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2.
Ultrason Sonochem ; 88: 106096, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35868210

ABSTRACT

Sonocrystallization implies the application of ultrasound radiation to control the nucleation and crystal growth depending on the actuation time and intensity. Its application allows to induce nucleation at lower supersaturations than required under standard conditions. Although extended in inorganic and organic crystallization, it has been scarcely explored in protein crystallization. Now, that industrial protein crystallization is gaining momentum, the interest on new ways to control protein nucleation and crystal growth is advancing. In this work we present the development of a novel ultrasound bioreactor to study its influence on protein crystallization in agarose gel. Gel media minimize convention currents and sedimentation, favoring a more homogeneous and stable conditions to study the effect of an externally generated low energy ultrasonic irradiation on protein crystallization avoiding other undesired effects such as temperature increase, introduction of surfaces which induce nucleation, destructive cavitation phenomena, etc. In-depth statistical analysis of the results has shown that the impact of ultrasound in gel media on crystal size populations are statistically significant and reproducible.


Subject(s)
Hydrogels , Muramidase , Ultrasonic Waves , Crystallization/methods , Muramidase/chemistry , Proteins/chemistry
3.
Sci Rep ; 12(1): 8354, 2022 05 19.
Article in English | MEDLINE | ID: mdl-35589817

ABSTRACT

Corneal mechanical changes are believed to occur before any visible structural alterations observed during routine clinical evaluation. This study proposed developing an elastography technique based on torsional waves (TWE) adapted to the specificities of the cornea. By measuring the displacements in the propagation plane perpendicular to the axis of the emitter, the effect of guided waves in plate-like media was proven negligible. Ex vivo experiments were carried out on porcine corneal samples considering a group of control and one group of alkali burn treatment ([Formula: see text]OH) that modified the mechanical properties. Phase speed was recovered as a function of intraocular pressure (IOP), and a Kelvin-Voigt rheological model was fitted to the dispersion curves to estimate viscoelastic parameters. A comparison with uniaxial tensile testing with thin-walled assumptions was also performed. Both shear elasticity and viscosity correlated positively with IOP, being the elasticity lower and the viscosity higher for the treated group. The viscoelastic parameters ranged from 21.33 to 63.17 kPa, and from 2.82 to 5.30 Pa s, for shear elasticity and viscosity, respectively. As far as the authors know, no other investigations have studied this mechanical plane under low strain ratios, typical of dynamic elastography in corneal tissue. TWE reflected mechanical properties changes after treatment, showing a high potential for clinical diagnosis due to its rapid performance time and paving the way for future in vivo studies.


Subject(s)
Elasticity Imaging Techniques , Animals , Cornea/diagnostic imaging , Elasticity , Elasticity Imaging Techniques/methods , Swine , Tonometry, Ocular , Viscosity
4.
Diagnostics (Basel) ; 11(12)2021 Nov 26.
Article in English | MEDLINE | ID: mdl-34943448

ABSTRACT

At the moment, several COVID-19 scoring systems have been developed. It is necessary to determine which one better predicts a poor outcome of the disease. We conducted a single-center prospective cohort study to validate four COVID-19 prognosis scores in adult patients with confirmed infection at ward. These are National Early Warning Score (NEWS) 2, Lung Ultrasound Score (LUS), COVID-19 Worsening Score (COWS), and Spanish Society of Infectious Diseases and Clinical Microbiology score (SEIMC Score). Our outcomes were the combined variable "poor outcome" (non-invasive mechanical ventilation, intubation, intensive care unit admission, and death at 28 days) and death at 28 days. Scores were analysed using univariate logistic regression models, receiver operating characteristic curves, and areas under the curve. Eighty-one patients were included, from which 21 had a poor outcome, and 9 died. We found a statistically significant correlation between poor outcome and NEWS2, LUS > 15, and COWS. Death at 28 days was statistically correlated with NEWS2 and SEIMC Score although COWS also performs well. NEWS2, LUS, and COWS accurately predict poor outcome; and NEWS2, SEIMC Score, and COWS are useful for anticipating death at 28 days. Lung ultrasound is a diagnostic tool that should be included in COVID-19 patients evaluation.

5.
Environ Int ; 156: 106734, 2021 11.
Article in English | MEDLINE | ID: mdl-34224998

ABSTRACT

BACKGROUND: Despite restrictions on their production and use, most of the population is still exposed to Persistent Organic Pollutants (POPs), including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). These chemicals are thought to contribute to the aetiology of highly prevalent chronic conditions, such as cardiovascular diseases (CVDs), although current evidences are still controversial. OBJECTIVES: To explore the potential contribution of historical POP exposure to 15-year pharmaceutical consumption in relation to CVD. METHODS: This study is framed within GraMo adult cohort. Participants (n = 387) were recruited in two hospitals in Granada province, Southern Spain (2003-2004). Historical exposure to 5 OCPs and 3 non-dioxine-like PCBs was estimated by analysing adipose tissue concentrations at recruitment. Pharmaceutical consumption from recruitment until year 2017 was quantified by reviewing dispensation databases. Average consumption increase (ACI) in CVD medication was calculated by subtracting average consumption in 2002 to the average yearly consumption during follow-up. ACI was expressed as Defined Daily Dose (DDD)/year units. Data analyses were carried out using a multivariable multinomial logistic regression and weighted quantile sum regression (WQS), with ACI categorized in quartiles (Q) as the dependent variable. RESULTS: Concentrations of most pollutants showed a positive trend with the quartiles of ACI. Particularly, PCB-153 showed increasing and statistically significant odds ratios (ORs) for Q2 (OR: 1.27, 95% confidence interval (CI): 1.07-1.52), Q3 (OR: 1.49, 95 %CI: 1.17-1.88) and Q4 (OR: 1.42, 95 %CI: 1.13-1.78) vs Q1. Similarly, beta-hexachlorocyclohexane (ß-HCH) also showed increasing ORs, that reached statistical significance in Q4 (OR: 1.36, 95 %CI: 1.06-1.74) vs Q1. These findings were corroborated by WQS analyses, that revealed a significant mixture effect, predominantly accounted for by PCB-153 and ß-HCH. DISCUSSION: Our results suggest that long-term POP exposure might represent a modifiable risk factor for CVD. These findings are relevant for public health campaigns and management, since pharmaceutical consumption is considered an indicator of both morbidity and health expenditure.


Subject(s)
Cardiovascular Diseases , Environmental Pollutants , Hydrocarbons, Chlorinated , Pesticides , Pharmaceutical Preparations , Polychlorinated Biphenyls , Adult , Cardiovascular Diseases/chemically induced , Cardiovascular Diseases/epidemiology , Environmental Pollutants/analysis , Humans , Hydrocarbons, Chlorinated/analysis , Persistent Organic Pollutants , Primary Health Care
6.
Materials (Basel) ; 14(9)2021 Apr 29.
Article in English | MEDLINE | ID: mdl-33946632

ABSTRACT

Mechanical compatibility with the human dentin is a considerable issue when fabricating dental fiber posts. To this purpose, this study introduces a new method of fabricating compatible dental posts using braiding techniques of thermoplastic fibers (matrix) with glass fibers (reinforcement). Fifty fiber-reinforced composite (FRC) posts of thermoplastic yarns polypropylene (PP) braided with continuous filaments glass fibers (GFs) for reinforcement, varying in fiber volume fraction (FVF), and core types are fabricated and tested. Posts are performed using a braiding machine, and braids are placed in an aluminum mold. The filled mold is playced inside an oven at the melting temperature of the polypropylene to produce the final post's shape. An ultrasonic test is conducted to measure the shear modulus and Young's modulus of FRC post specimens by measuring the velocities of both the P-wave and S-wave. In order to ensure the accuracy of the measurements, each sample is measured three times, and then the means and standard deviations of each sample are calculated before analyzing the test results using the means of two steps, namely, clustering and comparing the P and R² values of each cluster, which revealed that FVF, fiber mass, and core type of the specimen had a significant effect on the resulted Young's and shear modulus. The results indicate that the proposed method can fabricate competitive dental posts with regard to different fabricating variables. The samples show Young's modulus ranges of from 10.08 GPa to 31.83 GPa. The following tested hypothesis is supported: the braiding technique of thermoplastic fibers with glass fibers will improve the mechanical compatibility of the resulting posts (ex vivo).

7.
Am J Obstet Gynecol ; 225(3): 308.e1-308.e14, 2021 09.
Article in English | MEDLINE | ID: mdl-33823150

ABSTRACT

BACKGROUND: In women with late preterm preeclampsia, the optimal time for delivery remains a controversial topic, because of the fine balance between the maternal benefits from early delivery and the risks for prematurity. It remains challenging to define prognostic markers to identify women at highest risk for complications, in which case a selective, planned delivery may reduce the adverse maternal and perinatal outcomes. OBJECTIVE: This trial aimed to determine whether using an algorithm based on the maternal levels of placental growth factor in women with late preterm preeclampsia to evaluate the best time for delivery reduced the progression to preeclampsia with severe features without increasing the adverse perinatal outcomes. STUDY DESIGN: This parallel-group, open-label, multicenter, randomized controlled trial was conducted at 7 maternity units across Spain. We compared selective planned deliveries based on maternal levels of placental growth factor at admission (revealed group) and expectant management under usual care (concealed group) with individual randomization in singleton pregnancies with late preterm preeclampsia from 34 to 36+6 weeks' gestation. The coprimary maternal outcome was the progression to preeclampsia with severe features. The coprimary neonatal outcome was morbidity at infant hospital discharge with a noninferiority hypothesis (noninferiority margin of 10% difference in incidence). Analyses were conducted according to intention-to-treat. RESULTS: Between January 1, 2016, and December 31, 2019, 178 women were recruited. Of those women, 88 were assigned to the revealed group and 90 were assigned to the concealed group. The data analysis was performed before the completion of the required sample size. The proportion of women with progression to preeclampsia with severe features was significantly lower in the revealed group than in the concealed group (adjusted relative risk, 0.5; 95% confidence interval, 0.33-0.76; P=.001). The proportion of infants with neonatal morbidity was not significantly different between groups (adjusted relative risk, 0.77; 95% confidence interval, 0.39-1.53; P=.45). CONCLUSION: There is evidence to suggest that the use of an algorithm based on placental growth factor levels in women with late preterm preeclampsia leads to a lower rate of progression to preeclampsia with severe features and reduces maternal complications without worsening the neonatal outcomes. This trade-off should be discussed with women with late preterm preeclampsia to allow shared decision making about the timing of delivery.


Subject(s)
Placenta Growth Factor/blood , Pre-Eclampsia/blood , Adult , Algorithms , Biomarkers/blood , Disease Progression , Female , Humans , Infant, Newborn , Pregnancy , Prognosis , Watchful Waiting
8.
Front Physiol ; 12: 749372, 2021.
Article in English | MEDLINE | ID: mdl-35140623

ABSTRACT

The Finite Element Method (FEM) models are valuable tools to create an idea of the behavior of any structure. The complexity of the joints, materials, attachment areas, and boundary conditions is an open issue in biomechanics that needs to be addressed. Scapholunate instability is the leading cause of wrist pain and disability among patients of all ages. It is needed a better understanding of pathomechanics to develop new effective treatments. Previous models have emulated joints like the ankle or the knee but there are few about the wrist joint. The elaboration of realistic computational models of the carpus can give critical information to biomedical research and surgery to develop new surgical reconstructions. Hence, a 3D model of the proximal carpal row has been created through DICOM images, making a reduced wrist model. The materials, contacts, and ligaments definition were made via open-source software to extract results and carry on a reference comparison. Thus, considering the limitations that a reduced model could carry on (unbalanced forces and torques), the stresses that result in the scapholunate interosseous ligament (SLIL) lead us to a bones relative displacement, which support the kinematics hypothesis in the literature as the distal carpal row moves as a rigid solid with the capitate bone. Also, experimental testing is performed, successfully validating the linear strength values of the scapholunate ligament from the literature.

9.
Diagnostics (Basel) ; 10(11)2020 Nov 18.
Article in English | MEDLINE | ID: mdl-33218002

ABSTRACT

Transient or acoustic radiation force elastography (ARFE) is becoming the most extended technology to assess cervical effacement, additionally to the Bishop test and conventional ultrasound. However, a debate on the fetal safety has been opened due to the high intensity focused beam emitted to produce shear waves. This work is aimed at providing preliminary data to assess clinical effects of fetal exposure. A follow-up study in newborns of 42 women exposed to ARFE during pregnancy was carried out to explore neonatal hypoacusia, Apgar test, and anthropometry. No hypoacusia cases attributable to ARFE were observed. The Apgar test at five minutes scored normally in all the newborns. Comparisons between anthropometric measurements showed no significant statistically differences. The results preclude to state the harmfulness nor the safety of ARFE. However, given the concern on the high level of energy and the potential risk of harmful bioeffects, larger studies are recommended.

10.
Sensors (Basel) ; 20(16)2020 Aug 05.
Article in English | MEDLINE | ID: mdl-32764345

ABSTRACT

This paper presents the results of the comparison between a proposed Fourth Order Elastic Constants (FOECs) nonlinear model defined in the sense of Landau's theory, and the two most contrasted hyperelastic models in the literature, Mooney-Rivlin, and Ogden models. A mechanical testing protocol is developed to investigate the large-strain response of ex vivo cervical tissue samples in uniaxial tension in its two principal anatomical locations, the epithelial and connective layers. The final aim of this work is to compare the reconstructed shear modulus of the epithelial and connective layers of cervical tissue. According to the obtained results, the nonlinear parameter A from the proposed FOEC model could be an important biomarker in cervical tissue diagnosis. In addition, the calculated shear modulus depended on the anatomical location of the cervical tissue (µepithelial = 1.29 ± 0.15 MPa, and µconnective = 3.60 ± 0.63 MPa).


Subject(s)
Nonlinear Dynamics , Uterine Cervical Diseases , Elasticity , Female , Humans , Stress, Mechanical , Uterine Cervical Diseases/diagnosis
11.
J Obstet Gynaecol ; 40(6): 767-771, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32648534

ABSTRACT

To assess the opinion and the level of satisfaction of patients concerning analgesia during external cephalic version (ECV), we present the results of a survey of 120 women undergoing ECV at term during a randomised controlled trial (July 2012 to February 2013) comparing remifentanil and nitrous oxide. Overall, 110 (91.7%) women said they would repeat the procedure and 111 (92.5%) that they would recommend it to another pregnant woman, with no significant differences by type of analgesia. The administration and sense of comfort were rated better in the remifentanil group (p < .01). In conclusion, the use of analgesia during ECV is associated with a high rate of willingness among women to repeat the procedure and recommend it to other pregnant women.Impact statementWhat is already known on this subject? ECV is commonly a painful manoeuvre for the woman. This pain triggers maternal reactive abdominal muscle contraction and involuntary abdominal tensing, reducing the likelihood of successful version and causing some women to reject the technique.What do the results of this study add? The use of analgesia during ECV is associated with a high rate of willingness among women to repeat the procedure and recommend it to other pregnant women. The sense of comfort during ECV was also significantly better in the remifentanil group, probably because of its greater analgesic power and greater comfort during its administration.What are the implications of these findings for clinical practice and/or further research? ECV should be carried out under analgesia, when available, not only to decrease pain but also to encourage wider adoption of the technique and enable more women to benefit from it.


Subject(s)
Analgesia, Obstetrical/psychology , Pain Management/psychology , Pain, Procedural/psychology , Patient Satisfaction/statistics & numerical data , Version, Fetal/psychology , Adult , Analgesia, Obstetrical/methods , Analgesics, Non-Narcotic/therapeutic use , Analgesics, Opioid/therapeutic use , Breech Presentation/therapy , Female , Humans , Nitrous Oxide/therapeutic use , Pain Management/methods , Pain Measurement , Pain, Procedural/drug therapy , Pain, Procedural/etiology , Pregnancy , Remifentanil/therapeutic use , Term Birth/psychology , Version, Fetal/adverse effects
12.
Sensors (Basel) ; 20(8)2020 Apr 22.
Article in English | MEDLINE | ID: mdl-32331295

ABSTRACT

The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues' mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.


Subject(s)
Elasticity Imaging Techniques/methods , Viscosity , Biomechanical Phenomena , Humans
13.
Diagnostics (Basel) ; 10(2)2020 Feb 19.
Article in English | MEDLINE | ID: mdl-32092900

ABSTRACT

The clinical ultrasound community demands mechanisms to obtain the viscoelastic biomarkers of soft tissue in order to quantify the tissue condition and to be able to track its consistency. Torsional Wave Elastography (TWE) is an emerging technique proposed for interrogating soft tissue mechanical viscoelastic constants. Torsional waves are a particular configuration of shear waves, which propagate asymmetrically in-depth and are radially transmitted by a disc and received by a ring. This configuration is shown to be particularly efficient in minimizing spurious p-waves components and is sensitive to mechanical constants, especially in cylinder-shaped organs. The objective of this work was to validate (TWE) technique against Shear Wave Elasticity Imaging (SWEI) technique through the determination of shear wave velocity, shear moduli, and viscosity of ex vivo chicken liver samples and tissue mimicking hydrogel phantoms. The results of shear moduli for ex vivo liver tissue vary 1.69-4.0kPa using TWE technique and 1.32-4.48kPa using SWEI technique for a range of frequencies from 200 to 800Hz. Kelvin-Voigt viscoelastic parameters reported values of µ = 1.51kPa and η = 0.54Pa·s using TWE and µ = 1.02kPa and η = 0.63Pa·s using SWEI. Preliminary results show that the proposed technique successfully allows reconstructing shear wave velocity, shear moduli, and viscosity mechanical biomarkers from the propagated torsional wave, establishing a proof of principle and warranting further studies.

14.
Sensors (Basel) ; 19(15)2019 Jul 25.
Article in English | MEDLINE | ID: mdl-31349721

ABSTRACT

The reconstruction of viscous properties of soft tissues, and more specifically, of cervical tissue is a challenging problem. In this paper, a new method is proposed to reconstruct the viscoelastic parameters of cervical tissue-mimicking phantoms by a Torsional Wave Elastography (TWE) technique. The reconstruction method, based on a Probabilistic Inverse Problem (PIP) approach, is presented and experimentally validated against Shear Wave Elastography (SWE). The anatomy of the cervical tissue has been mimicked by means of a two-layer gelatine phantom that simulates the epithelial and connective layers. Five ad hoc oil-in-gelatine phantoms were fabricated at different proportion to test the new reconstruction technique. The PIP approach was used for reconstructing the Kelvin-Voigt (KV) viscoelastic parameters by comparing the measurements obtained from the TWE technique with the synthetic signals from a Finite Difference Time Domain (FDTD) KV wave propagation model. Additionally, SWE tests were realized in order to characterize the viscoelastic properties of each batch of gelatine. Finally, validation was carried out by comparing the KV parameters inferred from the PIP with those reconstructed from the shear wave dispersion curve obtained from the SWE measurements. In order to test the degree of agreement between both techniques, a Student's T-test and a Pearson's correlation study were performed. The results indicate that the proposed method is able to reconstruct the KV viscoelastic properties of the cervical tissue, for both the epithelial and connective layers, as well as the thickness of the first layer with acceptable accuracy.


Subject(s)
Cervix Uteri/diagnostic imaging , Elasticity Imaging Techniques/methods , Phantoms, Imaging , Viscosity , Adult , Biomechanical Phenomena , Cervix Uteri/physiology , Elasticity , Female , Gelatin/chemistry , Humans , Pregnancy
15.
Sensors (Basel) ; 19(15)2019 Jul 24.
Article in English | MEDLINE | ID: mdl-31344796

ABSTRACT

A torsional wave (TW) sensor prototype was employed to quantify stiffness of the cervix in pregnant women. A cross-sectional study in a total of 18 women between 16 weeks and 35 weeks + 5 days of gestation was performed. The potential of TW technique to assess cervical ripening was evaluated by the measurement of stiffness related to gestational age and cervical length. Statistically significant correlations were found between cervical stiffness and gestational age ( R 2 = 0.370 , p = 0.0074 , using 1 kHz waves and R 2 = 0.445 , p = 0.0250 , using 1.5 kHz waves). A uniform decrease in stiffness of the cervical tissue was confirmed to happen during the complete gestation. There was no significant correlation between stiffness and cervical length. A stronger association between gestational age and cervical stiffness was found compared to gestational age and cervical length correlation. As a conclusion, TW technique is a feasible approach to objectively quantify the decrease of cervical stiffness related to gestational age. Further research is required to evaluate the application of TW technique in obstetric evaluations, such as prediction of preterm delivery and labor induction failure.


Subject(s)
Cervix Uteri/diagnostic imaging , Elasticity Imaging Techniques/methods , Torsion Abnormality/diagnostic imaging , Adult , Cervical Ripening/physiology , Cervix Uteri/physiopathology , Cross-Sectional Studies , Elasticity , Female , Gestational Age , Humans , Labor, Induced , Pregnancy , Torsion Abnormality/physiopathology
16.
J Perinat Med ; 47(6): 625-630, 2019 Aug 27.
Article in English | MEDLINE | ID: mdl-31141492

ABSTRACT

Background Obesity in pregnancy is increasing worldwide, reaching epidemic proportions in many countries and frequently creating challenges for obstetricians. We conducted this study to assess the effects of maternal obesity on maternal and perinatal outcomes. Methods A historical cohort study was performed on 16,609 women who delivered singleton babies in a 5-year period (2013-2017). Data were retrieved from the Cruces Perinatal Database (CPD) and only women whose prepregnancy body mass index (BMI) was known were included. Women were categorized according to the World Health Organization (WHO) classification: normal weight (BMI 20-24.9 kg/m2) and obesity (BMI ≥ 30 kg/m2). Obstetric, perinatal and neonatal outcomes were compared, and adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) were calculated using the normal-weight group as the reference. Results Compared to women of normal weight (n = 9778), obese women (n = 2207) had a higher risk of preeclampsia (aOR 2.199, 95% CI: 1.46-3.29), rectovaginal group B streptococcus colonization (aOR 1.299, 95% CI: 1.14-1.47), induction of labor (aOR 1.593, 95% CI: 1.44-1.75), cesarean section (aOR 2.755, 95% CI: 2.46-3.08), cesarean section in women with a history of cesarean delivery (aOR 1.409, 95% CI: 1.03-1.92), fetal weight ≥4000 g (aOR 2.090, 95% CI: 1.803-2.422) and admission to the neonatal intensive care unit (NICU) (aOR 1.341, 95% CI: 1.12-1.59). No association was found with preterm birth (aOR 0.936, 95% CI: 0.77-1.13), stillbirth (aOR 0.921, 95% CI: 0.41-2.02) or neonatal mortality (aOR 2.205, 95% CI: 0.86-5.62). Conclusion Maternal obesity is associated with a higher risk of adverse pregnancy and perinatal outcomes. Pregnancy in this population of women should be considered and managed as high risk.


Subject(s)
Cesarean Section/statistics & numerical data , Diabetes, Gestational/epidemiology , Obesity, Maternal , Pre-Eclampsia/epidemiology , Pregnancy Complications , Premature Birth/epidemiology , Adult , Body Mass Index , Female , Humans , Infant , Infant Mortality , Infant, Newborn , Maternal Age , Obesity, Maternal/diagnosis , Obesity, Maternal/epidemiology , Pregnancy , Pregnancy Complications/diagnosis , Pregnancy Complications/epidemiology , Pregnancy Outcome/epidemiology , Pregnancy, High-Risk , Spain/epidemiology , Stillbirth/epidemiology
17.
Sensors (Basel) ; 18(9)2018 Sep 07.
Article in English | MEDLINE | ID: mdl-30205422

ABSTRACT

Optimizing an experimental design is a complex task when a model is required for indirect reconstruction of physical parameters from the sensor readings. In this work, a formulation is proposed to unify the probabilistic reconstruction of mechanical parameters and an optimization problem. An information-theoretic framework combined with a new metric of information density is formulated providing several comparative advantages: (i) a straightforward way to extend the formulation to incorporate additional concurrent models, as well as new unknowns such as experimental design parameters in a probabilistic way; (ii) the model causality required by Bayes' theorem is overridden, allowing generalization of contingent models; and (iii) a simpler formulation that avoids the characteristic complex denominator of Bayes' theorem when reconstructing model parameters. The first step allows the solving of multiple-model reconstructions. Further extensions could be easily extracted, such as robust model reconstruction, or adding alternative dimensions to the problem to accommodate future needs.

18.
Sensors (Basel) ; 17(9)2017 Sep 11.
Article in English | MEDLINE | ID: mdl-28891995

ABSTRACT

A novel torsional wave sensor designed to characterize mechanical properties of soft tissues is presented in this work. Elastography is a widely used technique since the 1990s to map tissue stiffness. Moreover, quantitative elastography uses the velocity of shear waves to achieve the shear stiffness. This technique exhibits significant limitations caused by the difficulty of the separation between longitudinal and shear waves and the pressure applied while measuring. To overcome these drawbacks, the proposed torsional wave sensor can isolate a pure shear wave, avoiding the possibility of multiple wave interference. It comprises a rotational actuator disk and a piezoceramic receiver ring circumferentially aligned. Both allow the transmission of shear waves that interact with the tissue before being received. Experimental tests are performed using tissue mimicking phantoms and cervical tissues. One contribution is a sensor sensitivity study that has been conducted to evaluate the robustness of the new proposed torsional wave elastography (TWE) technique. The variables object of the study are both the applied pressure and the angle of incidence sensor-phantom. The other contribution consists of a cervical tissue characterization. To this end, three rheological models have fit the experimental data and a static independent testing method has been performed. The proposed methodology permits the reconstruction of the mechanical constants from the propagated shear wave, providing a proof of principle and warranting further studies to confirm the validity of the results.


Subject(s)
Neck , Elasticity Imaging Techniques , Phantoms, Imaging , Rheology
19.
Sensors (Basel) ; 17(6)2017 Jun 15.
Article in English | MEDLINE | ID: mdl-28617353

ABSTRACT

Torsion mechanical waves have the capability to characterize shear stiffness moduli of soft tissue. Under this hypothesis, a computational methodology is proposed to design and optimize a piezoelectrics-based transmitter and receiver to generate and measure the response of torsional ultrasonic waves. The procedure employed is divided into two steps: (i) a finite element method (FEM) is developed to obtain a transmitted and received waveform as well as a resonance frequency of a previous geometry validated with a semi-analytical simplified model and (ii) a probabilistic optimality criteria of the design based on inverse problem from the estimation of robust probability of detection (RPOD) to maximize the detection of the pathology defined in terms of changes of shear stiffness. This study collects different options of design in two separated models, in transmission and contact, respectively. The main contribution of this work describes a framework to establish such as forward, inverse and optimization procedures to choose a set of appropriate parameters of a transducer. This methodological framework may be generalizable for other different applications.


Subject(s)
Ultrasonography , Finite Element Analysis , Transducers , Vibration
20.
Sci Rep ; 7(1): 407, 2017 03 24.
Article in English | MEDLINE | ID: mdl-28341826

ABSTRACT

Decellularized vascular scaffolds are promising materials for vessel replacements. However, despite the natural origin of decellularized vessels, issues such as biomechanical incompatibility, immunogenicity risks and the hazards of thrombus formation, still need to be addressed. In this study, we coated decellularized vessels obtained from porcine carotid arteries with poly (ethylmethacrylate-co-diethylaminoethylacrylate) (8g7) with the purpose of improving endothelial coverage and minimizing platelet attachment while enhancing the mechanical properties of the decellularized vascular scaffolds. The polymer facilitated binding of endothelial cells (ECs) with high affinity and also induced endothelial cell capillary tube formation. In addition, platelets showed reduced adhesion on the polymer under flow conditions. Moreover, the coating of the decellularized arteries improved biomechanical properties by increasing its tensile strength and load. In addition, after 5 days in culture, ECs seeded on the luminal surface of 8g7-coated decellularized arteries showed good regeneration of the endothelium. Overall, this study shows that polymer coating of decellularized vessels provides a new strategy to improve re-endothelialization of vascular grafts, maintaining or enhancing mechanical properties while reducing the risk of thrombogenesis. These results could have potential applications in improving tissue-engineered vascular grafts for cardiovascular therapies with small caliber vessels.


Subject(s)
Carotid Arteries/physiology , Carotid Artery Thrombosis/prevention & control , Endothelial Cells/physiology , Methylmethacrylates/chemistry , Tissue Engineering/methods , Tissue Scaffolds/chemistry , Animals , Biocompatible Materials/chemistry , Biopolymers , Blood Platelets/physiology , Blood Vessel Prosthesis , Carotid Arteries/ultrastructure , Endothelium, Vascular/physiology , Human Umbilical Vein Endothelial Cells/physiology , Humans , Swine
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