Agrawal A, Guttapalli A, Narayan S, Albert TJ, Shapiro IM, Risbud MV. Normoxic stabilization of HIF-1␣ drives glycolytic metabolism and regulates aggrecan gene expression in nucleus pulposus cells of the rat intervertebral disk. Am J Physiol Cell Physiol 293: C621-C631, 2007. First published April 18, 2007; doi:10.1152/ajpcell.00538.2006.-The nucleus pulposus is an aggrecan-rich, avascular tissue that permits the intervertebral disk to resist compressive loads. In the disk, nucleus pulposus cells express hypoxia-inducible factor (HIF)-1␣, a transcription factor that responds to oxygen tension and regulates glycolysis. The goal of the present study was to examine the importance of HIF-1␣ in rat nucleus pulposus cells and to probe the function of this transcription factor in terms of regulating aggrecan gene expression. We found that HIF-1␣ protein levels and mRNA stability were similar at 20 and 2% O2; there was a small, but significant increase in HIF-1␣ transactivation domain activity in hypoxia. With respect to HIF-1␣ target genes GAPDH, GLUT-1, and GLUT-3, mRNA and protein levels were independent of the oxygen tension. Other than a modest increase in 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase reporter activity, the oxemic state did not change GAPDH, GLUT-1, and GLUT-3 promoter activities. Treatment of cells with 2-deoxyglucose (2-DG), a glycolytic inhibitor, resulted in a significant suppression in ATP synthesis in normoxia, whereas treatment with mitochondrial inhibitors did not affect ATP production and cell viability. However, measurement of the rate of fatty acid oxidation indicated that these cells contained functioning mitochondria. Finally, we showed that when HIF-1␣ was suppressed, irrespective of the oxemic state, there was a partial loss of aggrecan expression and promoter activity. Moreover, when cells were treated with 2-DG, there was inhibition in aggrecan promoter activity. Results of this study indicate that oxygen-independent stabilization of HIF-1␣ in nucleus pulposus cells is a metabolic adaptation that drives glycolysis and aggrecan expression. hypoxia; hypoxia-inducible factor-1␣ THE LOCAL OXYGEN TENSION promotes cellular differentiation and regulates tissue energy metabolism. When the oxygen tension is low, there is almost complete reliance on glycolysis to generate ATP and reducing equivalents (12,29,30). In specialized tissues such as the intervertebral disk, the mechanism by which cells conserve energy has received little attention. Nonetheless, it is known that in the intervertebral disk, the nucleus pulposus has no direct vascular supply (8,24,33), and ATP is probably generated by anaerobic glycolysis (1, 10). The dependence on glycolysis reflects the low oxygen tension in the disk, which has been reported to be low as low as 2%, and the observation that modulation in the oxygen supply can cause vertebral defects (15). Regulation of glycolysis is mediated by hypoxia-inducible factor (HIF)-1␣, a transcription factor that responds to the local oxygen tension, and has been show...
PurposeCatheters and guidewires are used extensively in cardiac catheterization procedures such as heart arrhythmia treatment (ablation), angioplasty, and congenital heart disease treatment. Detecting their positions in fluoroscopic X‐ray images is important for several clinical applications, for example, motion compensation, coregistration between 2D and 3D imaging modalities, and 3D object reconstruction.MethodsFor the generalized framework, a multiscale vessel enhancement filter is first used to enhance the visibility of wire‐like structures in the X‐ray images. After applying adaptive binarization method, the centerlines of wire‐like objects were extracted. Finally, the catheters and guidewires were detected as a smooth path which is reconstructed from centerlines of target wire‐like objects. In order to classify electrode catheters which are mainly used in electrophysiology procedures, additional steps were proposed. First, a blob detection method, which is embedded in vessel enhancement filter with no additional computational cost, localizes electrode positions on catheters. Then the type of electrode catheters can be recognized by detecting the number of electrodes and also the shape created by a series of electrodes. Furthermore, for detecting guiding catheters or guidewires, a localized machine learning algorithm is added into the framework to distinguish between target wire objects and other wire‐like artifacts. The proposed framework were tested on total 10,624 images which are from 102 image sequences acquired from 63 clinical cases.ResultsDetection errors for the coronary sinus (CS) catheter, lasso catheter ring and lasso catheter body are 0.56 ± 0.28 mm, 0.64 ± 0.36 mm, and 0.66 ± 0.32 mm, respectively, as well as success rates of 91.4%, 86.3%, and 84.8% were achieved. Detection errors for guidewires and guiding catheters are 0.62 ± 0.48 mm and success rates are 83.5%.ConclusionThe proposed computational framework do not require any user interaction or prior models and it can detect multiple catheters or guidewires simultaneously and in real‐time. The accuracy of the proposed framework is sub‐mm and the methods are robust toward low‐dose X‐ray fluoroscopic images, which are mainly used during procedures to maintain low radiation dose.
UPJO causes hydronephrosis and progressive renal impairment may ensue if left uncorrected. Open pyeloplasty remains the standard against which new technique must be compared. We analyzed the comparison of Laparoscopic and open pyeloplasty in a randomized prospective trial. A prospective randomized study was done from January 2004 to January 2007 in which a total of 28 Laparoscopic and 34 open pyeloplasty were done. All laparoscopic pyeloplasties were performed transperitoneally. Standard open Anderson Hynes pyeloplasty, spiral flap or VY plasty was done depending on anatomic consideration. Patients were followed with DTPA scan at 3 months and IVP at 6 months. Perioperative parameters including operative time, analgesic use, hospital stay, and complication and success rates were compared. Mean total operative time with stent placement in LP group was 244.2 min (188-300 min) compared to 122 min (100-140 min) in open group. Compared to open pyeloplasty the post operative diclofenac requirement was significantly less in LP group (mean107.14 mg) and open group required mean of (682.35 mg) The duration of analgesic requirement was also significantly less in LP group. The post operative hospital stay in LP was mean 8.29 days (7-11) and was significantly less than open group (mean 3.14 Days (2-7 days). Open pyeloplasty has been the gold standard for UPJO repair and achieves success rates exceeding 90%. Laparoscopic pyeloplasty provides a minimally invasive alternative to repair UPJO and has developed world wide as the first minimally option to match success rate of open pyeloplasty. Its potential advantages including less post op pain, shorter hospital stay an improved cosmesis has been proved in some comparative series. The only disadvantage seems to be longer operative time. LP has a minimal level of morbidity and short hospital stay compared to open approach Although Laparoscopic pyeloplasty has the disadvantages of longer operative time and requires significant skill of intracorporeal knotting but it is here to stay and represents an emerging standard of care.
The materials available for the Right Ventricular Outflow Tract (RVOT) reconstruction in patients with Tetralogy of Fallot (TOF)/pulmonary atresia come with the severe limitation of long-term degeneration and lack of growth potential, causing right ventricular dysfunction, aneurysm formation and arrhythmias, thus necessitating several high-risk reoperations throughout patients' life.In this study, we evaluated the capacity of Mesenchymal Stem Cells (MSCs) derived from the Wharton's Jelly (WJ-MSCs), the gelatinous inner portion of the umbilical cord, to grow and recellularize an extracellular matrix (ECM) graft in our optimised xeno-free, good manufacturing practice-compliant culture system. WJ-MSCs were phenotypically and functionally characterised by flow cytometry and multi-lineage differentiation capacity, respectively. The typical MSCs immunophenotype and functional characteristics were retained in our xeno-free culture system, as well as the capacity to grow and engraft onto a naturally occurring scaffold. Wharton's Jelly MSCs, from both human and swine source, showed excellent capacity to recellularize ECM graft producing a living cell-seeded construct.In addition, we have provided an in vivo proof of concept of feasibility of the cellularised conduit, engineered with swine Wharton's Jelly MSCs, to be used in a novel porcine model of main pulmonary artery reconstruction, where it showed good integration within the host tissue.Our study indicates that the addition of WJ-MSCs to the ECM scaffold can upgrade the material, converting it into a living tissue, with the potential to grow, repair and remodel the RVOT. These results could potentially represent a paradigm shift in paediatric cardiac intervention towards new modalities for effective and personalised surgical restoration of pulmonary artery and RVOT function in TOF/pulmonary atresia patients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.