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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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- Veronese, N., et al.
(författare)
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Inverse relationship between body mass index and mortality in older nursing home residents : a meta-analysis of 19,538 elderly subjects
- 2015
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Ingår i: Obesity Reviews. - : Wiley. - 1467-7881 .- 1467-789X. ; 16:11, s. 1001-1015
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Forskningsöversikt (refereegranskat)abstract
- Body mass index (BMI) and mortality in old adults from the general population have been related in a U-shaped or J-shaped curve. However, limited information is available for elderly nursing home populations, particularly about specific cause of death. A systematic PubMed/EMBASE/CINAHL/SCOPUS search until 31 May 2014 without language restrictions was conducted. As no published study reported mortality in standard BMI groups (<18.5, 18.5-24.9, 25-29.9, 30kg/m(2)), the most adjusted hazard ratios (HRs) according to a pre-defined list of covariates were obtained from authors and pooled by random-effect model across each BMI category. Out of 342 hits, 20 studies including 19,538 older nursing home residents with 5,223 deaths during a median of 2 years of follow-up were meta-analysed. Compared with normal weight, all-cause mortality HRs were 1.41 (95% CI=1.26-1.58) for underweight, 0.85 (95% CI=0.73-0.99) for overweight and 0.74 (95% CI=0.57-0.96) for obesity. Underweight was a risk factor for higher mortality caused by infections (HR=1.65 [95% CI=1.13-2.40]). RR results corroborated primary HR results, with additionally lower infection-related mortality in overweight and obese than in normal-weight individuals. Like in the general population, underweight is a risk factor for mortality in old nursing home residents. However, uniquely, not only overweight but also obesity is protective, which has relevant nutritional goal implications in this population/setting.
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- Akiyama, Kazunori, et al.
(författare)
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First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
- 2022
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal and nonthermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 mu m, and in the X-ray. All models fail at least one constraint. Light-curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (magnetically arrested disk (MAD)) models and a large fraction of weakly magnetized models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination i <= 30 degrees. They have accretion rate (5.2-9.5) x 10(-9) M (circle dot) yr(-1), bolometric luminosity (6.8-9.2) x 10(35) erg s(-1), and outflow power (1.3-4.8) x 10(38) erg s(-1). We also find that all models with i >= 70 degrees fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, nonthermal model sets tend to have higher 2.2 mu m flux density; and the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally, we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.
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- Burdge, Kevin B., et al.
(författare)
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A 62-minute orbital period black widow binary in a wide hierarchical triple
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 605:7908, s. 41-45
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Tidskriftsartikel (refereegranskat)abstract
- Over a dozen millisecond pulsars are ablating low-mass companions in close binary systems. In the original 'black widow', the eight-hour orbital period eclipsing pulsar PSR J1959+2048 (PSR B1957+20)(1), high-energy emission originating from the pulsar2 is irradiating and may eventually destroy(3) a low-mass companion. These systems are not only physical laboratories that reveal the interesting results of exposing a close companion star to the relativistic energy output of a pulsar, but are also believed to harbour some of the most massive neutron stars(4), allowing for robust tests of the neutron star equation of state. Here we report observations of ZTF J1406+1222, a wide hierarchical triple hosting a 62-minute orbital period black widow candidate, the optical flux of which varies by a factor of more than ten. ZTF J1406+1222 pushes the boundaries of evolutionary models(5), falling below the 80-minute minimum orbital period of hydrogen-rich systems. The wide tertiary companion is a rare low-metallicity cool subdwarf star, and the system has a Galactic halo orbit consistent with passing near the Galactic Centre, making it a probe of formation channels, neutron star kick physics(6) and binary evolution.
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| 13. |
- Gan, H. Y., et al.
(författare)
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Reduction of droplet volume by controlling actuating waveforms in inkjet printing for micro-pattern formation
- 2009
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 19:5, s. 055010-
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Tidskriftsartikel (refereegranskat)abstract
- Inkjet printing has proven to be a promising and flexible process methodology for low cost and drop-on-demand pattern formation in small-scale production of micro-electro-mechanical systems. To optimize the micro-patterns formed by inkjet printing, an accurate control of droplet volume is essential and critical. In this study, an inkjet system with a nozzle driven by a circular piezoelectric element was used to explore the impact of different waveforms on droplet volume. The investigation into this study included the impact of unipolar, bipolar, M-shaped and W-shaped waveforms as well as the effects of their amplitudes and pulse durations. The inkjetting behavior of Newtonian and non-Newtonian fluids under different actuating waveforms was studied in order to obtain a maximum reduction in ejected droplet sizes. An effective reduction of droplet volume in the range of 50-80% was demonstrated. The results of inkjetting PEDOT ink on a polished silicon surface showed that a 50% reduction in line width was achieved.
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| 14. |
- Lok, Veeleah, et al.
(författare)
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Changes in anxiety and depression during the COVID-19 pandemic in the European population : A meta-analysis of changes and associations with restriction policies
- 2023
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Ingår i: European psychiatry. - 0924-9338 .- 1778-3585. ; 66:1
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Forskningsöversikt (refereegranskat)abstract
- Background. Early studies of common mental disorders (CMDs) during the COVID-19 pandemic mainly report increases; however, more recent findings have been mixed. Also, studies assessing the effects of restriction measures on CMDs show varied results. The aim of this meta-analysis was to assess changes in levels of CMDs from pre-/early to during the pandemic and the effects of restriction policies in the European population.Methods. We searched for studies assessing both pre-pandemic and peri-pandemic self-reported emotional distress and symptoms of depression or anxiety among nationally/regionally representative samples in Europe and collected microdata from those studies. Estimates of corona containment index were related to changes in CMDs using random-effects meta-regression.Results. Our search strategy resulted in findings from 15 datasets drawn from 8 European countries being included in the meta-analysis. There was no evidence of change in the prevalence of emotional distress, anxiety, or depression from before to during the pandemic; but from early pandemic periods to later periods, there were significant decreases in emotional distress and anxiety. Increased school restrictions and social distancing were associated with small increases in self-reported emotional distress.Conclusions. Despite initial concerns of increased emotional distress and mental illness due to the COVID-19 pandemic, the results from this meta-analysis indicate that there was a decrease in emotional distress and no change in anxiety or depression in the general population in Europe. Overall, our findings support the importance of strong governance when implementing periodic and robust restriction measures to combat the spread of COVID-19.
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- Vidal-Quadras, Maite, et al.
(författare)
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Endocytic turnover of Rab8 controls cell polarization
- 2017
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 130:6, s. 1147-1157
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Tidskriftsartikel (refereegranskat)abstract
- Adaptation of cell shape and polarization through the formation and retraction of cellular protrusions requires balancing of endocytosis and exocytosis combined with fine-tuning of the local activity of small GTPases like Rab8. Here, we show that endocytic turnover of the plasma membrane at protrusions is directly coupled to surface removal and inactivation of Rab8. Removal is induced by reduced membrane tension and mediated by the GTPase regulator associated with focal adhesion kinase-1 (GRAF1, also known as ARHGAP26), a regulator of clathrin-independent endocytosis. GRAF1-depleted cells were deficient in multi-directional spreading and displayed elevated levels of GTP-loaded Rab8, which was accumulated at the tips of static protrusions. Furthermore, GRAF1 depletion impaired lumen formation and spindle orientation in a 3D cell culture system, indicating that GRAF1 activity regulates polarity establishment. Our data suggest that GRAF1-mediated removal of Rab8 from the cell surface restricts its activity during protrusion formation, thereby facilitating dynamic adjustment of the polarity axis.
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| 18. |
- Yau, Wai-Lok, et al.
(författare)
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Model System for the Formation of Tick-Borne Encephalitis Virus Replication Compartments without Viral RNA Replication
- 2019
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Ingår i: Journal of Virology. - : AMER SOC MICROBIOLOGY. - 0022-538X .- 1098-5514. ; 93:18
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Tidskriftsartikel (refereegranskat)abstract
- Flavivirus is a positive-sense, single-stranded RNA viral genus, with members causing severe diseases in humans such as tick-borne encephalitis, yellow fever, and dengue fever. Flaviviruses are known to cause remodeling of intracellular membranes into small cavities, where replication of the viral RNA takes place. Nonstructural (NS) proteins are not part of the virus coat and are thought to participate in the formation of these viral replication compartments (RCs). Here, we used tick-borne encephalitis virus (TBEV) as a model for the flaviviruses and developed a stable human cell line in which the expression of NS proteins can be induced without viral RNA replication. The model system described provides a novel and benign tool for studies of the viral components under controlled expression levels. We show that the expression of six NS proteins is sufficient to induce infection-like dilation of the endoplasmic reticulum (ER) and the formation of RC-like membrane invaginations. The NS proteins form a membrane-associated complex in the ER, and electron tomography reveals that the dilated areas of the ER are closely associated with lipid droplets and mitochondria. We propose that the NS proteins drive the remodeling of ER membranes and that viral RNA, RNA replication, viral polymerase, and TBEV structural proteins are not required. IMPORTANCE TBEV infection causes a broad spectrum of symptoms, ranging from mild fever to severe encephalitis. Similar to other flaviviruses, TBEV exploits intracellular membranes to build RCs for viral replication. The viral NS proteins have been suggested to be involved in this process; however, the mechanism of RC formation and the roles of individual NS proteins remain unclear. To study how TBEV induces membrane remodeling, we developed an inducible stable cell system expressing the TBEV NS polyprotein in the absence of viral RNA replication. Using this system, we were able to reproduce RC-like vesicles that resembled the RCs formed in flavivirus-infected cells, in terms of morphology and size. This cell system is a robust tool to facilitate studies of flavivirus RC formation and is an ideal model for the screening of antiviral agents at a lower biosafety level.
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