scholarly journals Visualization of Polypropylene and Polyvinylidene Fluoride Slings in Perineal Ultrasound and Correlation with Clinical Outcome

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Laila Najjari ◽  
Julia Hennemann ◽  
Ruth Kirschner-Hermanns ◽  
Nicolai Maass ◽  
Thomas Papathemelis
Keyword(s):  
Clinical Outcome ◽  
Significant Influence ◽  
Material Properties ◽  
Polyvinylidene Fluoride ◽  
Vertical Displacement ◽  
Valsalva Manoeuvre ◽  
Perineal Ultrasound ◽  
Future Studies ◽  
Vertical Stability

Introduction and Hypothesis.Complications and malfunctioning after TOT can occur due to several factors, such as the material of the sling. The aim of the present study is to evaluate morphology and functionality of two types of slings (PVDF; polypropylene)in vivousing perineal ultrasound (PUS).Materials. Inn=47women with TOT four criteria for PUS were taken and checked for possible differences: vertical stability of the sling position during Valsalva manoeuvre and contraction; distance “sling to urethra”; width of the sling and condition of the selvedges.Results. We observed an increased vertical displacement of the PP-slings, a significantly smaller variance to the extent of the displacement in PVDF-slings (P<0.01), a significantly larger distance between sling and urethra (P<0.001) in PVDF-slings, and a significantly smaller width of the PP-slings (P<0.0001).Conclusion. Significant differences were found between the slings according to the four criteria. There was no difference established between the slings in the improvement of continence and no significant influence of the parameters was found for the resulting state of continence. In future studies, PUS may help to link differences in the morphology and functionality ofin vivoslings to their material properties.

Dependence of Mechanical Behavior of the Murine Tail Disc on Regional Material Properties: A Parametric Finite Element Study

2005 ◽  
Vol 127 (7) ◽  
pp. 1158-1167 ◽  
Author(s):  
Adam H. Hsieh ◽  
Diane R. Wagner ◽  
Louis Y. Cheng ◽  
Jeffrey C. Lotz
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Nucleus Pulposus ◽  
Material Properties ◽  
Mechanical Response ◽  
Swelling Pressure ◽  
Transient Behavior ◽  
Sensitivity Analyses ◽  
Intact Mouse

In vivo rodent tail models are becoming more widely used for exploring the role of mechanical loading on the initiation and progression of intervertebral disc degeneration. Historically, finite element models (FEMs) have been useful for predicting disc mechanics in humans. However, differences in geometry and tissue properties may limit the predictive utility of these models for rodent discs. Clearly, models that are specific for rodent tail discs and accurately simulate the disc’s transient mechanical behavior would serve as important tools for clarifying disc mechanics in these animal models. An FEM was developed based on the structure, geometry, and scale of the mouse tail disc. Importantly, two sources of time-dependent mechanical behavior were incorporated: viscoelasticity of the matrix, and fluid permeation. In addition, a novel strain-dependent swelling pressure was implemented through the introduction of a dilatational stress in nuclear elements. The model was then validated against data from quasi-static tension-compression and compressive creep experiments performed previously using mouse tail discs. Finally, sensitivity analyses were performed in which material parameters of each disc subregion were individually varied. During disc compression, matrix consolidation was observed to occur preferentially at the periphery of the nucleus pulposus. Sensitivity analyses revealed that disc mechanics was greatly influenced by changes in nucleus pulposus material properties, but rather insensitive to variations in any of the endplate properties. Moreover, three key features of the model—nuclear swelling pressure, lamellar collagen viscoelasticity, and interstitial fluid permeation—were found to be critical for accurate simulation of disc mechanics. In particular, collagen viscoelasticity dominated the transient behavior of the disc during the initial 2200s of creep loading, while fluid permeation governed disc deformation thereafter. The FEM developed in this study exhibited excellent agreement with transient creep behavior of intact mouse tail motion segments. Notably, the model was able to produce spatial variations in nucleus pulposus matrix consolidation that are consistent with previous observations in nuclear cell morphology made in mouse discs using confocal microscopy. Results of this study emphasize the need for including nucleus swelling pressure, collagen viscoelasticity, and fluid permeation when simulating transient changes in matrix and fluid stress/strain. Sensitivity analyses suggest that further characterization of nucleus pulposus material properties should be pursued, due to its significance in steady-state and transient disc mechanical response.

Abstract 562: Human Carotid Atherosclerosis Plaque Progression and Vessel Material Stiffness at Follow Up Had Positive Correlation: An in vivo Vessel Stiffness MRI Follow Up Study

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Qingyu Wang ◽  
Dalin Tang ◽  
Gador Canton ◽  
Jian Guo ◽  
Xiaoya Guo ◽  
...  
Keyword(s):  
Negative Correlation ◽  
Material Properties ◽  
Stretch Ratio ◽  
Patient Specific ◽  
Plaque Progression ◽  
Material Stiffness ◽  
Variation Rate ◽  
Vessel Material

It is hypothesized that artery stiffness may be associated with plaque progression. However, in vivo vessel material stiffness follow-up data is lacking in the literature. In vivo 3D multi-contrast and Cine magnetic resonance imaging (MRI) carotid plaque data were acquired from 8 patients with follow-up (18 months) with written informed consent obtained. Cine MRI and 3D thin-layer models were used to determine parameter values of the Mooney-Rivlin models for the 81slices from 16 plaques (2 scans/patient) using our established iterative procedures. Effective Young’s Modulus (YM) values for stretch ratio [1.0,1.3] were calculated for each slice for analysis. Stress-stretch ratio curves from Mooney-Rivlin models for the 16 plaques and 81 slices are given in Fig. 1. Average YM value of the 81 slices was 411kPa. Slice YM values varied from 70 kPa (softest) to 1284 kPa (stiffest), a 1734% difference. Average slice YM values by vessel varied from 109 kPa (softest) to 922 kPa (stiffest), a 746% difference. Location-wise, the maximum slice YM variation rate within a vessel was 306% (139 kPa vs. 564 kPa). Average slice YM variation rate within a vessel for the 16 vessels was 134%. Average variation of YM values from baseline (T1) to follow up (T2) for all patients was 61.0%. The range of the variation of YM values was [-28.4%, 215%]. For progression study, YM increase (YMI=YM T2 -TM T1 ) showed negative correlation with plaque progression measured by wall thickness increase (WTI), (r= -0.6802, p=0.0634). YM T2 showed strong negative correlation with WTI (r= -0.7764, p=0.0235). Correlation between YM T1 and WTI was not significant (r= -0.4353, p= 0.2811). Conclusion In vivo carotid vessel material properties have large variations from patient to patient, along the vessel segment within a patient, and from baseline to follow up. Use of patient-specific, location specific and time-specific material properties could potentially improve the accuracy of model stress/strain calculations.

scholarly journals Cellular morphological changes detected by laser scanning in vivo confocal microscopy associated with clinical outcome in fungal keratitis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jaya D. Chidambaram ◽  
Namperumalsamy V. Prajna ◽  
Srikanthi Palepu ◽  
Shruti Lanjewar ◽  
Manisha Shah ◽  
...  
Keyword(s):  
Confocal Microscopy ◽  
Clinical Outcome ◽  
Laser Scanning ◽  
Morphological Changes ◽  
Fungal Keratitis ◽  
In Vivo Confocal Microscopy

scholarly journals Infarcted Left Ventricles Have Stiffer Material Properties and Lower Stiffness Variation: Three-Dimensional Echo-Based Modeling to Quantify In Vivo Ventricle Material Properties

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Longling Fan ◽  
Jing Yao ◽  
Chun Yang ◽  
Dalin Tang ◽  
Di Xu
Keyword(s):  
Wall Thickness ◽  
Material Properties ◽  
Strain Curve ◽  
Stress And Strain ◽  
Stress Strain ◽  
Material Stiffness ◽  
The Mean ◽  
Lv Volume ◽  
Parameter Values

Methods to quantify ventricle material properties noninvasively using in vivo data are of great important in clinical applications. An ultrasound echo-based computational modeling approach was proposed to quantify left ventricle (LV) material properties, curvature, and stress/strain conditions and find differences between normal LV and LV with infarct. Echo image data were acquired from five patients with myocardial infarction (I-Group) and five healthy volunteers as control (H-Group). Finite element models were constructed to obtain ventricle stress and strain conditions. Material stiffening and softening were used to model ventricle active contraction and relaxation. Systolic and diastolic material parameter values were obtained by adjusting the models to match echo volume data. Young's modulus (YM) value was obtained for each material stress–strain curve for easy comparison. LV wall thickness, circumferential and longitudinal curvatures (C- and L-curvature), material parameter values, and stress/strain values were recorded for analysis. Using the mean value of H-Group as the base value, at end-diastole, I-Group mean YM value for the fiber direction stress–strain curve was 54% stiffer than that of H-Group (136.24 kPa versus 88.68 kPa). At end-systole, the mean YM values from the two groups were similar (175.84 kPa versus 200.2 kPa). More interestingly, H-Group end-systole mean YM was 126% higher that its end-diastole value, while I-Group end-systole mean YM was only 29% higher that its end-diastole value. This indicated that H-Group had much greater systole–diastole material stiffness variations. At beginning-of-ejection (BE), LV ejection fraction (LVEF) showed positive correlation with C-curvature, stress, and strain, and negative correlation with LV volume, respectively. At beginning-of-filling (BF), LVEF showed positive correlation with C-curvature and strain, but negative correlation with stress and LV volume, respectively. Using averaged values of two groups at BE, I-Group stress, strain, and wall thickness were 32%, 29%, and 18% lower (thinner), respectively, compared to those of H-Group. L-curvature from I-Group was 61% higher than that from H-Group. Difference in C-curvature between the two groups was not statistically significant. Our results indicated that our modeling approach has the potential to determine in vivo ventricle material properties, which in turn could lead to methods to infer presence of infarct from LV contractibility and material stiffness variations. Quantitative differences in LV volume, curvatures, stress, strain, and wall thickness between the two groups were provided.

Thermal Stress in Teeth

1978 ◽  
Vol 57 (4) ◽  
pp. 571-582 ◽  
Author(s):  
B.A. Lloyd ◽  
M.B. McGinley ◽  
W.S. Brown
Keyword(s):  
Thermal Stress ◽  
Numerical Analysis ◽  
Material Properties ◽  
Thermal Stresses ◽  
In Vivo Studies ◽  
Tooth Structure ◽  
Analysis Techniques ◽  
Tooth Type

Observations of crack damage in the tooth structure from in vivo studies and in vitro experimental thermal cycling studies were combined with numerical analysis techniques to identify and isolate the influence of thermal stresses an the creation and propagation of cracks in teeth. The factors considered in this study included: (a) variations in tooth type or geometry (molar, bicuspid, etc.), (b) tooth age, (c) material properties of the tooth, (d) the magnitude of the change in the temperature of the environment surrounding the tooth, and (e) the thermal resistance between the tooth and the medium surrounding the tooth.

Influence of estrogen on individual exercise motivation and bone protection in ovariectomized rats

2018 ◽  
Vol 52 (5) ◽  
pp. 479-489 ◽  
Author(s):  
Sebastian T Müller ◽  
Annekathrin M Keiler ◽  
Kristin Kräker ◽  
Oliver Zierau ◽  
Ricardo Bernhardt
Keyword(s):  
Bone Loss ◽  
Ex Vivo ◽  
Voluntary Exercise ◽  
Ovariectomized Rats ◽  
Protective Effects ◽  
Exercise Motivation ◽  
Running Wheel ◽  
Future Studies ◽  
Bone Protection

Bone protection and metabolism are directly linked to estrogen levels, but exercise is also considered to have bone protective effects. Reduced estrogen levels lead to a variety of disorders, for example, bone loss and reduced movement drive. The objective of this study was to investigate the effects of estrogen on individual voluntary exercise motivation and bone protection. We investigated sham operated, ovariectomized, and ovariectomized with estrogen supplemented Wistar rats (20 weeks old) either with or without access to exercise wheels. We selected an experimental approach where we could monitor the individual exercise of group-housed rats with ad libitum access to a running wheel with the help of a subcutaneous chip. In vivo and ex vivo microcomputed tomography analyses of the tibia were performed at two-week intervals from week 0 to week 6. Furthermore, tibial trabecular structure was evaluated based on histomorphometric analyses. We observed a significant bone protective effect of E2. For exercise performance, a substantially high intra-group variability was observed, especially in the E2 group. We presume that dominant behavior occurs within the group-housed rats resulting in a hierarchical access to the running wheel and a high variability of distance run. Exercise did not prevent ovariectomy-induced bone loss. However, lack of estrogen within the ovariectomized rats led to a drastically reduced activity prevented by estrogen supplementation. Our findings are important for future studies working with group-housed rats and exercise. The reason for the high intra-group variability in exercise needs to be investigated in future studies.

scholarly journals Droplet Based Measurements of Mechanical Forces and Material Properties, In Vivo and In Vitro

2018 ◽  
Vol 114 (3) ◽  
pp. 666a
Author(s):  
Elijah Shelton ◽  
Adam Lucio ◽  
Hannah Gustafson ◽  
Alessandro Mongera ◽  
Friedhelm Serwane ◽  
...  
Keyword(s):  
Material Properties ◽  
Mechanical Forces

Preclinical studies conducted on nanozyme antioxidants: shortcomings and challenges based on US FDA regulations

Nanomedicine ◽  
2021 ◽  
Author(s):  
Milad Ghorbani ◽  
Zhila Izadi ◽  
Samira Jafari ◽  
Eudald Casals ◽  
Foroogh Rezaei ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Clinical Trials ◽  
Clinical Studies ◽  
In Vivo Studies ◽  
Preclinical Studies ◽  
Future Studies ◽  
Clinical Stages ◽  
Us Fda ◽  
Considerable Body

The wide prevalence of oxidative stress-induced diseases has led to a growing demand for antioxidant therapeutics worldwide. Nanozyme antioxidants are drawing enormous attention as practical alternatives for conventional antioxidants. The considerable body of research over the last decade and the promising results achieved signify the potential of nanozyme antioxidants to secure a place in the expanding market of antioxidant therapeutics. Nonetheless, there is no report on clinical trials for their further evaluation. Through analyzing in-depth selected papers which have conducted in vivo studies on nanozyme antioxidants, this review aims to pinpoint and discuss possible reasons impeding development of research toward clinical studies and to offer some practical solutions for future studies to bridge the gap between preclinical and clinical stages.

scholarly journals From the Origins of Pharmacogenetics to First Applications in Psychiatry

2019 ◽  
Vol 53 (04) ◽  
pp. 155-161 ◽  
Author(s):  
Daniel J. Müller ◽  
Zoe Rizhanovsky
Keyword(s):  
Side Effects ◽  
Clinical Outcome ◽  
Conceptual Framework ◽  
Drug Targets ◽  
Genetic Factors ◽  
Psychiatric Treatment ◽  
Clinical Pharmacologist ◽  
Genetic Traits ◽  
Future Studies ◽  
Practical Implications

AbstractPharmacogenetics is the division of science addressing how genetic factors contribute to the metabolism, response, and side effects of a given medication. What was once regarded as a subdivision of genetics and pharmacology is now recognized as its own field and has its own unique story of origin. While the term “pharmacogenetics” was coined by Friedrich Vogel in 1959, the relevance of inherited genetic traits in affecting the clinical outcome to xenobiotics has been observed long before. In fact, there is much hope that pharmacogenetics can help unravel the “mysteries” as to why different people may display variable responses to the same medication as well as identify new drug targets. This article will highlight the conceptual framework for pharmacogenetics advanced by pioneer scientists Arno Motulsky and Friedrich Vogel (both human geneticists), as well as Werner Kalow (clinical pharmacologist), leading up to the creation of modern pharmacogenetics. Finally, the practical implications and first steps toward implementation for current psychiatric treatment are reviewed followed by an outlook on future studies.

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