Localized characterization of brain tissue mechanical properties by needle induced cavitation rheology and volume controlled cavity expansion.

Changes in the elastic properties of brain tissue have been correlated with injury, cancers, and neurodegenerative diseases. However, discrepancies in the reported elastic moduli of brain tissue are persistent, and spatial inhomogeneities complicate the interpretation of macroscale measurements such as rheology. Here we introduce needle induced cavitation rheology (NICR) and volume-controlled cavity expansion (VCCE) as facile methods to measure the apparent Young's modulus E of minimally manipulated brain tissue, at specific tissue locations and with sub-millimeter spatial resolution.

Probing Mechanical Properties of Brain in a Tuberous Sclerosis Model of Autism.

Causes of autism spectrum disorders (ASD) are understood poorly, making diagnosis and treatment challenging. While many studies have investigated the biochemical and genetic aspects of ASD, whether and how mechanical characteristics of the autistic brain can modulate neuronal connectivity and cognition in ASD are unknown. Previously, it has been shown that ASD brains are characterized by abnormal white matter and disorganized neuronal connectivity; we hypothesized that these significant cellular-level structural changes may translate to changes in the mechanical properties of the autistic brain or regions therein.

High-velocity micro-particle impact on gelatin and synthetic hydrogel.

The high-velocity impact response of gelatin and synthetic hydrogel samples is investigated using a laser-based microballistic platform for launching and imaging supersonic micro-particles. The micro-particles are monitored during impact and penetration into the gels using a high-speed multi-frame camera that can record up to 16 images with nanosecond time resolution. The trajectories are compared with a Poncelet model for particle penetration, demonstrating good agreement between experiments and the model for impact in gelatin.

Characterizing viscoelastic mechanical properties of highly compliant polymers and biological tissues using impact indentation.

Unlabelled: Precise and accurate measurement of viscoelastic mechanical properties becomes increasingly challenging as sample stiffness decreases to elastic moduli <1 kPa, largely due to difficulties detecting initial contact with the compliant sample surface. This limitation is particularly relevant to characterization of biological soft tissues and compliant gels. Here, we employ impact indentation which, in contrast to shear rheology and conventional indentation, does not require contact detection a priori, and present a novel method to extract viscoelastic moduli and relaxation time constants directly from the impact response.

Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry.

To design and engineer materials inspired by the properties of the brain, whether for mechanical simulants or for tissue regeneration studies, the brain tissue itself must be well characterized at various length and time scales. Like many biological tissues, brain tissue exhibits a complex, hierarchical structure. However, in contrast to most other tissues, brain is of very low mechanical stiffness, with Young's elastic moduli E on the order of 100s of Pa.

An improved electrical impedance myography (EIM) tongue array for use in clinical trials.

Objectives: Electrical impedance myography (EIM) measurements of the tongue could provide valuable information about bulbar dysfunction in amyotrophic lateral sclerosis (ALS). A prototype tongue depressor EIM array produced gag reflexes. The objectives of this study were to determine the reliability, mean phase values, and tolerability of tongue EIM measurements using a smaller electrode array.

Optimizing outpatient phlebotomy staffing: tools to assess staffing needs and monitor effectiveness.

Context: Short patient wait times are critical for patient satisfaction with outpatient phlebotomy services. Although increasing phlebotomy staffing is a direct way to improve wait times, it may not be feasible or appropriate in many settings, particularly in the context of current economic pressures in health care.

Objective: To effect sustainable reductions in patient wait times, we created a simple, data-driven tool to systematically optimize staffing across our 14 phlebotomy sites with varying patient populations, scope of service, capacity, and process workflows.

Optimizing electrical impedance myography measurements by using a multifrequency ratio: a study in Duchenne muscular dystrophy.

Objective: Electrical impedance myography (EIM) is an electrophysiological technique for neuromuscular evaluation that is impacted by subcutaneous fat (SF). Exploiting the differing frequency dependences of muscle and fat, we assessed a 2-frequency EIM phase ratio in Duchenne muscular dystrophy (DMD) boys.

Methods: Twenty-eight DMD boys aged 2-13years underwent EIM and the 6-minute walk test (6MWT).

Cross-sectional evaluation of electrical impedance myography and quantitative ultrasound for the assessment of Duchenne muscular dystrophy in a clinical trial setting.

Background: Electrical impedance myography and quantitative ultrasound are two noninvasive, painless, and effort-independent approaches for assessing neuromuscular disease. Both techniques have potential to serve as useful biomarkers in clinical trials in Duchenne muscular dystrophy. However, their comparative sensitivity to disease status and how they relate to one another are unknown.

An intervention to improve the timing of vancomycin levels.

Objectives: Blood samples for vancomycin levels are often drawn too early, leading to potential misinterpretation of results. However, only a few studies describe interventions to reduce mistimed vancomycin levels.

Methods: We implemented an information technology (IT)-based intervention that provided educational instructions to nurses and determined the percentage of levels drawn too early for 27 months before (n = 6,291) and 14 months after (n = 3,608) the intervention.