Integrating Electrophysiological, Mechanical, and Optical Methods to Define the Mechanisms of Painful Facet Joint Injury

Persistent pain is a common occurrence following whiplash injuries produced during motor vehicle crashes. The cervical facet joint and its capsule have often been identified as the source of chronic pain in patients with whiplash-associated disorders. However, for the majority of patients, no radiographic evidence of cervical spine injury is present. A capsular ligament stretch-based mechanism for initiating facet-mediated pain has been proposed based on human cadaveric studies of the facet joint kinematics during whiplash stimulations. However, without direct evidence of capsule damage during whiplash, the biomechanical and physiological mechanisms by which altered vertebral kinematics produce a facet capsule injury have not been fully elucidated. The goal of this thesis was to identify the facet joint loading conditions that produce microstructural damage to the facet capsular ligament and determine whether such loading can initiate neuronal plasticity in the spinal cord. Using a rat model of cervical facet joint loading, spinal neuron hyperexcitability was quantified from extracellular voltage recordings after imposing joint loading conditions that do and do not produce persistent pain symptoms. To determine whether neuronal hyperexcitability corresponds to a detectable change in the microstructure of the facet capsular ligament, a quantitative polarized light imaging technique was employed to define collagen fiber kinematics during capsule loading. A vector correlation analysis technique was developed to localize anomalies in the fiber kinematics of the human facet capsular ligament during tensile loading and was compared to changes in the mechanical response of the tissue during loading. The collagen fiber kinematics of the rat facet capsular ligament were also defined and compared to the joint loading conditions that produce neuronal plasticity and persistent pain symptoms. Altered fiber alignment and changes in the mechanical function of the human facet capsule were quantified after a subfailure vertebral retraction to determine the potential for microstructural damage in the facet capsule following whiplash-like motion. This work demonstrates that facet capsule stretch can cause microstructural changes to the capsular ligament in the absence of capsule rupture and establishes a framework to identify the mechanisms of facet joint injury and the development of central sensitization and persistent pain

Cervical facet capsular ligament yield defines the threshold for injury and persistent joint-mediated cervical pain

The cervical facet joint has been identified as a source of neck pain, and its capsular ligament is a likely candidate for injury during whiplash. Many studies have shown that the mechanical properties of ligaments can be altered by subfailure injury. However, the subfailure mechanical response of the facet capsular ligament has not been well defined, particularly in the context of physiology and pain. Therefore, the goal of this study was to quantify the structural mechanics of the cervical facet capsule and define the threshold for altered structural responses in this ligament during distraction. Tensile failure tests were preformed using isolated C6/C7 rat facet capsular ligaments (n=8); gross ligament failure, the occurrence of minor ruptures and ligament yield were measured. Gross failure occurred at 2.45±0.60 N and 0.92±0.17 mm. However, the yield point occurred at 1.68±0.56 N and 0.57±0.08 mm, which was significantly less than gross failure (p\u3c0.001 for both measurements). Maximum principal strain in the capsule at yield was 80±24%. Energy to yield was 14.3±3.4% of the total energy for a complete tear of the ligament. Ligament yield point occurred at a distraction magnitude in which pain symptoms begin to appear in vivo in the rat. These mechanical findings provide insight into the relationship between gross structural failure and painful loading for the facet capsular ligament, which has not been previously defined for such neck injuries. Findings also present a framework for more in-depth methods to define the threshold for persistent pain and could enable extrapolation to the human response

Vector Correlation Technique for Pixel-wise Detection of Collagen Fiber Realignment During Injurious Tensile Loading

Excessive soft tissue loading can produce adverse structural and physiological changes in the absence of any visible tissue rupture. However, image-based analysis techniques to assess microstructural changes during loading without any visible rupture remain undeveloped. Quantitative polarized light imaging (QPLI) can generate spatial maps of collagen fiber alignment during loading with high temporal resolution and can provide a useful technique to measure microstructural responses. While collagen fibers normally realign in the direction that tissue is loaded, rapid, atypical fiber realignment during loading may be associated with the response of a local collagenous network to fiber failure. A vector correlation technique was developed to detect this atypical fiber realignment using QPLI and mechanical data collected from human facet capsular ligaments (n=16) loaded until visible rupture. Initial detection of anomalous realignment coincided with a measurable decrease in the tissue stiffness in every specimen and occurred at significantly lower strains than those at visible rupture (ρ \u3c 0.004), suggesting this technique may be sensitive to a loss of microstructural integrity. The spatial location of anomalous realignment was significantly associated with regions where visible rupture developed (ρ \u3c 0.001). This analysis technique provides a foundation to identify regional differences in soft tissue injury tolerances and relevant mechanical thresholds

Structural Changes in the Cervical Facet Capsular Ligament: Potential Contributions to Pain Following Subfailure Loading

While studies have demonstrated the cervical facet capsule is at risk for tensile injury during whiplash, the relationship between joint loading, changes in the capsule’s structure, and pain is not yet fully characterized. Complementary approaches were employed to investigate the capsule’s structure-function relationship in the context of painful joint loading. Isolated C6/C7 facet joints (n=8) underwent tensile mechanical loading, and measures of structural modification were compared for two distraction magnitudes: 300 μm (PV) and 700 μm (SV). In a matched in vivo study, C6/C7 facet joints (n=4) were harvested after the same SV distraction and the tissue was sectioned to analyze collagen fiber organization using polarized light microscopy. Laxity following SV distraction (7.30±3.01%) was significantly greater (p\u3c0.001) than that produced following PV distraction (0.99±0.44%). Also, SV distractions produced significantly higher maximum principal strain (p\u3c0.001) in the capsule and resulted in significantly greater decreases in stiffness (p=0.002) when compared to PV distraction. After SV distraction in vivo, mean angular deviation of the fiber direction (16.8±2.6º) was significantly increased (p=0.004) relative to naive samples in the lateral region of the capsule, indicating collagen fiber disorganization. These findings demonstrate that certain subfailure loading conditions are associated with altered joint mechanics and collagen fiber disorganization and imply ligament damage. Substructural damage in the capsule has the potential to both directly modulate nerve fiber signaling and produce sustained physiologic modifications that may initiate persistent pain

From single cells to tissues: interactions between the matrix and human breast cells in real time.

International audienceMammary gland morphogenesis involves ductal elongation, branching, and budding. All of these processes are mediated by stroma--epithelium interactions. Biomechanical factors, such as matrix stiffness, have been established as important factors in these interactions. For example, epithelial cells fail to form normal acinar structures in vitro in 3D gels that exceed the stiffness of a normal mammary gland. Additionally, heterogeneity in the spatial distribution of acini and ducts within individual collagen gels suggests that local organization of the matrix may guide morphogenesis. Here, we quantified the effects of both bulk material stiffness and local collagen fiber arrangement on epithelial morphogenesis. The formation of ducts and acini from single cells and the reorganization of the collagen fiber network were quantified using time-lapse confocal microscopy. MCF10A cells organized the surrounding collagen fibers during the first twelve hours after seeding. Collagen fiber density and alignment relative to the epithelial surface significantly increased within the first twelve hours and were a major influence in the shaping of the mammary epithelium. The addition of Matrigel to the collagen fiber network impaired cell-mediated reorganization of the matrix and increased the probability of spheroidal acini rather than branching ducts. The mechanical anisotropy created by regions of highly aligned collagen fibers facilitated elongation and branching, which was significantly correlated with fiber organization. In contrast, changes in bulk stiffness were not a strong predictor of this epithelial morphology. Localized regions of collagen fiber alignment are required for ductal elongation and branching suggesting the importance of local mechanical anisotropy in mammary epithelial morphogenesis. Similar principles may govern the morphology of branching and budding in other tissues and organs

Targeted temperature management in patients with intracerebral haemorrhage, subarachnoid haemorrhage, or acute ischaemic stroke: updated consensus guideline recommendations by the Neuroprotective Therapy Consensus Review (NTCR) group

Background: There is a lack of consistent, evidence-based guidelines for the management of patients with fever after brain injury. The aim was to update previously published consensus recommendations on targeted temperature management after intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke in patients who require admission to critical care. Methods: A modified Delphi consensus, the Neuroprotective Therapy Consensus Review (NTCR), included 19 international neuro-intensive care experts with a subspecialty interest in the acute management of intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke. An online, anonymised survey was completed ahead of the meeting before the group came together to consolidate consensus and finalise recommendations on targeted temperature management. A threshold of ≥80% for consensus was set for all statements. Results: Recommendations were formulated based on existing evidence, literature review, and consensus. After intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke in patients who require critical care admission, core temperature should ideally be monitored continuously and maintained between 36.0°C and 37.5°C using automated feedback-controlled devices, where possible. Targeted temperature management should be commenced within 1 h of first fever identification with appropriate diagnosis and treatment of infection, maintained for as long as the brain remains at risk of secondary injury, and rewarming should be controlled. Shivering should be monitored and managed to limit risk of secondary injury. Following a single protocol for targeted temperature management across intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke is desirable. Conclusions: Based on a modified Delphi expert consensus process, these guidelines aim to improve the quality of targeted temperature management for patients after intracerebral haemorrhage, aneurysmal subarachnoid haemorrhage, and acute ischaemic stroke in critical care, highlighting the need for further research to improve clinical guidelines in this setting

Metabotyping of docosahexaenoic acid - Treated alzheimer's disease cell model

10.1371/journal.pone.0090123PLoS ONE92-POLN

Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context

Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts

Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas

Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN