Whole body hypoxic preconditioning-mediated multiorgan protection in db/db mice via nitric oxide-BDNF-GSK-3β-Nrf2 signaling pathway

Yuefang Li,Yan Huang,Xi Cheng,Youjun He,Xin Hu 대한생리학회-대한약리학회 2021 The Korean Journal of Physiology & Pharmacology Vol.25 No.4

The beneficial effects of hypoxic preconditioning are abolished in the diabetes. The present study was designed to investigate the protective effects and mechanisms of repeated episodes of whole body hypoxic preconditioning (WBHP) in db/db mice. The protective effects of preconditioning were explored on diabetes-induced vascular dysfunction, cognitive impairment and ischemia-reperfusion (IR)-induced increase in myocardial injury. Sixteen-week old db/db (diabetic) and C57BL/6 (non-diabetic) mice were employed. There was a significant impairment in cognitive function (Morris Water Maze test), endothelial function (acetylcholine-induced relaxation in aortic rings) and a significant increase in IR-induced heart in-jury (Langendorff apparatus) in db/db mice. WBHP stimulus was given by exposing mice to four alternate cycles of low (8%) and normal air O2 for 10 min each. A single episode of WBHP failed to produce protection; however, two and three episodes of WBHP significantly produced beneficial effects on the heart, brain and blood vessels. There was a significant increase in the levels of brain-derived neurotrophic factor (BDNF) and nitric oxide (NO) in response to 3 episodes of WBHP. Moreover, pretreat-ment with the BDNF receptor, TrkB antagonist (ANA-12) and NO synthase inhibitor (L-NAME) attenuated the protective effects imparted by three episodes of WBHP. These pharmacological agents abolished WBHP-induced restoration of p-GSK-3β/GSK-3βratio and Nrf2 levels in IR-subjected hearts. It is concluded that repeated episodes of WHBP attenuate cognitive impairment, vascular dysfunction and enhancement in IR-induced myocardial injury in diabetic mice be due to increase in NO and BDNF levels that may eventually activate GSK-3β and Nrf2 signaling pathway to confer protec-tion.

INTERACTIONS OF THE INFRARED BUBBLE N4 WITH ITS SURROUNDINGS

Liu, Hong-Li,Li, Jin-Zeng,Wu, Yuefang,Yuan, Jing-Hua,Liu, Tie,Dubner, G.,Paron, S.,Ortega, M. E.,Molinari, Sergio,Huang, Maohai,Zavagno, Annie,Samal, Manash R.,Huang, Ya-Fang,Zhang, Si-Ju American Astronomical Society 2016 The Astrophysical journal Vol.818 No.1

<P>The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with H II regions have been considered to be good samples for investigating triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the H II. region G11.898+0.747, analyzing its interaction with its surroundings and star formation histories therein, with the aim of determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a wide wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 x 10(22) cm(-2), mean volume density of about 4.4 x 10(4) cm(-3), and a mean mass of 320M(circle dot). In addition, from PAH emission seen at 8 mu m, free-free emission detected at 20 cm, and a probability density function in special regions, we could identify clear signatures of the influence of the H II region on the surroundings. There are hints of star formation, though further investigation is required to demonstrate that N4 is the triggering source.</P>

A FEEDBACK-DRIVEN BUBBLE G24.136+00.436: A POSSIBLE SITE OF TRIGGERED STAR FORMATION

Liu, Hong-Li,Wu, Yuefang,Li, JinZeng,Yuan, Jing-Hua,Liu, Tie,Dong, Xiaoyi IOP Publishing 2015 The Astrophysical journal Vol.798 No.1

<P>We present a multi-wavelength study of the IR bubble G24.136+00.436. The J = 1-0 observations of (CO)-C-12, (CO)-C-13, and (CO)-O-18 were carried out with the Purple Mountain Observatory 13.7 m telescope. Molecular gas with a velocity of 94.8 km s(-1) is found prominently in the southeast of the bubble, shaped as a shell with a total mass of similar to 2 x 10(4) M-circle dot. It was likely assembled during the expansion of the bubble. The expanding shell consists of six dense cores, whose dense (a few of 10(3) cm(-3)) and massive (a few of 10(3) M-circle dot) characteristics coupled with the broad linewidths (>2.5 km s(-1)) suggest that they are promising sites for forming high-mass stars or clusters. This could be further consolidated by the detection of compact H II regions in Cores A and E. We tentatively identified and classified 63 candidate young stellar objects (YSOs) based on the Spitzer and UKIDSS data. They are found to be dominantly distributed in regions with strong molecular gas emission, indicative of active star formation, especially in the shell. The H II region inside the bubble is mainly ionized by a similar to O8V star(s), of the dynamical age of similar to 1.6 Myr. The enhanced number of candidate YSOs and secondary star formation in the shell as well as the timescales involved, indicate a possible scenario for triggering star formation, signified by the 'collect and collapse' process.</P>

A STUDY OF DYNAMICAL PROCESSES IN THE ORION KL REGION USING ALMA-PROBING MOLECULAR OUTFLOW AND INFLOW

Wu, Yuefang,Liu, Tie,Qin, Sheng-Li IOP Publishing 2014 The Astrophysical journal Vol.791 No.2

<P>This work reports high spatial resolution observations toward the Orion KL region with high critical density lines of CH3CN (124-114) and CH3OH (8-1,8-70,7), as well as a continuum at similar to 1.3 mm band. The observations were made using the Atacama Large Millimeter/Submillimeter Array with a spatial resolution of similar to 1.'' 5 and sensitivity of about 0.07 K and similar to 0.18 K for continuum and line, respectively. The observational results showed that the gas in the Orion KL region consists of jet-propelled cores at the ridge and dense cores east and south of the region that are shaped like a wedge ring. The outflow has multiple lobes, which may originate from an explosive ejection, and is not driven by young stellar objects. Four infrared bubbles were found in the Spitzer/IRAC emissions. These bubbles, the distributions of the previously found H-2 jets, the young stellar objects, and molecular gas suggest that BN is the explosive center. The burst time was estimated to be similar to 1300 yr. At the same time, signatures of gravitational collapse toward Source I and the hot core were detected with material infall velocities of 1.5 km s(-1) and similar to 0.6 km s(-1), corresponding to mass accretion rates of 1.2 x 10-3M(circle dot)/yr and 8.0 x 10-5M(circle dot)/yr, respectively. These observations may support the belief that high-mass stars form via the accretion model, similar to their low-mass counterparts.</P>

High-mass Star Formation through Filamentary Collapse and Clump-fed Accretion in G22

Yuan, Jinghua,Li, Jin-Zeng,Wu, Yuefang,Ellingsen, Simon P.,Henkel, Christian,Wang, Ke,Liu, Tie,Liu, Hong-Li,Zavagno, Annie,Ren, Zhiyuan,Huang, Ya-Fang American Astronomical Society 2018 The Astrophysical journal Vol.852 No.1

<P>How mass is accumulated from cloud-scale down to individual stars is a key open question in understanding highmass star formation. Here, we present the mass accumulation process in a hub-filament cloud G22 that is composed of four supercritical filaments. Velocity gradients detected along three filaments indicate that they are collapsing with a total mass infall rate of about 440M(circle dot) Myr(-1), suggesting the hub mass would be doubled in six free-fall times, adding up to similar to 2 Myr. A fraction of the masses in the central clumps C1 and C2 can be accounted for through large-scale filamentary collapse. Ubiquitous blue profiles in HCO+. (3-2) and (CO)-C-13. (3-2) spectra suggest a clump-scale collapse scenario in the most massive and densest clump C1. The estimated infall velocity and mass infall rate are 0.31 km s(-1) and 7.2 x. 10(-4)M(circle dot) yr(-1), respectively. In clump C1, a hot molecular core (SMA1) is revealed by the Submillimeter Array observations and an outflow-driving high-mass protostar is located at the center of SMA1. The mass of the protostar is estimated to be 11-15M(circle dot) and it is still growing with an accretion rate of 7 x. 10(-5)M(circle dot) yr(-1). The coexistent infall in filaments, clump C1, and the central hot core in G22 suggests that pre-assembled mass reservoirs (i.e., high-mass starless cores) may not be required to form high-mass stars. In the course of high-mass star formation, the central protostar, the core, and the clump can simultaneously grow in mass via core-fed/disk accretion, clump-fed accretion, and filamentary/cloud collapse.</P>

SMA OBSERVATIONS OF THE W3(OH) COMPLEX: PHYSICAL AND CHEMICAL DIFFERENTIATION BETWEEN W3(H₂O) AND W3(OH)

Qin, Sheng-Li,Schilke, Peter,Wu, Jingwen,Wu, Yuefang,Liu, Tie,Liu, Ying,Sá,nchez-Monge, Á,lvaro IOP Publishing 2015 The Astrophysical journal Vol.803 No.1

<P>We report on the Submillimeter Array (SMA) observations of molecular lines at 270 GHz toward the W3(OH) and W3(H2O) complex. Although previous observations already resolved the W3(H2O) into two or three subcomponents, the physical and chemical properties of the two sources are not well constrained. Our SMA observations clearly resolved the W3(OH) and W3(H2O) continuum cores. Taking advantage of the line fitting tool XCLASS, we identified and modeled a rich molecular spectrum in this complex, including multiple CH3CN and CH3OH transitions in both cores. HDO, C2H5CN, (OCS)-C-13, and vibrationally excited lines of HCN, CH3CN, and CH3OCHO were only detected in W3(H2O). We calculate gas temperatures and column densities for both cores. The results show that W3(H2O) has higher gas temperatures and larger column densities than W3(OH) as previously observed, suggesting physical and chemical differences between the two cores. We compare the molecular abundances in W3(H2O) to those in the Sgr B2(N) hot core, the Orion KL hot core, and the Orion Compact Ridge, and discuss the chemical origin of specific species. An east-west velocity gradient is seen in W3 (H2O), and the extension is consistent with the bipolar outflow orientation traced by water masers and radio jets. A north-south velocity gradient across W3(OH) is also observed. However, with current observations we cannot be assured whether the velocity gradients are caused by rotation, outflow, or radial velocity differences of the subcomponents of W3(OH).</P>

High-mass Starless Clumps in the Inner Galactic Plane: The Sample and Dust Properties

Yuan, Jinghua,Wu, Yuefang,Ellingsen, Simon P.,II, Neal J. Evans,Henkel, Christian,Wang, Ke,Liu, Hong-Li,Liu, Tie,Li, Jin-Zeng,Zavagno, Annie American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.231 No.1

<P>We report a sample of 463 high-mass starless clump (HMSC) candidates within -60 degrees < l < 60 degrees and -1 degrees < b < 1 degrees. This sample has been singled out from 10,861 ATLASGAL clumps. None of these sources are associated with any known star-forming activities collected in SIMBAD and young stellar objects identified using color-based criteria. We also make sure that the HMSC candidates have neither point sources at 24 and 70 mu m. nor strong extended emission at 24 mu m. Most of the identified HMSCs are infrared dark, and some are even dark at 70 mu m. Their distribution shows crowding in Galactic spiral arms and toward the Galactic center and some wellknown star-forming complexes. Many HMSCs are associated with large-scale filaments. Some basic parameters were attained from column density and dust temperature maps constructed via fitting far-infrared and submillimeter continuum data to modified blackbodies. The HMSC candidates have sizes, masses, and densities similar to clumps associated with Class II methanol masers and H. II. regions, suggesting that they will evolve into star-forming clumps. More than 90% of the HMSC candidates have densities above some proposed thresholds for forming high-mass stars. With dust temperatures and luminosity-to-mass ratios significantly lower than that for star-forming sources, the HMSC candidates are externally heated and genuinely at very early stages of high-mass star formation. Twenty sources with equivalent radii r(eq) < 0.15 pc and mass surface densities Sigma > 0.08 g cm(-2) could be possible high-mass starless cores. Further investigations toward these HMSCs would undoubtedly shed light on comprehensively understanding the birth of high-mass stars.</P>

FOLLOW-UP OBSERVATIONS TOWARD PLANCK COLD CLUMPS WITH GROUND-BASED RADIO TELESCOPES

LIU, TIE,WU, YUEFANG,MARDONES, DIEGO,KIM, KEE-TAE,MENTEN, KARL M.,TATEMATSU, KEN,CUNNINGHAM, MARIA,JUVELA, MIKA,ZHANG, QIZHOU,GOLDSMITH, PAUL F,LIU, SHENG-YUAN,ZHANG, HUA-WEI,MENG, FANYI,LI, DI,LO, NA The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

The physical and chemical properties of prestellar cores, especially massive ones, are still far from being well understood due to the lack of a large sample. The low dust temperature (< 14 K) of Planck cold clumps makes them promising candidates for prestellar objects or for sources at the very initial stages of protostellar collapse. We have been conducting a series of observations toward Planck cold clumps (PCCs) with ground-based radio telescopes. In general, when compared with other star forming samples (e.g. infrared dark clouds), PCCs are more quiescent, suggesting that most of them may be in the earliest phase of star formation. However, some PCCs are associated with protostars and molecular outflows, indicating that not all PCCs are in a prestellar phase. We have identified hundreds of starless dense clumps from a mapping survey with the Purple Mountain Observatory (PMO) 13.7-m telescope. Follow-up observations suggest that these dense clumps are ideal targets to search for prestellar objects.

ALMA Reveals Sequential High-mass Star Formation in the G9.62+0.19 Complex

Liu, Tie,Lacy, John,Li, Pak Shing,Wang, Ke,Qin, Sheng-Li,Zhang, Qizhou,Kim, Kee-Tae,Garay, Guido,Wu, Yuefang,Mardones, Diego,Zhu, Qingfeng,Tatematsu, Ken’ichi,Hirota, Tomoya,Ren, Zhiyuan,Liu, Sheng-Yu American Astronomical Society 2017 The Astrophysical journal Vol.849 No.1

<P>Stellar feedback from high-mass stars (e.g., H II regions) can strongly influence the surrounding interstellar medium and regulate star formation. Our new ALMA observations reveal sequential high-mass star formation taking place within one subvirial filamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense cores (MM1-MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to the UC H II region phase. Three dense cores (MM6, MM7/G, MM8/F) are associated with outflows. The mass-velocity diagrams of the outflows associated with MM7/G and MM8/F can be well-fit by broken power laws. The mass-velocity diagram of the SiO outflow associated with MM8/F breaks much earlier than other outflow tracers (e.g., CO, SO, CS, HCN), suggesting that SiO traces newly shocked gas, while the other molecular lines (e.g., CO, SO, CS, HCN) mainly trace the ambient gas continuously entrained by outflow jets. Five cores (MM1, MM3, MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M-circle dot, assuming a dust temperature of <= 20 K. The shocks from the expanding H II regions ('B' and 'C') to the west may have a great impact on the G9.62 clump by compressing it into a filament and inducing core collapse successively, leading to sequential star formation. Our findings suggest that stellar feedback from H II regions may enhance the star formation efficiency and suppress low-mass star formation in adjacent pre-existing massive clumps.</P>

The Properties of Planck Galactic Cold Clumps in the L1495 Dark Cloud

Tang, Mengyao,Liu, Tie,Qin, Sheng-Li,Kim, Kee-Tae,Wu, Yuefang,Tatematsu, Ken’ichi,Yuan, Jinghua,Wang, Ke,Parsons, Harriet,Koch, Patrick M.,Sanhueza, Patricio,Ward-Thompson, D.,Tó,th, L. Viktor,S American Astronomical Society 2018 The Astrophysical journal Vol.856 No.2