Mechanobiology of conjunctival epithelial cells exposed to wall shear stresses.

The human conjunctival epithelial cells (HCEC) line the inner sides of the eyelids and the anterior part of the sclera. They include goblet cells that secret mucus into the tear film that protects the ocular surface. The conjunctival epithelium is subjected to mechano-physical stimuli due to eyelid movement during blinking, during wiping and rubbing the eyes, and when exposed to wind and air currents.

The effect of clinically recommended Evolut sizes on anchorage forces after BASILICA.

Coronary artery obstruction (CAO), a fatal complication of transcatheter aortic valve replacement (TAVR), is commonly found after Valve-in-Valve implantation inside a degenerated bioprosthetic valve. Leaflet laceration (BASILICA technique) has been proposed to prevent CAO and to potentially reduce the risk of leaflet thrombosis. We have previously demonstrated that this technique can reduce the anchorage forces of the TAVR device, which may lead to future complications.

Tissue-engineered arterial intima model exposed to steady wall shear stresses.

The arterial intima is continuously under pulsatile wall shear stresses (WSS) imposed by the circulating blood. The knowledge of the contribution of smooth muscle cells (SMC) to the response of endothelial cell (EC) to WSS is still incomplete. We developed a co-culture model of EC on top of SMC that mimics the inner in vivo structure of the arterial intima of large arteries.

Novel Design of Peripheral Infusion Catheter Improves the Kinetics of Intravenous Drug Release.

Short peripheral catheters are ubiquitous in today's healthcare environment, enabling effective and direct delivery of fluids and medications intravenously. A commonly associated complication of their use is thrombophlebitis-thrombus formation-involved inflammation of the vein wall. A novel design of a very short peripheral catheter showed promising results in a pig model in reducing the mechanical irritation to the vein wall.

Tissue engineered endometrial barrier exposed to peristaltic flow shear stresses.

Cyclic myometrial contractions of the non-pregnant uterus induce intra-uterine peristaltic flows, which have important roles in transport of sperm and embryos during early stages of reproduction. Hyperperistalsis in young females may lead to migration of endometrial cells and development of adenomyosis or endometriosis. We conducted an study of the biological response of a tissue engineered endometrial barrier exposed to peristaltic wall shear stresses (PWSSs).

Numerical models of valve-in-valve implantation: effect of intentional leaflet laceration on the anchorage.

Transcatheter aortic valve implantation (TAVI) is currently recommended in practice guidelines for patients who are at intermediate to high surgical risk for surgical aortic valve replacement. Coronary artery obstruction is a fatal complication of TAVI that occurs in up to 3.5% of the implantations inside a failed surgical bioprosthetic valve (valve-in-valve, ViV).

In vitro exposure of nasal epithelial cells to atmospheric dust.

Dust storms are common phenomena in many parts of the world, and significantly increase the level of atmospheric particulate matter (PM). The soil-derived dust is a mixture of organic and inorganic particles and even remnants of pesticides from agricultural areas nearby. The risk of human exposure to atmospheric dust is well documented, but very little is known on the impact of inhaled PM on the biological lining of the nasal cavity, which is the natural filter between the external environment and the respiratory tract.

Pressure drop and arterial compliance - Two arterial parameters in one measurement.

Coronary artery pressure-drop and distensibility (compliance) are two major, seemingly unrelated, parameters in the cardiovascular clinical setting, which are indicative of coronary arteries patency and atherosclerosis severity. While pressure drop is related to flow, and therefore serves as a functional indicator of a stenosis severity, the arterial distensibility is indicative of the arterial stiffness, and hence the arterial wall composition. In the present study, we hypothesized that local pressure drops are dependent on the arterial distensibility, and hence can provide information on both indices.

Ex Vivo Human Placental Perfusion Model for Analysis of Fetal Circulation in the Chorionic Plate.

Objectives: The purpose of this study was to develop an ex vivo placental perfusion model to assess changes in the umbilical artery systolic-to-diastolic (S/D) ratio due to progressive occlusion of the placental arterial system.

Methods: Ex vivo human placentas were connected to a computerized pulse duplicator mimicking pulsatile flow from the fetal heart. Doppler sonographic measurements were conducted on the umbilical and chorionic arteries of 25 mature placentas.

Evaluation of nasal airway patency by analysis of breathing sounds.

Conclusions: A simple non-invasive method, based on acoustic analysis of breathing signals, revealed a potential for objective evaluation of differences between the patency of nasal passageways.

Objectives: To examine whether acoustic signals of nasal breathing contain information that can differentiate between obstructed and patent nasal passageways.

Method: A technical study aimed to examine measurements of nasal airflow acoustic signals, taken, non-invasively, simultaneously from both external sides of the nostrils.

High accuracy differential pressure measurements using fluid-filled catheters - A feasibility study in compliant tubes.

High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes.

General tube law for collapsible thin and thick-wall tubes.

Modeling the complex deformations of cylindrical tubes under external pressure is of interest in engineering and physiological applications. The highly non-linear post-buckling behavior of cross-section of the tube during collapse attracted researchers for years. Major efforts were concentrated on studying the behavior of thin-wall tubes.

Method for high accuracy differential pressure measurements using fluid-filled catheters.

The advantage of measuring differential pressure using fluid-filled catheters is that the system is relatively inexpensive, but the readings are not accurate and affected by the common mode pressure (CMP) distortion. High accuracy differential pressure measurements are required in various biomedical applications, such as in fluid-dynamic test rigs, or in the cath-lab, from cardiac valves efficacy to functional assessment of arterial stenoses. We have designed and built a unique system in which the pressure difference was measured along the fluid flow inside a rigid circular tube using a fluid-filled double-lumen catheter.

Wall shear stress effects on endothelial-endothelial and endothelial-smooth muscle cell interactions in tissue engineered models of the vascular wall.

Vascular functions are affected by wall shear stresses (WSS) applied on the endothelial cells (EC), as well as by the interactions of the EC with the adjacent smooth muscle cells (SMC). The present study was designed to investigate the effects of WSS on the endothelial interactions with its surroundings. For this purpose we developed and constructed two co-culture models of EC and SMC, and compared their response to that of a single monolayer of cultured EC.

Analysis of facial and inspiratory muscles performance during breastfeeding.

Background: Breastfeeding is a dynamic process in which the infant recruits several muscle groups in his face, head and throat.

Objective: The objective of this study was to explore the relative role of the submental muscle group, the orbicularis oris and the sternocleidomastoid muscles to breastfeeding process and to the relatively high intra-oral vacuum measured during this process.

Methods: Electromyography (EMG) measurements were conducted on 11 infants (mean age 1.

Fluid-flow induced wall shear stress and epithelial ovarian cancer peritoneal spreading.

Epithelial ovarian cancer (EOC) is usually discovered after extensive metastasis have developed in the peritoneal cavity. The ovarian surface is exposed to peritoneal fluid pressures and shear forces due to the continuous peristaltic motions of the gastro-intestinal system, creating a mechanical micro-environment for the cells. An in vitro experimental model was developed to expose EOC cells to steady fluid flow induced wall shear stresses (WSS).

Evaluation of fatigue of respiratory and lower limb muscles during prolonged aerobic exercise.

The respiratory muscles may fatigue during prolonged exercises and thereby become a factor that limits extreme physical activity. The aim of the current study was to determine whether respiratory muscle fatigue imposes a limitation on extreme physical activity of well-trained young men. Electromyography (EMG) signals of respiratory (external intercostal and sternomastoid) and calf muscles (gastrocnemius) were measured (N = 8) during 1 hr of treadmill marching at a speed of 8 km/hr with and without a 15 kg backpack.

Large, but not small sustained tensile strains stimulate adipogenesis in culture.

Understanding the mechanoresponsiveness of adipocytes and the characteristics of the mechanical stimuli that regulate adipogenesis is critically important in establishing knowledge in regard to the long-term effects of a sedentary lifestyle (or immobility in extreme medical conditions) as well as concerning obesity and related diseases. In this study we subjected 3T3-L1 preadipocytes cultured on elastic substrata to different levels of static equiaxial tensile strains within the physiological range, up to substrate tensile strain (STS) of 12%, while inducing differentiation in the cultures. Based on prior work which revealed that adipogenesis is accelerated in cultures subjected to STS of 12% by activating the mitogen-activated protein kinase kinase signaling pathway, we were specifically interested in identifying the STS levels which trigger this process.

Static mechanical stretching accelerates lipid production in 3T3-L1 adipocytes by activating the MEK signaling pathway.

Understanding mechanotransduction in adipocytes is important for research of obesity and related diseases. We cultured 3T3-L1 preadipocytes on elastic substrata and applied static tensile strains of 12% to the substrata while inducing differentiation. Using an image processing method, we monitored lipid production for a period of 3-4 wk.

Climate chamber for environmentally controlled laboratory airflow experiments.

Climate chambers have been widely used in in vitro and in vivo studies which require controlled environmental temperature and humidity conditions. This article describes a new desktop climate chamber that was developed for application of respiratory airflows on cultured nasal epithelial cells (NEC) under controlled temperature and humidity conditions. Flow experiments were performed by connecting the climate chamber to an airflow generator via a flow chamber with cultured NEC.

Custom-designed wells and flow chamber for exposing air-liquid interface cultures to wall shear stress.

The effects of mechanical stimuli such as wall shear stresses (WSS) on cellular processes have been studied in vitro in numerous cell types. In order to study WSS effects on cells cultured under air-liquid interface (ALI) conditions, we developed a custom-designed well that can be disassembled into sub-units that allow installation of the cultured cells in a flow chamber, and then, re-assembled for further incubation or biological tests. Human nasal epithelial cells were cultured in the new wells under ALI conditions, and some of their biological characteristics were compared with those cultured in commercial Millicells.

In vitro simulations of embryo transfer in a laboratory model of the uterus.

Embryo transfer (ET) is the final manual intervention during which the newly formed embryo is placed within the uterus by a transcervical catheter. The loading of the syringe-catheter complex with the transferred volume consists of the transfer media (which contains the embryos) separated by air spaces on both sides. The dynamics involved in injecting the syringe-catheter complex is not well understood nor has it been investigated to date.

Cellular alterations in cultured endothelial cells exposed to therapeutic ultrasound irradiation.

Restoration of blood supply to tissue with impaired perfusion depends on spontaneous or mediated angiogenesis, which among other mechanisms includes stimulation, migration, and proliferation of endothelial cells (ECs). Therapeutic ultrasound (US) irradiation is known as an inducer of cellular modifications and is used to accelerate wound healing. An in vitro setup was developed in order to allow for a comprehensive investigation of cellular alterations induced in cultured ECs after exposure to different modes of therapeutic US irradiation.

Endonasal geometry changes in elderly people: acoustic rhinometry measurements.

Background: Skeletal nasal changes in elderly people have been extensively investigated, but data on variation of the endonasal architecture with age do not exist. We evaluated endonasal parameters in an elderly population as compared with those in a young group.

Methods: Acoustic rhinometry measurements were performed on 165 participants in the age range of 20-93 years.

A glance into the uterus during in vitro simulation of embryo transfer.

Background: The currently low implantation rate after embryo transfer (ET) is partially attributed to technical aspects, such as catheter type, catheter load, placement of catheter tip and physician skills.

Methods: Mock ET simulations were conducted with a transparent laboratory model of the uterine cavity. The catheter was loaded with alternating air and coloured liquid media.