Curvature in Biological Systems: Its Quantification, Emergence, and Implications across the Scales.

Surface curvature both emerges from, and influences the behavior of, living objects at length scales ranging from cell membranes to single cells to tissues and organs. The relevance of surface curvature in biology is supported by numerous experimental and theoretical investigations in recent years. In this review, first, a brief introduction to the key ideas of surface curvature in the context of biological systems is given and the challenges that arise when measuring surface curvature are discussed.

Wall Shear Stress Analysis and Optimization in Tissue Engineering TPMS Scaffolds.

When designing scaffolds for bone tissue engineering (BTE), the wall shear stress (WSS), due to the fluid flow inside the scaffold, is an important factor to consider as it influences the cellular process involved in new tissue formation. The present work analyzed the average WSS in Schwartz diamond (SD) and gyroid (SG) scaffolds with different surface topologies and mesh elements using computational fluid dynamics (CFD) analysis. It was found that scaffold meshes with a smooth surface topology with tetrahedral elements had WSS levels 35% higher than the equivalent scaffold with a non-smooth surface topology with hexahedral elements.

3D Modeling of the Crystalline Lens Complex under Pseudoexfoliation.

Pseudoexfoliation, one of the most frequent crystalline lens complex disorders, is prevalent in up to 30% of individuals older than 60 years old. This disease can lead to severe conditions, such as subluxation or dislocation of the lens, due to the weakening of the zonules. The goal for the present study was to understand the relevant biomechanical features that can lead to the worsening of an individual's visual capacity under pseudoexfoliation.

Challenges in computational fluid dynamics applications for bone tissue engineering.

Bone injuries or defects that require invasive surgical treatment are a serious clinical issue, particularly when it comes to treatment success and effectiveness. Accordingly, bone tissue engineering (BTE) has been researching the use of computational fluid dynamics (CFD) analysis tools to assist in designing optimal scaffolds that better promote bone growth and repair. This paper aims to offer a comprehensive review of recent studies that use CFD analysis in BTE.

Effects of neonatal dopaminergic lesion on oral cocaine self-administration in rats: Higher female vulnerability to cocaine consumption.

The dopaminergic system is associated with cocaine-seeking behaviors, being influenced by other neurotransmitters such as GABA and deregulated by chronic cocaine self-administration. Administration of 6-hydroxydopamine (6-OHDA) to neonatal rats produces a depletion of brain dopamine, mainly, that results in behavioral alterations in adulthood. This model can be applied to better understanding of the role of the dopaminergic system in cocaine use and how its behavioral effects can modulate drug intake.

Modeling the musculoskeletal loading in bone remodeling at the hip of a child.

Background And Objectives: The mechanical load associated with physical activity affects the bone adaptation process. The bone adaptationeffect varies with age, being more effective during childhood and adolescence, particularly during pre-pubertal years. Bone-strengthening physical activity is recommended for children and adolescents.

New methodology to assess in-vivo quality of motion in cervical spine.

Background: Understanding the kinematics of the spine in the interaction with an implanted device is of utmost importance from a clinical point of view. The characterization of the biomechanical movement of the spine occurring at each functional unit is a difficult task as it involves the measurement of complex patterns of motion while identifying more delicate abnormalities that could result in longer-term disease complications. Center of rotation is a biomechanical parameter that represents the ratio between rotation and translation.

Numerical-experimental analysis of the permeability-porosity relationship in triply periodic minimal surfaces scaffolds.

Bone Tissue Engineering has been focusing on improving the current methods for bone repair, being the use of scaffolds presented as an upgrade to traditional surgery techniques. Scaffolds are artificially porous matrices, meant to promote cell seeding and proliferation, being these properties influenced by the permeability of the structure. This work employed experimental pressure drop tests and Computational Fluid Dynamics models to assess permeability (and fluid streamlines) within different triply periodic minimal surfaces scaffold geometries (Schwarz D, Gyroid and Schwarz P).

On the permeability of TPMS scaffolds.

This study presents an experimental evaluation of permeability of triply periodic minimal surfaces (TPMS). Permeability is widely used to characterize scaffolds for Tissue Engineering (TE) applications as it gives information about the structure porosity, pore size, tortuosity and pore interconnectivity which have an important impact in cell seeding and proliferation. Three different TPMS structures were used: Schwartz Diamond (SD), Gyroid (SG) and Schwartz Primitive (SP), in four different porosity levels (50, 60, 70 and 80%).

The effects of caffeine on alcohol oral self-administration behavior in rats.

Caffeine and alcohol are some of the most commonly used psychoactive substances in the world, and are often used concomitantly. However, little is known about the effect of caffeine on alcohol consumption. Here, our aim was to investigate the co-exposure of alcohol mixed with caffeine in self-administration.

Chondrogenic differentiation of mesenchymal stem/stromal cells on 3D porous poly (ε-caprolactone) scaffolds: Effects of material alkaline treatment and chondroitin sulfate supplementation.

Cartilage defects resultant from trauma or degenerative diseases (e.g., osteoarthritis) can potentially be repaired using tissue engineering (TE) strategies combining progenitor cells, biomaterial scaffolds and bio-physical/chemical cues.

Impact of contact lens materials on the mfERG response of the human retina.

Purpose: To investigate the effect of different hydrophilic and rigid gas-permeable contact lens (CL) materials on multifocal electroretinography (mfERG).

Methods: The mfERG was recorded in 18 healthy subjects with RETI-port/scan21™: 11 subjects underwent mfERG recording wearing two different hydrophilic CLs with different water contents in a randomized order (1 silicone hydrogel-Comfilcon A, 48%EWC, and 1 hydrogel-Omafilcon A, 62% EWC) and 7 other subjects wore a hydrophobic rigid gas-permeable scleral lens (SL)-Hexafocon A. Control measures were recorded without CL in both groups.

Automated femoral landmark extraction for optimal prosthesis placement in total hip arthroplasty.

The automated extraction of anatomical reference landmarks in the femoral volume may improve speed, precision, and accuracy of surgical procedures, such as total hip arthroplasty. These landmarks are often hard to achieve, even via surgical incision. In addition, it provides a presurgical guidance for prosthesis sizing and placement.

Fully automatic segmentation of femurs with medullary canal definition in high and in low resolution CT scans.

Femur segmentation can be an important tool in orthopedic surgical planning. However, in order to overcome the need of an experienced user with extensive knowledge on the techniques, segmentation should be fully automatic. In this paper a new fully automatic femur segmentation method for CT images is presented.

Computational design and fabrication of a novel bioresorbable cage for tibial tuberosity advancement application.

Tibial tuberosity advancement (TTA) is a promising method for the treatment of cruciate ligament rupture in dogs that usually implies the implantation of a titanium cage as bone implant. This cage is non-biodegradable and fails in providing adequate implant-bone tissue integration. The objective of this work is to propose a new process chain for designing and manufacturing an alternative biodegradable cage that can fulfill specific patient requirements.

In silico Mechano-Chemical Model of Bone Healing for the Regeneration of Critical Defects: The Effect of BMP-2.

The healing of bone defects is a challenge for both tissue engineering and modern orthopaedics. This problem has been addressed through the study of scaffold constructs combined with mechanoregulatory theories, disregarding the influence of chemical factors and their respective delivery devices. Of the chemical factors involved in the bone healing process, bone morphogenetic protein-2 (BMP-2) has been identified as one of the most powerful osteoinductive proteins.

Bioresorbable scaffolds for bone tissue engineering: optimal design, fabrication, mechanical testing and scale-size effects analysis.

Bone scaffolds for tissue regeneration require an optimal trade-off between biological and mechanical criteria. Optimal designs may be obtained using topology optimization (homogenization approach) and prototypes produced using additive manufacturing techniques. However, the process from design to manufacture remains a research challenge and will be a requirement of FDA design controls to engineering scaffolds.

Peripheral refraction with eye and head rotation with contact lenses.

Purpose: To evaluate the impact of eye and head rotation in the measurement of peripheral refraction with an open-field autorefractometer in myopic eyes wearing two different center-distance designs of multifocal contact lenses (MFCLs).

Methods: Nineteen right eyes from 19 myopic patients (average central M ± SD = -2.67 ± 1.

Is the callus shape an optimal response to a mechanobiological stimulus?

After bone trauma, the natural response to restore bone function is the formation of a callus around the fracture. Although several bone healing models have been developed, none have effectively perceived early callus formation and shape as the result of an optimal response to a mechanobiological stimulus. In this paper, we investigate which stimulus regulates early callus formation.

Oscillatory fluid flow influences primary cilia and microtubule mechanics.

Many tissues are sensitive to mechanical stimuli; however, the mechanotransduction mechanism used by cells remains unknown in many cases. The primary cilium is a solitary, immotile microtubule-based extension present on nearly every mammalian cell which extends from the basal body. The cilium is a mechanosensitive organelle and has been shown to transduce fluid flow-induced shear stress in tissues, such as the kidney and bone.

Optimization of scaffold design for bone tissue engineering: A computational and experimental study.

In bone tissue engineering, the scaffold has not only to allow the diffusion of cells, nutrients and oxygen but also provide adequate mechanical support. One way to ensure the scaffold has the right properties is to use computational tools to design such a scaffold coupled with additive manufacturing to build the scaffolds to the resulting optimized design specifications. In this study a topology optimization algorithm is proposed as a technique to design scaffolds that meet specific requirements for mass transport and mechanical load bearing.

Biomechanical analysis of the tibial tray design in TKA: comparison between modular and offset tibial trays.

Purpose: The aim of this work was to develop a computational biomechanical study to compare the performance of tibial trays with different offsets for a total knee arthroplasty. The goal was to investigate whether the offset tibial tray shifts the bone stress distribution, influencing the clinical outcome.

Methods: Three geometric models were developed for the intact tibia bone: one considering a standard tibia case and the other two reproducing tibias with a medial or a lateral offset of the metaphysis.

Adaptation to multifocal and monovision contact lens correction.

Purpose: To compare visual performance with the Biofinity multifocal (MF) contact lens with monovision (MV) with the Biofinity single-vision contact lens.

Methods: A crossover study of 20 presbyopic patients was conducted. Patients were randomized first into either an MF or an MV lens for 15 days for each modality, with a washout period between each lens type.

Subject-specific bone remodelling of the scapula.

Finite element analyses, with increasing levels of detail and complexity, are becoming effective tools to evaluate the performance of joint replacement prostheses and to predict the behaviour of bone. As a first step towards the study of the complications of shoulder arthroplasty, the aim of this work was the development and validation of a 3D finite element model of an intact scapula for the prediction of the bone remodelling process based on a previously published model that attempts to follow Wolff's law. The boundary conditions applied include full muscle and joint loads taken from a multibody system of the upper limb based on the same subject whose scapula was here analysed.

A finite element model to simulate femoral fractures in calves: testing different polymers for intramedullary interlocking nails.

Objective: To verify if the finite element method can correctly estimate the performance of polyacetal and polyamide 6 intramedullary nails in stabilizing a femoral fracture in calves and to estimate the performance of a polypropylene nail in same conditions.

Study Design: Computational and experimental study.

Sample Population: Finite element models (FEMs).