Biomechanical analysis of the upper thoracic spine after decompressive procedures

Background contextDecompressive procedures such as laminectomy, facetectomy, and costotransversectomy are routinely performed for various pathologies in the thoracic spine. The thoracic spine is unique, in part, because of the sternocostovertebral articulations that provide additional strength to the region relative to the cervical and lumbar spines. During decompressive surgeries, stability is compromised at a presently unknown point.PurposeTo evaluate thoracic spinal stability after common surgical decompressive procedures in thoracic spines with intact sternocostovertebral articulations.Study designBiomechanical cadaveric study.MethodsFresh-frozen human cadaveric spine specimens with intact rib cages, C7–L1 (n=9), were used. An industrial robot tested all spines in axial rotation (AR), lateral bending (LB), and flexion-extension (FE) by applying pure moments (±5 Nm). The specimens were first tested in their intact state and then tested after each of the following sequential surgical decompressive procedures at T4–T5 consisting of laminectomy; unilateral facetectomy; unilateral costotransversectomy, and subsequently instrumented fusion from T3–T7.ResultsWe found that in all three planes of motion, the sequential decompressive procedures caused no statistically significant change in motion between T3–T7 or T1–T12 when compared with intact. In comparing between intact and instrumented specimens, our study found that instrumentation reduced global range of motion (ROM) between T1–T12 by 16.3% (p=.001), 12% (p=.002), and 18.4% (p=.0004) for AR, FE, and LB, respectively. Age showed a negative correlation with motion in FE (r=?0.78, p=.01) and AR (r=?0.7, p=.04).ConclusionsThoracic spine stability was not significantly affected by sequential decompressive procedures in thoracic segments at the level of the true ribs in all three planes of motion in intact thoracic specimens. Age appeared to negatively correlate with ROM of the specimen. Our study suggests that thoracic spinal stability is maintained immediately after unilateral decompression at the level of the true ribs. These preliminary observations, however, do not depict the long-term sequelae of such procedures and warrant further investigation.     

Modulation of AT-1R/CHOP-JNK-Caspase12 pathway by olmesartan treatment attenuates ER stress-induced renal apoptosis in streptozotocin-induced diabetic mice

There is evidence that the activation of renal angiotensin (Ang)-II plays a critical role in the pathogenesis of diabetic kidney diseases (DN) via the ER stress-induced renal apoptosis. Since, the potential negative role of Ang-II in the pathogenesis of ER stress-mediated apoptosis is poorly understood; we evaluated whether treatment of mice with AT-1R specific blocker, olmesartan is associated with the reduction of ER stress-induced renal apoptosis in streptozotocin (STZ)-induced diabetic animal model. We employed western blot analysis to measure the renal protein expressions level of NADPH oxidase subunits, ER chaperone GRP78 and the ER-associated apoptosis proteins. Furthermore, TUNEL staining was used to measure the renal apoptosis. Additionally, dihydroethidium staining and TBARS assay, and immunohistochemistry were performed to measure the renal superoxide radical production and lipid peroxidation, and activation of an Ang-II, respectively. The diabetic kidney mice were found to have increased protein expressions of NADPH oxidase subunits, GRP78 and ER-associated apoptosis proteins, such as TRAF2, IRE-1α, CHOP, p-JNK and procaspase-12, in comparison to normal mice, and which were significantly blunted by the olmesartan treatment in diabetic kidney mice. Furthermore, the diabetic kidney mice were found to have significant increment in renal apoptosis, superoxide radical production, MDA level and activation of an Ang-II and which were also attenuated by the olmesartan treatment. Considering all the findings, it is suggested that the AT-1R specific blocker-olmesartan treatment could be a potential therapy in treating ER stress-induced renal apoptosis via the modulation of AT-1R/CHOP-JNK-Caspase12 pathway in STZ-induced diabetic mice.     

Modulation of AT-1R/AMPK-MAPK cascade plays crucial role for the pathogenesis of diabetic cardiomyopathy in transgenic type 2 diabetic (Spontaneous Diabetic Torii) rats

There are evidences that the activation of AMPK is playing pivotal role in the lipid and glucose metabolism. It has been reported that both the AMPK and angiotensin-II acts as a negative regulator for each protein. It has been well proven that the MAPK cascade could be modulated by the presence of angiotensin-II. Moreover, studies were shown that p38 MAPK stimulates glucose uptake through the AMPK activation. Therefore, we speculate and tried to demonstrate that the modulation of AT-R/MAPK pathway through AMPK might play crucial roles for the pathogenesis of diabetic cardiomyopathy, using the transgenic (Spontaneous Diabetic Torii-SDT) rats. We performed Western blot analysis for the measurement of myocardial AT-R, AMPK and MAPK cascades-related protein expressions, p67-phox and caspase-12. In addition, we employed dihydroethidium (DHE), Azan Mallory and hemotoxylin eosin (HE) staining methods to demonstrate the superoxide radical production, fibrosis and hypertrophy, respectively. The protein expressions, such as AT-1R, p-ERK1/2, p67-phox and caspase-12 were found to be significantly increased and conversely, the Ang-(1-7) mas R, Tak1, LKB1 and p-AMPKα1, p-p38 MAPK and p-JNK protein expressions were found to be considerably decreased in the SDT rats, in comparison to the normal rats. The DHE, Azan Mallory and HE stainings also revealed that the SDT rats have more superoxide radical production, fibrosis and hypertrophy, respectively than the normal rats. Taken together, it is suggested that the modulation of AT-1R/AMPK-MAPK pathway might play crucial roles for the pathogenesis of diabetic cardiomyopathy and it could become an important therapeutic target to ameliorate the diabetic cardiomyopathy.     

Machine Learning for Detection of Correct Peripherally Inserted Central Catheter Tip Position from Radiology Reports in Infants

Background  In critically ill infants, the position of a peripherally inserted central catheter (PICC) must be confirmed frequently, as the tip may move from its original position and run the risk of hyperosmolar vascular damage or extravasation into surrounding spaces. Automated detection of PICC tip position holds great promise for alerting bedside clinicians to noncentral PICCs. Objectives  This research seeks to use natural language processing (NLP) and supervised machine learning (ML) techniques to predict PICC tip position based primarily on text analysis of radiograph reports from infants with an upper extremity PICC. Methods  Radiographs, containing a PICC line in infants under 6 months of age, were manually classified into 12 anatomical locations based on the radiologist''s textual report of the PICC line''s tip. After categorization, we performed a 70/30 train/test split and benchmarked the performance of seven different (neural network, support vector machine, the naïve Bayes, decision tree, random forest, AdaBoost, and K-nearest neighbors) supervised ML algorithms. After optimization, we calculated accuracy, precision, and recall of each algorithm''s ability to correctly categorize the stated location of the PICC tip. Results  A total of 17,337 radiographs met criteria for inclusion and were labeled manually. Interrater agreement was 99.1%. Support vector machines and neural networks yielded accuracies as high as 98% in identifying PICC tips in central versus noncentral position (binary outcome) and accuracies as high as 95% when attempting to categorize the individual anatomical location (12-category outcome). Conclusion  Our study shows that ML classifiers can automatically extract the anatomical location of PICC tips from radiology reports. Two ML classifiers, support vector machine (SVM) and a neural network, obtained top accuracies in both binary and multiple category predictions. Implementing these algorithms in a neonatal intensive care unit as a clinical decision support system may help clinicians address PICC line position.     

Inter-tester reliability of non-invasive technique for measurement of innominate motion

Although the complex anatomical orientation and position of the sacroiliac joints (SIJ) has rendered their 3D kinematic evaluation difficult, recent techniques of palpation-digitization of pelvic landmarks using electromagnetic tracking device have been able to accurately and non-invasively quantify the subtle SIJ kinematics. While this technique demonstrates radiographic validity and high test-retest reliability, it is yet to be assessed with regards to inter-tester and trial-to-trial reliability. A single-group repeated measure design using 4 testers was conducted to evaluate the inter-tester and trial-to-trial reliability of palpation-digitization technique for innominate vector length measurements using the Polhemus electromagnetic tracking device. Fourteen young, healthy adults between the ages of 18-40 years participated in the study. The innominate vector length was calculated from 3D co-ordinates of palpated and digitized pelvic landmarks in two test positions of hip. A sensitivity analysis was conducted to determine how palpation-digitization errors for pelvic landmarks impacts on innominate angle calculation. Reliability indexes of Intraclass correlation coefficient (ICC) (≥0.97) and Standard error of measurement (SEM) (≤2.02 mm) demonstrated very high inter-tester and trial-to-trial reliability and accuracy of palpation-digitization technique for innominate vector length measurements, irrespective of the two test positions. A higher consistency of measurements was obtained within-testers as compared to between testers, and sensitivity analysis demonstrated a negligible influence of palpation-digitization errors on the innominate angle measurements. The results support clinical and research utility of this technique for non-invasive kinematic evaluation of SIJ motion for this population. Further research on the use of this palpation-digitization technique in symptomatic population is warranted.     

Comparison of self-reported physical activity levels and quality of life between individuals with dysvascular and non-dysvascular below-knee amputation: A cross-sectional study

Background

Decreased physical ability of individuals with a dysvascular amputation when compared with non-dysvascular counterpart may impact on their ability to participate in regular physical activity and concomitant quality of life.

Uptake of O-(2-[18F]fluoroethyl)-L-tyrosine in reactive astrocytosis in the vicinity of cerebral gliomas

PET using O-(2-[¹⁸F]fluoroethyl)-L-tyrosine (¹⁸F-FET) allows improved imaging of tumor extent of cerebral gliomas in comparison to MRI. In experimental brain infarction and hematoma, an unspecific accumulation of ¹⁸F-FET has been detected in the area of reactive astrogliosis which is a common cellular reaction in the vicinity of cerebral gliomas. The aim of this study was to investigate possible ¹⁸F-FET uptake in the area of reactive gliosis in the vicinity of untreated and irradiated rat gliomas.MethodsF98-glioma cells were implanted into the caudate nucleus of 33 Fisher CDF rats. Sixteen animals remained untreated and in 17 animals the tumor was irradiated by Gamma Knife 5–8 days after implantation (2/50 Gy, 3/75 Gy, 6/100 Gy, 6/150 Gy). After 8–17 days of tumor growth the animals were sacrificed following injection of ¹⁸F-FET. Brains were removed, cut in coronal sections and autoradiograms of ¹⁸F-FET distribution were produced and compared with histology (toluidine blue) and reactive astrogliosis (GFAP staining). ¹⁸F-FET uptake in the tumors and in areas of reactive astrocytosis was evaluated by lesion to brain ratios (L/B).ResultsLarge F98-gliomas were present in all animals showing increased ¹⁸F-FET-uptake which was similar in irradiated and non-irradiated tumors (L/B: 3.9 ± 0.8 vs. 4.0 ± 1.3). A pronounced reactive astrogliosis was noted in the vicinity of all tumors that showed significantly lower ¹⁸F-FET-uptake than the tumors (L/B: 1.5 ± 0.4 vs. 3.9 ± 1.1). The area of ¹⁸F-FET-uptake in the tumor was congruent with histological tumor extent in 31/33 animals. In 2 rats irradiated with 150 Gy, however, high ¹⁸F-FET uptake was noted in the area of astrogliosis which led to an overestimation of the tumor size.ConclusionsReactive astrogliosis in the vicinity of gliomas generally leads to only a slight ¹⁸F-FET-enrichment that appears not to affect the correct definition of tumor extent for treatment planning.     

Decrease in left atrium volume after successful balloon mitral valvuloplasty: an echocardiographic and hemodynamic study

Background: Left atrium (LA) remodeling has a crucial adverse impact on outcome and prognosis in mitral stenosis. Few studies have reported the effect of balloon mitral valvuloplasty (BMV) on LA volume. The aim of this study was to assess the evolution of LA volume immediately and 1 month after successful BMV in patients in sinus rhythm. Methods: Thirty‐three consecutive patients (70% women; age 31 ± 8 years; range 19–45) with moderate to severe mitral stenosis (mitral valve area ≤1.5 cm²) who underwent successful BMV were included prospectively. Using two‐dimensional echocardiography, and according to the prolate ellipse method, LA volume and LA volume indexed to body surface area were determined before BMV, and 24 hours and 1 month after BMV. Tricuspid and pulmonary regurgitation jets were recorded systematically using continuous‐wave Doppler. Pulmonary artery–right ventricular (PA–RV) gradients, reflecting pulmonary pressures, and pulmonary vascular resistance were measured. Results: Mitral valve area increased from 0.88 ± 0.16 to 1.55 ± 0.26 cm² (P < 0.0001). Mean mitral valve gradient (MVG) decreased from 16 ± 6 to 6 ± 2 mmHg (P < 0.0001) immediately after BMV. Indexed LA volume fell from 56 ± 14 to 48 ± 12 mL/m² (P = 0.0002) immediately after BMV and to 45 ± 13 mL/m² at 1 month (P < 0.0001). Only patients with a median LA volume ≥55 mL/m² before BMV had a significant reduction in LA volume (P = 0.0001). Decrease in LA volume was correlated with decreases in PA–RV peak diastolic gradient (r = 0.45, P = 0.008) and MVG (r = 0.35, P = 0.04). Conclusion: In patients with mitral stenosis in sinus rhythm, successful BMV results in an immediate decrease in LA volume. This reduction, maximal immediately after BMV, correlates with decreases in MVG and PA–RV peak diastolic gradient, and is significant only when LA volume before BMV is severely enlarged. (Echocardiography 2011;28:154‐160)