Computational Tools for the Investigation of the Male Lower Urinary Tract Functionality in Health and Disease

Purpose This paper aims to show the potentialities of computational bioengineering in the field of lower urinary tract pathophysiology. Engineering methods allow the investigation of urine flow in healthy and pathologic conditions and the analysis of urethral occlusion by means of artificial urinary sphincters. Methods Computational models of bladder and urethra were developed and exploited to investigate the lower urinary tract physiology in health and in disease. Average male morphometric configurations were assumed, together with typical properties of both biological tissues and fluids. The reliability of the models was assessed by the mutual comparison of results and the investigation of data from experimental and clinical activities. Results The developed models allowed to analyze typical situations, such as the micturition in health and in disease, and the lumen occlusion by external devices. The models provided information that clinical and experimental tests barely provide, as the occurrence of turbulent phenomena within urine flow, the shear stresses at the lumen wall, the external pressure that is strictly required to occlude the lumen. Conclusions The methods of bioengineering allow broadening and deepening the knowledge of the lower urinary tract functionality. More in detail, modeling techniques provide information that contributes to explain the occurrence of pathological situations, and allows to design and to optimize clinical-surgical procedures and devices

Computational Biomechanics: In-Silico Tools for the Investigation of Surgical Procedures and Devices

Biomechanical investigations of surgical procedures and devices are usually developed by means of human or animal models. The exploitation of computational methods and tools can reduce, refine, and replace (3R) the animal experimentations for scientific purposes and for pre-clinical research. The computational model of a biological structure characterizes both its geometrical conformation and the mechanical behavior of its building tissues. Model development requires coupled experimental and computational activities. Medical images and anthropometric information provide the geometrical definition of the computational model. Histological investigations and mechanical tests on tissue samples allow for characterizing biological tissues\u2019 mechanical response by means of constitutive models. The assessment of computational model reliability requires comparing model results and data from further experimentations. Computational methods allow for the in-silico analysis of surgical procedures and devices\u2019 functionality considering many different influencing variables, the experimental investigation of which should be extremely expensive and time consuming. Furthermore, computational methods provide information that experimental methods barely supply, as the strain and the stress fields that regulate important mechano-biological phenomena. In this work, general notes about the development of biomechanical tools are proposed, together with specific applications to different fields, as dental implantology and bariatric surgery

Negative Affectivity Predicts Lower Quality of Life and Metabolic Control in Type 2 Diabetes Patients: A Structural Equation Modeling Approach

Introduction: It is essential to consider the clinical assessment of psychological aspects in patients with Diabetes Mellitus (DM), in order to prevent potentially adverse self-management care behaviors leading to diabetes-related complications, including declining levels of Quality of Life (QoL) and negative metabolic control.Purpose: In the framework of Structural Equation Modeling (SEM), the specific aim of this study is to evaluate the influence of distressed personality factors as Negative Affectivity (NA) and Social Inhibition (SI) on diabetes-related clinical variables (i.e., QoL and glycemic control).Methods: The total sample consists of a clinical sample, including 159 outpatients with Type 2 Diabetes Mellitus (T2DM), and a control group composed of 102 healthy respondents. All participants completed the following self- rating scales: The Type D Scale (DS14) and the World Health Organization QoL Scale (WHOQOLBREF). Furthermore, the participants of the clinical group were assessed for HbA1c, disease duration, and BMI. The observed covariates were BMI, gender, and disease duration, while HbA1c was considered an observed variable.Results: SEM analysis revealed significant differences between groups in regards to the latent construct of NA and the Environmental dimension of QoL. For the clinical sample, SEM showed that NA had a negative impact on both QoL dimensions and metabolic control.Conclusions: Clinical interventions aiming to improve medication adherence in patients with T2DM should include the psychological evaluation of Type D Personality traits, by focusing especially on its component of NA as a significant risk factor leading to negative health outcomes

An anatomo-radiological study of the infrapatellar fat pad

The infrapatellar fat pad (IFP) is an intracapsular, but extrasynovial structure, located between the patellar tendon, femoral condyles and tibial plateau. We have recently described the microscopic orgnisation of the IFP, which consists of white adipose tissue (fibroadipose, lobular type), organised in lobuli delimited by thin connective septa. The aim of the study is to describe the sonoanatomical features of IFP in subjects without knee pathology during flexo-extension movements. Twentyfour volunteers subjects with no history of knee diseases (5M, 19F, mean age: 45yo)were analysed. Examinations was performed using high-resolution grey-scale ultrasound. The mean area of the deepest recognisable adipose chamber in extension were 0,12 and in flexion 0,19 mm2, and the circumference were in extension 1,36 and in flexion 1,19 mm. The area of the closest adipose chamber to the patellar tendon were in extension 0,29 and flexion 0,12 mm2(

Biomechanical analysis of heel pad tissues

The biomechanical behaviour of the heel pad tissues, including the calcaneal fat pad and skin, is investigated by means of a combined experimental and computational approach, for the definition of numerical models of the biological structures. The constitutive models are formulated starting from the analysis of the complex micro-structural configuration of the tissues and evaluating the relationship between tissue histology and mechanical properties. A visco-hyperelastic model is formulated with regard to the calcaneal fat pad. The model takes into account the typical features of the mechanical response, such as large displacement and strain, non-linear elasticity and time-dependent effects. A fiber reinforced hyperelastic model is provided to interpret the skin mechanical response, such as anisotropic configuration, geometric non-linearity, and non-linear elasticity. In order to define the numerical models, experimental data from mechanical tests are analyzed to achieve information about the tissue mechanical response and to evaluate the constitutive parameters. The definition of constitutive parameters is performed using a specific procedure based on the comparison of experimental data and model results through a cost function. The minimisation of the cost function is performed by a stochastic-deterministic optimization algorithm, leading to the definition of the optimal set of parameters. The first step is performed by considering data from in vitro and in vivo experimental tests, in order to evaluate a preliminary set of constitutive parameters that describe the stress-strain relationship under uni-axial tests. The second step involves the analysis of an in situ test on the heel pad, with and without skin. The comparison of data from in situ tests and numerical results leads to an optimal domain of parameters which can interpret the mechanical response of real heel pad tissues. The procedure is validated by considering experimental data from additional in situ and in vivo experimental tests. The numerical models developed represent the basis for the interpretation of the physiological behaviour of the heel pad, considering the effects induced by specific loadings, and for the evaluation of the interaction phenomena between the foot and footwearLo studio del comportamento biomeccanico dei tessuti molli del retro piede, intensi come tessuto adiposo plantare e pelle, ha richiesto un approccio fortemente integrato di tipo computazionale e sperimentale. La valutazione del comportamento meccanico di tale regione è ottenuta in considerazione dell’analisi della configurazione micro strutturale dei tessuti e valutando la correlazione tra configurazione istologica e comportamento meccanico. Al fine di analizzare aspetti tipici della risposta meccanica del tessuto adiposo calcaneare, come la non linearità per geometria e materiale, e la dipendenza dal tempo è stato utilizzato un modello costitutivo di tipo visco-iperelastico. Gli aspetti tipici della risposta meccanica della pelle, ovvero la non linearità per geometria e per materiale, e la configurazione anisotropa sono stati descritti mediante la formulazione di un modello costitutivo di tipo iperelastico fibro-rinforzato. La valutazione dei parametri costitutivi ha richiesto lo sviluppo di modelli analitici e numerici capaci di interpretare le prove sperimentali considerate. I risultati di modello ed i risultati sperimentali sono stati confrontati attraverso una funzione costo, la cui minimizzazione ha portato alla definizione dei parametri oggetto dello studio. La procedura è stata conseguita in step successivi. Una prima valutazione dei parametri costitutivi è stata ottenuta considerando prove monoassiali, sviluppate su campioni dei tessuti in esame. Successivamente sono state considerate delle prove sperimentali su piede cadaverico in assenza ed in presenza della pelle. Questa analisi ha portato alla definizione di un dominio di parametri costitutivi tutti in grado di interpretare in maniera adeguata la risposta meccanica dei tessuti in esame. La procedura adottata è stata infine validata considerando ulteriori prove sperimentali in situ ed in vivo. I modelli numerici sviluppati permettono di valutare la risposta meccanica dei tessuti in condizioni fisiologiche, come ad esempio durante la camminata, nonché di valutare i fenomeni di interazione tra piede ed elementi biomedicali, come solette e calzatur

Biomechanics of Hollow Organs: Experimental Testing and Computational Modeling

Hollow organs are visceral organs that are hollow tubes or pouches (such as the intestine or the stomach, respectively) or that include a cavity (such as the heart) and which subserve a vital function [...

Biomechanics of Hollow Organs: Experimental Testing and Computational Modeling

Hollow organs are visceral organs that are hollow tubes or pouches (such as the intestine or the stomach, respectively) or that include a cavity (such as the heart) and which subserve a vital function [...

Evaluation of the mechanical behaviour of Telemark ski boots: Part I - materials characterization in use conditions

This study reports the first part of the analysis for the evaluation of the mechanical behaviour of ski boots by means of an integrated approach that considers polymeric materials characterization, in Part I, and numerical structural analysis, in Part II. In the present Part I, different techniques are adopted to characterize the mechanical behaviour of the polymeric materials used for ski boots, to define the elastic, visco-elastic, temperature and weathering-dependent characteristics. Experimental data provide fundamental information on mechanical response, in particular taking into account the effect of the environmental conditions, due to temperature variation, ultraviolet radiation and water absorption, which are correlated to the definition of reliability and durability of the materials. In more detail, experimental results from tensile tests and dynamic mechanical analysis are reported, evaluating mechanical response and chemical conformation of the polymers. Materials properties are correlated with the specific use conditions and boot structure, to be able to evaluate and preserve overall performances and general safety requirements of ski boots. This activity represents a reference procedure for the evaluation of the material mechanical behaviour that must be considered within the structural analysis