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.

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.

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.

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.

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.

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.

Awareness and Attitudes of Nigerian Men Living in Abuja on Prostate Cancer and Screening.

Prostate cancer (PCa) is the most commonly diagnosed cancer among Nigerian men. The prevalence of PCa varies within Nigeria, with the highest prevalence of 1046 per 100,000 in men over the age of 40 reported in Lagos. Unfortunately, 40% of these men are diagnosed with locally advanced disease and 35% with metastatic disease.

Proteoglycans contribute locally to swelling, but globally to compressive mechanics, in intact cervine medial meniscus.

Loss of charged proteoglycans in the knee meniscus, which aid in the support of compressive loads by entraining water, is an effect of degeneration and is often associated with osteoarthritis. In healthy menisci, proteoglycan content is highest in the inner white zone and decreases towards the peripheral red zone. We hypothesized that loss of proteoglycans would reduce both osmotic swelling and compressive stiffness, spatially localized to the avascular white zone of the meniscus.

Thirty Years of the Journal of Cancer Education: a Review.

Since its foundation in 1986, the Journal of Cancer Education (JCE) has served as an important outlet for myriad aspects of cancer education and currently serves as the official journal of the American and European Associations for Cancer Education. During its history, the JCE has been under the auspices of five publishers, with its first full year under the current publisher, Springer, in 2010. Print and distribution metrics from 2010 to present were obtained from Springer.

Residual strains in the intervertebral disc annulus fibrosus suggest complex tissue remodeling in response to in-vivo loading.

The annulus fibrosus (AF) of the intervertebral disc (IVD) serves the dual roles of containing hydrostatic pressure from the inner nucleus pulposus (NP) and allowing flexible connection between adjacent vertebral bodies. Previous work has indicated that in the unloaded state, the AF is under a state of residual circumferential strain that, on average, is comparable to that which is believed to reduce peak stresses in other pressure containing organs. The complex in-vivo loading of the IVD, however, led us to hypothesize that variations with anatomical region should also exist.

A Fulbright Specialist in Poland.

One of the greatest rewards in cancer education is working with colleagues from around the world. This manuscript reports on the development and conduct of a cancer research training program in Wroclaw, Poland, supported by the Fulbright Commission. The precipitating need for this program was the desire and lack of opportunity for medical trainees to develop skills necessary to conduct cancer education research.