Enzymatic Digestion of the Intervertebral Disc Alters Intradiscal Injection and Leakage Mechanics.

Intradiscal injection is required to deliver therapeutic agents to the intervertebral disc (IVD) nucleus pulposus (NP). However, injectate leakage following needle retraction may result in decreased treatment efficacy and adverse side effects. While enzymatic digestion is a common research approach for simulating degeneration in healthy animal IVDs, contributions to the leakage phenomenon are unknown.

Three-dimensional fiber patterning in the annulus fibrosus can be derived from vertebral endplate topography.

Introduction: The annulus fibrosus (AF) of the Intervertebral disc (IVD) is composed of concentric lamellae of helically wound collagen fibers. Understanding the spatial variation of collagen fiber orientations in these lamellae, and the resulting material anisotropy, is crucial to predicting the mechanical behavior of the complete IVD.

Methods: This study builds on a prior model predicated on path-independent displacement of fiber endpoints during vertebral body growth to predict a complete, three-dimensional annulus fibrosus fiber network from a small number of subject-independent input parameters and vertebral endplate topographies obtained from clinical imaging.

Climate change projected to impact structural hillslope connectivity at the global scale.

Structural connectivity describes how landscapes facilitate the transfer of matter and plays a critical role in the flux of water, solutes, and sediment across the Earth's surface. The strength of a landscape's connectivity is a function of climatic and tectonic processes, but the importance of these drivers is poorly understood, particularly in the context of climate change. Here, we provide global estimates of structural connectivity at the hillslope level and develop a model to describe connectivity accounting for tectonic and climate processes.

Urbanization as a limiter and catalyst of watershed-scale sediment transport: Insights from probabilistic connectivity modeling.

The conversion of rural lands to urban areas exerts considerable influence on the hydrologic processes governing sediment transport at the watershed scale. While the effects of urbanization on hydrology have been well-studied, the corresponding impact to the spatial and temporal variability of sediment detachment, transport, and connectivity is less certain. To address this knowledge gap, we apply process-based hydrologic simulation, probabilistic connectivity modeling, and in situ turbidity sensing to five watersheds positioned along a steep land use gradient in Kansas, USA.

The Use of Temperature and Pressure Data Loggers to Validate the Steam Sterilization of Category A Clinical Waste.

Introduction: Over the past decade, there have been outbreaks associated with high consequence infectious diseases such as Ebola virus disease, Lassa fever, and Monkeypox. The proper handling of clinical waste from patients infected with such pathogens is critical to ensure healthcare personnel and community safety.

Methods: Mock clinical waste bags were created to simulate four distinct waste streams: personal protective equipment (PPE), dry linens, wet linens, and solidified liquids.

Fluorescent labeling with 5-DTAF reduces collagen fiber uncrimping in loaded tendons.

A fluorescent dye commonly used to image tissues under load (5-DTAF) has previously been shown to stiffen tendons. This study hypothesized that 5-DTAF staining stiffens tendons through reduced fiber sliding, altering the rate at which crimped collagen fibers straighten under load. This was tested by using reflected cross-polarized light microscopy to measure fiber crimp period of cervine extensor digitorum longus tendon specimens under axial load.

Establishing a through-puncture model for assessing post-injection leakage in the intervertebral disc.

Purpose: Needle injection through the outer annulus fibrosus of the intervertebral disc (IVD) is the most practical approach for delivery of therapeutic agents, which have been shown to potentially leak following needle retraction. The goal of this work was to establish a protocol for quantifying post-injection leakage and test its sensitivity to factors believed to affect needle track geometry.

Methods: A through-puncture defect procedure, followed by controlled injection, was performed on bovine caudal IVDs.

Models of Intermediate Care Organization and Staffing at an Academic Medical Center: Considerations of an Inpatient Planning Committee.

Geographic co-localization of patients and provider teams (geography) may improve care efficiency and quality. Patients requiring intermediate care present a unique challenge to the geographic model. Identify the best organizational and staffing model for intermediate care at our academic medical center.

Selective Interruption of Auditory Interhemispheric Cross Talk Impairs Discrimination Learning of Frequency-Modulated Tone Direction But Not Gap Detection and Discrimination.

Functional hemispheric lateralization is a basic principle of brain organization. In the auditory domain, the right auditory cortex (AC) determines the pitch direction of continuous auditory stimuli whereas the left AC discriminates gaps in these stimuli. The involved functional interactions between the two sides, mediated by commissural connections, are poorly understood.

Cargo properties play a critical role in myosin Va-driven cargo transport along actin filaments.

High-resolution experiments revealed that a single myosin-Va motor can transport micron-sized cargo on actin filaments in a stepwise manner. However, intracellular cargo transport is mediated through the dense actin meshwork by a team of myosin Va motors. The mechanism of how motors interact mechanically to bring about efficient cargo transport is still poorly understood.

Guiding Attention via a Cognitive Aid During a Simulated In-Hospital Cardiac Arrest Scenario: A Salience Effort Expectancy Value Model Analysis.

Objective: To investigate the effect of a cognitive aid on the visual attention distribution of the operator using the Salience Effort Expectancy Value (SEEV) model.

Background: Cognitive aids aim to support an operator during the execution of a task. The effect of cognitive aids on performance is frequently evaluated but whether a cognitive aid improved, for example, attention distribution has not been considered.

Reflected cross-polarized light microscopy as a method for measuring collagen fiber crimp in musculoskeletal tissues.

Many musculoskeletal tissues are composed primarily of type I collagen, which takes on a periodic crimp morphology that allows large tensile strains in the tissue. The spatial period of collagen fiber crimp may be used to infer internal strains in a tissue and is typically measured using transmitted cross-polarized light imaging of thin slices. However, slicing may induce specimen distortion and precludes mechanical loading of the specimen during imaging.

Radial trend in murine annulus fibrosus fiber orientation is best explained by vertebral growth.

Purpose: The intervertebral disc (IVD) annulus fibrosus (AF) is composed of concentric lamellae with alternating right- and left-handed helically oriented collagen fiber bundles. This arrangement results in anisotropic material properties, which depend on local fiber orientations. Prior measurements of fiber inclination angles in human lumbar and bovine caudal IVDs found a significantly higher inclination angle in the inner AF than outer, though it is currently unknown if this pattern is conserved in smaller mammalian species.

Mentoring in Global Cancer Research Training.

This manuscript illustrates general concepts of mentoring in low- and middle-income countries (LMICs). The focus of this manuscript is on public health research based on our experiences with the Cancer Epidemiology Education in Special Populations (CEESP) Program which is further illustrated in this Supplement. While the CEESP Program provides research training in global and US minority settings, this manuscript is focused on the global aspects of the program.

The Validity of the SEEV Model as a Process Measure of Situation Awareness: The Example of a Simulated Endotracheal Intubation.

Objective: In the context of anesthesiology, we investigated whether the salience effort expectancy value (SEEV) model fit is associated with situation awareness and perception scores.

Background: The distribution of visual attention is important for situation awareness-that is, understanding what is going on-in safety-critical domains. Although the SEEV model has been suggested as a process situation awareness measure, the validity of the model as a predictor of situation awareness has not been tested.

Modeling linkages between erosion and connectivity in an urbanizing landscape.

Erosion and connectivity are spatially varied processes key to determining sediment transport and delivery to downstream waterbodies. However, we find few studies that explicitly model the linkages of where erosion and connectivity coincide and where they contradict, particularly in urbanizing settings. In this study, we couple in-stream aquatic sensing, the Revised Universal Soil Loss Equation (RUSLE), the Index of Connectivity (IC), and the Sediment Delivery Ratio (SDR), together with Monte Carlo uncertainty analysis, to generate a new Erosion-Connectivity Mapping (ECM) framework.

Level-wise differences in lateral bending moment are associated with microstructural alterations in bovine caudal intervertebral discs.

Despite its common use as a laboratory model, little is known about the forces and moments applied to the bovine caudal intervertebral disc. Such aspects are crucial, as intervertebral disc tissue is known to remodel in response to repeated loading. We hypothesized that the magnitude of loading from muscle contraction during a typical lateral bending motion varies between caudal levels and is accompanied by variations in tissue microstructure.

Smoking and Unemployment: A Photo Elicitation Project.

Introduction: Research has documented higher smoking prevalence with unemployment and greater difficulty with gaining re-employment for those who smoke. Using photo elicitation methods, we sought to gain a deeper understanding of the connection between job-seeking and tobacco use.

Methods: Unemployed daily smokers (18 men, 1 woman) were recruited from the San Francisco Employment Development Department (EDD) and provided disposable cameras with 27 exposures and a list of 20 photo prompts related to job-seeking and tobacco.

Bridging the Gap: Science and Technology Policy in the (Bio)Engineering Classroom.

Engineers and scientists have a key role to play in the creation and implementation of government policy. Policymakers need access to the technical expertise that is critical to our national progress and security; however, this need is often overlooked by engineering students, faculty, and professionals. Even though a substantial fraction of scientists and engineers end up pursuing jobs in government, engineering curricula do not usually provide any background in policy and for many, the policy-making process remains a black box.

Slow depressurization following intradiscal injection leads to injectate leakage in a large animal model.

Needle injection has been indicated as the most practical method of delivering therapeutic agents to the intervertebral disc due to the disc's largely avascular nature. As the disc is characterized by both high stiffness and low permeability, injection requires substantial pressure, which may not relax on practical time scales. Additionally, needle puncture results in a localized disruption to the annulus fibrosus that can provide a leakage pathway for pressurized injectate.

Increased lumbar spinal column laxity due to low-angle, low-load cyclic flexion may predispose to acute injury.

Lumbar spinal column laxity contributes to instability, increasing the risk of low back injury and pain. Until the laxity increase due to the cyclic loads of daily living can be quantified, the associated injury risk cannot be predicted clinically. This work cyclically loaded 5-vertebra lumbar motion segments (7 skeletally-mature cervine specimens, 5 osteoporotic human cadaver specimens) for 20 000 cycles of low-load low-angle (15°) flexion.

A growth-based model for the prediction of fiber angle distribution in the intervertebral disc annulus fibrosus.

There is a growing interest in the development of patient-specific finite element models of the human lumbar spine for both the assessment of injury risk and the development of treatment strategies. A current challenge in implementing these models is that the outer annulus fibrosus of the disc is composed of concentric sheets of aligned collagen fibers, the helical angles of which vary spatially. In finite element models, fiber angle is typically assumed to be constant, based on average experimental measurements from a small number of locations.

Mapping of Intervertebral Disk Annulus Fibrosus Compressive Properties Is Sensitive to Specimen Boundary Conditions.

Predicting the mechanical behavior of the intervertebral disk (IVD) in health and in disease requires accurate spatial mapping of its compressive mechanical properties. Previous studies confirmed that residual strains in the annulus fibrosus (AF) of the IVD, which result from nonuniform extracellular matrix deposition in response to in vivo loads, vary by anatomical regions (anterior, posterior, and lateral) and zones (inner, middle, and outer). We hypothesized that as the AF is composed of a nonlinear, anisotropic, viscoelastic material, the state of residual strain in the transverse plane would influence the apparent values of axial compressive properties.

Quality Appraisal of Systematic Reviews for Behavioral Treatments of Attention Disorders in Traumatic Brain Injury.

Objective: This review appraised the quality of systematic reviews (SRs) and meta-analyses (MAs) to summarize research on behavioral interventions for attention disorders in persons with traumatic brain injury.

Methods: A search of 7 databases revealed 15 MAs/SRs reporting outcomes for attention treatments in traumatic brain injury. Two examiners independently coded the quality of reviews with the Critical Appraisal of Systematic Review or Meta-Analysis and the Evidence in Augmentative and Alternative Communication Systematic Review Scale.

Critical appraisal of systematic reviews of executive function treatments in TBI.

Objective: To appraise the quality of systematic reviews (SRs) and meta-analyses (MAs) that summarize the treatment literature for executive function (EF) impairments following traumatic brain injury (TBI).

Methods: We used five data sources (PubMed; PsycINFO; ANCDS.org; Cochrane Collaboration; American Speech-Language-Hearing Association Compendium; Psychological Database for Brain Impairment Treatment Efficacy) and identified 19 reviews that met eligibility criteria (adults with TBI; behavioural treatments for EF impairments; no pharmacologic treatments).