Cold atmospheric pressure plasma is currently being investigated for a wide range of clinical applications, including skin sterilization, blood coagulation [1, 2], malignant cell apoptosis [1], and wound healing [1]. However, the effect of non-thermal plasma on the vasculature is unclear. Blood vessels are affected during plasma treatment of all tissues, and vessels themselves may be an important potential target for clinical plasma therapy.

Benign prostatic hyperplasia (BPH) is one of the most common disorders and the most common cause of lower urinary tract symptoms (LUTS) in elderly men [1]. Transurethral resection of the prostate (TURP) is considered the gold standard treatment; however, laser prostatectomy has several advantages with regard to reduced catheterization and morbidity particularly in high-risk patients [2]. Of the many lasers that can be used in the laser prostatectomy, the GreenLight potassium-titanyl-phosphate (KTP) laser is one of the most commonly used [3]. The optimum outcome of this laser procedure is ablation with minimal or no coagulation. Our objective was to experimentally and theoretically characterize the KTP laser-tissue interactions in order to understand the laser and tissue parameters that lead to an optimal outcome.

Apical contraction is the major tissue movement during remodeling of epithelial sheets in development. During apical contraction, groups of cells narrow their apices to form bottle-shaped structures, driving events such as sea-urchin gastrulation [1], Drosophila ventral-furrow formation, vertebrate neurulation and wound healing [2]. Tissue-folding events such as invagination, ingression and involution involve this tissue movement in which cells actively build “rifts” and “tubes”. Epithelial cells integrate genetic information, mechanical signals, and biochemical gradients to build these structures, but how they do so is unknown [3]. Theoretical models [4] provide some mechanical explanation for these events. Here we experimentally induce apical contractions controllably for the first time in amphibian embryos. Two independent methods, namely, laser ablation of cell membranes and nano-perfusion with cell lysate induce cell contraction in tissue isolates and in whole embryos. We demonstrate a biochemical pathway that stimulates rapid actin-reorganization/ polymerization accompanied by increases in α-actinin. The F-actin remodeling correlates with increased levels of Ca ++ . Cell contraction begins within few seconds of laser ablation or nano-perfusion, peaks within a minute and is followed by a similar relaxation. Acute control of epithelial mechanics will allow us to better understand how molecular genetic processes drive shape change in tissues and will help future bioengineers build complex 3D epithelial organs.

Aseptic loosening in the acetabular component is the most prevalent cause of failure in cemented total hip arthroplasty (THA) [1]. There is clinical evidence of high polyethylene cup wear accompanying acetabular aseptic loosening [2]. One such study discriminated between cups experiencing low and high wear, showing the revision rate in the high-wear group was approximately eight times that of the low-wear group after seventeen years in vivo , and could not be linked to osteolysis [2]. In the present study a finite element (FE) model was used to simulate aseptic loosening in THA acetabular components with different rates of polyethylene cup penetration to measure the effect on cement fatigue life.

Computational models can be used to predict the blood pressure and blood flow in a region of interest within the vascular system. A computational model includes a region of interest geometry and boundary conditions. The outlet boundary conditions not only need to reflect the downstream network of vessels, but also the dynamic nature of the downstream network. An example of this is the pulmonary vasculature, which has arterioles that dilate and constrict during the respiratory process altering the resistance/impedance of the downstream network [1]. In order to accurately model a system with a dynamic change, such as the pulmonary system, a dynamic boundary condition should be utilized.

Recent interest in better understanding the biomechanical behavior of the patellofemoral joint is driven, in part, by the frequency with which patellofemoral osteoarthritis is reported to occur in the general population. Abnormal joint-contact stress is believed to be one of the possible causes of cartilage degeneration and anterior knee pain [1]. A number of literature studies suggest that stair ascent is one of the most demanding daily activities in relation to patellofemoral joint loading [2]. Accurate measurement of in vivo kinematics is essential for a thorough understanding of patellofemoral function during weight-bearing activity [3]. In this study, an innovative experimental setup involving two synchronized single-plane X-ray fluoroscopy units, 3D motion capture, portable force plates, computed muscle forces and MRI-derived bone geometries were integrated to evaluate patellofemoral joint function in four healthy subjects during stair walking. Our specific aim was to quantify medial and lateral patellofemoral joint loading, joint pressure distribution, and cartilage pressure maps on a subject-specific basis.

Electroporation is an elegant means to gain access to the cytoplasm, and to deliver molecules into the cell while simultaneously maintaining viability and functionality. In this technique, electric pulses are applied to transiently permeabilize the cell membrane. Biologically active agents, such as DNA, RNA, and amino acids, can then enter the cell to perform tasks such as gene and cancer therapy. Despite wide applications, electroporation faces significant challenges to achieve simultaneous high delivery efficiency and cell viability. Addressing such challenges requires the development of good fundamental understanding and a quantitative prediction capability, and the current work is a step toward this goal.

For patients with cerebral palsy who walk in a crouched posture, gait is often a strenuous activity. In order to improve gait, surgeons and therapists attempt to identify individual muscles that can be strengthened, surgically lengthened, or otherwise treated to improve patients’ abilities to support their body weight and propel themselves forward. However, little is known about the role of individual muscles during crouch gait, and current treatments often produce inconsistent results. The goal of this study was to identify which muscles are employed during crouch gait to support the body during single-limb stance. Understanding how the support strategy of crouch gait compares to unimpaired gait can provide insight into the underlying causes of crouch gait. Traditional movement analysis cannot fully characterize the role of individual muscles during gait. Therefore, we developed dynamic simulations to examine the contribution of lower-extremity muscles to support and progression.

Reduced skeletal loading causes cortical and trabecular bone loss in humans and other animals, but trabecular bone responds to disuse more rapidly and shows greater losses than cortical bone for a given period of inactivity [1–2]. Manifestations of disuse on trabecular bone include unbalanced bone remodeling, decreased bone mineral density, and compromised bone architecture [3].

According to the Arthritis Foundation, 66 million Americans (or nearly 1 in 3 adults) currently suffer from arthritis, with osteoarthritis (OA) being the most common form, and the knee being the joint most commonly affected. Despite the need for early treatment, few clinical interventions slow the progression of knee OA. Since articular cartilage is responsive to the amount of joint loading, reducing compressive loads in the diseased compartment may slow the rate of cartilage breakdown. Because medial compartment load cannot be measured non-invasively in vivo , an external measure to quantify the desired load reduction has been sought. The best candidate found thus far is the external knee adduction moment during gait [1]. This moment exhibits two peaks during the gait cycle, one during early stance phase and the other during late stance. A high peak knee adduction moment has been correlated with increased disease severity [2] and an increased rate of disease progression [3].

Silicone is a synthetic polymer consisting of a linear backbone of repeating, alternating silicone and oxygen atoms. Each silicone atom has two groups attached to it, referred to as R groups, representing any organic group that may be attached to the backbone. These rubbers can therefore undergo large recoverable deformations, hence the wide use of silicone rubbers as material analogues in the study of arterial vessels [1,2] and other soft tissues. Abdominal aortic aneurysms (AAAs) are permanent irreversible dilations of the infrarenal section of the aorta that will eventually expand to the point of rupture if left untreated. Many previous studies have focussed on the numerical prediction of wall stresses and ultimately rupture prediction of AAAs [3,4]. However, there have been limited reports as to how these aneurysms behave experimentally [2,5]. Also, previous experimental work has employed the use of a single material to represent the AAA wall, even though it is known that a realistic AAA may have differing materials properties at various locations throughout the aneurysm [6].

New Car Assessment Program (NCAP) gives star ratings to the vehicles based on their crashworthiness. The program uses results of crash tests performed with 50% male HYBRID III dummies in the driver and right front passenger seats and gives separate star ratings for the driver and right front passenger positions. These star ratings are available from the safer car website [1], and are perceived as an indicator of general safety of the vehicles for people trying to purchase a vehicle. A one-star rating would show the lowest, and five-star would be the highest safety ranking. As the NCAP star ratings of the vehicles have improved over years, front occupant protection has improved as well; however, recent studies have shown that rear occupants are less protected in newer model years of vehicles [2]. Safety of rear occupants is not evaluated with the NCAP program. In this paper an attempt is made to verify whether the NCAP scores can show the level of protection provided to the rear occupants or not.

Low and/or oscillatory Wall Shear Stress (WSS) has been correlated with elevated risk for increased intima media thickness and atherosclerosis in several studies during the last decades [1, 2]. Most of the studies have addressed laminar flows, in which the oscillations mainly are due to the pulsating nature of blood flow. Turbulent flows however show significant spatial and temporal fluctuations although the mean flow is steady.

Secondary osteons, the fundamental units of cortical bone, consist of cylindrical lamellar composites composed of mineralized collagen fibrils. Due to its lamellar structure, a multiscale knowledge of the mechanical properties of cortical bone is required to understand the biomechanical function of the tissue. In this light, nanoindentation tests were performed along the axial and transverse directions following a radial path from the Haversian canal to the osteonal edges. Different length scales are explored by means of indentations at different maximum penetration depths. Indentation moduli and hardness data were then interpreted in the context of the known microstructure. Results suggest that secondary osteons hierarchical structure is responsible for an observed length scale effect, homogenization phenomena and anisotropy of mechanical properties.

To date patient-specific analysis (both CFD and FEA) is limited by the complex pre-processing procedure needed for generating a patient-specific mesh [1,2]. Following the classical approach, CT / MRI images undergo first reconstruction/segmentation, leading to STL surfaces, and finally a mesh is generated. This multi-step procedure suffers from operator-dependence, is time consuming, does not allow a parametric mesh generation and requires several dedicated softwares. A novel approach is proposed for 3D angiographic coronary data, which allows generating structured parametric patient-specific mesh using a single open-source software, limiting the operator-dependence and the pre-processing time.

The aortic valve has received much attention in the biomedical research community during recent years. As a critical part of the cardiovascular system, any alteration in its structure or in the surrounding area directly or because of pathologies would change the flow pattern of that region as a consequence. Numerous studies have been done and regardless of the approach, the aim of all these studies is the same: to understand the intricacies of the healthy aortic valve and, perhaps, to mimic it in the realm of prosthetics.

Activity monitoring is an important consideration for a number of conditions associated with health maintenance in an aging population. For example, reduced bone mineral density (BMD) in the aging population puts this group at a higher risk of fall related fractures [1]. Bone density and bone health is in part dependent upon mechanical stimuli caused by everyday physical activity and loading [2]. The number of steps taken per day and walking velocity [3] are important parameters to consider when studying bone density as well as other health related conditions. However, there is a need for effective and efficient methods/protocols to ensure that representative daily activity data can be collected.

The meniscus plays a crucial role in the dynamics of the knee. Damage to the meniscus can influence proprioception, stability, and mobility of the knee [1]. Risk factors of meniscal tears include prolonged or repeated deep knee bending, obesity, and sporting injuries [2]. Acute injury, as seen in alpine sports, involves complex dynamics which can damage singular or multiple tissue structures of the knee [2]. It is not uncommon for meniscal injuries to occur in conjunction with ACL lesions, and the loading imbalance that results in ACL lesions may also initiate meniscal tears [3, 4]. Investigations of meniscal tears following ACL rupture have indicated chronic damage to medial menisci more so than lateral menisci [5]. However, experimental studies of acute damage following ACL transection are not consistent, with some showing more lateral damage acutely and some showing equality between medial and lateral meniscal damage [5].

Atherosclerotic disease in the carotid artery is a high risk factor for stroke. Stroke is the third-leading cause of death, constituting approximately 700,000 cases each year in the United States [1]. The susceptibility of atherosclerotic plaque to rupture during the carotid angioplasty and stenting (CAS) procedure [2] makes it necessary to determine the force the plaque can withstand without the risk of embolisation.

The tricuspid valve (TV) is the right atrio-ventricular valve. The most common TV disease is secondary or functional tricuspid regurgitation (FTR), an important complication of left-sided valvular heart lesions, which frequently persists after mitral and aortic valve operations. FTR is associated with high mortality and morbidity and requires surgical intervention, the preferential solution being TV repair through techniques such as annuloplasty performed during left heart surgery. However, significant residual regurgitation persists or recurs in 10% to 20% after annuloplasty, thus highlighting the incomplete understanding of the underlying mechanisms and the need for deeper insight into TV pathophysiology. At this purpose finite element models (FEMs) could be adopted, as suggested by their effective application to the biomechanical analysis of left heart valves. However, while for those several data are available regarding morphology and tissue mechanical properties, such information is missing for the TV, making it difficult to implement a FEM of the TV.