Evaluation of lumbar disc and spine morphology: long-term repeatability and comparison of methods

Establishing the long-term repeatability of quantitative measures of lumbar intervertebral disc and spinal morphology is important for planning interventional studies. We aimed to examine this issue and to determine to what extent a smaller number of measurements per disc or vertebral level could be used to save operator time without compromising measurement precision. Twenty-one healthy male subjects were scanned at baseline and 1.5 years later. On sagittal MR-scans intervertebral disc cross-sectional area, anterior disc height, posterior disc height, intervertebral angle and intervertebral length were measured. The repeatability of the average value from all sagittal images or from 1, 3, 5 or 7 images centred at the spinous process was evaluated. Bland-Altman analysis showed all measurements to be repeatable between testing days. Intervertebral length was the most precise measurement (coefficients of variation [CVs] between 1.2% and 1.5%), followed by disc cross-sectional area (CVs between 2.9% and 3.6%). Variance component analysis showed that using 7 images, but not 1, 3 or 5 images, resulted in a similar level of measurement error as when measurements from all images were included.

Virtual lumbar spine of multi-body model based on simbody

The spine is an important and complex skeletal structure in the human body. It is a vulnerable part of our skeleton that is open to many medical problems. Hence it is necessary to establish a virtual spine model to assist surgeons to understand biomechanics of the spine. In this study, we aim to propose a virtual spine multi-body model. The computational biomechanical modeling of the spine is based on the theory of multi-body dynamics and implemented with SimBody open-source SDK. Simbody was then used to solve the kinetic equations and simulate the movement of spine. The spine model was validated by comparing its simulation results with experimental results from literature. The spine model will be helpful to understand biomechanics of the spine under loading.

Alterations in microRNAs miR-21 and let-7a correlate with aberrant STAT3 signaling and downstream effects during cervical carcinogenesis

BACKGROUND: Present study provides clinical evidence of existence of a functional loop involving miR-21 and let-7a as potential regulators of aberrant STAT3 signaling recently reported by our group in an experimental setup (Shishodia et al. BMC Cancer 2014, 14:996). The study is now extended to a set of cervical tissues that represent natural history of human papillomavirus (HPV)-induced tumorigenic transformation. MATERIALS AND METHODS: Cervical tissues from histopathologically-confirmed pre-cancer (23) and cancer lesions (56) along with the normal control tissues (23) were examined for their HPV infection status, expression level of miR-21 & let-7a and STAT3 & pSTAT3 (Y705) by PCR-based genotyping, quantitative real-time PCR and immunoblotting. RESULTS: Analysis of cancer tissues revealed an elevated miR-21 and reduced let-7a expression that correspond to the level of STAT3 signaling. While miR-21 showed direct association, let-7a expression was inversely related to STAT3 expression and its activation. In contrast, a similar reciprocal expression kinetics was absent in LSIL and HSIL tissues which overexpressed let-7a. miR-21 was found differentially overexpressed in HPV16-positive lesions with a higher oncoprotein E6 level. Overexpression of miR-21 was accompanied by elevated level of other STAT3-regulated gene products MMP-2 and MMP-9. Enhanced miR-21 was found associated with decreased level of STAT3 negative regulator PTEN and negative regulator of MMPs, TIMP-3. CONCLUSION: Overall, our study suggests that the microRNAs, miR-21 and let-7a function as clinically relevant integral components of STAT3 signaling and are responsible for maintaining activated state of STAT3 in HPV-infected cells during cervical carcinogenesis.

Finding line of action of the force exerted on erect spine based on lateral bending test in personalization of scoliotic spine models

In multi-body models of scoliotic spine, personalization of mechanical properties of joints significantly improves reconstruction of the spine shape. In personalization methods based on lateral bending test, simulation of bending positions is an essential step. To simulate, a force is exerted on the spine model in the erect position. The line of action of the force affects the moment of the force about the joints and thus, if not correctly identified, causes over/underestimation of mechanical properties. Therefore, we aimed to identify the line of action, which has got little attention in previous studies. An in-depth analysis was performed on the scoliotic spine movement from the erect to four spine positions in the frontal plane by using pre-operative X-rays of 18 adolescent idiopathic scoliosis (AIS) patients. To study the movement, the spine curvature was considered as a 2D chain of micro-scale motion segments (MMSs) comprising rigid links and 1-degree-of-freedom (DOF) rotary joints. It was found that two MMSs representing the inflection points of the erect spine had almost no rotation (0.0028° ± 0.0021°) in the movement. The small rotation can be justified by weak moment of the force about these MMSs due to very small moment arm. Therefore, in the frontal plane, the line of action of the force to simulate the left/right bending position was defined as the line that passes through these MMSs in the left/right bending position. Through personalization of a 3D spine model for our patients, we demonstrated that our line of action could result in good estimates of the spine shape in the bending positions and other positions not included in the personalization, supporting our proposed line of action.