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- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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- Teichert, M, et al.
(författare)
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Pericyte-expressed Tie2 controls angiogenesis and vessel maturation
- 2017
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8, s. 16106-
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Tidskriftsartikel (refereegranskat)abstract
- The Tie receptors with their Angiopoietin ligands act as regulators of angiogenesis and vessel maturation. Tie2 exerts its functions through its supposed endothelial-specific expression. Yet, Tie2 is also expressed at lower levels by pericytes and it has not been unravelled through which mechanisms pericyte Angiopoietin/Tie signalling affects angiogenesis. Here we show that human and murine pericytes express functional Tie2 receptor. Silencing of Tie2 in pericytes results in a pro-migratory phenotype. Pericyte Tie2 controls sprouting angiogenesis in in vitro sprouting and in vivo spheroid assays. Tie2 downstream signalling in pericytes involves Calpain, Akt and FOXO3A. Ng2-Cre-driven deletion of pericyte-expressed Tie2 in mice transiently delays postnatal retinal angiogenesis. Yet, Tie2 deletion in pericytes results in a pronounced pro-angiogenic effect leading to enhanced tumour growth. Together, the data expand and revise the current concepts on vascular Angiopoietin/Tie signalling and propose a bidirectional, reciprocal EC-pericyte model of Tie2 signalling.
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- Cortez, Daniel, et al.
(författare)
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Noninvasive predictors of perioperative atrial arrhythmias in patients with tetralogy of Fallot undergoing pulmonary valve replacement
- 2017
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Ingår i: Clinical Cardiology. - : Wiley. - 0160-9289. ; 40:8, s. 591-596
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with tetralogy of Fallot (TOF) have increased risk of atrial arrhythmias. Hypothesis: A measure of atrial dispersion, the P-wave vector magnitude (Pvm), can identify patients at risk for perioperative atrial flutter (AFL) or intra-atrial re-entrant tachycardia (IART) in a large TOF cohort. Methods: We performed a blinded, retrospective analysis of 158 TOF patients undergoing pulmonary valve replacement between 1997 and 2015. History of AFL/IART was documented using electrocardiogram, Holter monitor, exercise stress test, implanted cardiac device, and electrophysiology study. P-R intervals, Pvm, QRS duration, and QRS vector magnitude were assessed from resting sinus-rhythm 12-lead electrocardiograms and identification of those with AFL/IART was determined. Results: Fourteen patients (8.9%) were found to have AFL/IART. Pvm, QRS duration, and QRS vector magnitude significantly differentiated those with AFL/IART from those without on univariate analysis: 0.09±0.04 vs 0.18±0.07 mV, 161.3±21.9 vs 137.7±31.4ms, and 1.2 (interquartile range, 1.0-1.2) vs 1.6 mV (1.0-2.3), respectively (P < 0.05 for each). The Pvm had the highest area under the ROC curve (0.88) and was the only significant predictor on multivariate analysis, with odds ratio of 0.02 (95% confidence interval: 0.01-0.53). P-R duration, MRI volumes, and right-heart hemodynamics did not significantly differentiate those with vs those without AFL/IART. Conclusions: In TOF patients undergoing pulmonary valve replacement, Pvm has significant value in predicting those with perioperative AFL/IART. These clinical features may help further evaluate TOF patients at risk for perioperative atrial arrhythmias. Prospective studies are warranted.
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- Cortez, Daniel, et al.
(författare)
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Noninvasive Predictors of Ventricular Arrhythmias in Patients With Tetralogy of Fallot Undergoing Pulmonary Valve Replacement
- 2017
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Ingår i: JACC: Clinical Electrophysiology. - : Elsevier BV. - 2405-500X. ; 3:2, s. 162-170
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This study sought to test the hypothesis that a vectorcardiographic parameter, the QRS vector magnitude (QRSVm), can risk stratify those patients at risk for sustained spontaneous ventricular arrhythmias (VAs) or ventricular arrhythmia inducibility (VAI) in a large cohort of patients with tetralogy of Fallot (TOF). Background: Patients with TOF have an increased risk of VAs, but predicting those at risk can often be challenging. Methods: Blinded retrospective analyses of 177 TOF patients undergoing pulmonary valve replacement (PVR) between 1997 and 2015 were performed. VAI was evaluated by programmed electrical stimulation in 48 patients. QRS intervals and QRSVm voltage measurements were assessed from resting 12-lead electrocardiograms, and risk of VA was determined. Clinical characteristics, including imaging and cardiac catheterizations, were used for other modality comparisons. Results: Sustained spontaneous VA occurred in 12 patients and inducible VA in 18 patients. Age and QRSVm were significant univariate predictors of VA. QRSVm was the only independent predictor of VAI (p < 0.001). Using a root mean square QRS value of 1.24 mV, the positive and negative predictive values were 47.9% and 97.8%, respectively, for spontaneous sustained VA. For VAI, using a QRSVm cutoff of 1.31 mV, positive and negative predictive values were 63.0% and 95.3%, respectively. Conclusions: In TOF patients undergoing PVR, older age was associated with increased spontaneous VA risk. Lower QRSVm predicted spontaneous VA or VAI risk with high negative predictive values. QRSVm is the only independent predictor of VAI. These clinical features may help further risk stratify TOF patients requiring therapies to prevent sudden death.
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