structure. Future studies aim to optimize titanium-based tissue engineered osteochondral constructs to best match the structural architecture and strength of native grafts. Statement of Significance The studies described in this manuscript follow up on previous studies from our lab pertaining to the fabrication of osteochondral grafts that consist of a bone-like porous metal and a chondrocyte-seeded hydrogel. Here, tissue engineered osteochondral grafts were cultured to native stiffness using adult chondrocytes, a clinically relevant cell source, and a porous titanium base, a material currently used in clinical implants. This porous titanium is manufactured via selective laser melting, offering the advantages of precise control over shape, pore size, and orientation. Additionally, this manuscript describes the mechanical influence of the porous base, which may have applicability to porous bases derived from other materials. PMID:26320541

  1. Distribution, persistence and interchange of Epstein-Barr virus strains among PBMC, plasma and saliva of primary infection subjects.

    Science.gov (United States)

    Kwok, Hin; Chan, Koon Wing; Chan, Kwok Hung; Chiang, Alan Kwok Shing

    2015-01-01

    Our study aimed at investigating the distribution, persistence and interchange of viral strains among peripheral blood mononuclear cells (PBMC), plasma and saliva of primary Epstein-Barr virus (EBV) infection subjects. Twelve infectious mononucleosis (IM) patients and eight asymptomatic individuals (AS) with primary EBV infection were followed longitudinally at several time points for one year from the time of diagnosis, when blood and saliva samples were collected and separated into PBMC, plasma and saliva, representing circulating B cell, plasma and epithelial cell compartments, respectively. To survey the viral strains, genotyping assays for the natural polymorphisms in two latent EBV genes, EBNA2 and LMP1, were performed and consisted of real-time PCR on EBNA2 to distinguish type 1 and 2 viruses, fluorescent-based 30-bp typing assay on LMP1 to distinguish deletion and wild type LMP1, and fluorescent-based heteroduplex tracking assays on both EBNA2 and LMP1 to distinguish defined polymorphic variants. No discernible differences were observed between IM patients and AS. Multiple viral strains were acquired early at the start of infection. Stable persistence of dominant EBV strains in the same tissue compartment was observed throughout the longitudinal samples. LMP1-defined strains, China 1, China 2 and Mediterranean+, were the most common strains observed. EBNA2-defined groups 1 and 3e predominated the PBMC and saliva compartments. Concordance of EBNA2 and LMP1 strains between PBMC and saliva suggested ready interchange of viruses between circulating B cell and epithelial cell pools, whilst discordance of viral strains observed between plasma and PBMC/saliva indicated presence of viral pools in other undetermined tissue compartments. Taken together, the results indicated that the distribution, persistence and interchange of viral strains among the tissue compartments are more complex than those proposed by the current model of EBV life cycle.

  2. Radionuclide investigation of the blood flow in tumor and normal rat tissues in induced hyperglycemia

    International Nuclear Information System (INIS)

    Istomin, Yu.P.; Shitikov, B.D.; Markova, L.V.

    1991-01-01

    Radionuclide angiography was performed in rats with transplantable tumors. Induced hyperglycemia was shown to result in blood flow inhibition in tumor and normal tissues of tumor-bearing rats. Some differences were revealed in a degree of reversibility of blood flow disorders in tissues of the above strains. The results obtained confirmed the advisability of radiation therapy at the height of a decrease in tumor blood

  3. Mechanical modulation of nascent stem cell lineage commitment in tissue engineering scaffolds.

    Science.gov (United States)

    Song, Min Jae; Dean, David; Knothe Tate, Melissa L

    2013-07-01

    Taking inspiration from tissue morphogenesis in utero, this study tests the concept of using tissue engineering scaffolds as delivery devices to modulate emergent structure-function relationships at early stages of tissue genesis. We report on the use of a combined computational fluid dynamics (CFD) modeling, advanced manufacturing methods, and experimental fluid mechanics (micro-piv and strain mapping) for the prospective design of tissue engineering scaffold geometries that deliver spatially resolved mechanical cues to stem cells seeded within. When subjected to a constant magnitude global flow regime, the local scaffold geometry dictates the magnitudes of mechanical stresses and strains experienced by a given cell, and in a spatially resolved fashion, similar to patterning during morphogenesis. In addition, early markers of mesenchymal stem cell lineage commitment relate significantly to the local mechanical environment of the cell. Finally, by plotting the range of stress-strain states for all data corresponding to nascent cell lineage commitment (95% CI), we begin to "map the mechanome", defining stress-strain states most conducive to targeted cell fates. In sum, we provide a library of reference mechanical cues that can be delivered to cells seeded on tissue engineering scaffolds to guide target tissue phenotypes in a temporally and spatially resolved manner. Knowledge of these effects allows for prospective scaffold design optimization using virtual models prior to prototyping and clinical implementation. Finally, this approach enables the development of next generation scaffolds cum delivery devices for genesis of complex tissues with heterogenous properties, e.g., organs, joints or interface tissues such as growth plates. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Finite-Element Modeling of Viscoelastic Cells During High-Frequency Cyclic Strain

    Directory of Open Access Journals (Sweden)

    David W. Holdsworth

    2012-03-01

    Full Text Available Mechanotransduction refers to the mechanisms by which cells sense and respond to local loads and forces. The process of mechanotransduction plays an important role both in maintaining tissue viability and in remodeling to repair damage; moreover, it may be involved in the initiation and progression of diseases such as osteoarthritis and osteoporosis. An understanding of the mechanisms by which cells respond to surrounding tissue matrices or artificial biomaterials is crucial in regenerative medicine and in influencing cellular differentiation. Recent studies have shown that some cells may be most sensitive to low-amplitude, high-frequency (i.e., 1–100 Hz mechanical stimulation. Advances in finite-element modeling have made it possible to simulate high-frequency mechanical loading of cells. We have developed a viscoelastic finite-element model of an osteoblastic cell (including cytoskeletal actin stress fibers, attached to an elastomeric membrane undergoing cyclic isotropic radial strain with a peak value of 1,000 µstrain. The results indicate that cells experience significant stress and strain amplification when undergoing high-frequency strain, with peak values of cytoplasmic strain five times higher at 45 Hz than at 1 Hz, and peak Von Mises stress in the nucleus increased by a factor of two. Focal stress and strain amplification in cells undergoing high-frequency mechanical stimulation may play an important role in mechanotransduction.

  5. Thermoresistance in radioresistant strains of 'Drosophila nebulosa'

    International Nuclear Information System (INIS)

    Kratz, F.L.

    1977-01-01

    The detection of thermoresistance in radioresistant strains of 'D. nebulosa' is described, as well as some conclusions on the genetic nature of these differences are presented. The strains used in this experiment were MF 204, from 'Morro de Ferro', in Pocos de Caldas (MG) (one of the biggest radioactive anomalies in the world) whose radioresistance is due to its additive genetic components (Kratz, 1973 and 1975); 85(87) R, an induced radioresistant strain; and MF K a control 'pooled' strain obtained near 'Morro do Ferro'. Survival tests, 72 hours after temperature shocks, performed in the interval of 36 0 C to 39 0 C showed a decreasing gradient of thermoresistance with the following regression coefficients: MF 204 b= - 5,4; 85(87)R b= - 7,2 and MF K b= - 7,9. Bifactorial analysis (strains and sexes) performed at 38 0 C and 39 0 C confirmed differences among strains (P [pt

  6. The many shades of prion strain adaptation.

    Science.gov (United States)

    Baskakov, Ilia V

    2014-01-01

    In several recent studies transmissible prion disease was induced in animals by inoculation with recombinant prion protein amyloid fibrils produced in vitro. Serial transmission of amyloid fibrils gave rise to a new class of prion strains of synthetic origin. Gradual transformation of disease phenotypes and PrP(Sc) properties was observed during serial transmission of synthetic prions, a process that resembled the phenomenon of prion strain adaptation. The current article discusses the remarkable parallels between phenomena of prion strain adaptation that accompanies cross-species transmission and the evolution of synthetic prions occurring within the same host. Two alternative mechanisms underlying prion strain adaptation and synthetic strain evolution are discussed. The current article highlights the complexity of the prion transmission barrier and strain adaptation and proposes that the phenomenon of prion adaptation is more common than previously thought.

  7. Lagrangian displacement tracking using a polar grid between endocardial and epicardial contours for cardiac strain imaging.

    Science.gov (United States)

    Ma, Chi; Varghese, Tomy

    2012-04-01

    Accurate cardiac deformation analysis for cardiac displacement and strain imaging over time requires Lagrangian description of deformation of myocardial tissue structures. Failure to couple the estimated displacement and strain information with the correct myocardial tissue structures will lead to erroneous result in the displacement and strain distribution over time. Lagrangian based tracking in this paper divides the tissue structure into a fixed number of pixels whose deformation is tracked over the cardiac cycle. An algorithm that utilizes a polar-grid generated between the estimated endocardial and epicardial contours for cardiac short axis images is proposed to ensure Lagrangian description of the pixels. Displacement estimates from consecutive radiofrequency frames were then mapped onto the polar grid to obtain a distribution of the actual displacement that is mapped to the polar grid over time. A finite element based canine heart model coupled with an ultrasound simulation program was used to verify this approach. Segmental analysis of the accumulated displacement and strain over a cardiac cycle demonstrate excellent agreement between the ideal result obtained directly from the finite element model and our Lagrangian approach to strain estimation. Traditional Eulerian based estimation results, on the other hand, show significant deviation from the ideal result. An in vivo comparison of the displacement and strain estimated using parasternal short axis views is also presented. Lagrangian displacement tracking using a polar grid provides accurate tracking of myocardial deformation demonstrated using both finite element and in vivo radiofrequency data acquired on a volunteer. In addition to the cardiac application, this approach can also be utilized for transverse scans of arteries, where a polar grid can be generated between the contours delineating the outer and inner wall of the vessels from the blood flowing though the vessel.

  8. Tritium metabolism in rat tissues

    International Nuclear Information System (INIS)

    Takeda, H.

    1982-01-01

    As part of a series of studies designed to evaluate the relative radiotoxicity of various tritiated compounds, metabolism of tritium in rat tissues was studied after administration of tritiated water, leucine, thymidine, and glucose. The distribution and retention of tritium varied widely, depending on the chemical compound administered. Tritium introduced as tritiated water behaved essentially as body water and became uniformly distributed among the tissues. However, tritium administered as organic compounds resulted in relatively high incorporation into tissue constituents other than water, and its distribution differed among the various tissues. Moreover, the excretion rate of tritium from tissues was slower for tritiated organic compounds than for tritiated water. Administrationof tritiated organic compounds results in higher radiation doses to the tissues than does administration of tritiated water. Among the tritiated compounds examined, for equal radioactivity administered, leucine gave the highest radiation dose, followed in turn by thymidine, glucose, and water. (author)

  9. Bioprinting for Neural Tissue Engineering.

    Science.gov (United States)

    Knowlton, Stephanie; Anand, Shivesh; Shah, Twisha; Tasoglu, Savas

    2018-01-01

    Bioprinting is a method by which a cell-encapsulating bioink is patterned to create complex tissue architectures. Given the potential impact of this technology on neural research, we review the current state-of-the-art approaches for bioprinting neural tissues. While 2D neural cultures are ubiquitous for studying neural cells, 3D cultures can more accurately replicate the microenvironment of neural tissues. By bioprinting neuronal constructs, one can precisely control the microenvironment by specifically formulating the bioink for neural tissues, and by spatially patterning cell types and scaffold properties in three dimensions. We review a range of bioprinted neural tissue models and discuss how they can be used to observe how neurons behave, understand disease processes, develop new therapies and, ultimately, design replacement tissues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Computational Modeling in Tissue Engineering

    CERN Document Server

    2013-01-01

    One of the major challenges in tissue engineering is the translation of biological knowledge on complex cell and tissue behavior into a predictive and robust engineering process. Mastering this complexity is an essential step towards clinical applications of tissue engineering. This volume discusses computational modeling tools that allow studying the biological complexity in a more quantitative way. More specifically, computational tools can help in:  (i) quantifying and optimizing the tissue engineering product, e.g. by adapting scaffold design to optimize micro-environmental signals or by adapting selection criteria to improve homogeneity of the selected cell population; (ii) quantifying and optimizing the tissue engineering process, e.g. by adapting bioreactor design to improve quality and quantity of the final product; and (iii) assessing the influence of the in vivo environment on the behavior of the tissue engineering product, e.g. by investigating vascular ingrowth. The book presents examples of each...

  11. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    DEFF Research Database (Denmark)

    Blucher, J.T.; Knudsen, Per; Grant, N.J.

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with decre......Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

  12. Contribution of collagen fibers to the compressive stiffness of cartilaginous tissues.

    Science.gov (United States)

    Römgens, Anne M; van Donkelaar, Corrinus C; Ito, Keita

    2013-11-01

    Cartilaginous tissues such as the intervertebral disk are predominantly loaded under compression. Yet, they contain abundant collagen fibers, which are generally assumed to contribute to tensile loading only. Fiber tension is thought to originate from swelling of the proteoglycan-rich nucleus. However, in aged or degenerate disk, proteoglycans are depleted, whereas collagen content changes little. The question then rises to which extend the collagen may contribute to the compressive stiffness of the tissue. We hypothesized that this contribution is significant at high strain magnitudes and that the effect depends on fiber orientation. In addition, we aimed to determine the compression of the matrix. Bovine inner and outer annulus fibrosus specimens were subjected to incremental confined compression tests up to 60 % strain in radial and circumferential direction. The compressive aggregate modulus was determined per 10 % strain increment. The biochemical composition of the compressed specimens and uncompressed adjacent tissue was determined to compute solid matrix compression. The stiffness of all specimens increased nonlinearly with strain. The collagen-rich outer annulus was significantly stiffer than the inner annulus above 20 % compressive strain. Orientation influenced the modulus in the collagen-rich outer annulus. Finally, it was shown that the solid matrix was significantly compressed above 30 % strain. Therefore, we concluded that collagen fibers significantly contribute to the compressive stiffness of the intervertebral disk at high strains. This is valuable for understanding the compressive behavior of collagen-reinforced tissues in general, and may be particularly relevant for aging or degenerate disks, which become more fibrous and less hydrated.

  13. Surface instabilities during straining of anisotropic materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Richelsen, Ann Bettina

    2006-01-01

    The development of instabilities in traction-free surfaces is investigated numerically using a unit cell model. Full finite strain analyses are conducted using isotropic as well as anisotropic yield criteria and both plane strain tension and compression are considered. In the load range of tensio...... of principal overall strain. For other orientations surface instabilities are seen when non-associated plastic flow is taken into account. Compared to tension, smaller compressive deformations are needed in order to initiate a surface instability....

  14. Strain comparisons in aquaculture species: a manual

    OpenAIRE

    Ponzoni, R.W.; James, J.W.; Nguyen, N.H.; Mekkawy, W.; Khaw, H.L.

    2013-01-01

    When different strains or breeds of a particular species are available, the best choice is seldom immediately obvious for producers. Scientists are also interested in the relative performance of different strains because it provides a basis for recommendations to producers and it often stimulates the conduct of work aimed at unraveling the underlying biological mechanisms involved in the expression of such differences. Hence, strain or breed comparisons of some sort are frequently conducted. ...

  15. Polyploidization in liver tissue.

    Science.gov (United States)

    Gentric, Géraldine; Desdouets, Chantal

    2014-02-01

    Polyploidy (alias whole genome amplification) refers to organisms containing more than two basic sets of chromosomes. Polyploidy was first observed in plants more than a century ago, and it is known that such processes occur in many eukaryotes under a variety of circumstances. In mammals, the development of polyploid cells can contribute to tissue differentiation and, therefore, possibly a gain of function; alternately, it can be associated with development of disease, such as cancer. Polyploidy can occur because of cell fusion or abnormal cell division (endoreplication, mitotic slippage, or cytokinesis failure). Polyploidy is a common characteristic of the mammalian liver. Polyploidization occurs mainly during liver development, but also in adults with increasing age or because of cellular stress (eg, surgical resection, toxic exposure, or viral infections). This review will explore the mechanisms that lead to the development of polyploid cells, our current state of understanding of how polyploidization is regulated during liver growth, and its consequence on liver function. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  16. Soft tissue angiosarcomas

    Energy Technology Data Exchange (ETDEWEB)

    Morales, P.H.; Lindberg, R.D.; Barkley, H.T.

    1981-12-01

    From 1949 to 1979, 12 patients with soft tissue angiosarcoma received radiotherapy (alone or in combination with other modalities of treatment) with curative intent at The University of Texas M.D. Anderson Hospital and Tumor Institute. The primary site was the head and neck in six patients (scalp, four; maxillary antrum, one; and oral tongue, one), the breast in four patients, and the thigh in two patients. All four patients with angiosarcoma of the scalp had advanced multifocal tumors, and two of them had clinically positive neck nodes. None of these tumors were controlled locally, and local recurrences occurred within and/or at a distance from the generous fields of irradiation. The remaining two patients with head and neck lesions had their disease controlled by surgery and postoperative irradiation. Three of the four angiosarcomas of the breast were primary cases which were treated by a combination of surgery (excisional biopsy, simple mastectomy, radical mastectomy) and postoperative irradiation. One patient also received adjuvant chemotherapy. The fourth patient was treated for scar recurrence after radical mastectomy. All four patients had their disease locally controlled, and two of them have survived over 5 years. The two patients with angiosarcoma of the thigh were treated by conservative surgical excision and postoperative irradiation. One patient had her disease controlled; the other had a local recurrence requiring hip disarticulation and subsequent hemipelvectomy for salvage.

  17. [Characteristics of Lactobacillus strains contained in pharmaceuticals].

    Science.gov (United States)

    Banach, W; Bucholc, B; Wójcik, B

    2001-01-01

    The aim of the study was to characterize lactic acid bacteria (LAB) which are components of drugs administered orally in cases of intestinal disturbances, or antibiotic--related diarrhea. Biochemical properties, growth behavior, bile tolerance, and survival at low pH of six LAB strains (four strains L. rhamnosus and two L. acidophilus) were studied. The survival at low pH was determined in MRS broth (Difco) acidified to pH 1; 2; 3; and 4. Bile tolerance was tested on MRS broth with 0.3% oxgall (Difco). Between tested strains differences in ability to grow at low pH and survival in bile were observed. Only 0.01% inoculum of all examined strains survived at pH 1. Differences between strains in survival at low pH (pH 2 and pH 3) and tolerance of bile were observed. However, after 2 h incubation at pH 4, 100% of strains stayed alive. Examined strains demonstrated good 3% bile tolerance. All strains met the criteria for probiotic strains: ability to survive at pH 3 and in the presence of bile.

  18. Properties of strain gages at cryogenic temperature

    International Nuclear Information System (INIS)

    Shibata, Nobuo; Fujiyoshi, Toshimitsu.

    1978-01-01

    At the time of developing superconduction generators, the stress measurement for rotor parts is required to grasp the safety and performance of the rotor at cryogenic temperature, which is cooled with liquid helium. In case of carrying out the stress measurement with strain gages, the problems are as follows. The strain gages and lead wires are exposed to cryogenic temperature from 4 to 10 K and strong magnetic field of about 3T, and subjected to high centrifugal acceleration of about 500G. In order to establish the techniques of the stress measurement under such conditions, the adhesives and damp-proof coatings for strain gages and strain gages themselves in Japan and foreign countries were examined on the properties at cryogenic temperature. As for the properties of strain gages, mainly the apparent strain owing to temperature change was investigated, and the change of the gage factors was studies only at liquid nitrogen temperature. The stress measurement with strain gages at low temperature had been studied in detail down to liquid nitrogen temperature concerning LNG tanks. The experimental apparatus, the samples, the testing methods and the test results of cooling tests on adhesives and damp-proof coatings, and the temperature characteristics of strain gages are reported. The usable adhesives and coatings were found, and correction by accurate temperature measurement is required for apparent strain. (Kako, I.)

  19. A Pseudomonas aeruginosa strain isolated from a contact lens-induced acute red eye (CLARE) is protease-deficient.

    Science.gov (United States)

    Estrellas, P S; Alionte, L G; Hobden, J A

    2000-03-01

    Pseudomonas aeruginosa proteases are thought to be important virulence factors in the pathogenesis of corneal disease. This study examined protease production from two strains of P. aeruginosa responsible for two very distinct clinical diseases: strain Paer1, isolated from a Contact Lens-induced Acute Red Eye (CLARE), and strain KEI 1025, isolated from a corneal ulcer. Strains were compared to a laboratory strain (ATCC 19660) known to produce severe keratitis in experimentally infected mice for protease production and for ocular virulence. Protease production was examined with colorimetric assays, gelatin zymography and western blots. Elastase A activity was quantitated with a staphylolytic assay. Ocular virulence was examined using a mouse scratch model of keratitis. In contrast to strains KEI 1025 or ATCC 19660, Paer1 was unable to produce enzymatically active elastase A, elastase, and protease IV. All three strains produced active alkaline protease. Strains KEI 1025 and ATCC 19660 produced a fulminant keratitis in mice whereas Paer1 produced a mild transient infection. Restoration of elastase activity in Paer1 via genetic complementation did not result in a virulent phenotype. Co-infection of mouse eyes with strains Paer1 and ATCC 19660 resulted in the eventual loss of Paer1 from corneal tissue. These studies suggest that P. aeruginosa elastase A and/or protease IV, but not alkaline protease or elastase, contribute to the ocular virulence of this organism.

  20. Synthetic Phage for Tissue Regeneration

    Directory of Open Access Journals (Sweden)

    So Young Yoo

    2014-01-01

    Full Text Available Controlling structural organization and signaling motif display is of great importance to design the functional tissue regenerating materials. Synthetic phage, genetically engineered M13 bacteriophage has been recently introduced as novel tissue regeneration materials to display a high density of cell-signaling peptides on their major coat proteins for tissue regeneration purposes. Structural advantages of their long-rod shape and monodispersity can be taken together to construct nanofibrous scaffolds which support cell proliferation and differentiation as well as direct orientation of their growth in two or three dimensions. This review demonstrated how functional synthetic phage is designed and subsequently utilized for tissue regeneration that offers potential cell therapy.

  1. Tissue Harmonic Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Rasmussen, Joachim

    The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB...

  2. Micro-mechanical model for the tension-stabilized enzymatic degradation of collagen tissues

    Science.gov (United States)

    Nguyen, Thao; Ruberti, Jeffery

    We present a study of how the collagen fiber structure influences the enzymatic degradation of collagen tissues. Experiments of collagen fibrils and tissues show that mechanical tension can slow and halt enzymatic degradation. Tissue-level experiments also show that degradation rate is minimum at a stretch level coincident with the onset of strain-stiffening in the stress response. To understand these phenomena, we developed a micro-mechanical model of a fibrous collagen tissue undergoing enzymatic degradation. Collagen fibers are described as sinusoidal elastica beams, and the tissue is described as a distribution of fibers. We assumed that the degradation reaction is inhibited by the axial strain energy of the crimped collagen fibers. The degradation rate law was calibrated to experiments on isolated single fibrils from bovine sclera. The fiber crimp and properties were fit to uniaxial tension tests of tissue strips. The fibril-level kinetic and tissue-level structural parameters were used to predict tissue-level degradation-induced creep rate under a constant applied force. We showed that we could accurately predict the degradation-induce creep rate of the pericardium and cornea once we accounted for differences in the fiber crimp structure and properties.

  3. Comparative genome analysis of the high pathogenicity Salmonella Typhimurium strain UK-1.

    Directory of Open Access Journals (Sweden)

    Yingqin Luo

    Full Text Available Salmonella enterica serovar Typhimurium, a gram-negative facultative rod-shaped bacterium causing salmonellosis and foodborne disease, is one of the most common isolated Salmonella serovars in both developed and developing nations. Several S. Typhimurium genomes have been completed and many more genome-sequencing projects are underway. Comparative genome analysis of the multiple strains leads to a better understanding of the evolution of S. Typhimurium and its pathogenesis. S. Typhimurium strain UK-1 (belongs to phage type 1 is highly virulent when orally administered to mice and chickens and efficiently colonizes lymphoid tissues of these species. These characteristics make this strain a good choice for use in vaccine development. In fact, UK-1 has been used as the parent strain for a number of nonrecombinant and recombinant vaccine strains, including several commercial vaccines for poultry. In this study, we conducted a thorough comparative genome analysis of the UK-1 strain with other S. Typhimurium strains and examined the phenotypic impact of several genomic differences. Whole genomic comparison highlights an extremely close relationship between the UK-1 strain and other S. Typhimurium strains; however, many interesting genetic and genomic variations specific to UK-1 were explored. In particular, the deletion of a UK-1-specific gene that is highly similar to the gene encoding the T3SS effector protein NleC exhibited a significant decrease in oral virulence in BALB/c mice. The complete genetic complements in UK-1, especially those elements that contribute to virulence or aid in determining the diversity within bacterial species, provide key information in evaluating the functional characterization of important genetic determinants and for development of vaccines.

  4. Modeling collagen remodeling in tissue engineered cardiovascular tissues

    NARCIS (Netherlands)

    Soares, A.L.F.

    2012-01-01

    Commonly, heart valve replacements consist of non-living materials lacking the ability to grow, repair and remodel. Tissue engineering (TE) offers a promising alternative to these replacement strategies since it can overcome its disadvantages. The technique aims to create an autologous living tissue

  5. Comparison of Thermal Creep Strain Calculation Results Using Time Hardening and Strain Hardening Rules

    International Nuclear Information System (INIS)

    Kim, Junehyung; Cheon, Jinsik; Lee, Byoungoon; Lee, Chanbock

    2014-01-01

    One of the design criteria for the fuel rod in PGSFR is the thermal creep strain of the cladding, because the cladding is exposed to a high temperature for a long time during reactor operation period. In general, there are two kind of calculation scheme for thermal creep strain: time hardening and strain hardening rules. In this work, thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules are compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule are compared with those by using MACSIS. Thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules were compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule were compared with those by using MACSIS. Tertiary creep started earlier in time hardening rule than in strain hardening rule. Also, calculation results by MACSIS with strain hardening and those obtained by using LIFE-METAL were almost identical to each other

  6. Safety and efficacy of an attenuated Chinese QX-like infectious bronchitis virus strain as a candidate vaccine.

    Science.gov (United States)

    Zhao, Ye; Cheng, Jin-long; Liu, Xiao-yu; Zhao, Jing; Hu, Yan-xin; Zhang, Guo-zhong

    2015-10-22

    Infectious bronchitis (IB) is a highly contagious respiratory and urogenital disease of chickens caused by infectious bronchitis virus (IBV). This disease is of considerable economic importance and is primarily controlled through biosecurity and immunization with live attenuated and inactivated IB vaccines of various serotypes. In the present study, we tested the safety and efficacy of an attenuated predominant Chinese QX-like IBV strain. The results revealed that the attenuated strain has a clear decrease in pathogenicity for specific-pathogen-free (SPF) chickens compared with the parent strain. Strain YN-inoculated birds had clinical signs of varying severity with 30% mortality, while the attenuated group appeared healthy, with less tissue damage. The attenuated strain also had relatively low tissue replication rates and higher antibody levels. The superior protective efficacy of the attenuated strain was observed when vaccinated birds were challenged with a homologous or heterologous field IBV strain, indicating the potential of the attenuated YN (aYN) as a vaccine. Producing a vaccine targeting the abundant serotype in China is essential to reducing the economic impact of IB on the poultry industry. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Gene expression profiles of irradiated lung tissue in three mouse strains

    Data.gov (United States)

    National Aeronautics and Space Administration — The aim of our research is to clarify the mechanisms generating heterogeneity in response to C-ion irradiation that arise from individual genetic variations in...

  8. The Effect of the Elimination of Micromotion and Tissue Strain on Intracortical Device Performance

    Science.gov (United States)

    2016-10-01

    ultraviolet radiation . We have recently published an article (Ecker et al., 2016) detailing a study in which SMP materials were submitted to the...devices can tolerate sterilization. Established methods, accepted by the Food and Drug Administration, include steam, ethylene oxide (EtO), and

  9. Diagnostics of Stresses and Strains of Hard Bio-tissues in vivo

    OpenAIRE

    Fomin, N; Bazylev, NB; Denisova, YL; Rubnikovich, SP; 4th Micro and Nano Flows Conference (MNF2014)

    2014-01-01

    This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, U...

  10. Clinical management of soft tissue sarcomas

    International Nuclear Information System (INIS)

    Pinedo, H.M.; Verweij, J.

    1986-01-01

    This book is concerned with the clinical management of soft tissue sarcomas. Topics covered include: Radiotherapy; Pathology of soft tissue sarcomas; Surgical treatment of soft tissue sarcomas; and Chemotherapy in advanced soft tissue sarcomas

  11. Aging changes in organs - tissue - cells

    Science.gov (United States)

    ... and structure to the skin and internal organs. Epithelial tissue provides a covering for deeper body layers. The ... such as the gastrointestinal system, are made of epithelial tissue. Muscle tissue includes three types of tissue: Striated ...

  12. New methodology for mechanical characterization of human superficial facial tissue anisotropic behaviour in vivo.

    Science.gov (United States)

    Then, C; Stassen, B; Depta, K; Silber, G

    2017-07-01

    Mechanical characterization of human superficial facial tissue has important applications in biomedical science, computer assisted forensics, graphics, and consumer goods development. Specifically, the latter may include facial hair removal devices. Predictive accuracy of numerical models and their ability to elucidate biomechanically relevant questions depends on the acquisition of experimental data and mechanical tissue behavior representation. Anisotropic viscoelastic behavioral characterization of human facial tissue, deformed in vivo with finite strain, however, is sparse. Employing an experimental-numerical approach, a procedure is presented to evaluate multidirectional tensile properties of superficial tissue layers of the face in vivo. Specifically, in addition to stress relaxation, displacement-controlled multi-step ramp-and-hold protocols were performed to separate elastic from inelastic properties. For numerical representation, an anisotropic hyperelastic material model in conjunction with a time domain linear viscoelasticity formulation with Prony series was employed. Model parameters were inversely derived, employing finite element models, using multi-criteria optimization. The methodology provides insight into mechanical superficial facial tissue properties. Experimental data shows pronounced anisotropy, especially with large strain. The stress relaxation rate does not depend on the loading direction, but is strain-dependent. Preconditioning eliminates equilibrium hysteresis effects and leads to stress-strain repeatability. In the preconditioned state tissue stiffness and hysteresis insensitivity to strain rate in the applied range is evident. The employed material model fits the nonlinear anisotropic elastic results and the viscoelasticity model reasonably reproduces time-dependent results. Inversely deduced maximum anisotropic long-term shear modulus of linear elasticity is G ∞,max aniso =2.43kPa and instantaneous initial shear modulus at an

  13. Aging enhances the vulnerability of mesenchymal stromal cells to uniaxial tensile strain-induced apoptosis.

    Science.gov (United States)

    McKayed, Katey; Prendergast, Patrick J; Campbell, Veronica A

    2016-02-08

    Mechanical priming can be employed in tissue engineering strategies to control the fate and differentiation pattern of mesenchymal stromal cells. This is relevant to regenerative medicine whereby mechanical cues can promote the regeneration of a specific tissue type from mesenchymal precursors. The ability of cells to respond to mechanical forces is dependent upon mechanotransduction pathways that involve membrane-associated proteins, such as integrins. During the aging process changes in the mechanotransduction machinery may influence how cells from aged individuals respond to mechanical priming. In this study mesenchymal stromal cells were prepared from young adult and aged rats and exposed to uniaxial tensile strain at 5% and 10% for 3 days, or 2.5% for 7 days. Application of 5% tensile strain had no impact on cell viability. In contrast, application of 10% tensile strain evoked apoptosis and the strain-induced apoptosis was significantly higher in the mesenchymal stromal cells prepared from the aged rats. In parallel to the age-related difference in cellular responsiveness to strain, an age-related decrease in expression of α2 integrin and actin, and enhanced lipid peroxidation was observed. This study demonstrates that mesenchymal stem cells from aged animals have an altered membrane environment, are more vulnerable to the pro-apoptotic effects of 10% tensile strain and less responsive to the pro-osteogenic effects of 2.5% tensile strain. Thus, it is essential to consider how aged cells respond to mechanical stimuli in order to identify optimal mechanical priming strategies that minimise cell loss, particularly if this approach is to be applied to an aged population. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Comparative proteome analysis of Helicobacter pylori clinical strains by two-dimensional gel electrophoresis.

    Science.gov (United States)

    Zhang, Ya-nan; Ding, Shi-gang; Huang, Liu-huan; Zhang, Jing; Shi, Yan-yan; Zhong, Li-jun

    2011-10-01

    To investigate the pathogenic properties of Helicobacter pylori by comparing the proteome map of H. pylori clinical strains. Two wild-type H. pylori strains, YN8 (isolated from biopsy tissue of a gastric cancer patient) and YN14 (isolated from biopsy tissue of a gastritis and duodenal ulcer patient), were used. Proteomic analysis, using a pH range of 3-10 and 5-8, was performed. The individual proteins were identified by quadrupole time-of-flight (Q-TOF) mass spectrometer and protein database search. Variation in spot patterns directed towards differential protein expression levels was observed between the strains. The gel revealed prominent proteins with several protein "families". The comparison of protein expressions of the two strains reveals a high variability. Differentially present or absent spots were observed. Nine differentially expressed protein spots identified by Q-TOF included adenosine triphosphate (ATP)-binding protein, disulfide oxidoreductase B (DsbB)-like protein, N utilization substance A (NusA), ATP-dependent protease binding subunit/heat shock protein, hydantoin utilization protein A, seryl-tRNA synthetase, molybdenum ABC transporter ModD, and hypothetical proteins. This study suggests that H. pylori strains express/repress protein variation, not only in terms of the virulence proteins, but also in terms of physiological proteins, when they infect a human host. The difference of protein expression levels between H. pylori strains isolated from gastric cancer and gastritis may be the initiator of inflammation, and result in the different clinical presentation. In this preliminary study, we report seven differential proteins between strains, with molecule weights from approximately 10 kDa to approximately 40 kDa. Further studies are needed to investigate those proteins and their function associated with H. pylori colonization and adaptation to host environment stress.

  15. Multiaxial mechanical response and constitutive modeling of esophageal tissues: Impact on esophageal tissue engineering.

    Science.gov (United States)

    Sommer, Gerhard; Schriefl, Andreas; Zeindlinger, Georg; Katzensteiner, Andreas; Ainödhofer, Herwig; Saxena, Amulya; Holzapfel, Gerhard A

    2013-12-01

    Congenital defects of the esophagus are relatively frequent, with 1 out of 2500 babies suffering from such a defect. A new method of treatment by implanting tissue engineered esophagi into newborns is currently being developed and tested using ovine esophagi. For the reconstruction of the biological function of native tissues with engineered esophagi, their cellular structure as well as their mechanical properties must be considered. Since very limited mechanical and structural data for the esophagus are available, the aim of this study was to investigate the multiaxial mechanical behavior of the ovine esophagus and the underlying microstructure. Therefore, uniaxial tensile, biaxial tensile and extension-inflation tests on esophagi were performed. The underlying microstructure was examined in stained histological sections through standard optical microscopy techniques. Moreover, the uniaxial ultimate tensile strength and residual deformations of the tissue were determined. Both the mucosa-submucosa and the muscle layers showed nonlinear and anisotropic mechanical behavior during uniaxial, biaxial and inflation testing. Cyclical inflation of the intact esophageal tube caused marked softening of the passive esophagi in the circumferential direction. The rupture strength of the mucosa-submucosa layer was much higher than that of the muscle layer. Overall, the ovine esophagus showed a heterogeneous and anisotropic behavior with different mechanical properties for the individual layers. The intact and layer-specific multiaxial properties were characterized using a well-known three-dimensional microstructurally based strain-energy function. This novel and complete set of data serves the basis for a better understanding of tissue remodeling in diseased esophagi and can be used to perform computer simulations of surgical interventions or medical-device applications. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Chitin Scaffolds in Tissue Engineering

    Science.gov (United States)

    Jayakumar, Rangasamy; Chennazhi, Krishna Prasad; Srinivasan, Sowmya; Nair, Shantikumar V.; Furuike, Tetsuya; Tamura, Hiroshi

    2011-01-01

    Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine. PMID:21673928

  17. [Cellular subcutaneous tissue. Anatomic observations].

    Science.gov (United States)

    Marquart-Elbaz, C; Varnaison, E; Sick, H; Grosshans, E; Cribier, B

    2001-11-01

    We showed in a companion paper that the definition of the French "subcutaneous cellular tissue" considerably varied from the 18th to the end of the 20th centuries and has not yet reached a consensus. To address the anatomic reality of this "subcutaneous cellular tissue", we investigated the anatomic structures underlying the fat tissue in normal human skin. Sixty specimens were excised from the surface to the deep structures (bone, muscle, cartilage) on different body sites of 3 cadavers from the Institut d'Anatomie Normale de Strasbourg. Samples were paraffin-embedded, stained and analysed with a binocular microscope taking x 1 photographs. Specimens were also excised and fixed after subcutaneous injection of Indian ink, after mechanic tissue splitting and after performing artificial skin folds. The aspects of the deep parts of the skin greatly varied according to their anatomic localisation. Below the adipose tissue, we often found a lamellar fibrous layer which extended from the interlobular septa and contained horizontally distributed fat cells. No specific tissue below the hypodermis was observed. Artificial skin folds concerned either exclusively the dermis, when they were superficial or included the hypodermis, but no specific structure was apparent in the center of the fold. India ink diffused to the adipose tissue, mainly along the septa, but did not localise in a specific subcutaneous compartment. This study shows that the histologic aspects of the deep part of the skin depend mainly on the anatomic localisation. Skin is composed of epidermis, dermis and hypodermis and thus the hypodermis can not be considered as being "subcutaneous". A difficult to individualise, fibrous lamellar structure in continuity with the interlobular septa is often found under the fat lobules. This structure is a cleavage line, as is always the case with loose connective tissues, but belongs to the hypodermis (i.e. fat tissue). No specific tissue nor any virtual space was

  18. Predicting creep rupture from early strain data

    International Nuclear Information System (INIS)

    Holmstroem, Stefan; Auerkari, Pertti

    2009-01-01

    To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40-165 MPa) and temperature (125-350 deg. C) were fitted to the models in the strain range of 0.1-38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is

  19. Conduction band structure and electron mobility in uniaxially strained Si via externally applied strain in nanomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Chen Feng [Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Euaruksakul, Chanan; Himpsel, F J; Lagally, Max G [University of Wisconsin-Madison, Madison, WI 53706 (United States); Liu Zheng; Liu Feng, E-mail: lagally@engr.wisc.edu [University of Utah, Salt Lake City, UT 84112 (United States)

    2011-08-17

    Strain changes the band structure of semiconductors. We use x-ray absorption spectroscopy to study the change in the density of conduction band (CB) states when silicon is uniaxially strained along the [1 0 0] and [1 1 0] directions. High stress can be applied to silicon nanomembranes, because their thinness allows high levels of strain without fracture. Strain-induced changes in both the sixfold degenerate {Delta} valleys and the eightfold degenerate L valleys are determined quantitatively. The uniaxial deformation potentials of both {Delta} and L valleys are directly extracted using a strain tensor appropriate to the boundary conditions, i.e., confinement in the plane in the direction orthogonal to the straining direction, which correspond to those of strained CMOS in commercial applications. The experimentally determined deformation potentials match the theoretical predictions well. We predict electron mobility enhancement created by strain-induced CB modifications.

  20. Lagrangian speckle model and tissue-motion estimation--theory.

    Science.gov (United States)

    Maurice, R L; Bertrand, M

    1999-07-01

    It is known that when a tissue is subjected to movements such as rotation, shearing, scaling, etc., changes in speckle patterns that result act as a noise source, often responsible for most of the displacement-estimate variance. From a modeling point of view, these changes can be thought of as resulting from two mechanisms: one is the motion of the speckles and the other, the alterations of their morphology. In this paper, we propose a new tissue-motion estimator to counteract these speckle decorrelation effects. The estimator is based on a Lagrangian description of the speckle motion. This description allows us to follow local characteristics of the speckle field as if they were a material property. This method leads to an analytical description of the decorrelation in a way which enables the derivation of an appropriate inverse filter for speckle restoration. The filter is appropriate for linear geometrical transformation of the scattering function (LT), i.e., a constant-strain region of interest (ROI). As the LT itself is a parameter of the filter, a tissue-motion estimator can be formulated as a nonlinear minimization problem, seeking the best match between the pre-tissue-motion image and a restored-speckle post-motion image. The method is tested, using simulated radio-frequency (RF) images of tissue undergoing axial shear.

  1. A biphasic model for bleeding in soft tissue

    Science.gov (United States)

    Chang, Yi-Jui; Chong, Kwitae; Eldredge, Jeff D.; Teran, Joseph; Benharash, Peyman; Dutson, Erik

    2017-11-01

    The modeling of blood passing through soft tissues in the body is important for medical applications. The current study aims to capture the effect of tissue swelling and the transport of blood under bleeding or hemorrhaging conditions. The soft tissue is considered as a non-static poro-hyperelastic material with liquid-filled voids. A biphasic formulation effectively, a generalization of Darcy's law-is utilized, treating the phases as occupying fractions of the same volume. The interaction between phases is captured through a Stokes-like friction force on their relative velocities and a pressure that penalizes deviations from volume fractions summing to unity. The soft tissue is modeled as a hyperelastic material with a typical J-shaped stress-strain curve, while blood is considered as a Newtonian fluid. The method of Smoothed Particle Hydrodynamics is used to discretize the conservation equations based on the ease of treating free surfaces in the liquid. Simulations of swelling under acute hemorrhage and of draining under gravity and compression will be demonstrated. Ongoing progress in modeling of organ tissues under injuries and surgical conditions will be discussed.

  2. A mechano-biological model of multi-tissue evolution in bone

    Science.gov (United States)

    Frame, Jamie; Rohan, Pierre-Yves; Corté, Laurent; Allena, Rachele

    2017-12-01

    Successfully simulating tissue evolution in bone is of significant importance in predicting various biological processes such as bone remodeling, fracture healing and osseointegration of implants. Each of these processes involves in different ways the permanent or transient formation of different tissue types, namely bone, cartilage and fibrous tissues. The tissue evolution in specific circumstances such as bone remodeling and fracturing healing is currently able to be modeled. Nevertheless, it remains challenging to predict which tissue types and organization can develop without any a priori assumptions. In particular, the role of mechano-biological coupling in this selective tissue evolution has not been clearly elucidated. In this work, a multi-tissue model has been created which simultaneously describes the evolution of bone, cartilage and fibrous tissues. The coupling of the biological and mechanical factors involved in tissue formation has been modeled by defining two different tissue states: an immature state corresponding to the early stages of tissue growth and representing cell clusters in a weakly neo-formed Extra Cellular Matrix (ECM), and a mature state corresponding to well-formed connective tissues. This has allowed for the cellular processes of migration, proliferation and apoptosis to be described simultaneously with the changing ECM properties through strain driven diffusion, growth, maturation and resorption terms. A series of finite element simulations were carried out on idealized cantilever bending geometries. Starting from a tissue composition replicating a mid-diaphysis section of a long bone, a steady-state tissue formation was reached over a statically loaded period of 10,000 h (60 weeks). The results demonstrated that bone formation occurred in regions which are optimally physiologically strained. In two additional 1000 h bending simulations both cartilaginous and fibrous tissues were shown to form under specific geometrical and loading

  3. Biomaterials for tissue engineering: summary

    Science.gov (United States)

    Christenson, L.; Mikos, A. G.; Gibbons, D. F.; Picciolo, G. L.; McIntire, L. V. (Principal Investigator)

    1997-01-01

    This article summarizes presentations and discussion at the workshop "Enabling Biomaterial Technology for Tissue Engineering," which was held during the Fifth World Biomaterials Congress in May 1996. Presentations covered the areas of material substrate architecture, barrier effects, and cellular response, including analysis of biomaterials challenges involved in producing specific tissue-engineered products.

  4. Biomimetic heterogenous elastic tissue development.

    Science.gov (United States)

    Tsai, Kai Jen; Dixon, Simon; Hale, Luke Richard; Darbyshire, Arnold; Martin, Daniel; de Mel, Achala

    2017-01-01

    There is an unmet need for artificial tissue to address current limitations with donor organs and problems with donor site morbidity. Despite the success with sophisticated tissue engineering endeavours, which employ cells as building blocks, they are limited to dedicated labs suitable for cell culture, with associated high costs and long tissue maturation times before available for clinical use. Direct 3D printing presents rapid, bespoke, acellular solutions for skull and bone repair or replacement, and can potentially address the need for elastic tissue, which is a major constituent of smooth muscle, cartilage, ligaments and connective tissue that support organs. Thermoplastic polyurethanes are one of the most versatile elastomeric polymers. Their segmented block copolymeric nature, comprising of hard and soft segments allows for an almost limitless potential to control physical properties and mechanical behaviour. Here we show direct 3D printing of biocompatible thermoplastic polyurethanes with Fused Deposition Modelling, with a view to presenting cell independent in-situ tissue substitutes. This method can expeditiously and economically produce heterogenous, biomimetic elastic tissue substitutes with controlled porosity to potentially facilitate vascularisation. The flexibility of this application is shown here with tubular constructs as exemplars. We demonstrate how these 3D printed constructs can be post-processed to incorporate bioactive molecules. This efficacious strategy, when combined with the privileges of digital healthcare, can be used to produce bespoke elastic tissue substitutes in-situ, independent of extensive cell culture and may be developed as a point-of-care therapy approach.

  5. Preclinical evaluation of oncolytic vaccinia virus for therapy of canine soft tissue sarcoma.

    Directory of Open Access Journals (Sweden)

    Ivaylo Gentschev

    Full Text Available Virotherapy using oncolytic vaccinia virus (VACV strains is one promising new strategy for canine cancer therapy. In this study we describe the establishment of an in vivo model of canine soft tissue sarcoma (CSTS using the new isolated cell line STSA-1 and the analysis of the virus-mediated oncolytic and immunological effects of two different Lister VACV LIVP1.1.1 and GLV-1h68 strains against CSTS. Cell culture data demonstrated that both tested VACV strains efficiently infected and destroyed cells of the canine soft tissue sarcoma line STSA-1. In addition, in our new canine sarcoma tumor xenograft mouse model, systemic administration of LIVP1.1.1 or GLV-1h68 viruses led to significant inhibition of tumor growth compared to control mice. Furthermore, LIVP1.1.1 mediated therapy resulted in almost complete tumor regression and resulted in long-term survival of sarcoma-bearing mice. The replication of the tested VACV strains in tumor tissues led to strong oncolytic effects accompanied by an intense intratumoral infiltration of host immune cells, mainly neutrophils. These findings suggest that the direct viral oncolysis of tumor cells and the virus-dependent activation of tumor-associated host immune cells could be crucial parts of anti-tumor mechanism in STSA-1 xenografts. In summary, the data showed that both tested vaccinia virus strains and especially LIVP1.1.1 have great potential for effective treatment of CSTS.

  6. Nanocomposite Strain Gauges Having Small TCRs

    Science.gov (United States)

    Gregory, Otto; Chen, Ximing

    2009-01-01

    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  7. Strain differentiation of polioviruses with monoclonal antibodies.

    NARCIS (Netherlands)

    A.D.M.E. Osterhaus (Albert); A.L. van Wezel; A.J.H. Stegmann; J.A.A.M. van Asten (Jack)

    1984-01-01

    textabstractPanels of monoclonal antibodies raised against different poliovirus type 1, 2 and 3 strains, were tested in a micro-neutralization test and in a micro-enzyme linked immunosorbent assay against a large number of poliovirus strains. The results were compared with those obtained with the

  8. Organic metabolites produced by Vibrio parahaemolyticus strain ...

    African Journals Online (AJOL)

    Identification and action of several antibacterial metabolites produced by a fish pathogen Vibrio parahaemolyticus strain An3 from marine ecosystem of Goa has been demonstrated. Antibacterial activity of the crude cell extract of the test bacterium has been evaluated against indicator pathogenic bacterial strains such as ...

  9. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...

  10. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

    Hjollund, N H; Kold Jensen, T; Bonde, Jens Peter

    1998-01-01

    The association between fertility and job strain defined as high job demands and low job control has not previously been studied. A follow-up study was conducted with prospective collection of information on job strain among women, achievement of pregnancy, and potential confounding variables....

  11. Medically Complex Home Care and Caregiver Strain

    Science.gov (United States)

    Moorman, Sara M.; Macdonald, Cameron

    2013-01-01

    Purpose of the study: To examine (a) whether the content of caregiving tasks (i.e., nursing vs. personal care) contributes to variation in caregivers' strain and (b) whether the level of complexity of nursing tasks contributes to variation in strain among caregivers providing help with such tasks. Design and methods: The data came from the Cash…

  12. Five challenges in modelling interacting strain dynamics

    DEFF Research Database (Denmark)

    Wikramaratna, Paul S; Kurcharski, Adam; Gupta, Sunetra

    2015-01-01

    population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity...

  13. Multiple Genome Sequences of Lactobacillus plantarum Strains

    OpenAIRE

    Kafka, Thomas A.; Geissler, Andreas J.; Vogel, Rudi F.

    2017-01-01

    ABSTRACT We report here the genome sequences of four Lactobacillus plantarum strains which vary in surface hydrophobicity. Bioinformatic analysis, using additional genomes of Lactobacillus plantarum strains, revealed a possible correlation between the cell wall teichoic acid-type and cell surface hydrophobicity and provide the basis for consecutive analyses.

  14. Preliminary characterization of slow growing rhizobial strains ...

    African Journals Online (AJOL)

    In this paper, we did some preliminary characterization of six slow growing rhizobial strains, isolated from Retama monosperma (L.) Boiss. root nodules sampled from 3 sites along the coast of Oran (CapeFalcon, Bousfer and MersElHadjadj) in Northwestern Algeria. Results of this study showed that all strains had a very ...

  15. Typing of lymphogranuloma venereum Chlamydia trachomatis strains

    NARCIS (Netherlands)

    Christerson, Linus; de Vries, Henry J. C.; de Barbeyrac, Bertille; Gaydos, Charlotte A.; Henrich, Birgit; Hoffmann, Steen; Schachter, Julius; Thorvaldsen, Johannes; Vall-Mayans, Martí; Klint, Markus; Herrmann, Björn; Morré, Servaas A.

    2010-01-01

    We analyzed by multilocus sequence typing 77 lymphogranuloma venereum Chlamydia trachomatis strains from men who have sex with men in Europe and the United States. Specimens from an outbreak in 2003 in Europe were monoclonal. In contrast, several strains were in the United States in the 1980s,

  16. Typing of Lymphogranuloma Venereum Chlamydia trachomatis Strains

    Science.gov (United States)

    Christerson, Linus; de Vries, Henry J.C.; de Barbeyrac, Bertille; Gaydos, Charlotte A.; Henrich, Birgit; Hoffmann, Steen; Schachter, Julius; Thorvaldsen, Johannes; Vall-Mayans, Martí; Klint, Markus; Morré, Servaas A.

    2010-01-01

    We analyzed by multilocus sequence typing 77 lymphogranuloma venereum Chlamydia trachomatis strains from men who have sex with men in Europe and the United States. Specimens from an outbreak in 2003 in Europe were monoclonal. In contrast, several strains were in the United States in the 1980s, including a variant from Europe. PMID:21029543

  17. MARSI: metabolite analogues for rational strain improvement

    DEFF Research Database (Denmark)

    Cardoso, João G. R.; Zeidan, Ahmad A; Jensen, Kristian

    2018-01-01

    reactions in an organism can be used to predict effects of MAs on cellular phenotypes. Here, we present the Metabolite Analogues for Rational Strain Improvement (MARSI) framework. MARSI provides a rational approach to strain improvement by searching for metabolites as targets instead of genes or reactions...

  18. General Strain Theory and Delinquency: Focusing on the Influences of Key Strain Characteristics on Delinquency

    Science.gov (United States)

    Moon, Byongook; Blurton, David; McCluskey, John D.

    2008-01-01

    The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…

  19. Strain localization band width evolution by electronic speckle pattern interferometry strain rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)], E-mail: bruno.guelorget@utt.fr; Francois, Manuel; Montay, Guillaume [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2009-04-15

    In this paper, electronic speckle pattern interferometry strain rate measurements are used to quantify the width of the strain localization band, which occurs when a sheet specimen is submitted to tension. It is shown that the width of this band decreases with increasing strain. Just before fracture, this measured width is about five times wider than the shear band and the initial sheet thickness.

  20. Limitations of Hollomon and Ludwigson stress-strain relations in assessing the strain hardening parameters

    International Nuclear Information System (INIS)

    Samuel, K G

    2006-01-01

    It is shown that the deviation from the ideal Hollomon relation in describing the stress-strain behaviour is characteristic of all materials at low strains. The Ludwigson relation describing the deviation from the Hollomon relation at low strains is critically analysed and it is shown that the deviation at low strains is a consequence of some unknown 'plastic strain equivalent' present in the material. Stress strain curves obeying an ideal Hollomon relation as well as that of a structurally modified (prior cold worked) material were simulated and compared. The results show that the yield strength and the flow strength of a material at constant strain rate and temperature are dictated by the magnitude of the 'plastic strain equivalent' term. It is shown that this component need not necessarily mean a prior plastic strain present in the material due to prior cold work alone and that prior cold work strain will add to this. If this component is identified, the stress-strain behaviour can be adequately described by the Swift relation. It is shown that in both formalisms, the strain hardening index is a function of the yield strength of the material

  1. [Antagonism against Beauveria bassiana by lipopeptide metabolites produced by entophyte Bacillus amyloliquefaciens strain SWB16].

    Science.gov (United States)

    Wang, Jingjie; Zhao, Dongyang; Liu, Yonggui; Ao, Xiang; Fan, Rui; Duan, Zhengqiao; Liu, Yanping; Chen, Qianqian; Jin, Zhixiong; Wan, Yongji

    2014-07-04

    We screened bacterial strains that have strong antagonism against Beauveria bassiana, an important pathogen of silkworm industry, and detected the antagonistic activity of lipopeptide metabolites. We identified bacterium SWB16 by morphological observation, physiological and biochemical experiments, 16SrRNA, and gyrA gene sequence analysis, tested antagonistic activity of strain SWB16 against Beauveria bassiana by measuring the inhibition zone diameter using filter paper diffusion method (Kirby-Bauer method), obtained lipopeptide metabolites of the strain using methanol extraction and observed the antagonism of strain SWB16 lipopeptide extracts against the conidia and hyphae of Beauveria bassiana, detected main ingredients and genes of lipopeptide metabolites by high-performance liquid chromatography-mass spectrometry and PCR amplification. SWB16 isolated from tissue of plant Dioscorea zingiberensis C. H. Wright belongs to Bacillus amyloliquefaciens and showed high antagonistic activity to Beauveria bassiana, and the lipopeptide extracts of isolate SWB16 exhibited significant inhibition to conidial germination and mycelial growth of Beauveria bassiana. The result of mass spectrometric detection indicated main component of the lipopeptide metabolites were fengcin and iturin, and genes fenB, ituA involved in the synthesis of them were amplified in the genome. Bacillus amyloliquefaciens strain SWB16 could produce lipopeptide antibiotics with strong antagonism to the entomopathogenic fungus Beauveria bassiana, and the results suggested that strain SWB16 has potential application value for controlling white muscardine of economic insects including silkworm.

  2. Comparisons of Venezuelan encephalitis virus strains by hemagglutination-inhibition tests with chicken antibodies.

    Science.gov (United States)

    Scherer, W F; Pancake, B A

    1977-01-01

    Twenty strains of Venezuelan encephalitis (VE) virus inoculated intravenously in large doses into roosters produced hemagglutination-inhibition (HI) antibodies detectable in plasmas within 7 to 10 days. No signs of illness occurred, and there was no evidence of viral growth in tissues since blood concentrations of infectious virus steadily decreased after inoculation. HI antibodies in early plasmas were specific for VE virus and did not cross-react significantly with two other North American alphaviruses, eastern and western encephalitis viruses. VE virus strains could be distinquished by virus-dilution, short-incubation HI, but not by plasma-dilution neutralization tests, by using early rooster antibodies. The distinctions by HI test were similar with some strains to, but different with other strains from, those described by Young and Johnson with the spiny rat antisera used to establish their subtype classifications of VE virus (14, 28). Nevertheless, results of HI tests with rooster antibodies correlated with equine virulence, as did results with spiny rat antibodies, and distinguished the new strains of virus that appeared in Middle America during the VE outbreak of 1969 from preexisting strains. PMID:591629

  3. Genotypic and Phenotypic Assessment of Hyaluronidase among Type Strains of a Select Group of Staphylococcal Species

    Directory of Open Access Journals (Sweden)

    Mark E. Hart

    2009-01-01

    Full Text Available Hyaluronidases degrade hyaluronic acid, a major polysaccharide of the extracellular matrix of tissues, and are considered important for virulence in a number of Gram-positive and -negative bacteria. The purpose of the present study was to determine the prevalence of hyaluronidase among clinical strains of Staphylococcus aureus and among other Staphylococcus species. Spent media and chromosomal DNA were assessed for hyaluronidase activity and the absence or presence of a hyaluronidase gene (hysA by Southern analysis, respectively. All S. aureus strains examined exhibited at least one hybridizing band (half of the strains exhibited two or more hybridizing bands when probed for hysA and all but three of these strains produced hyaluronidase. In contrast, none of the type strains of 19 other species exhibited either hyaluronidase activity or hybridizing bands when probed for hysA. These data support the hypothesis that among members of the Staphylococcus genus only strains of S. aureus possess the enzyme hyaluronidase. This would suggest that hyaluronidase represents yet another potential virulence factor employed by S. aureus to cause disease and may represent a diagnostically important characteristic for distinguishing S. aureus from other members of this genus.

  4. Preliminary Evaluation of Probiotic Properties of Lactobacillus Strains Isolated from Sardinian Dairy Products

    Directory of Open Access Journals (Sweden)

    Maria Barbara Pisano

    2014-01-01

    Full Text Available Twenty-three Lactobacillus strains of dairy origin were evaluated for some functional properties relevant to their use as probiotics. A preliminary subtractive screening based on the abilities to inhibit the growth of microbial pathogens and hydrolyze conjugated bile salts was applied, and six strains were selected for further characterization including survival under gastrointestinal environmental conditions, adhesion to gut epithelial tissue, enzymatic activity, and some safety properties. All selected strains maintained elevated cell numbers under conditions simulating passage through the human gastrointestinal tract, well comparable to the values obtained for the probiotic strain Lactobacillus rhamnosus GG, and were able to adhere to Caco-2 cells to various extents (from 3 to 20%. All strains exhibited high aminopeptidase, and absent or very low proteolytic and strong β-galactosidase activities; none was found to be haemolytic or to produce biogenic amines and all were susceptible to tetracycline, chloramphenicol, erythromycin, ampicillin, and amoxicillin/clavulanic acid. Our results indicate that the Lactobacillus strains analyzed could be considered appropriate probiotic candidates, due to resistance to GIT simulated conditions, antimicrobial activity, adhesion to Caco-2 cell-line, and absence of undesirable properties. They could be used as adjunct cultures for contributing to the quality and health related functional properties of dairy products.

  5. Immune Modulating Capability of Two Exopolysaccharide-Producing Bifidobacterium Strains in a Wistar Rat Model

    Directory of Open Access Journals (Sweden)

    Nuria Salazar

    2014-01-01

    Full Text Available Fermented dairy products are the usual carriers for the delivery of probiotics to humans, Bifidobacterium and Lactobacillus being the most frequently used bacteria. In this work, the strains Bifidobacterium animalis subsp. lactis IPLA R1 and Bifidobacterium longum IPLA E44 were tested for their capability to modulate immune response and the insulin-dependent glucose homeostasis using male Wistar rats fed with a standard diet. Three intervention groups were fed daily for 24 days with 10% skimmed milk, or with 109 cfu of the corresponding strain suspended in the same vehicle. A significant increase of the suppressor-regulatory TGF-β cytokine occurred with both strains in comparison with a control (no intervention group of rats; the highest levels were reached in rats fed IPLA R1. This strain presented an immune protective profile, as it was able to reduce the production of the proinflammatory IL-6. Moreover, phosphorylated Akt kinase decreased in gastroctemius muscle of rats fed the strain IPLA R1, without affecting the glucose, insulin, and HOMA index in blood, or levels of Glut-4 located in the membrane of muscle and adipose tissue cells. Therefore, the strain B. animalis subsp. lactis IPLA R1 is a probiotic candidate to be tested in mild grade inflammation animal models.

  6. Pathogenesis of New Strains of Newcastle Disease Virus From Israel and Pakistan.

    Science.gov (United States)

    Pandarangga, P; Brown, C C; Miller, P J; Haddas, R; Rehmani, S F; Afonso, C L; Susta, L

    2016-07-01

    In the past few years, Newcastle disease virus (NDV) strains with epizootic characteristics belonging to subgenotypes VIIi and XIIIb emerged in the Middle East and Asia. In this study, 2 NDV strains-1 representative of subgenotype VIIi isolated in Israel (Kvuzat/13) and 1 representative of subgenotype XIIIb isolated in Pakistan (Karachi/07)-were characterized by intracerebral pathogenicity index and detailed clinicopathologic assessment. The intracerebral pathogenicity index values for Kvuzat/13 and Karachi/07 were 1.89 and 1.85, respectively, classifying these strains as virulent by international standards. In 4-week-old White Leghorn chickens, both strains caused 100% mortality within 4 (Kvuzat/13) and 5 (Karachi/07) days postinfection. Histopathology and immunohistochemistry for NDV nucleoprotein showed that both strains had wide systemic distribution, especially targeting lymphoid organs and mucosa-associated lymphoid tissues in the respiratory and intestinal tracts. Results of the animal experiment confirm that both Kvuzat/13 and Karachi/07 are highly virulent and behaved as velogenic viscerotropic NDV strains. © The Author(s) 2016.

  7. Tissue Engineering of the Penis

    Directory of Open Access Journals (Sweden)

    Manish N. Patel

    2011-01-01

    Full Text Available Congenital disorders, cancer, trauma, or other conditions of the genitourinary tract can lead to significant organ damage or loss of function, necessitating eventual reconstruction or replacement of the damaged structures. However, current reconstructive techniques are limited by issues of tissue availability and compatibility. Physicians and scientists have begun to explore tissue engineering and regenerative medicine strategies for repair and reconstruction of the genitourinary tract. Tissue engineering allows the development of biological substitutes which could potentially restore normal function. Tissue engineering efforts designed to treat or replace most organs are currently being undertaken. Most of these efforts have occurred within the past decade. However, before these engineering techniques can be applied to humans, further studies are needed to ensure the safety and efficacy of these new materials. Recent progress suggests that engineered urologic tissues and cell therapy may soon have clinical applicability.

  8. Commercial considerations in tissue engineering.

    Science.gov (United States)

    Mansbridge, Jonathan

    2006-10-01

    Tissue engineering is a field with immense promise. Using the example of an early tissue-engineered skin implant, Dermagraft, factors involved in the successful commercial development of devices of this type are explored. Tissue engineering has to strike a balance between tissue culture, which is a resource-intensive activity, and business considerations that are concerned with minimizing cost and maximizing customer convenience. Bioreactor design takes place in a highly regulated environment, so factors to be incorporated into the concept include not only tissue culture considerations but also matters related to asepsis, scaleup, automation and ease of use by the final customer. Dermagraft is an allogeneic tissue. Stasis preservation, in this case cryopreservation, is essential in allogeneic tissue engineering, allowing sterility testing, inventory control and, in the case of Dermagraft, a cellular stress that may be important for hormesis following implantation. Although the use of allogeneic cells provides advantages in manufacturing under suitable conditions, it raises the spectre of immunological rejection. Such rejection has not been experienced with Dermagraft. Possible reasons for this and the vision of further application of allogeneic tissues are important considerations in future tissue-engineered cellular devices. This review illustrates approaches that indicate some of the criteria that may provide a basis for further developments. Marketing is a further requirement for success, which entails understanding of the mechanism of action of the procedure, and is illustrated for Dermagraft. The success of a tissue-engineered product is dependent on many interacting operations, some discussed here, each of which must be performed simultaneously and well.

  9. Atlas of stress-strain curves

    CERN Document Server

    2002-01-01

    The Atlas of Stress-Strain Curves, Second Edition is substantially bigger in page dimensions, number of pages, and total number of curves than the previous edition. It contains over 1,400 curves, almost three times as many as in the 1987 edition. The curves are normalized in appearance to aid making comparisons among materials. All diagrams include metric (SI) units, and many also include U.S. customary units. All curves are captioned in a consistent format with valuable information including (as available) standard designation, the primary source of the curve, mechanical properties (including hardening exponent and strength coefficient), condition of sample, strain rate, test temperature, and alloy composition. Curve types include monotonic and cyclic stress-strain, isochronous stress-strain, and tangent modulus. Curves are logically arranged and indexed for fast retrieval of information. The book also includes an introduction that provides background information on methods of stress-strain determination, on...

  10. [New antibiotics produced by Bacillus subtilis strains].

    Science.gov (United States)

    Malanicheva, I A; Kozlov, D G; Efimenko, T A; Zenkova, V A; Kastrukha, G S; Reznikova, M I; Korolev, A M; Borshchevskaia, L N; Tarasova, O D; Sineokiĭ, S P; Efremenkova, O V

    2014-01-01

    Two Bacillus subtilis strains isolated from the fruiting body of a basidiomycete fungus Pholiota squarrosa exhibited a broad range of antibacterial activity, including those against methicillin-resistant Staphylococcus aureus INA 00761 (MRSA) and Leuconostoc mes6nteroides VKPM B-4177 resistant to glycopep-> tide antibiotics, as well as antifungal activity. The strains were identified as belonging to the "B. subtilis" com- plex based on their morphological and physiological characteristics, as well as by sequencing of the 16S rRNA gene fragments. Both strains (INA 01085 and INA 01086) produced insignificant amounts of polyene antibiotics (hexaen and pentaen, respectively). Strain INA 01086 produced also a cyclic polypeptide antibiotic containing Asp, Gly, Leu, Pro, Tyr, Thr, Trp, and Phe, while the antibiotic of strain INA 01085 contained, apart from these, two unidentified nonproteinaceous amino acids. Both polypeptide antibiotics were new compounds efficient against gram-positive bacteria and able to override the natural bacterial antibiotic resistance.

  11. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are invest......In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields...... are investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... in the multiple parameter version of the phenomenological SGP theory. Since this also dominates the mechanics of indentation testing, results suggest that length parameters characteristic of mode I fracture should be inferred from nanoindentation....

  12. Dark field electron holography for strain measurement

    Energy Technology Data Exchange (ETDEWEB)

    Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

    2011-02-15

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  13. Pseudomagnetic fields and triaxial strain in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Jauho, Antti-Pekka

    2016-01-01

    Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions ("pseudoma......Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions......-binding calculations of single pseudomagnetic dots in extended graphene sheets confirm these predictions, and are also used to study the effect of rotating the strain direction with respect to the underlying graphene lattice, and varying the size of the pseudomagnetic dot....

  14. MODERNIZATION OF GENEOTIPING OF STRAINS B. PERTUSSIS

    Directory of Open Access Journals (Sweden)

    G. A. Ivashinnikova

    2013-01-01

    Full Text Available The new rapid molecular genotyping method was developed for studying the structure of ptxP promoter of pertussis toxin. Method is based on PCR-RFLP analysis, which allows studying the specific restriction profiles of the B. pertussis strains and allows differentiation of the strains with the ptxP structural particularities. The developed method for genotyping of strains of B. pertussis can be hhelpful when monitoring strains of the causative agent of whooping cough in system of an epidemiological surveillance over pertussis infections, allowing observation over circulating population of B.pertussis, revealing strains of the causative agent of whooping cough with high production of pertussis toxin and to watch their distribution.

  15. Strain rate effects in stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Parkins, R.N. (Newcastle upon Tyne Univ. (UK). Dept. of Metallurgy and Engineering Materials)

    1990-03-01

    Slow strain rate testing (SSRT) was initially developed as a rapid, ad hoc laboratory method for assessing the propensity for metals an environments to promote stress corrosion cracking. It is now clear, however, that there are good theoretical reasons why strain rate, as opposed to stress per se, will often be the controlling parameter in determining whether or not cracks are nucleated and, if so, are propagated. The synergistic effects of the time dependence of corrosion-related reactions and microplastic strain provide the basis for mechanistic understanding of stress corrosion cracking in high-pressure pipelines and other structures. However, while this may be readily comprehended in the context of laboratory slow strain tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that strain or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.

  16. Strain-controlled nonvolatile magnetization switching

    Science.gov (United States)

    Geprägs, S.; Brandlmaier, A.; Brandt, M. S.; Gross, R.; Goennenwein, S. T. B.

    2014-11-01

    We investigate different approaches towards a nonvolatile switching of the remanent magnetization in single-crystalline ferromagnets at room temperature via elastic strain using ferromagnetic thin film/piezoelectric actuator hybrids. The piezoelectric actuator induces a voltage-controllable strain along different crystalline directions of the ferromagnetic thin film, resulting in modifications of its magnetization by converse magnetoelastic effects. We quantify the magnetization changes in the hybrids via ferromagnetic resonance spectroscopy and superconducting quantum interference device magnetometry. These measurements demonstrate a significant strain-induced change of the magnetization, limited by an inefficient strain transfer and domain formation in the particular system studied. To overcome these obstacles, we address practicable engineering concepts and use a model to demonstrate that a strain-controlled, nonvolatile magnetization switching should be possible in appropriately engineered ferromagnetic/piezoelectric actuator hybrids.

  17. Micropropagation and maintenance of phytoplasmas in tissue culture.

    Science.gov (United States)

    Bertaccini, Assunta; Paltrinieri, Samanta; Martini, Marta; Tedeschi, Mara; Contaldo, Nicoletta

    2013-01-01

    Maintenance of phytoplasma strains in tissue culture is achievable for all strains transmitted to periwinkle (Catharanthus roseus), and also for other naturally infected plant host species. Shoots of 1-3 cm length are grown in a solid medium containing Murashige and Skoog (MS) micro- and macroelements and 0.12 mg/L benzylaminopurine. The continued presence of phytoplasmas in infected shoots of periwinkle that have been maintained in micropropagation for up to 20 years can be shown by diagnostic methods such as nested PCR tests using the 16S rDNA gene (see Chapters 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,and 26 for phytoplasma diagnostic methods).

  18. Anaerobic Cultures from Preserved Tissues of Baby Mammoth

    Science.gov (United States)

    Pikuta, Elena V.; Hoover, Richard B.; Fisher, Daniel

    2011-01-01

    Microbiological analysis of several cold-preserved tissue samples from the Siberian baby mammoth known as Lyuba revealed a number of culturable bacterial strains that were grown on anaerobic media at 4 C. Lactic acid produced by LAB (lactic acid bacteria) group, usually by members of the genera Carnobacterium and Lactosphera, appears to be a wonderful preservative that prevents other bacteria from over-dominating a system. Permafrost and lactic acid preserved the body of this one-month old baby mammoth and kept it in exceptionally good condition, resulting in this mammoth being the most complete such specimen ever recovered. The diversity of novel anaerobic isolates was expressed on morphological, physiological and phylogenetic levels. Here we discuss the specifics of the isolation of new strains, differentiation from trivial contamination, and preliminary results for the characterization of cultures.

  19. Mechanisms of lamellar collagen formation in connective tissues.

    Science.gov (United States)

    Ghazanfari, Samaneh; Khademhosseini, Ali; Smit, Theodoor H

    2016-08-01

    The objective of tissue engineering is to regenerate functional tissues. Engineering functional tissues requires an understanding of the mechanisms that guide the formation and evolution of structure in the extracellular matrix (ECM). In particular, the three-dimensional (3D) collagen fiber arrangement is important as it is the key structural determinant that provides mechanical integrity and biological function. In this review, we survey the current knowledge on collagen organization mechanisms that can be applied to create well-structured functional lamellar tissues and in particular intervertebral disc and cornea. Thus far, the mechanisms behind the formation of cross-aligned collagen fibers in the lamellar structures is not fully understood. We start with cell-induced collagen alignment and strain-stabilization behavior mechanisms which can explain a single anisotropically aligned collagen fiber layer. These mechanisms may explain why there is anisotropy in a single layer in the first place. However, they cannot explain why a consecutive collagen layer is laid down with an alternating alignment. Therefore, we explored another mechanism, called liquid crystal phasing. While dense concentrations of collagen show such behavior, there is little evidence that the conditions for liquid crystal phasing are actually met in vivo. Instead, lysyl aldehyde-derived collagen cross-links have been found essential for correct lamellar matrix deposition. Furthermore, we suggest that supra-cellular (tissue-level) shear stress may be instrumental in the alignment of collagen fibers. Understanding the potential mechanisms behind the lamellar collagen structure in connective tissues will lead to further improvement of the regeneration strategies of functional complex lamellar tissues. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Explicit hypoxia targeting with tumor suppression by creating an "obligate" anaerobic Salmonella Typhimurium strain.

    Science.gov (United States)

    Yu, Bin; Yang, Mei; Shi, Lei; Yao, Yandan; Jiang, Qinqin; Li, Xuefei; Tang, Lei-Han; Zheng, Bo-Jian; Yuen, Kwok-Yung; Smith, David K; Song, Erwei; Huang, Jian-Dong

    2012-01-01

    Using bacteria as therapeutic agents against solid tumors is emerging as an area of great potential in the treatment of cancer. Obligate and facultative anaerobic bacteria have been shown to infiltrate the hypoxic regions of solid tumors, thereby reducing their growth rate or causing regression. However, a major challenge for bacterial therapy of cancer with facultative anaerobes is avoiding damage to normal tissues. Consequently the virulence of bacteria must be adequately attenuated for therapeutic use. By placing an essential gene under a hypoxia conditioned promoter, SalmonellaTyphimurium strain SL7207 was engineered to survive only in anaerobic conditions (strain YB1) without otherwise affecting its functions. In breast tumor bearing nude mice, YB1 grew within the tumor, retarding its growth, while being rapidly eliminated from normal tissues. YB1 provides a safe bacterial vector for anti-tumor therapies without compromising the other functions or tumor fitness of the bacterium as attenuation methods normally do.

  1. Explicit hypoxia targeting with tumor suppression by creating an “obligate” anaerobic Salmonella Typhimurium strain

    Science.gov (United States)

    Yu, Bin; Yang, Mei; Shi, Lei; Yao, Yandan; Jiang, Qinqin; Li, Xuefei; Tang, Lei-Han; Zheng, Bo-Jian; Yuen, Kwok-Yung; Smith, David K.; Song, Erwei; Huang, Jian-Dong

    2012-01-01

    Using bacteria as therapeutic agents against solid tumors is emerging as an area of great potential in the treatment of cancer. Obligate and facultative anaerobic bacteria have been shown to infiltrate the hypoxic regions of solid tumors, thereby reducing their growth rate or causing regression. However, a major challenge for bacterial therapy of cancer with facultative anaerobes is avoiding damage to normal tissues. Consequently the virulence of bacteria must be adequately attenuated for therapeutic use. By placing an essential gene under a hypoxia conditioned promoter, Salmonella Typhimurium strain SL7207 was engineered to survive only in anaerobic conditions (strain YB1) without otherwise affecting its functions. In breast tumor bearing nude mice, YB1 grew within the tumor, retarding its growth, while being rapidly eliminated from normal tissues. YB1 provides a safe bacterial vector for anti-tumor therapies without compromising the other functions or tumor fitness of the bacterium as attenuation methods normally do. PMID:22666539

  2. Comparison of game-farm and wild-strain mallard ducks in accumulation of methylmercury

    Science.gov (United States)

    Heinz, G.H.

    1979-01-01

    The accumulation of mercury was compared in game-farm and wild-strain mallard ducks fed a diet containing 0.5 ppm mercury in the form of methylmercury dicyandiamide. There were no significant differences between the two strains in levels of mercury that accumulated in blood, kidney, liver, breast muscle, brain, eggs, or ducklings. Mercury levels in blood were significantly correlated with levels in other tissues and eggs, as were levels in down feathers of ducklings with levels in carcasses of ducklings. The results indicate that game-farm mallards are probably suitable substitutes for wild mallards in toxicological work, that blood samples can be used to estimate levels of mercury in other tissues of adults, and that down feathers are predictive of mercury levels in duckling carcasses.

  3. Tissue bioengineering and artificial organs.

    Science.gov (United States)

    Llames, Sara; García, Eva; Otero Hernández, Jesús; Meana, Alvaro

    2012-01-01

    The scarcity of organs and tissues for transplant and the need of immunosuppressive drugs to avoid rejection constitute two reasons that justify organ and tissue production in the laboratory. Tissue engineering based tissues (TE) could allow to regenerate the whole organ from a fragment or even to produce several organs from an organ donor for grafting purposes. TE is based in: (1) the ex vivo expansion of cells, (2) the seeding of these expanded cells in tridimensional structures that mimic physiological conditions and, (3) grafting the prototype. In order to graft big structures it is necessary that the organ or tissue produced "ex vivo" bears a vascular tree to ensure the nutrition of its deep layers. At present, no technology has been developed to provide this vascular tree to TE derived products. Thus, these tissues must be thin enough to acquire nutrients during the first days by diffusion from surrounding tissues. This fact constitutes nowadays the greatest limitation of technologies for organ development in the laboratory.In this chapter, all these problems and their possible solutions are commented. Also, the present status of TE techniques in the regeneration of different organ systems is reviewed.

  4. On the dynamic behavior of mineralized tissues

    Science.gov (United States)

    Kulin, Robb Michael

    Mineralized tissues, such as bone and antler, are complex hierarchical materials that have adapted over millennia to optimize strength and fracture resistance for their in vivo applications. As a structural support, skeletal bone primarily acts as a rigid framework that is resistant to fracture, and able to repair damage and adapt to sustained loads during its lifetime. Antler is typically deciduous and subjected to large bending moments and violent impacts during its annual cycle. To date, extensive characterization of the quasi-static mechanical properties of these materials has been performed. However, very little has been done to characterize their dynamic properties, despite the fact that the majority of failures in these materials occur under impact loads. Here, an in depth analysis of the dynamic mechanical behavior of these two materials is presented, using equine bone obtained post-mortem from donors ranging in age from 6 months to 28 years, and antler from the North American Elk. Specimens were tested under compressive strain rates of 10-3, 100, and 103 sec-1 in order to investigate their strain rate dependent compressive response. Fracture toughness experiments were performed using a four-point bending geometry on single and double-notch specimens in order to measure fracture toughness, as well as observe differences in crack propagation between dynamic (˜2x105 MPa˙m1/2/s) and quasi-static (˜0.25 MPa˙m1/2/s) loading rates. After testing, specimens were analyzed using a combination of optical, electron and confocal microscopy. Results indicated that the mechanical response of these materials is highly dependent on loading rate. Decreasing quasi-static fracture toughness is observed with age in bone specimens, while dynamic specimens show no age trends, yet universally decreased fracture toughness compared to those tested quasi-statically. For the first time, rising R-curve behavior in bone was also shown to exist under both quasi-static and dynamic

  5. Amerindian Helicobacter pylori strains go extinct, as european strains expand their host range.

    Directory of Open Access Journals (Sweden)

    Maria G Domínguez-Bello

    Full Text Available We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1, all from Spanish were European (hpEurope and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination. The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

  6. Strain-encoding cardiovascular magnetic resonance for assessment of right-ventricular regional function

    Directory of Open Access Journals (Sweden)

    Abraham M Roselle

    2008-07-01

    Full Text Available Abstract Background Tissue tagging by cardiovascular magnetic resonance (CMR is a comprehensive method for the assessment of cardiac regional function. However, imaging the right ventricle (RV using this technique is problematic due to the thin wall of the RV relative to tag spacing which limits assessment of regional function using conventional in-plane tagging. Hypothesis We hypothesize that the use of through-plane tags in the strain-encoding (SENC CMR technique would result in reproducible measurements of the RV regional function due to the high image quality and spatial resolution possible with SENC. Aim To test the intra- and inter-observer variabilities of RV peak systolic strain measurements with SENC CMR for assessment of RV regional function (systolic strain in healthy volunteers. Methods Healthy volunteers (n = 21 were imaged using SENC. A four-chamber view was acquired in a single breath-hold. Circumferential strain was measured during systole at six equidistant points along the RV free wall. Peak contraction is defined as the maximum value of circumferential strain averaged from the six points, and regional function is defined as the strain value at each point at the time of peak contraction. Results Mean values for peak circumferential strain (± standard deviation of the basal, mid, and apical regions of the RV free wall were -20.4 ± 2.9%, -18.8 ± 3.9%, and -16.5 ± 5.7%, Altman plots showed good intra- and inter-observer agreements with mean difference of 0.11% and 0.32% and limits of agreement of -4.038 to 4.174 and -4.903 to 5.836, respectively. Conclusion SENC CMR allows for rapid quantification of RV regional function with low intra- and inter-observer variabilities, which could permit accurate quantification of regional strain in patients with RV dysfunction.

  7. Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Bintu, Alexandra [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Vincze, Gabriela, E-mail: gvincze@ua.pt [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Picu, Catalin R. [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Lopes, Augusto B. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Grácio, Jose J. [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Barlat, Frederic [Materials Mechanics Laboratory, Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2015-04-01

    TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS.

  8. Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

    International Nuclear Information System (INIS)

    Bintu, Alexandra; Vincze, Gabriela; Picu, Catalin R.; Lopes, Augusto B.; Grácio, Jose J.; Barlat, Frederic

    2015-01-01

    TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS

  9. Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

    Directory of Open Access Journals (Sweden)

    Ben Lane

    2018-03-01

    Full Text Available The aim of this investigation was to establish the strains and strain rates experienced by tennis ball cores during impact to inform material characterisation testing and finite element modelling. Three-dimensional surface strains and strain rates were measured using two high-speed video cameras and corresponding digital image correlation software (GOM Correlate Professional. The results suggest that material characterisation testing to a maximum strain of 0.4 and a maximum rate of 500 s−1 in tension and to a maximum strain of −0.4 and a maximum rate of −800 s−1 in compression would encapsulate the demands placed on the material during impact and, in turn, define the range of properties required to encapsulate the behavior of the material during impact, enabling testing to be application-specific and strain-rate-dependent properties to be established and incorporated in finite element models.

  10. Factors affecting finite strain estimation in low-grade, low-strain clastic rocks

    Science.gov (United States)

    Pastor-Galán, Daniel; Gutiérrez-Alonso, Gabriel; Meere, Patrick A.; Mulchrone, Kieran F.

    2009-12-01

    The computer strain analysis methods SAPE, MRL and DTNNM have permitted the characterization of finite strain in two different regions with contrasting geodynamic scenarios; (1) the Talas Ala Tau (Tien Shan, Kyrgyzs Republic) and (2) the Somiedo Nappe and Narcea Antiform (Cantabrian to West Asturian-Leonese Zone boundary, Variscan Belt, NW of Iberia). The performed analyses have revealed low-strain values and the regional strain trend in both studied areas. This study also investigates the relationship between lithology (grain size and percentage of matrix) and strain estimates the two methodologies used. The results show that these methods are comparable and the absence of significant finite strain lithological control in rocks deformed under low metamorphic and low-strain conditions.

  11. Lymphoid Tissue Grafts in Man

    Energy Technology Data Exchange (ETDEWEB)

    Kay, H. E.M. [Royal Marsden Hospital, Institute of Cancer Research, London (United Kingdom)

    1969-07-15

    Grafts of lymphoid tissue or of lymphoid stem cells may be appropriate in the treatment of some congenital immune deficiency disorders. The reasons for preferring tissues of foetal origin are discussed and the evidence for foetal immunocompetence is briefly summarized. Methods of storing foetal liver cells and cells or fragments of thymus are mentioned, and the organization of the Foetal Tissue Bank of the Royal Marsden Hospital is described. Clinical data from transplantation of lymphoid cells in various immune deficiency disorders are briefly presented. (author)

  12. Soft tissue tumors - imaging methods

    International Nuclear Information System (INIS)

    Arlart, I.P.

    1985-01-01

    Soft Tissue Tumors - Imaging Methods: Imaging methods play an important diagnostic role in soft tissue tumors concerning a preoperative evaluation of localization, size, topographic relationship, dignity, and metastatic disease. The present paper gives an overview about diagnostic methods available today such as ultrasound, thermography, roentgenographic plain films and xeroradiography, radionuclide methods, computed tomography, lymphography, angiography, and magnetic resonance imaging. Besides sonography particularly computed tomography has the most important diagnostic value in soft tissue tumors. The application of a recently developed method, the magnetic resonance imaging, cannot yet be assessed in its significance. (orig.) [de

  13. Force transmission in epithelial tissues.

    Science.gov (United States)

    Vasquez, Claudia G; Martin, Adam C

    2016-03-01

    In epithelial tissues, cells constantly generate and transmit forces between each other. Forces generated by the actomyosin cytoskeleton regulate tissue shape and structure and also provide signals that influence cells' decisions to divide, die, or differentiate. Forces are transmitted across epithelia because cells are mechanically linked through junctional complexes, and forces can propagate through the cell cytoplasm. Here, we review some of the molecular mechanisms responsible for force generation, with a specific focus on the actomyosin cortex and adherens junctions. We then discuss evidence for how these mechanisms promote cell shape changes and force transmission in tissues. © 2016 Wiley Periodicals, Inc.

  14. Differentiation of Metastatic and Non-Metastatic Mesenteric Lymph Nodes by Strain Elastography in Surgical Specimens

    DEFF Research Database (Denmark)

    Havre, R F; Leh, S M; Gilja, O H

    2016-01-01

    Purpose: To investigate if strain elastography could differentiate between metastatic and non-metastatic mesenteric lymph nodes ex-vivo. Materials and Methods: 90 mesenteric lymph nodes were examined shortly after resection from 25 patients including 17 patients with colorectal cancer and 8...... patients with Crohn's disease. Ultrasound-based strain elastography was performed with a linear probe. Tissue hardness in lymph nodes was assessed using visual scales and measuring the strain ratio. B-mode characteristics were also recorded. Pathological diagnosis with grading of fibrosis served...... non-metastatic nodes, but the difference was not significant (65.5 vs. 55.0, p = 0.055). There was no difference between lymph nodes in Crohn's and non-metastatic cancer specimens. The metastatic lymph nodes were significantly more fibrotic than the non-metastatic lymph nodes by the ordinal fibrosis...

  15. Effect of Microgravity on Bone Tissue and Calcium Metabolism

    Science.gov (United States)

    1997-01-01

    Session TA4 includes short reports concerning: (1) Human Bone Tissue Changes after Long-Term Space Flight: Phenomenology and Possible Mechanics; (2) Prediction of Femoral Neck Bone Mineral Density Change in Space; (3) Dietary Calcium in Space; (4) Calcium Metabolism During Extended-Duration Space Flight; (5) External Impact Loads on the Lower Extremity During Jumping in Simulated Microgravity and the Relationship to Internal Bone Strain; and (6) Bone Loss During Long Term Space Flight is Prevented by the Application of a Short Term Impulsive Mechanical Stimulus.

  16. Pulmonary ultrasound elastography: a feasibility study with phantoms and ex-vivo tissue

    Science.gov (United States)

    Nguyen, Man Minh; Xie, Hua; Paluch, Kamila; Stanton, Douglas; Ramachandran, Bharat

    2013-03-01

    Elastography has become widely used for minimally invasive diagnosis in many tumors as seen with breast, liver and prostate. Among different modalities, ultrasound-based elastography stands out due to its advantages including being safe, real-time, and relatively low-cost. While lung cancer is the leading cause of cancer mortality among both men and women, the use of ultrasound elastography for lung cancer diagnosis has hardly been investigated due to the limitations of ultrasound in air. In this work, we investigate the use of static-compression based endobronchial ultrasound elastography by a 3D trans-oesophageal echocardiography (TEE) transducer for lung cancer diagnosis. A water-filled balloon was designed to 1) improve the visualization of endobronchial ultrasound and 2) to induce compression via pumping motion inside the trachea and bronchiole. In a phantom study, we have successfully generated strain images indicating the stiffness difference between the gelatin background and agar inclusion. A similar strain ratio was confirmed with Philips ultrasound strain-based elastography product. For ex-vivo porcine lung study, different tissue ablation methods including chemical injection, Radio Frequency (RF) ablation, and direct heating were implemented to achieve tumor-mimicking tissue. Stiff ablated lung tissues were obtained and detected with our proposed method. These results suggest the feasibility of pulmonary elastography to differentiate stiff tumor tissue from normal tissue.

  17. Chemical Profile of Monascus ruber Strains

    Directory of Open Access Journals (Sweden)

    Ahamed M. Moharram

    2012-01-01

    Full Text Available Chemical profile of Monascus ruber strains has been studied using gas chromatography-mass spectrometry (GC/MS analysis. The colour intensity of the red pigment and secondary metabolic products of two M. ruber strains (AUMC 4066 and AUMC 5705 cultivated on ten different media were also studied. Metabolic products can be classified into four categories: anticholesterol, anticancer, food colouring, and essential fatty acids necessary for human health. Using GC/MS, the following 88 metabolic products were detected: butyric acid and its derivatives (25 products, other fatty acids and their derivatives (19 products, pyran and its derivatives (22 products and other metabolites (22 products. Among these, 32 metabolites were specific for AUMC 4066 strain and 34 for AUMC 5705 strain, whereas 22 metabolites were produced by both strains on different tested substrates. Production of some metabolites depended on the substrate used. High number of metabolites was recorded in the red pigment extract obtained by both strains grown on malt broth and malt agar. Also, 42 aroma compounds were recorded (4 alcohols, 2 benzaldehydes, 27 esters, 3 lactones, 1 phenol, 1 terpenoid, 3 thiol compounds and acetate-3-mercapto butyric acid. Thin layer chromatography and GC/MS analyses revealed no mycotoxin citrinin in any media used for the growth of the two M. ruber strains.

  18. Resolution of axial shear strain elastography

    International Nuclear Information System (INIS)

    Thitaikumar, Arun; Righetti, Raffaella; Krouskop, Thomas A; Ophir, Jonathan

    2006-01-01

    The technique of mapping the local axial component of the shear strain due to quasi-static axial compression is defined as axial shear strain elastography. In this paper, the spatial resolution of axial shear strain elastography is investigated through simulations, using an elastically stiff cylindrical lesion embedded in a homogeneously softer background. Resolution was defined as the smallest size of the inclusion for which the strain value at the inclusion/background interface was greater than the average of the axial shear strain values at the interface and inside the inclusion. The resolution was measured from the axial shear strain profile oriented at 45 0 to the axis of beam propagation, due to the absence of axial shear strain along the normal directions. The effects of the ultrasound system parameters such as bandwidth, beamwidth and transducer element pitch along with signal processing parameters such as correlation window length (W) and axial shift (ΔW) on the estimated resolution were investigated. The results show that the resolution (at 45 0 orientation) is determined by the bandwidth and the beamwidth. However, the upper bound on the resolution is limited by the larger of the beamwidth and the window length, which is scaled inversely to the bandwidth. The results also show that the resolution is proportional to the pitch and not significantly affected by the axial window shift

  19. Stress and strain provide positional and directional cues in development.

    Directory of Open Access Journals (Sweden)

    Behruz Bozorg

    2014-01-01

    Full Text Available The morphogenesis of organs necessarily involves mechanical interactions and changes in mechanical properties of a tissue. A long standing question is how such changes are directed on a cellular scale while being coordinated at a tissular scale. Growing evidence suggests that mechanical cues are participating in the control of growth and morphogenesis during development. We introduce a mechanical model that represents the deposition of cellulose fibers in primary plant walls. In the model both the degree of material anisotropy and the anisotropy direction are regulated by stress anisotropy. We show that the finite element shell model and the simpler triangular biquadratic springs approach provide equally adequate descriptions of cell mechanics in tissue pressure simulations of the epidermis. In a growing organ, where circumferentially organized fibers act as a main controller of longitudinal growth, we show that the fiber direction can be correlated with both the maximal stress direction and the direction orthogonal to the maximal strain direction. However, when dynamic updates of the fiber direction are introduced, the mechanical stress provides a robust directional cue for the circumferential organization of the fibers, whereas the orthogonal to maximal strain model leads to an unstable situation where the fibers reorient longitudinally. Our investigation of the more complex shape and growth patterns in the shoot apical meristem where new organs are initiated shows that a stress based feedback on fiber directions is capable of reproducing the main features of in vivo cellulose fiber directions, deformations and material properties in different regions of the shoot. In particular, we show that this purely mechanical model can create radially distinct regions such that cells expand slowly and isotropically in the central zone while cells at the periphery expand more quickly and in the radial direction, which is a well established growth pattern

  20. Stress and strain provide positional and directional cues in development.

    Science.gov (United States)

    Bozorg, Behruz; Krupinski, Pawel; Jönsson, Henrik

    2014-01-01

    The morphogenesis of organs necessarily involves mechanical interactions and changes in mechanical properties of a tissue. A long standing question is how such changes are directed on a cellular scale while being coordinated at a tissular scale. Growing evidence suggests that mechanical cues are participating in the control of growth and morphogenesis during development. We introduce a mechanical model that represents the deposition of cellulose fibers in primary plant walls. In the model both the degree of material anisotropy and the anisotropy direction are regulated by stress anisotropy. We show that the finite element shell model and the simpler triangular biquadratic springs approach provide equally adequate descriptions of cell mechanics in tissue pressure simulations of the epidermis. In a growing organ, where circumferentially organized fibers act as a main controller of longitudinal growth, we show that the fiber direction can be correlated with both the maximal stress direction and the direction orthogonal to the maximal strain direction. However, when dynamic updates of the fiber direction are introduced, the mechanical stress provides a robust directional cue for the circumferential organization of the fibers, whereas the orthogonal to maximal strain model leads to an unstable situation where the fibers reorient longitudinally. Our investigation of the more complex shape and growth patterns in the shoot apical meristem where new organs are initiated shows that a stress based feedback on fiber directions is capable of reproducing the main features of in vivo cellulose fiber directions, deformations and material properties in different regions of the shoot. In particular, we show that this purely mechanical model can create radially distinct regions such that cells expand slowly and isotropically in the central zone while cells at the periphery expand more quickly and in the radial direction, which is a well established growth pattern in the meristem.

  1. Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

    Science.gov (United States)

    Nakagawa, Youji; Ogihara, Hiroyuki; Mochizuki, Chisato; Yamamura, Hideki; Iimura, Yuzuru; Hayakawa, Masayuki

    2017-03-01

    Previously reported self-cloning procedures for breeding of industrial yeast strains require DNA from other strains, plasmid DNA, or mutagenesis. Therefore, we aimed to construct a self-cloning baker's yeast strain that exhibits freeze tolerance via an improved self-cloning procedure. We first disrupted the URA3 gene of a prototrophic baker's yeast strain without the use of any marker gene, resulting in a Δura3 homozygous disruptant. Then, the URA3 gene of the parental baker's yeast strain was used as a selection marker to introduce the constitutive TDH3 promoter upstream of the PDE2 gene encoding high-affinity cyclic AMP phosphodiesterase. This self-cloning procedure was performed without using DNA from other Saccharomyces cerevisiae strains, plasmid DNA, or mutagenesis and was therefore designated an intra-strain self-cloning procedure. Using this self-cloning procedure, we succeeded in producing self-cloning baker's yeast strains that harbor the TDH3p-PDE2 gene heterozygously and homozygously, designated TDH3p-PDE2 hetero and TDH3p-PDE2 homo strains, respectively. These self-cloning strains expressed much higher levels of PDE2 mRNA than the parental strain and exhibited higher viability after freeze stress, as well as higher fermentation ability in frozen dough, when compared with the parental strain. The TDH3p-PDE2 homo strain was genetically more stable than the TDH3p-PDE2 hetero strain. These results indicate that both heterozygous and homozygous strains of self-cloning PDE2-overexpressing freeze-tolerant strains of industrial baker's yeast can be prepared using the intra-strain self-cloning procedure, and, from a practical viewpoint, the TDH3p-PDE2 homo strain constructed in this study is preferable to the TDH3p-PDE2 hetero strain for frozen dough baking. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  2. [Screening and optimization of cholesterol conversion strain].

    Science.gov (United States)

    Fan, Dan; Xiong, Bingjian; Pang, Cuiping; Zhu, Xiangdong

    2014-10-04

    Bacterial strain SE-1 capable of transforming cholesterol was isolated from soil and characterized. The transformation products were identified. Fermentation conditions were optimized for conversion. Cholesterol was used as sole carbon source to isolate strain SE-1. Morphology, physiological and biochemical characteristics of strain SE-1 were studied. 16S rRNA gene was sequenced and subjected to phylogenetic analysis. Fermentation supernatants were extracted with chloroform, the transformation products were analyzed by silica gel thin layer chromatography and Sephadex LH20. Their structures were identified by 1H-NMR and 13C-NMR. Fermentation medium including carbon and nitrogen, methods of adding substrates and fermentation conditions for Strain SE-1 were optimized. Strain SE-1 was a Gram-negative bacterium, exhibiting the highest homologs to Burkholderia cepacia based on the physiological analysis. The sequence analysis of 16S rRNA gene of SE-1 strain and comparison with related Burkholderia show that SE-1 strain was very close to B. cepacia (Genbank No. U96927). The similarity was 99%. The result of silica gel thin layer chromatography shows that strain SE-1 transformed cholesterol to two products, 7beta-hydroxycholesterol and the minor product was 7-oxocholesterol. The optimum culture conditions were: molasses 5%, (NH4 )2SO4 0.3%, 4% of inoculation, pH 7.5 and 36 degrees C. Under the optimum culture condition, the conversion rate reached 34.4% when concentration of cholesterol-Tween 80 was 1 g/L. Cholesterol 7beta-hydroxylation conversion rate under optimal conditions was improved by 20.8%. Strain SE-1 isolated from soil is capable of converting cholesterol at lab-scale.

  3. Practical obstacles and their mitigation strategies in compressional optical coherence elastography of biological tissues

    Directory of Open Access Journals (Sweden)

    Vladimir Y. Zaitsev

    2017-11-01

    Full Text Available In this paper, we point out some practical obstacles arising in realization of compressional optical coherence elastography (OCE that have not attracted sufficient attention previously. Specifically, we discuss (i complications in quantification of the Young modulus of tissues related to partial adhesion between the OCE probe and soft intervening reference layer sensor, (ii distorting influence of tissue surface curvature/corrugation on the subsurface strain distribution mapping, (iii ways of signal-to-noise ratio (SNR enhancement in OCE strain mapping when periodic averaging is not realized, and (iv potentially significant influence of tissue elastic nonlinearity on quantification of its stiffness. Potential practical approaches to mitigate the effects of these complications are also described.

  4. Bacterial strain changes during chronic otitis media surgery.

    Science.gov (United States)

    Kim, G J; Yoo, S; Han, S; Bu, J; Hong, Y; Kim, D-K

    2017-09-01

    Cultures obtained from pre-operative middle-ear swabs from patients with chronic otitis media have traditionally been used to guide antibiotic selection. This study investigated changes in the bacterial strains of the middle ear during chronic otitis media surgery. Pre-operative bacterial cultures of otorrhoea, and peri-operative cultures of the granulation tissue in either the middle ear or mastoid cavity, were obtained. Post-operative cultures were selectively obtained when otorrhoea developed after surgery. Bacterial growth was observed in 45.5 per cent of pre-operative cultures, 13.5 per cent of peri-operative cultures and 4.5 per cent of post-operative cultures. Methicillin-resistant Staphylococcus aureus was identified as the most common bacteria in all pre-operative (32.4 per cent), peri-operative (52.4 per cent) and post-operative (71.4 per cent) tests, and the percentage of Methicillin-resistant S aureus increased from the pre- to the post-operative period. The bacterial culture results for post-operative otorrhoea showed low agreement with those for pre-operative or peri-operative culture, and strain re-identification was required.

  5. Thermomechanical effect of pulse-periodic laser radiation on cartilaginous and eye tissues

    Science.gov (United States)

    Baum, O. I.; Zheltov, G. I.; Omelchenko, A. I.; Romanov, G. S.; Romanov, O. G.; Sobol, E. N.

    2013-08-01

    This paper is devoted to theoretical and experimental studies into the thermomechanical action of laser radiation on biological tissues. The thermal stresses and strains developing in biological tissues under the effect of pulse-periodic laser radiation are theoretically modeled for a wide range of laser pulse durations. The models constructed allow one to calculate the magnitude of pressures developing in cartilaginous and eye tissues exposed to laser radiation and predict the evolution of cavitation phenomena occurring therein. The calculation results agree well with experimental data on the growth of pressure and deformations, as well as the dynamics of formation of gas bubbles, in the laser-affected tissues. Experiments on the effect of laser radiation on the trabecular region of the eye in minipigs demonstrated that there existed optimal laser irradiation regimens causing a substantial increase in the hydraulic permeability of the radiation-exposed tissue, which can be used to develop a novel glaucoma treatment method.

  6. Thermomechanical effect of pulse-periodic laser radiation on cartilaginous and eye tissues

    International Nuclear Information System (INIS)

    Baum, O I; Omelchenko, A I; Sobol, E N; Zheltov, G I; Romanov, G S; Romanov, O G

    2013-01-01

    This paper is devoted to theoretical and experimental studies into the thermomechanical action of laser radiation on biological tissues. The thermal stresses and strains developing in biological tissues under the effect of pulse-periodic laser radiation are theoretically modeled for a wide range of laser pulse durations. The models constructed allow one to calculate the magnitude of pressures developing in cartilaginous and eye tissues exposed to laser radiation and predict the evolution of cavitation phenomena occurring therein. The calculation results agree well with experimental data on the growth of pressure and deformations, as well as the dynamics of formation of gas bubbles, in the laser-affected tissues. Experiments on the effect of laser radiation on the trabecular region of the eye in minipigs demonstrated that there existed optimal laser irradiation regimens causing a substantial increase in the hydraulic permeability of the radiation-exposed tissue, which can be used to develop a novel glaucoma treatment method. (paper)

  7. Ductile Damage Evolution and Strain Path Dependency

    International Nuclear Information System (INIS)

    Tasan, C. C.; Hoefnagels, J. M. P.; Peerlings, R. H. J.; Geers, M. G. D.; ten Horn, C. H. L. J.; Vegter, H.

    2007-01-01

    Forming limit diagrams are commonly used in sheet metal industry to define the safe forming regions. These diagrams are built to define the necking strains of sheet metals. However, with the rise in the popularity of advance high strength steels, ductile fracture through damage evolution has also emerged as an important parameter in the determination of limit strains. In this work, damage evolution in two different steels used in the automotive industry is examined to observe the relationship between damage evolution and the strain path that is followed during the forming operation

  8. Strain-energy effects on dynamic fragmentation

    International Nuclear Information System (INIS)

    Glenn, L.A.; Chudnovsky, A.

    1986-01-01

    Grady's model of the dynamic fragmentation process, in which the average fragment size is determined by balancing the local kinetic energy and the surface energy, is modified to include the stored elastic (strain) energy. The revised model predicts that the strain energy should dominate for brittle materials, with low fracture toughness and high fracture-initiation stress. This conclusion is not borne out, however, by limited experimental data on brittle steels, even when the kinetic-energy density is small compared with the strain-energy density

  9. Stability of germanene under tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-09-01

    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  10. Stability of germanene under tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.; Schwingenschlö gl, Udo

    2013-01-01

    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  11. Assessment of right ventricular systolic function by tissue Doppler echocardiography

    DEFF Research Database (Denmark)

    Kjærgaard, Jesper

    2012-01-01

    This thesis summarizes a series of studies performed in order to assess the clinical usefulness of a novel echocardiographic technology that allows non-invasive assessment of regional right ventricular myocardial velocities and deformation: tissue Doppler echocardiography. While the technology...... is a promising tool for improving our understanding of right ventricular hemodynamics, several aspects of the technology must be evaluated. The accuracy and reproducibility of the technology is evaluated in vitro, and normal values, impact of changes in loading of the right ventricle, response to exercise...... on right ventricular hemodynamics: pulmonary embolism, Arrhythmogenic right ventricular cardiomyopathy and pulmonary regurgitation, the latter in an animal model. The conclusions of the thesis are: Color tissue Doppler echocardiography accurately measures velocities, SR and strain in vitro. No systematic...

  12. Dynamics of anisotropic tissue growth

    Energy Technology Data Exchange (ETDEWEB)

    Bittig, Thomas; Juelicher, Frank [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany); Wartlick, Ortrud; Kicheva, Anna; Gonzalez-Gaitan, Marcos [Department of Biochemistry and Department of Molecular Biology, Geneva University, Sciences II, Quai Ernest-Ansermet 30, 1211 Geneva 4 (Switzerland)], E-mail: Marcos.Gonzalez@biochem.unige.ch, E-mail: julicher@pks.mpg.de

    2008-06-15

    We study the mechanics of tissue growth via cell division and cell death (apoptosis). The rearrangements of cells can on large scales and times be captured by a continuum theory which describes the tissue as an effective viscous material with active stresses generated by cell division. We study the effects of anisotropies of cell division on cell rearrangements and show that average cellular trajectories exhibit anisotropic scaling behaviors. If cell division and apoptosis balance, there is no net growth, but for anisotropic cell division the tissue undergoes spontaneous shear deformations. Our description is relevant for the study of developing tissues such as the imaginal disks of the fruit fly Drosophila melanogaster, which grow anisotropically.

  13. Molecular, cellular, and tissue engineering

    CERN Document Server

    Bronzino, Joseph D

    2015-01-01

    Known as the bible of biomedical engineering, The Biomedical Engineering Handbook, Fourth Edition, sets the standard against which all other references of this nature are measured. As such, it has served as a major resource for both skilled professionals and novices to biomedical engineering. Molecular, Cellular, and Tissue Engineering, the fourth volume of the handbook, presents material from respected scientists with diverse backgrounds in molecular biology, transport phenomena, physiological modeling, tissue engineering, stem cells, drug delivery systems, artificial organs, and personalized medicine. More than three dozen specific topics are examined, including DNA vaccines, biomimetic systems, cardiovascular dynamics, biomaterial scaffolds, cell mechanobiology, synthetic biomaterials, pluripotent stem cells, hematopoietic stem cells, mesenchymal stem cells, nanobiomaterials for tissue engineering, biomedical imaging of engineered tissues, gene therapy, noninvasive targeted protein and peptide drug deliver...

  14. American Association of Tissue Banks

    Science.gov (United States)

    ... Committees Accreditation American Board of Tissue Banking Bylaws / Ethics Communications Donor Family Services Ad Hoc Committee Education Finance ... Bureau Accredited Bank Search Bookstore Bulletins Global Topics Communications & Media Job Center News Releases Patients and Community Useful ...

  15. Tissue equivalence in neutron dosimetry

    International Nuclear Information System (INIS)

    Nutton, D.H.; Harris, S.J.

    1980-01-01

    A brief review is presented of the essential features of neutron tissue equivalence for radiotherapy and gives the results of a computation of relative absorbed dose for 14 MeV neutrons, using various tissue models. It is concluded that for the Bragg-Gray equation for ionometric dosimetry it is not sufficient to define the value of W to high accuracy and that it is essential that, for dosimetric measurements to be applicable to real body tissue to an accuracy of better than several per cent, a correction to the total absorbed dose must be made according to the test and tissue atomic composition, although variations in patient anatomy and other radiotherapy parameters will often limit the benefits of such detailed dosimetry. (U.K.)

  16. Imaging of soft tissue sarcomas

    International Nuclear Information System (INIS)

    Vanel, D.; Le Treut, A.

    1988-01-01

    Modern imaging of soft tissue sarcomas now includes ultrasounds, CT and MRI. These new techniques allow a better evaluation of initial local extension, of the response to treatment and are able to detect local recurrences early [fr

  17. Symptomatic heterotopic suprarenal splenic tissue

    International Nuclear Information System (INIS)

    Heider, J.; Kreft, B.; Winter, P.

    1998-01-01

    We report on a 33-year-old man with symptomatic heterotopic suprarenal splenic tissue. Heterotopic splenic tissue can often be found after posttraumatic splenectomy. It is a result of autotransplantation induced by trauma (splenosis). Additionally it can grow during embryogenic development. Such an accessory spleen is found in 10-44% of all autopsies. In this case report the patient was treated by resection due to increasing flank pain and suspected neoplasm. (orig.) [de

  18. Rat Strain Ontology: structured controlled vocabulary designed to facilitate access to strain data at RGD.

    Science.gov (United States)

    Nigam, Rajni; Munzenmaier, Diane H; Worthey, Elizabeth A; Dwinell, Melinda R; Shimoyama, Mary; Jacob, Howard J

    2013-11-22

    The Rat Genome Database (RGD) ( http://rgd.mcw.edu/) is the premier site for comprehensive data on the different strains of the laboratory rat (Rattus norvegicus). The strain data are collected from various publications, direct submissions from individual researchers, and rat providers worldwide. Rat strain, substrain designation and nomenclature follow the Guidelines for Nomenclature of Mouse and Rat Strains, instituted by the International Committee on Standardized Genetic Nomenclature for Mice. While symbols and names aid in identifying strains correctly, the flat nature of this information prohibits easy search and retrieval, as well as other data mining functions. In order to improve these functionalities, particularly in ontology-based tools, the Rat Strain Ontology (RS) was developed. The Rat Strain Ontology (RS) reflects the breeding history, parental background, and genetic manipulation of rat strains. This controlled vocabulary organizes strains by type: inbred, outbred, chromosome altered, congenic, mutant and so on. In addition, under the chromosome altered category, strains are organized by chromosome, and further by type of manipulations, such as mutant or congenic. This allows users to easily retrieve strains of interest with modifications in specific genomic regions. The ontology was developed using the Open Biological and Biomedical Ontology (OBO) file format, and is organized on the Directed Acyclic Graph (DAG) structure. Rat Strain Ontology IDs are included as part of the strain report (RS: ######). As rat researchers are often unaware of the number of substrains or altered strains within a breeding line, this vocabulary now provides an easy way to retrieve all substrains and accompanying information. Its usefulness is particularly evident in tools such as the PhenoMiner at RGD, where users can now easily retrieve phenotype measurement data for related strains, strains with similar backgrounds or those with similar introgressed regions. This

  19. The growth of tissue engineering.

    Science.gov (United States)

    Lysaght, M J; Reyes, J

    2001-10-01

    This report draws upon data from a variety of sources to estimate the size, scope, and growth rate of the contemporary tissue engineering enterprise. At the beginning of 2001, tissue engineering research and development was being pursued by 3,300 scientists and support staff in more than 70 startup companies or business units with a combined annual expenditure of over $600 million. Spending by tissue engineering firms has been growing at a compound annual rate of 16%, and the aggregate investment since 1990 now exceeds $3.5 billion. At the beginning of 2001, the net capital value of the 16 publicly traded tissue engineering startups had reached $2.6 billion. Firms focusing on structural applications (skin, cartilage, bone, cardiac prosthesis, and the like) comprise the fastest growing segment. In contrast, efforts in biohybrid organs and other metabolic applications have contracted over the past few years. The number of companies involved in stem cells and regenerative medicine is rapidly increasing, and this area represents the most likely nidus of future growth for tissue engineering. A notable recent trend has been the emergence of a strong commercial activity in tissue engineering outside the United States, with at least 16 European or Australian companies (22% of total) now active.

  20. Biological assay of attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus.

    Science.gov (United States)

    Mengeling, W L; Pejsak, Z; Paul, P S

    1984-11-01

    Attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus (PPV) were titrated in vivo and in vitro under similar conditions to provide a better understanding of some of the factors involved in virulence of PPV in causing maternal reproductive failure of swine. Both strains cause fetal death when they are injected directly into fetal fluids, but only strain NADL-8 does so when administered to pregnant swine. The strains were tested for their hemagglutinating activity (HA), median cell culture infective dose (CCID50), median fetal infective dose (FID50), and median fetal lethal dose (FLD50). The FID50 and FLD50 were determined by injecting virus directly into the amniotic fluid of fetuses in utero at 44 +/- 2 days of gestation and collecting the fetuses 15 +/- 1 days later. Both strains had an HA titer of 64, suggesting that there is a similar number of virions in stock preparations. However, other measurements differed markedly. The CCID50, FID50, and FLD50 were 10(5.5), 10(3.5), and 10(0.5), respectively, for strain NADL-2, and 10(4.5), 10(7.7), and 10(6.3), respectively, for strain NADL-8. Collectively, the values indicate that more than 10,000 times as much strain NADL-2 would need to reach the conceptus transplacentally to establish infection. These observations may help to explain the different consequences of oronasal exposure of pregnant swine to these strains of PPV.

  1. Solitary waves in morphogenesis: Determination fronts as strain-cued strain transformations among automatous cells

    Science.gov (United States)

    Cox, Brian N.; Landis, Chad M.

    2018-02-01

    We present a simple theory of a strain pulse propagating as a solitary wave through a continuous two-dimensional population of cells. A critical strain is assumed to trigger a strain transformation, while, simultaneously, cells move as automata to tend to restore a preferred cell density. We consider systems in which the strain transformation is a shape change, a burst of proliferation, or the commencement of growth (which changes the shape of the population sheet), and demonstrate isomorphism among these cases. Numerical and analytical solutions describe a strain pulse whose height does not depend on how the strain disturbance was first launched, or the rate at which the strain transformation is achieved, or the rate constant in the rule for the restorative cell motion. The strain pulse is therefore very stable, surviving the imposition of strong perturbations: it would serve well as a timing signal in development. The automatous wave formulation is simple, with few model parameters. A strong case exists for the presence of a strain pulse during amelogenesis. Quantitative analysis reveals a simple relationship between the velocity of the leading edge of the pulse in amelogenesis and the known speed of migration of ameloblast cells. This result and energy arguments support the depiction of wave motion as an automatous cell response to strain, rather than as a response to an elastic energy gradient. The theory may also contribute to understanding the determination front in somitogenesis, moving fronts of convergent-extension transformation, and mitotic wavefronts in the syncytial drosophila embryo.

  2. Microgel Technology to Advance Modular Tissue Engineering

    NARCIS (Netherlands)

    Kamperman, Tom

    2018-01-01

    The field of tissue engineering aims to restore the function of damaged or missing tissues by combining cells and/or a supportive biomaterial scaffold into an engineered tissue construct. The construct’s design requirements are typically set by native tissues – the gold standard for tissue

  3. Tissue Banking: Current procedures, ethical consideration and ...

    African Journals Online (AJOL)

    Tissue banking provides safe and effective cells and tissues for transplantation in reconstruction surgery. Bone, amnion, skin, cartilage, heart valves and xenograft tissues are the most commonly used biological tissues. Acquisition of tissue is dependent on elaborate donor screening criteria based on medical and social ...

  4. Isolation of a mycoplasma from sarcoid tissue.

    Science.gov (United States)

    Jansson, E; Hannuksela, M; Eklund, H; Halme, H; Tuuri, S

    1972-10-01

    Using a modified cell-free culture medium, a mycoplasma was isolated from sarcoid lymph nodes in two cases and from sarcoid skin lesions in four out of seven cases of chronic sarcoidosis. Growth inhibition tests showed that the isolates were related to Mycoplasma orale type 1. By the indirect haemagglutination method, 244 cases of definite or probable sarcoidosis, 160 patients with other diseases, and 355 blood donors were tested for antibodies against an isolated mycoplasma (strain 215-M). Titres [unk] 16 were found in 14% of the patients with sarcoidosis and in 8% of the patients with other diseases but only in 0.6% of the blood donors. The proportion of patients with high antibody titres among those with sarcoidosis and erythema nodosum was smaller (8%) than among those with other forms of sarcoidosis (17%). The role of the mycoplasmas isolated from sarcoid tissues remains obscure, but it is possible that these organisms are only an expression of altered immunity in sarcoidosis.

  5. Five challenges in modelling interacting strain dynamics

    Directory of Open Access Journals (Sweden)

    Paul S. Wikramaratna

    2015-03-01

    Full Text Available Population epidemiological models where hosts can be infected sequentially by different strains have the potential to help us understand many important diseases. Researchers have in recent years started to develop and use such models, but the extra layer of complexity from multiple strains brings with it many technical challenges. It is therefore hard to build models which have realistic assumptions yet are tractable. Here we outline some of the main challenges in this area. First we begin with the fundamental question of how to translate from complex small-scale dynamics within a host to useful population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity accumulates over multiple exposures.

  6. (HN1) strain of Aspergillus niger

    African Journals Online (AJOL)

    login123

    2016-09-26

    Sep 26, 2016 ... olive oil) increased the production of lipase up to 20% in case of both the strains. The production of ... insoluble triacylglycerols to generate free fatty acids, mono and ... Two fermentation processes, including solid state.

  7. Mumps vaccine virus strains and aseptic meningitis.

    Science.gov (United States)

    Bonnet, Marie-Claude; Dutta, Anil; Weinberger, Clement; Plotkin, Stanley A

    2006-11-30

    Mumps immunization can easily be included in national schedules, particularly if combined with measles or measles and rubella vaccines, but debate continues concerning the relative safety of various licensed mumps vaccine strains. The opportunities for control of mumps are also being affected by differences in the cost of the vaccines prepared with different strains of mumps virus. The present report evaluates available data on the association of the Urabe and other strains of mumps vaccine with the occurrence of aseptic meningitis. We also review the comparative immunogenicity and efficacies of the most widely used mumps vaccines in controlled clinical trials and field evaluations, and briefly examine relative cost as it relates to the implementation of national immunization programs. We conclude that extensive experience with the most widely used mumps vaccine strains in many countries has shown that the risk-benefit ratio of live mumps vaccines is highly favourable for vaccination, despite the occasional occurence of aseptic meningitis.

  8. Characterization of 3 Strains of Yersinia Pestis

    National Research Council Canada - National Science Library

    Kournikakis, B

    2000-01-01

    .... Antibiotic sensitivities showed that the 3 strains were sensitive to aminoglycosides, the cephalosporins/ cephams, most of the beta lactams/penicillins (e.g. ampicillin) and quinolones (e.g. ciprofloxacin...

  9. Flexoelectricity: strain gradient effects in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Ma Wenhui [Department of Physics, Shantou Unversity, Shantou, Guangdong 515063 (China)

    2007-12-15

    Mechanical strain gradient induced polarization effect or flexoelectricity in perovskite-type ferroelectric and relaxor ferroelectric ceramics was investigated. The flexoelectric coefficients measured at room temperature ranged from about 1 {mu} C m{sup -1} for lead zirconate titanate to 100 {mu} C m{sup -1} for barium strontium titanate. Flexoelectric effects were discovered to be sensitive to chemical makeup, phase symmetry, and domain structures. Based on phenomenological discussion and experimental data on flexoelectricity, the present study proposed that mechanical strain gradient field could influence polarization responses in a way analogous to electric field. Flexoelectric coefficients were found to be nonlinearly enhanced by dielectric permittivity and strain gradient. Interfacial mismatch in epitaxial thin films can give rise to high strain gradients, enabling flexoelectric effects to make a significant impact in properly engineered ferroelectric heterostructure systems.

  10. Review of strain buckling: analysis methods

    International Nuclear Information System (INIS)

    Moulin, D.

    1987-01-01

    This report represents an attempt to review the mechanical analysis methods reported in the literature to account for the specific behaviour that we call buckling under strain. In this report, this expression covers all buckling mechanisms in which the strains imposed play a role, whether they act alone (as in simple buckling under controlled strain), or whether they act with other loadings (primary loading, such as pressure, for example). Attention is focused on the practical problems relevant to LMFBR reactors. The components concerned are distinguished by their high slenderness ratios and by rather high thermal levels, both constant and variable with time. Conventional static buckling analysis methods are not always appropriate for the consideration of buckling under strain. New methods must therefore be developed in certain cases. It is also hoped that this review will facilitate the coding of these analytical methods to aid the constructor in his design task and to identify the areas which merit further investigation

  11. Systems strategies for developing industrial microbial strains

    DEFF Research Database (Denmark)

    Lee, Sang Yup; Kim, Hyun Uk

    2015-01-01

    Industrial strain development requires system-wide engineering and optimization of cellular metabolism while considering industrially relevant fermentation and recovery processes. It can be conceptualized as several strategies, which may be implemented in an iterative fashion and in different...

  12. Characterization of 21 Strains of Bacillus Anthracis

    National Research Council Canada - National Science Library

    Kournikakis, B

    2000-01-01

    Twenty-one strains of Bacillus anthracis currently held in the culture collection at DRES were characterized by colonial morphology, antibiotic sensitivity and BiologTM metabolic identification profiles...

  13. Phenotypic variability among strains of Pasteurella multocida ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-05-02

    May 2, 2008 ... Available online at http://www.academicjournals.org/AJB. ISSN 1684–5315 ... extended phenotypic characterization methods supported by DNA ... septicaemia African (Obudu) strain (E:2) which are currently employed as ...

  14. Job strain and the risk of stroke

    DEFF Research Database (Denmark)

    Fransson, Eleonor I; Nyberg, Solja T; Heikkilä, Katriina

    2015-01-01

    BACKGROUND AND PURPOSE: Psychosocial stress at work has been proposed to be a risk factor for cardiovascular disease. However, its role as a risk factor for stroke is uncertain. METHODS: We conducted an individual-participant-data meta-analysis of 196 380 males and females from 14 European cohort...... studies to investigate the association between job strain, a measure of work-related stress, and incident stroke. RESULTS: In 1.8 million person-years at risk (mean follow-up 9.2 years), 2023 first-time stroke events were recorded. The age- and sex-adjusted hazard ratio for job strain relative to no job....... CONCLUSION: Job strain may be associated with an increased risk of ischemic stroke, but further research is needed to determine whether interventions targeting job strain would reduce stroke risk beyond existing preventive strategies....

  15. The radiographic observation of the cervical strain

    International Nuclear Information System (INIS)

    Rhee, Chung Sik

    1972-01-01

    A total of 100 cases of cervical disorders were analysed of clinical signs and symptoms. The cervical strain is proved by the loss of normal lordotic curvature of the cervical spinal column on the lateral x-ray film in Ewha University Hospital from January, 1970 to december 1971 with the following results. 1. The 53 cervical strain was diagnosed in radiographic study for its abnormal locations. The hyperextension with abnormal curve is twice more after than hyperflection type. 2. The most frequent location of the cervical strain is demonstrated in the 4-6 th cervical spinal bodies (80%). 3. Most pronounced symptoms of cervical strain are local tenderness (40%), limitation of motion (17%) and radiating pain (15%). 4. The ratio of the sex incidence of male female was 3:2

  16. The radiographic observation of the cervical strain

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, Chung Sik [Ewha Womans University College of Medicine, Seoul (Korea, Republic of)

    1972-12-15

    A total of 100 cases of cervical disorders were analysed of clinical signs and symptoms. The cervical strain is proved by the loss of normal lordotic curvature of the cervical spinal column on the lateral x-ray film in Ewha University Hospital from January, 1970 to december 1971 with the following results. 1. The 53 cervical strain was diagnosed in radiographic study for its abnormal locations. The hyperextension with abnormal curve is twice more after than hyperflection type. 2. The most frequent location of the cervical strain is demonstrated in the 4-6 th cervical spinal bodies (80%). 3. Most pronounced symptoms of cervical strain are local tenderness (40%), limitation of motion (17%) and radiating pain (15%). 4. The ratio of the sex incidence of male female was 3:2.

  17. Pseudofracture: an acute peripheral tissue trauma model.

    Science.gov (United States)

    Darwiche, Sophie S; Kobbe, Philipp; Pfeifer, Roman; Kohut, Lauryn; Pape, Hans-Christoph; Billiar, Timothy

    2011-04-18

    Following trauma there is an early hyper-reactive inflammatory response that can lead to multiple organ dysfunction and high mortality in trauma patients; this response is often accompanied by a delayed immunosuppression that adds the clinical complications of infection and can also increase mortality. Many studies have begun to assess these changes in the reactivity of the immune system following trauma. Immunologic studies are greatly supported through the wide variety of transgenic and knockout mice available for in vivo modeling; these strains aid in detailed investigations to assess the molecular pathways involved in the immunologic responses. The challenge in experimental murine trauma modeling is long term investigation, as fracture fixation techniques in mice, can be complex and not easily reproducible. This pseudofracture model, an easily reproduced trauma model, overcomes these difficulties by immunologically mimicking an extremity fracture environment, while allowing freedom of movement in the animals and long term survival without the continual, prolonged use of anaesthesia. The intent is to recreate the features of long bone fracture; injured muscle and soft tissue are exposed to damaged bone and bone marrow without breaking the native bone. The pseudofracture model consists of two parts: a bilateral muscle crush injury to the hindlimbs, followed by injection of a bone solution into these injured muscles. The bone solution is prepared by harvesting the long bones from both hindlimbs of an age- and weight-matched syngeneic donor. These bones are then crushed and resuspended in phosphate buffered saline to create the bone solution. Bilateral femur fracture is a commonly used and well-established model of extremity trauma, and was the comparative model during the development of the pseudofracture model. Among the variety of available fracture models, we chose to use a closed method of fracture with soft tissue injury as our comparison to the

  18. Use of Tissue-Specific MicroRNA to Control Pathology of Wild-Type Adenovirus without Attenuation of Its Ability to Kill Cancer Cells

    NARCIS (Netherlands)

    Cawood, R.; Chen, H.H.; Carroll, F.; Bazan-Peregrino, M.; Rooijen, van N.; Seymour, L.W.

    2009-01-01

    Replicating viruses have broad applications in biomedicine, notably in cancer virotherapy and in the design of attenuated vaccines; however, uncontrolled virus replication in vulnerable tissues can give pathology and often restricts the use of potent strains. Increased knowledge of tissue-selective

  19. Soft tissue engineering with micronized-gingival connective tissues.

    Science.gov (United States)

    Noda, Sawako; Sumita, Yoshinori; Ohba, Seigo; Yamamoto, Hideyuki; Asahina, Izumi

    2018-01-01

    The free gingival graft (FGG) and connective tissue graft (CTG) are currently considered to be the gold standards for keratinized gingival tissue reconstruction and augmentation. However, these procedures have some disadvantages in harvesting large grafts, such as donor-site morbidity as well as insufficient gingival width and thickness at the recipient site post-treatment. To solve these problems, we focused on an alternative strategy using micronized tissue transplantation (micro-graft). In this study, we first investigated whether transplantation of micronized gingival connective tissues (MGCTs) promotes skin wound healing. MGCTs (≤100 µm) were obtained by mincing a small piece (8 mm 3 ) of porcine keratinized gingiva using the RIGENERA system. The MGCTs were then transplanted to a full skin defect (5 mm in diameter) on the dorsal surface of immunodeficient mice after seeding to an atelocollagen matrix. Transplantations of atelocollagen matrixes with and without micronized dermis were employed as experimental controls. The results indicated that MGCTs markedly promote the vascularization and epithelialization of the defect area 14 days after transplantation compared to the experimental controls. After 21 days, complete wound closure with low contraction was obtained only in the MGCT grafts. Tracking analysis of transplanted MGCTs revealed that some mesenchymal cells derived from MGCTs can survive during healing and may function to assist in wound healing. We propose here that micro-grafting with MGCTs represents an alternative strategy for keratinized tissue reconstruction that is characterized by low morbidity and ready availability. © 2017 Wiley Periodicals, Inc.

  20. A strain gradient plasticity theory with application to wire torsion

    KAUST Repository

    Liu, J. X.; El Sayed, Tamer S.

    2014-01-01

    Based on the framework of the existing strain gradient plasticity theories, we have examined three kinds of relations for the plastic strain dependence of the material intrinsic length scale, and thus developed updated strain gradient plasticity

  1. MM98.57 Quantification of Combined Strain Paths

    DEFF Research Database (Denmark)

    Nielsen, Morten Sturgård; Wanheim, Tarras

    1998-01-01

    this curve into useful scalar relations from experimental data.The strain history for plane strain when assuming volume constancy may be plotted in a shear strain, normal strain diagram, which has the property of showing both the rotation of principal deformation axes during the deformation and the amount...... is to describe the total strain history as a curve in the 6-dimensional shear strain, normal strain space. In order to be able to use these experimental data for calculation, the development of this strain curve must be transformed into a set of scalar relations that may be used for predicting the yield surface...... at a given point in a new strain history. A simple example of this concept is to take the length of the strain curve as describing scalar relation: E.g. to use the equivalent strain as parameter for describing the yield stress. This paper focuses on the strain curve concept and the possibilities to convert...

  2. On generalization uniaxial stress-strain relation

    International Nuclear Information System (INIS)

    Sahay, C.; Dubey, R.N.

    1980-01-01

    Different forms of constitutive relations have been advanced for elastic, plastic and elastic-plastic behaviour of materials. It is shown that the various forms of the stress-strain relationship are specialized forms of generalization of a single stress-strain relation. For example, it is shown how the laws of elastic deformation, and the incremental and total deformation relationship for plastic behaviour are derivable from the Ramberg-Osgood relation. (orig.)

  3. Survival and activity of individual bioaugmentation strains

    DEFF Research Database (Denmark)

    Dueholm, Morten Simonsen; G. Marquesa, Irina; Karst, Søren Michael

    2015-01-01

    Successful application of bioaugmentation for enhanced degradation of environmental pollutants is often limited by the lack of methods to monitor the survival and activity of individual bioaugmentation strains. However, recent advancements in sequencing technologies and molecular techniques now...... allow us to address these limitations. Here a complementing set of general applicable molecular methods are presented that provides detailed information on the performance of individual bioaugmentation strains under in situ conditions. The approach involves genome sequencing to establish highly specific...

  4. Strain limit criteria to predict failure

    International Nuclear Information System (INIS)

    Flanders, H.E.

    1995-01-01

    In recent years extensive effort has been expended to qualify existing structures for conditions that are beyond the original design basis. Determination of the component failure load is useful for this type of evaluation. This paper presents criteria based upon strain limits to predict the load at failure. The failure modes addressed are excessive plastic deformations, localized plastic strains, and structural instability. The effects of analytical method sophistication, as built configurations, material properties degradation, and stress state are addressed by the criteria

  5. Deformation strain inhomogeneity in columnar grain nickel

    DEFF Research Database (Denmark)

    Wu, G.L.; Godfrey, A.; Juul Jensen, D.

    2005-01-01

    A method is presented for determination of the local deformation strain of individual grains in the bulk of a columnar grain sample. The method, based on measurement of the change in grain area of each grain, is applied to 12% cold rolled nickel. Large variations are observed in the local strain...... associated with each grain. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved....

  6. Antimicrobial properties of indigenous Lactobacillus sakei strain

    OpenAIRE

    Vesković-Moračanin Slavica; Obradović D.; Velebit B.; Borović Branka; Škrinjar Marija; Turubatović L.

    2010-01-01

    The strain I 154 of Lactobacillus sakei has been isolated from traditionally fermented sausages in the course of the realization of the international project (INCO PROJECT No ICA4-CT-2002-10037). This strain exhibited the ability for bacteriocin production. Antimicrobial properties of the isolated bacteriocin (sakacine), its sensibility towards proteolytic enzymes, as well as the effect of increased to high temperatures on its stability have been examined in this work. Semi purified bacterioc...

  7. Analysis of DNA methylation in various swine tissues.

    Directory of Open Access Journals (Sweden)

    Chun Yang

    Full Text Available DNA methylation is known to play an important role in regulating gene expression during biological development and tissue differentiation in eukaryotes. In this study, we used the fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP method to assess the extent and pattern of cytosine methylation in muscle, heart, liver, spleen, lung, kidney and stomach from the swine strain Laiwu, and we also examined specific methylation patterns in the seven tissues. In total, 96,371 fragments, each representing a recognition site cleaved by either or both EcoRI + HpaII and EcoRI + MspI, the HpaII and MspI are isoschizomeric enzymes, were amplified using 16 pairs of selective primers. A total of 50,094 sites were found to be methylated at cytosines in seven tissues. The incidence of DNA methylation was approximately 53.99% in muscle, 51.24% in the heart, 50.18% in the liver, 53.31% in the spleen, 51.97% in the lung, 51.15% in the kidney and 53.39% in the stomach, as revealed by the incidence of differential digestion. Additionally, differences in DNA methylation levels imply that such variations may be related to specific gene expression during tissue differentiation, growth and development. Three types of bands were generated in the F-MSAP profile, the total numbers of these three types of bands in the seven tissues were 46,277, 24,801 and 25,293, respectively.In addition, different methylation patterns were observed in seven tissues from pig, and almost all of the methylation patterns detected by F-MSAP could be confirmed by Southern analysis using the isolated amplified fragments as probes. The results clearly demonstrated that the F-MSAP technique can be adapted for use in large-scale DNA methylation detection in the pig genome.

  8. A closer look at prion strains

    Science.gov (United States)

    Solforosi, Laura; Milani, Michela; Mancini, Nicasio; Clementi, Massimo; Burioni, Roberto

    2013-01-01

    Prions are infectious proteins that are responsible for transmissible spongiform encephalopathies (TSEs) and consist primarily of scrapie prion protein (PrPSc), a pathogenic isoform of the host-encoded cellular prion protein (PrPC). The absence of nucleic acids as essential components of the infectious prions is the most striking feature associated to these diseases. Additionally, different prion strains have been isolated from animal diseases despite the lack of DNA or RNA molecules. Mounting evidence suggests that prion-strain-specific features segregate with different PrPSc conformational and aggregation states. Strains are of practical relevance in prion diseases as they can drastically differ in many aspects, such as incubation period, PrPSc biochemical profile (e.g., electrophoretic mobility and glycoform ratio) and distribution of brain lesions. Importantly, such different features are maintained after inoculation of a prion strain into genetically identical hosts and are relatively stable across serial passages. This review focuses on the characterization of prion strains and on the wide range of important implications that the study of prion strains involves. PMID:23357828

  9. Instrument for measuring fuel cladding strain

    International Nuclear Information System (INIS)

    Billeter, T.R.

    1976-01-01

    Development work to provide instrumentation for the continuous measurement of strain of material specimens such as nuclear fuel cladding has shown that a microwave sensor and associated instrumentation hold promise. The cylindrical sensor body enclosing the specimen results in a coaxial resonator absorbing microwave energy at frequencies dependent upon the diameter of the specimen. Diametral changes of a microinch can be resolved with use of the instrumentation. Very reasonable values of elastic strain were measured at 75 0 F and 1000 0 F for an internally pressurized 20 percent C.W. 316 stainless steel specimen simulating nuclear fuel cladding. The instrument also indicated the creep strain of the same specimen pressurized at 6500 psi and at a temperature of 1000 0 F for a period of 700 hours. Although the indicated strain appears greater than actual, the sensor/specimen unit experienced considerable oxidation even though an inert gas purge persisted throughout the test duration. By monitoring at least two modes of resonance, the measured strain was shown to be nearly independent of sensor temperature. To prevent oxidation, a second test was performed in which the specimen/sensor units were contained in an evacuated enclosure. The strain of the two prepressurized specimens as indicated by the microwave instrumentation agreed very closely with pre- and post-test measurements obtained with use of a laser interferometer

  10. Strain-controlled electrocatalysis on multimetallic nanomaterials

    Science.gov (United States)

    Luo, Mingchuan; Guo, Shaojun

    2017-11-01

    Electrocatalysis is crucial for the development of clean and renewable energy technologies, which may reduce our reliance on fossil fuels. Multimetallic nanomaterials serve as state-of-the-art electrocatalysts as a consequence of their unique physico-chemical properties. One method of enhancing the electrocatalytic performance of multimetallic nanomaterials is to tune or control the surface strain of the nanomaterials, and tremendous progress has been made in this area in the past decade. In this Review, we summarize advances in the introduction, tuning and quantification of strain in multimetallic nanocrystals to achieve more efficient energy conversion by electrocatalysis. First, we introduce the concept of strain and its correlation with other key physico-chemical properties. Then, using the electrocatalytic reduction of oxygen as a model reaction, we discuss the underlying mechanisms behind the strain-adsorption-reactivity relationship based on combined classical theories and models. We describe how this knowledge can be harnessed to design multimetallic nanocrystals with optimized strain to increase the efficiency of oxygen reduction. In particular, we highlight the unexpectedly beneficial (and previously overlooked) role of tensile strain from multimetallic nanocrystals in improving electrocatalysis. We conclude by outlining the challenges and offering our perspectives on the research directions in this burgeoning field.

  11. A pilot study using Tissue Velocity Ultrasound Imaging (TVI to assess muscle activity pattern in patients with chronic trapezius myalgia

    Directory of Open Access Journals (Sweden)

    Brodin Lars-Åke

    2008-09-01

    calculated and compared before and after pain provocation/exercise. Results This new methodology seems valuable when looking at local muscle changes and studying the mechanism behind chronic muscle pain. The univariate analyses indicate that patients with chronic trapezius myalgia after pain provocation due to exercise at group level showed decreased strain and unchanged strain rate while healthy controls had unchanged strain and increased strain rate. However, the multivariate analysis indicates that most patients showed lower levels according to both strain and strain rate after exercise compared to most controls. Conclusion Tissue velocity imaging can help describe musculoskeletal tissue activity and dynamics in patients with chronic pain conditions. An altered muscle tissue dynamic after pain provocation/exercise among the majority of trapezius myalgia patients compared with the healthy controls was found.

  12. Two-photon induced collagen cross-linking in bioartificial cardiac tissue

    Science.gov (United States)

    Kuetemeyer, Kai; Kensah, George; Heidrich, Marko; Meyer, Heiko; Martin, Ulrich; Gruh, Ina; Heisterkamp, Alexander

    2011-08-01

    Cardiac tissue engineering is a promising strategy for regenerative therapies to overcome the shortage of donor organs for transplantation. Besides contractile function, the stiffness of tissue engineered constructs is crucial to generate transplantable tissue surrogates with sufficient mechanical stability to withstand the high pressure present in the heart. Although several collagen cross-linking techniques have proven to be efficient in stabilizing biomaterials, they cannot be applied to cardiac tissue engineering, as cell death occurs in the treated area. Here, we present a novel method using femtosecond (fs) laser pulses to increase the stiffness of collagen-based tissue constructs without impairing cell viability. Raster scanning of the fs laser beam over riboflavin-treated tissue induced collagen cross-linking by two-photon photosensitized singlet oxygen production. One day post-irradiation, stress-strain measurements revealed increased tissue stiffness by around 40% being dependent on the fibroblast content in the tissue. At the same time, cells remained viable and fully functional as demonstrated by fluorescence imaging of cardiomyocyte mitochondrial activity and preservation of active contraction force. Our results indicate that two-photon induced collagen cross-linking has great potential for studying and improving artificially engineered tissue for regenerative therapies.

  13. Bioactive glass in tissue engineering

    Science.gov (United States)

    Rahaman, Mohamed N.; Day, Delbert E.; Bal, B. Sonny; Fu, Qiang; Jung, Steven B.; Bonewald, Lynda F.; Tomsia, Antoni P.

    2011-01-01

    This review focuses on recent advances in the development and use of bioactive glass for tissue engineering applications. Despite its inherent brittleness, bioactive glass has several appealing characteristics as a scaffold material for bone tissue engineering. New bioactive glasses based on borate and borosilicate compositions have shown the ability to enhance new bone formation when compared to silicate bioactive glass. Borate-based bioactive glasses also have controllable degradation rates, so the degradation of the bioactive glass implant can be more closely matched to the rate of new bone formation. Bioactive glasses can be doped with trace quantities of elements such as Cu, Zn and Sr, which are known to be beneficial for healthy bone growth. In addition to the new bioactive glasses, recent advances in biomaterials processing have resulted in the creation of scaffold architectures with a range of mechanical properties suitable for the substitution of loaded as well as non-loaded bone. While bioactive glass has been extensively investigated for bone repair, there has been relatively little research on the application of bioactive glass to the repair of soft tissues. However, recent work has shown the ability of bioactive glass to promote angiogenesis, which is critical to numerous applications in tissue regeneration, such as neovascularization for bone regeneration and the healing of soft tissue wounds. Bioactive glass has also been shown to enhance neocartilage formation during in vitro culture of chondrocyte-seeded hydrogels, and to serve as a subchondral substrate for tissue-engineered osteochondral constructs. Methods used to manipulate the structure and performance of bioactive glass in these tissue engineering applications are analyzed. PMID:21421084

  14. Tissue-electronics interfaces: from implantable devices to engineered tissues

    Science.gov (United States)

    Feiner, Ron; Dvir, Tal

    2018-01-01

    Biomedical electronic devices are interfaced with the human body to extract precise medical data and to interfere with tissue function by providing electrical stimuli. In this Review, we outline physiologically and pathologically relevant tissue properties and processes that are important for designing implantable electronic devices. We summarize design principles for flexible and stretchable electronics that adapt to the mechanics of soft tissues, such as those including conducting polymers, liquid metal alloys, metallic buckling and meandering architectures. We further discuss technologies for inserting devices into the body in a minimally invasive manner and for eliminating them without further intervention. Finally, we introduce the concept of integrating electronic devices with biomaterials and cells, and we envision how such technologies may lead to the development of bionic organs for regenerative medicine.

  15. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    International Nuclear Information System (INIS)

    Guelorget, Bruno; Francois, Manuel; Vial-Edwards, Cristian; Montay, Guillaume; Daniel, Laurent; Lu, Jian

    2006-01-01

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force (ε t ≅ 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements

  16. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)]. E-mail: bruno.guelorget@utt.fr; Francois, Manuel [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Vial-Edwards, Cristian [Departemento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, 6904411 Santiago (Chile); Montay, Guillaume [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Daniel, Laurent [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Lu, Jian [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2006-01-15

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force ({epsilon} {sup t} {approx_equal} 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements.

  17. Pathogenicity evaluation of twelve West Nile virus strains belonging to four lineages from five continents in a mouse model: discrimination between three pathogenicity categories.

    Science.gov (United States)

    Pérez-Ramírez, Elisa; Llorente, Francisco; Del Amo, Javier; Fall, Gamou; Sall, Amadou Alpha; Lubisi, Alison; Lecollinet, Sylvie; Vázquez, Ana; Jiménez-Clavero, Miguel Ángel

    2017-04-01

    Rodent models have been used extensively to study West Nile virus (WNV) infection because they develop severe neurological symptoms similar to those observed in human WNV neuroinvasive disease. Most of this research has focused on old lineage (L) 1 strains, while information about pathogenicity is lacking for the most recent L1 and L2 strains, as well as for newly defined lineages. In this study, 4-week-old Swiss mice were inoculated with a collection of 12 WNV isolates, comprising 10 old and recent L1 and L2 strains, the putative L6 strain from Malaysia and the proposed L7 strain Koutango (KOU). The intraperitoneal inoculation of 10-fold dilutions of each strain allowed the characterization of the isolates in terms of LD50, median survival times, ID50, replication in neural and extraneural tissues and antibody production. Based on these results, we classified the isolates in three groups: high virulence (all L1a strains, recent L2 strains and KOU), moderate virulence (B956 strain) and low virulence (Kunjin and Malaysian isolates). We determined that the inoculation of a single dose of 1000 p.f.u. would be sufficient to classify WNV strains by pathotype. We confirmed the enhanced virulence of the KOU strain with a high capacity to cause rapid systemic infection. We also corroborated that differences in pathogenicity among strains do not correlate with phylogenetic lineage or geographic origin, and confirmed that recent European and African WNV strains belonging to L1 and L2 are highly virulent and do not differ in their pathotype profile compared to the prototype NY99 strain.

  18. Novel nonsense mutation in the katA gene of a catalase-negative Staphylococcus aureus strain.

    Science.gov (United States)

    Lagos, Jaime; Alarcón, Pedro; Benadof, Dona; Ulloa, Soledad; Fasce, Rodrigo; Tognarelli, Javier; Aguayo, Carolina; Araya, Pamela; Parra, Bárbara; Olivares, Berta; Hormazábal, Juan Carlos; Fernández, Jorge

    2016-01-01

    We report the first description of a rare catalase-negative strain of Staphylococcus aureus in Chile. This new variant was isolated from blood and synovial tissue samples of a pediatric patient. Sequencing analysis revealed that this catalase-negative strain is related to ST10 strain, which has earlier been described in relation to S. aureus carriers. Interestingly, sequence analysis of the catalase gene katA revealed presence of a novel nonsense mutation that causes premature translational truncation of the C-terminus of the enzyme leading to a loss of 222 amino acids. Our study suggests that loss of catalase activity in this rare catalase-negative Chilean strain is due to this novel nonsense mutation in the katA gene, which truncates the enzyme to just 283 amino acids. Copyright © 2015 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  19. ANTHROPOMORPHIC PHANTOMS FOR ASSESSMENT OF STRAIN IMAGING METHODS INVOLVING SALINE-INFUSED SONOHYSTEROGRAPHY

    Science.gov (United States)

    Hobson, Maritza A.; Madsen, Ernest L.; Frank, Gary R.; Jiang, Jingfeng; Shi, Hairong; Hall, Timothy J.; Varghese, Tomy

    2008-01-01

    Two anthropomorphic uterine phantoms were developed which allow assessment and comparison of strain imaging systems adapted for use with saline-infused sonohysterography (SIS). Tissue-mimicking (TM) materials consist of dispersions of safflower oil in gelatin. TM fibroids are stiffer than the TM myometrium/cervix and TM polyps are softer. The first uterine phantom has 3-mm diameter TM fibroids randomly distributed in TM myometrium. The second uterine phantom has a 5-mm and an 8-mm spherical TM fibroid in addition to a 5-mm spherical and a 12.5-mm long (medicine-capsule-shaped) TM endometrial polyp protruding into the endometrial cavity; also, a 10-mm spherical TM fibroid projects from the serosal surface. Strain images using the first phantom show the stiffer 3-mm TM fibroids in the myometrium. Results from the second uterine phantom show that, as expected, parts of inclusions projecting into the uterine cavity will appear very stiff, whether they are stiff or soft. Results from both phantoms show that even though there is a five-fold difference in the Young’s moduli values, there is not a significant difference in the strain in the transition from the TM myometrium to the TM fat. These phantoms allow for realistic comparison and evolution of SIS strain imaging techniques and can aid clinical personnel to develop skills for SIS strain imaging. PMID:18514999

  20. Involvement of Trichoderma asperellum strain T6 in regulating iron acquisition in plants.

    Science.gov (United States)

    Zhao, Lei; Wang, Fei; Zhang, Yaqing; Zhang, Jiaojiao

    2014-07-01

    Iron (Fe) deficiency is a major plant nutritional disorder in many parts of the world, particularly in areas with saline soils. Among the numerous root-associated microbes that are beneficial for plant nutrient uptake, Trichoderma spp. are the most effective rhizosphere fungi for enhancing plant growth and plant resistance to biotic and abiotic stresses. To investigate the potential mechanisms of action of Trichoderma on insoluble Fe in the soil, which is difficult for plants to absorb and utilize, a high siderophore-producing strain of Trichoderma T6, was isolated from the rhizosphere of cucumber plants. The strain was identified as T. asperellum based on the morphological features and molecular phylogenetic analyses. Applying strain T6 to sterile soil could increase soil levels of Fe(2+) and siderophores, as well as increase Fe(2+) and Fe(3+)-chelate reductase (FCR) activity in cucumber tissues. Purified siderophore eluent (PSE) increased plant growth, thus confirming its role in plant growth promotion. Moreover, extracellular Fe(3+) reducing activity and three kinds of organic acids were detected in the culture filtrate of strain T6. These results indicate that strain T6 influences plant Fe absorption in several ways. Siderophore-based Fe chelation is effective in providing Fe to plants, organic acids, and Fe(3+) reducing enzymes may participate in the solubilization and reduction of insoluble Fe(3+) to Fe(2+). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Magnetic resonance imaging detects significant sex differences in human myocardial strain

    Directory of Open Access Journals (Sweden)

    Reynolds Lina M

    2011-08-01

    Full Text Available Abstract Background The pathophysiology responsible for the significant outcome disparities between men and women with cardiac disease is largely unknown. Further investigation into basic cardiac physiological differences between the sexes is needed. This study utilized magnetic resonance imaging (MRI-based multiparametric strain analysis to search for sex-based differences in regional myocardial contractile function. Methods End-systolic strain (circumferential, longitudinal, and radial was interpolated from MRI-based radiofrequency tissue tagging grid point displacements in each of 60 normal adult volunteers (32 females. Results The average global left ventricular (LV strain among normal female volunteers (n = 32 was significantly larger in absolute value (functionally better than in normal male volunteers (n = 28 in both the circumferential direction (Male/Female = -0.19 ± 0.02 vs. -0.21 ± 0.02; p = 0.025 and longitudinal direction (Male/Female = -0.14 ± 0.03 vs. -0.16 ± 0.02; p = 0.007. Conclusions The finding of significantly larger circumferential and longitudinal LV strain among normal female volunteers suggests that baseline contractile differences between the sexes may contribute to the well-recognized divergence in cardiovascular disease outcomes. Further work is needed in order to determine the pathologic changes that occur in LV strain between women and men with the onset of cardiovascular disease.

  2. Genotyping of Methicillin Resistant Staphylococcus aureus Strains Isolated from Hospitalized Children

    Directory of Open Access Journals (Sweden)

    Mouna Ben Nejma

    2014-01-01

    Full Text Available Community associated methicillin resistant Staphylococcus aureus (CA-MRSA is an emerging pathogen increasingly reported to cause skin and soft tissue infections for children. The emergence of highly virulencet CA-MRSA strains in the immunodeficiency of young children seemed to be the basic explanation of the increased incidence of CA-MRSA infections among this population. The subjects of this study were 8 patients hospitalized in the Pediatric Department at the University Hospital of Monastir. The patients were young children (aged from 12 days to 18 months who were suffering from MRSA skin infections; two of them had the infections within 72 h of their admission. The isolates were classified as community isolates as they all carried the staphylococcal cassette chromosome mec (SCCmec IV and pvl genes. Epidemiological techniques, pulsed-field gel electrophoresis (PFGE and multilocus sequence typing (MLST, were applied to investigate CA-MRSA strains. Analysis of molecular data revealed that MRSA strains were related according to PFGE patterns and they belonged to a single clone ST80. Antimicrobial susceptibility tests showed that all strains were resistant to kanamycin and 2 strains were resistant to erythromycin.

  3. Molecular typing of Brucella melitensis endemic strains and differentiation from the vaccine strain Rev-1.

    Science.gov (United States)

    Noutsios, Georgios T; Papi, Rigini M; Ekateriniadou, Loukia V; Minas, Anastasios; Kyriakidis, Dimitrios A

    2012-03-01

    In the present study forty-four Greek endemic strains of Br. melitensis and three reference strains were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four strains were discriminated from the vaccine strain Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine strains are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine strain can be discriminated from endemic strains by allele's clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic strains. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic strains two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic strains due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic strains of Br. melitensis and differentiate them from vaccine strain Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.

  4. Strain-dependent diffusion behavior of H within tungsten

    International Nuclear Information System (INIS)

    Ding, Wenyi; He, Haiyan; Liu, Changsong; Ding, Rui; Chen, Junling; Pan, Bicai

    2014-01-01

    The diffusion behaviors of H in tungsten, a promising material serving as the first wall facing the plasma in nuclear reactors, under either biaxial strain or isotropic strain are theoretically studied. We find that under the isotropic strain, an individual H atom may diffuse along all pathways, and under the biaxial strain, it preferably migrates along the direction perpendicular to the loaded strain. Moreover, in the case of either the isotropic or the biaxial strain, the loaded compressive strain weakens the diffusion of H, while the loaded tensile strain enhances the diffusion of H in bulk W.

  5. Strain-dependent diffusion behavior of H within tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Wenyi; He, Haiyan [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Liu, Changsong [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Ding, Rui; Chen, Junling [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Pan, Bicai, E-mail: bcpan@ustc.edu.cn [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-06-15

    The diffusion behaviors of H in tungsten, a promising material serving as the first wall facing the plasma in nuclear reactors, under either biaxial strain or isotropic strain are theoretically studied. We find that under the isotropic strain, an individual H atom may diffuse along all pathways, and under the biaxial strain, it preferably migrates along the direction perpendicular to the loaded strain. Moreover, in the case of either the isotropic or the biaxial strain, the loaded compressive strain weakens the diffusion of H, while the loaded tensile strain enhances the diffusion of H in bulk W.

  6. Information about the Current Strain of Clostridium difficile

    Science.gov (United States)

    ... fluoroquinolones may provide the new strain with an advantage over susceptible strains to spread within healthcare facilities where these antibiotics are commonly used. Top of page What should ...

  7. Effects of strain on the Schwinger pair creation in graphene

    International Nuclear Information System (INIS)

    Fanbanrai, P.; Hutem, A.; Boonchui, S.

    2015-01-01

    The effects of strain on mechanically deformed graphene are determined by looking at how the strain affects the amplitude of the Schwinger two particle pair state. The influences of the lattice distortions, such as isotropic tensile strain ϵ is , shear strain ϵ ss , uniaxial armchair strain ϵ as , and zigzag strain ϵ zs , on the photon emission spectrum have been analyzed. We find that the intensities of the emission increases or decreases when compared to those of the unstrained graphene, depending on the type of strain applied. Thus the structure of energy band, the frequencies of the photons and the emission spectrum can be controlled by use of the different strains

  8. Beauveria bassiana (Balsamo) Vuillemin as an endophyte in tissue culture banana (Musa spp.).

    Science.gov (United States)

    Akello, Juliet; Dubois, Thomas; Gold, Clifford S; Coyne, Daniel; Nakavuma, Jessica; Paparu, Pamela

    2007-09-01

    Beauveria bassiana is considered a virulent pathogen against the banana weevil Cosmopolites sordidus. However, current field application techniques for effective control against this pest remain a limitation and an alternative method for effective field application needs to be investigated. Three screenhouse experiments were conducted to determine the ability of B. bassiana to form an endophytic relationship with tissue culture banana (Musa spp.) plants and to evaluate the plants for possible harmful effects resulting from this relationship. Three Ugandan strains of B. bassiana (G41, S204 and WA) were applied by dipping the roots and rhizome in a conidial suspension, by injecting a conidial suspension into the plant rhizome and by growing the plants in sterile soil mixed with B. bassiana-colonized rice substrate. Four weeks after inoculation, plant growth parameters were determined and plant tissue colonization assessed through re-isolation of B. bassiana. All B. bassiana strains were able to colonize banana plant roots, rhizomes and pseudostem bases. Dipping plants in a conidial suspension achieved the highest colonization with no negative effect on plant growth or survival. Beauveria bassiana strain G41 was the best colonizer (up to 68%, 79% and 41% in roots, rhizome and pseudostem base, respectively) when plants were dipped. This study demonstrated that, depending on strain and inoculation method, B. bassiana can form an endophytic relationship with tissue culture banana plants, causing no harmful effects and might provide an alternative method for biological control of C. sordidus.

  9. Intramyocardial strain estimation from cardiac cine MRI.

    Science.gov (United States)

    Elnakib, Ahmed; Beache, Garth M; Gimel'farb, Georgy; El-Baz, Ayman

    2015-08-01

    Functional strain is one of the important clinical indicators for the quantification of heart performance and the early detection of cardiovascular diseases, and functional strain parameters are used to aid therapeutic decisions and follow-up evaluations after cardiac surgery. A comprehensive framework for deriving functional strain parameters at the endocardium, epicardium, and mid-wall of the left ventricle (LV) from conventional cine MRI data was developed and tested. Cine data were collected using short TR-/TE-balanced steady-state free precession acquisitions on a 1.5T Siemens Espree scanner. The LV wall borders are segmented using a level set-based deformable model guided by a stochastic force derived from a second-order Markov-Gibbs random field model that accounts for the object shape and appearance features. Then, the mid-wall of the segmented LV is determined based on estimating the centerline between the endocardium and epicardium of the LV. Finally, a geometrical Laplace-based method is proposed to track corresponding points on successive myocardial contours throughout the cardiac cycle in order to characterize the strain evolutions. The method was tested using simulated phantom images with predefined point locations of the LV wall throughout the cardiac cycle. The method was tested on 30 in vivo datasets to evaluate the feasibility of the proposed framework to index functional strain parameters. The cine MRI-based model agreed with the ground truth for functional metrics to within 0.30 % for indexing the peak systolic strain change and 0.29 % (per unit time) for indexing systolic and diastolic strain rates. The method was feasible for in vivo extraction of functional strain parameters. Strain indexes of the endocardium, mid-wall, and epicardium can be derived from routine cine images using automated techniques, thereby improving the utility of cine MRI data for characterization of myocardial function. Unlike traditional texture-based tracking, the

  10. Synthetic biology meets tissue engineering.

    Science.gov (United States)

    Davies, Jamie A; Cachat, Elise

    2016-06-15

    Classical tissue engineering is aimed mainly at producing anatomically and physiologically realistic replacements for normal human tissues. It is done either by encouraging cellular colonization of manufactured matrices or cellular recolonization of decellularized natural extracellular matrices from donor organs, or by allowing cells to self-organize into organs as they do during fetal life. For repair of normal bodies, this will be adequate but there are reasons for making unusual, non-evolved tissues (repair of unusual bodies, interface to electromechanical prostheses, incorporating living cells into life-support machines). Synthetic biology is aimed mainly at engineering cells so that they can perform custom functions: applying synthetic biological approaches to tissue engineering may be one way of engineering custom structures. In this article, we outline the 'embryological cycle' of patterning, differentiation and morphogenesis and review progress that has been made in constructing synthetic biological systems to reproduce these processes in new ways. The state-of-the-art remains a long way from making truly synthetic tissues, but there are now at least foundations for future work. © 2016 Authors; published by Portland Press Limited.

  11. Bladder tissue engineering through nanotechnology.

    Science.gov (United States)

    Harrington, Daniel A; Sharma, Arun K; Erickson, Bradley A; Cheng, Earl Y

    2008-08-01

    The field of tissue engineering has developed in phases: initially researchers searched for "inert" biomaterials to act solely as replacement structures in the body. Then, they explored biodegradable scaffolds--both naturally derived and synthetic--for the temporary support of growing tissues. Now, a third phase of tissue engineering has developed, through the subcategory of "regenerative medicine." This renewed focus toward control over tissue morphology and cell phenotype requires proportional advances in scaffold design. Discoveries in nanotechnology have driven both our understanding of cell-substrate interactions, and our ability to influence them. By operating at the size regime of proteins themselves, nanotechnology gives us the opportunity to directly speak the language of cells, through reliable, repeatable creation of nanoscale features. Understanding the synthesis of nanoscale materials, via "top-down" and "bottom-up" strategies, allows researchers to assess the capabilities and limits inherent in both techniques. Urology research as a whole, and bladder regeneration in particular, are well-positioned to benefit from such advances, since our present technology has yet to reach the end goal of functional bladder restoration. In this article, we discuss the current applications of nanoscale materials to bladder tissue engineering, and encourage researchers to explore these interdisciplinary technologies now, or risk playing catch-up in the future.

  12. Radiosensitivity of soft tissue sarcomas

    International Nuclear Information System (INIS)

    Hirano, Toru; Iwasaki, Katsuro; Suzuki, Ryohei; Monzen, Yoshio; Hombo, Zenichiro

    1989-01-01

    The correlation between the effectiveness of radiation therapy and the histology of soft tissue sarcomas was investigated. Of 31 cases with a soft tissue sarcoma of an extremity treated by conservative surgery and postoperative radiation of 3,000-6,000 cGy, local recurrence occurred in 12; 5 out of 7 synovial sarcomas, 4 of 9 MFH, one of 8 liposarcomas, none of 4 rhabdomyosarcomas and 2 of 3 others. As for the histological subtyping, the 31 soft tissue sarcomas were divided into spindle cell, pleomorphic cell, myxoid and round cell type, and recurrence rates were 75%, 33.3%, 16.7% and 0%, respectively. From the remarkable difference in recurrent rate, it was suggested that round cell and myxoid type of soft tissue sarcomas showed a high radiosensitivity compared to the spindle cell type with low sensitivity. Clarifying the degree of radiosensitivity is helpful in deciding on the management of limb salvage in soft tissue sarcomas of an extremity. (author)

  13. Effects of the Strain Rate Sensitivity and Strain Hardening on the Saturated Impulse of Plates

    Directory of Open Access Journals (Sweden)

    Ling Zhu

    Full Text Available Abstract This paper studies the stiffening effects of the material strain rate sensitivity and strain hardening on the saturated impulse of elastic, perfectly plastic plates. Finite element (FE code ABAQUS is employed to simulate the elastoplastic response of square plates under rectangular pressure pulse. Rigid-plastic analyses for saturated impulse, which consider strain rate sensitivity and strain hardening, are conducted. Satisfactory agreement between the finite element models (FEM and predictions of the rigid-plastic analysis is obtained, which verifies that the proposed rigid-plastic methods are effective to solve the problem including strain rate sensitivity and strain hardening. The quantitative results for the scale effect of the strain rate sensitivity are given. The results for the stiffening effects suggest that two general stiffening factors n 1 and n 2, which characterizes the strain rate sensitivity and strain hardening effect, respectively can be defined. The saturated displacement is inversely proportional to the stiffening factors (i.e. n 1 and n 2 and saturated impulse is inversely proportional to the square roots of the stiffening factors (i.e. n 1 and n 2. Formulae for displacement and saturated impulse are proposed based on the empirical analysis.

  14. Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical Strain versus Environmental Strains.

    Directory of Open Access Journals (Sweden)

    Elaheh Movahed

    Full Text Available The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird's droppings and decaying wood. Three environmental strains of C. neoformans originated from bird droppings (H4, S48B and S68B and C. neoformans reference clinical strain (H99 were used for intranasal infection in C57BL/6 mice. We showed that the H99 strain demonstrated higher virulence compared to H4, S48B and S68B strains. To examine if gene expression contributed to the different degree of virulence among these strains, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four strains. Our results revealed that out of 7,419 genes (22,257 probes examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B strains. The up-regulated genes in H99 strain include Hydroxymethylglutaryl-CoA synthase (MVA1, Mitochondrial matrix factor 1 (MMF1, Bud-site-selection protein 8 (BUD8, High affinity glucose transporter 3 (SNF3 and Rho GTPase-activating protein 2 (RGA2. Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 strain. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis.

  15. Variation in the strain anisotropy of Zircaloy with temperature and strain

    International Nuclear Information System (INIS)

    Hindle, E.D.; Worswick, D.

    1984-04-01

    Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

  16. An ultrasensitive strain sensor with a wide strain range based on graphene armour scales.

    Science.gov (United States)

    Yang, Yi-Fan; Tao, Lu-Qi; Pang, Yu; Tian, He; Ju, Zhen-Yi; Wu, Xiao-Ming; Yang, Yi; Ren, Tian-Ling

    2018-06-12

    An ultrasensitive strain sensor with a wide strain range based on graphene armour scales is demonstrated in this paper. The sensor shows an ultra-high gauge factor (GF, up to 1054) and a wide strain range (ε = 26%), both of which present an advantage compared to most other flexible sensors. Moreover, the sensor is developed by a simple fabrication process. Due to the excellent performance, this strain sensor can meet the demands of subtle, large and complex human motion monitoring, which indicates its tremendous application potential in health monitoring, mechanical control, real-time motion monitoring and so on.

  17. Differentiation and distribution of potato virus Y strains isolated from tobacco in South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Vorster, L L

    1986-01-01

    Four strains of potato virus Y (PVY) orginally isolated from tobacco in South Africa belonging to three different strain groups (PVY/sup N/, PVY/sup c/ and PVY/sup o/) were differentiated according to their effect on various tobacco cultivars. The results obtained in this study confirm previous reports which indicated that inoculation with PVY had a detrimental effect on the yield and quality of tobacco. The severity of the effects was generally related to the length of time that the virus was present in the host, with late infections having less effect than early infections. An important aspect that evolved from the present study is the differences in reactions of the various strains (necrotic to mild strains) of PVY on the tobacco cultivars tested. A direct correlation was evident between the virulence of the different PVY strains and the effect of O/sub 2/-uptake of the host. cDNA probes prepared from PVY-RNA are specific to RNA extracted from purified PVY suspensions as well as crude sap from tobacco plants infected with the PVY strains used in this study. Radioactive probes and /sup 32/Phosporus labelling were used in the DNA and RNA studies of PVY. A procedure described by Bar-Joseph, et al (1983) were used successfully for the isolation of viral double-stranded RNA from various tissues. However, from the results obtained in this study it is clear that this method is of little or no value for the detection and diagnosis of PVY strains.

  18. Engineered Muscle Actuators: Cells and Tissues

    National Research Council Canada - National Science Library

    Dennis, Robert G; Herr, Hugh; Parker, Kevin K; Larkin, Lisa; Arruda, Ellen; Baar, Keith

    2007-01-01

    .... Our primary objectives were to engineer living skeletal muscle actuators in culture using integrated bioreactors to guide tissue development and to maintain tissue contractility, to achieve 50...

  19. Micro- and nanotechnology in cardiovascular tissue engineering

    International Nuclear Information System (INIS)

    Zhang Boyang; Xiao Yun; Hsieh, Anne; Thavandiran, Nimalan; Radisic, Milica

    2011-01-01

    While in nature the formation of complex tissues is gradually shaped by the long journey of development, in tissue engineering constructing complex tissues relies heavily on our ability to directly manipulate and control the micro-cellular environment in vitro. Not surprisingly, advancements in both microfabrication and nanofabrication have powered the field of tissue engineering in many aspects. Focusing on cardiac tissue engineering, this paper highlights the applications of fabrication techniques in various aspects of tissue engineering research: (1) cell responses to micro- and nanopatterned topographical cues, (2) cell responses to patterned biochemical cues, (3) controlled 3D scaffolds, (4) patterned tissue vascularization and (5) electromechanical regulation of tissue assembly and function.

  20. Dynamic strains for earthquake source characterization

    Science.gov (United States)

    Barbour, Andrew J.; Crowell, Brendan W

    2017-01-01

    Strainmeters measure elastodynamic deformation associated with earthquakes over a broad frequency band, with detection characteristics that complement traditional instrumentation, but they are commonly used to study slow transient deformation along active faults and at subduction zones, for example. Here, we analyze dynamic strains at Plate Boundary Observatory (PBO) borehole strainmeters (BSM) associated with 146 local and regional earthquakes from 2004–2014, with magnitudes from M 4.5 to 7.2. We find that peak values in seismic strain can be predicted from a general regression against distance and magnitude, with improvements in accuracy gained by accounting for biases associated with site–station effects and source–path effects, the latter exhibiting the strongest influence on the regression coefficients. To account for the influence of these biases in a general way, we include crustal‐type classifications from the CRUST1.0 global velocity model, which demonstrates that high‐frequency strain data from the PBO BSM network carry information on crustal structure and fault mechanics: earthquakes nucleating offshore on the Blanco fracture zone, for example, generate consistently lower dynamic strains than earthquakes around the Sierra Nevada microplate and in the Salton trough. Finally, we test our dynamic strain prediction equations on the 2011 M 9 Tohoku‐Oki earthquake, specifically continuous strain records derived from triangulation of 137 high‐rate Global Navigation Satellite System Earth Observation Network stations in Japan. Moment magnitudes inferred from these data and the strain model are in agreement when Global Positioning System subnetworks are unaffected by spatial aliasing.