The BIORES-21 Survey: Insights Into Remote and Online Education in Biomechanics and Mechanobiology.

The COVID-19 pandemic necessitated mainstream adoption of online and remote learning approaches, which were highly advantageous yet challenging in many ways. The online modality, while teaching biomedical engineering-related topics in the areas of biomechanics, mechanobiology, and biomedical sciences, further added to the complexity faced by the faculty and students. Both the benefits and the challenges have not been explored systematically by juxtaposing experiences and reflections of both the faculty and students.

A Systems Approach to Biomechanics, Mechanobiology, and Biotransport.

The human body represents a collection of interacting systems that range in scale from nanometers to meters. Investigations from a systems perspective focus on how the parts work together to enact changes across spatial scales, and further our understanding of how systems function and fail. Here, we highlight systems approaches presented at the 2022 Summer Biomechanics, Bio-engineering, and Biotransport Conference in the areas of solid mechanics; fluid mechanics; tissue and cellular engineering; biotransport; and design, dynamics, and rehabilitation; and biomechanics education.

Effects of Porosity on Piezoelectric Characteristics of Polyvinylidene Fluoride Films for Biomedical Applications.

: The objective of this work is to study the effects of porosity on mechanical and piezoelectric properties of polyvinylidene fluoride (PVDF) films for biomedical applications. By investigating the piezoelectric properties of PVDF and the porosity effect on its electromechanical performance, there is potential for further development of PVDF as a hemodynamic sensor that can lead to further technological advancements in the biomedical field, benefiting patients and physicians alike. : PVDF thin films have shown potential in the application of hemodynamic flow sensing and monitoring the effects on blood flow caused by prosthetic valve implantation via the transcatheter aortic valve replacement operation.

Elucidating the signal for contact guidance contained in aligned fibrils with a microstructural-mechanical model.

Despite its importance in physiological processes and tissue engineering, the mechanism underlying cell contact guidance in an aligned fibrillar network has defied elucidation due to multiple interdependent signals that such a network presents to cells, namely, anisotropy of adhesion, porosity and mechanical behaviour. A microstructural-mechanical model of fibril networks was used to assess the relative magnitudes of these competing signals in networks of varied alignment strength based on idealized cylindrical pseudopods projected into the aligned and orthogonal directions and computing the anisotropy of metrics chosen for adhesion, porosity and mechanical behaviour: cylinder-fibre contact area for adhesion, persistence length of pores for porosity and total force to displace fibres from the cylindrical volume as well as network stiffness experienced upon cylinder retraction for mechanical behaviour. The signals related to mechanical anisotropy are substantially higher than adhesion and porosity anisotropy, especially at stronger network alignments, although their signal to noise (S/N) values are substantially lower.

Computational and experimental comparison on the effects of flow-induced compression on the permeability of collagen gels.

Collagen is a naturally occurring polymer and is popular in tissue engineering due to its high biocompatibility, ubiquity throughout the body, and its porous nature. The transport properties of collagen help dictate the delivery of nutrients to tissues, and the mechanical properties can help improve the function of engineered tissues. The objective of this study is to investigate experimentally the change in permeability as collagen gels undergo flow-induced compression and compare these results with model predictions using a finite element model.

Responses of ticks to immersion in hot bathing water: Effect of surface type, water temperature, and soap on tick motor control.

Preventing bites from undetected ticks through bathing practices would benefit public health, but the effects of these practices have been researched minimally. We immersed nymphal and adult hard ticks of species common in the eastern United States in tap water, using temperatures and durations that are realistic for human hot bathing. The effect of (a) different skin-equivalent surfaces (silicone and pig skin), and (b) water temperature was tested on Amblyomma americanum, Dermacentor variabilis and Ixodes scapularis nymphs.

Pandemic-Driven Online Teaching-The Natural Setting for a Flipped Classroom?

As the COVID-19 pandemic forced a sudden shift to online teaching and learning in April 2020, one of the more significant challenges faced by instructors is encouraging and maintaining student engagement in their online classes. This paper describes my experience of flipping an online classroom for a core Chemical Engineering Fluid Mechanics class to promote student engagement and collaboration in an online setting. Comparing exam scores with prior semesters involving in-person, traditional lecture-style classes suggests that students need a certain degree of adjustment to adapt to this new learning mode.

Cell contact guidance via sensing anisotropy of network mechanical resistance.

Despite the ubiquitous importance of cell contact guidance, the signal-inducing contact guidance of mammalian cells in an aligned fibril network has defied elucidation. This is due to multiple interdependent signals that an aligned fibril network presents to cells, including, at least, anisotropy of adhesion, porosity, and mechanical resistance. By forming aligned fibrin gels with the same alignment strength, but cross-linked to different extents, the anisotropic mechanical resistance hypothesis of contact guidance was tested for human dermal fibroblasts.

A computational multi-scale approach to investigate mechanically-induced changes in tricuspid valve anterior leaflet microstructure.

The tricuspid valve is an atrioventricular valve that prevents blood backflow from the right ventricle into the right atrium during ventricular contractions. It is important to study mechanically induced microstructural alterations in the tricuspid valve leaflets, as this aids both in understanding valvular diseases and in the development of new engineered tissue replacements. The structure and composition of the extracellular matrix (ECM) fiber networks are closely tied to an overall biomechanical function of the tricuspid valve.

Combination therapy with mandibular advancement and expiratory positive airway pressure valves reduces obstructive sleep apnea severity.

Study Objectives: Mandibular advancement splint (MAS) therapy is a well-tolerated alternative to continuous positive airway pressure for obstructive sleep apnea (OSA). Other therapies, including nasal expiratory positive airway pressure (EPAP) valves, can also reduce OSA severity. However, >50% of patients have an incomplete or no therapeutic response with either therapy alone and thus remain at risk of adverse health outcomes.

Mechanics of a two-fiber model with one nested fiber network, as applied to the collagen-fibrin system.

Unlabelled: The mechanical behavior of collagen-fibrin (col-fib) co-gels is both scientifically interesting and clinically relevant. Collagen-fibrin networks are a staple of tissue engineering research, but the mechanical consequences of changes in co-gel composition have remained difficult to predict or even explain. We previously observed fundamental differences in failure behavior between collagen-rich and fibrin-rich co-gels, suggesting an essential change in how the two components interact as the co-gel's composition changes.

Swelling of Collagen-Hyaluronic Acid Co-Gels: An In Vitro Residual Stress Model.

Tissue-equivalents (TEs), simple model tissues with tunable properties, have been used to explore many features of biological soft tissues. Absent in most formulations however, is the residual stress that arises due to interactions among components with different unloaded levels of stress, which has an important functional role in many biological tissues. To create a pre-stressed model system, co-gels were fabricated from a combination of hyaluronic acid (HA) and reconstituted Type-I collagen (Col).

Multiscale Mechanical Model of the Pacinian Corpuscle Shows Depth and Anisotropy Contribute to the Receptor's Characteristic Response to Indentation.

Cutaneous mechanoreceptors transduce different tactile stimuli into neural signals that produce distinct sensations of touch. The Pacinian corpuscle (PC), a cutaneous mechanoreceptor located deep within the dermis of the skin, detects high frequency vibrations that occur within its large receptive field. The PC is comprised of lamellae that surround the nerve fiber at its core.

A multiscale approach to modeling the passive mechanical contribution of cells in tissues.

In addition to their obvious biological roles in tissue function, cells often play a significant mechanical role through a combination of passive and active behaviors. This study focused on the passive mechanical contribution of cells in tissues by improving our multiscale model via the addition of cells, which were treated as dilute spherical inclusions. The first set of simulations considered a rigid cell, with the surrounding ECM modeled as (1) linear elastic, (2) Neo-Hookean, and (3) a fiber network.

A coupled fiber-matrix model demonstrates highly inhomogeneous microstructural interactions in soft tissues under tensile load.

A soft tissue's macroscopic behavior is largely determined by its microstructural components (often a collagen fiber network surrounded by a nonfibrillar matrix (NFM)). In the present study, a coupled fiber-matrix model was developed to fully quantify the internal stress field within such a tissue and to explore interactions between the collagen fiber network and nonfibrillar matrix (NFM). Voronoi tessellations (representing collagen networks) were embedded in a continuous three-dimensional NFM.

Microstructural and mechanical differences between digested collagen-fibrin co-gels and pure collagen and fibrin gels.

Collagen and fibrin are important extracellular matrix (ECM) components in the body, providing structural integrity to various tissues. These biopolymers are also common scaffolds used in tissue engineering. This study investigated how co-gelation of collagen and fibrin affected the properties of each individual protein network.

Mechanics of a fiber network within a non-fibrillar matrix: model and comparison with collagen-agarose co-gels.

While collagen is recognized as the predominant mechanical component of soft connective tissues, the role of the non-fibrillar matrix (NFM) is less well understood. Even model systems, such as the collagen-agarose co-gel, can exhibit complex behavior, making it difficult to identify relative contributions of specific tissue constituents. In the present study, we developed a two-component microscale model of collagen-agarose tissue analogs and used it to elucidate the interaction between collagen and NFM in uniaxial tension.

Mechanical behavior of collagen-fibrin co-gels reflects transition from series to parallel interactions with increasing collagen content.

Fibrin and collagen, biopolymers occurring naturally in the body, are biomaterials commonly-used as scaffolds for tissue engineering. How collagen and fibrin interact to confer macroscopic mechanical properties in collagen-fibrin composite systems remains poorly understood. In this study, we formulated collagen-fibrin co-gels at different collagen-to-fibrin ratios to observe changes in the overall mechanical behavior and microstructure.

The effect of altered Toll-like receptor 4 signaling on cancer cachexia.

Objective: To determine whether mice unable to mount an intact inflammatory response because of a Toll-like receptor (TLR) pathway defect will develop less severe cancer cachexia.

Design: Prospective animal study.

Setting: Academic research center.

Synovial sarcoma of the infratemporal fossa.

Objectives: A case is reported in which synovial sarcoma (SS) is arising within the infratemporal fossa.

Design And Setting: Case report and literature review from an academic tertiary referral practice.

Results: A 46-year-old white woman presented with a 1-month history of having paresthesias on the left side of her head.

Comparison of animal models for head and neck cancer cachexia.

Objectives/hypothesis: Despite its negative impact on cancer patients, there are few animal models of cancer cachexia. Our hypothesis was that different human cell lines would variably induce cachexia.

Study Design: Prospective animal study.

Immunocompetent murine model of cancer cachexia for head and neck squamous cell carcinoma.

Background: Muscle wasting and weight loss were observed when carcinomas were induced in a murine model of head and neck squamous cell carcinomas. Our hypothesis was C3H/HeN mice would develop evidence of cachexia when injected with tumor cells

Methods: Age- and weight-matched female mice were injected with SCCF/VII cells. Daily food intake and weights were measured.