| 1. |
- Anderberg, C., et al.
(författare)
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Deficiency for endoglin in tumor vasculature weakens the endothelial barrier to metastatic dissemination
- 2013
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 210:3, s. 563-579
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Tidskriftsartikel (refereegranskat)abstract
- Therapy-induced resistance remains a significant hurdle to achieve long-lasting responses and cures in cancer patients. We investigated the long-term consequences of genetically impaired angiogenesis by engineering multiple tumor models deprived of endoglin, a co-receptor for TGF-β in endothelial cells actively engaged in angiogenesis. Tumors from endoglin-deficient mice adapted to the weakened angiogenic response, and refractoriness to diminished endoglin signaling was accompanied by increased metastatic capability. Mechanistic studies in multiple mouse models of cancer revealed that deficiency for endoglin resulted in a tumor vasculature that displayed hallmarks of endothelial-to-mesenchymal transition, a process of previously unknown significance in cancer biology, but shown by us to be associated with a reduced capacity of the vasculature to avert tumor cell intra- and extravasation. Nevertheless, tumors deprived of endoglin exhibited a delayed onset of resistance to anti-VEGF (vascular endothelial growth factor) agents, illustrating the therapeutic utility of combinatorial targeting of multiple angiogenic pathways for the treatment of cancer.
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| 2. |
- Biver, N., et al.
(författare)
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Coma composition of comet 67P/Churyumov-Gerasimenko from radio-wave spectroscopy
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 672
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of a molecular survey of comet 67P/Churyumov-Gerasimenko undertaken with the Institut de RadioAstronomie Millimétrique (IRAM) 30-m radio telescope in November–December 2021, when it had its most favourable apparition in decades. Observations at IRAM 30-m during the 12–16 November period covered 8 GHz bandwidth at 3 mm, 16 GHz at 2 mm, and 60 GHz in the 1 mm window domain. These were completed by snapshots at 1 mm on 12–13 December and a short observation of the H2O line at 557 GHz with the Odin sub-millimetre observatory on 17.0 November 2021, and with 18-cm observations of OH with the Nançay radio telescope. Less sensitive observations obtained at a previous perihelion passage on 18–22 September 2015 with IRAM and 9–12 November 2015 with Odin are also presented. The gas outflow velocity, outgassing pattern, and temperature have been accurately constrained by the observations. They are perfectly consistent with those measured in situ with the Rosetta/MIRO sub-millimetre instrument in 2015. In particular, the asymmetry of the line is well represented by a jet concentrating three-quarters of the outgassing in about π steradians. We derived abundances relative to water for seven molecules and significant upper limits for approximately five others. The retrieved abundances were compared to those measured in situ at the previous perihelion with Rosetta. While those of HCN, CH3OH, and HNCO are comparable, 67P is found to be depleted in H2S and relatively normal in CS (H2S/CS ≈ 3) in strong contradiction with the Rosetta/ROSINA mass spectrometer measurement of the H2S/CS2 (≈100) abundance ratio. While the formaldehyde total abundance found with IRAM 30-m when assuming it to be mostly produced by a distributed source (Haser parent scale length ≈8000 km) is similar to the one derived by Rosetta/ROSINA, we find that the formaldehyde coming from the nucleus is one order of magnitude less abundant than measured in situ by Rosetta/ROSINA.
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| 3. |
- Desai, R. T., et al.
(författare)
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Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan's Ionosphere
- 2017
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 844:2
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Tidskriftsartikel (refereegranskat)abstract
- Cassini discovered a plethora of neutral and ionized molecules in Titan's ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q-1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950-1300 km. We report on detections consistently centered between 25.8 and 26.0 u q-1 and between 49.0-50.1 u q(-1) which are identified as belonging to the carbon chain anions, CN-/C3N- and/or C2H-/C4H-, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73-74 u q-1 could be attributed to the further carbon chain anions C5N-/C6H- but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at > 100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below < 1100 km, the low-mass anions (< 150 u q-1) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.
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| 4. |
- Patat, F., et al.
(författare)
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Multi epoch high resolution spectroscopy of sn 2011fe linking the progenitor to its environment
- 2013
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 549, s. A62-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. The nearby Type Ia supernova (SN) 2011fe has provided an unprecedented opportunity for deriving some of the properties of its progenitor. This work provides additional and independent information on the circumstellar environment in which the explosion took place. Methods. We obtained high-resolution spectroscopy of SN 2011fe for 12 epochs, from 8 to 86 days after the estimated date of explosion, testing in particular the time evolution of Ca II and Na I. Results. Three main absorption systems are identified from Ca II and Na I, one associated to the Milky Way, one probably arising within a high-velocity cloud, and one most likely associated to the halo of M101. The total (Galactic and host galaxy) reddening, deduced from the integrated equivalent widths (EW) of the Na I lines, is EB-V less than or similar to 0.05 mag. The host galaxy absorption is dominated by a component detected at the same velocity measured from the 21-cm H 1 line at the projected SN position (similar to 180 km s(-1)). During the similar to 3 months covered by our observations its EW peak-to-peak variation is 15.6 +/- 6.5 m angstrom. This small and marginally significant change is shown to be compatible with the geometric effects produced by the rapid SN photosphere expansion coupled to the patchy fractal structure of the interstellar medium (ISM). The observed behavior is fully consistent with ISM properties similar to those derived for our own Galaxy, with evidences for structures on scales less than or similar to 100 AU. Conclusions. SN 2011fe appears to be surrounded by a clean environment. The lack of blueshifted, time-variable absorption features is fully consistent with the progenitor being a binary system with a main-sequence, or even another degenerate star.
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| 5. |
- Cordiner, M. A., et al.
(författare)
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On the Nature of the Enigmatic Object IRAS 19312+1950: A Rare Phase of Massive Star Formation?
- 2016
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 828:1
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Tidskriftsartikel (refereegranskat)abstract
- IRAS 19312+1950 is a peculiar object that has eluded firm characterization since its discovery, with combined maser properties similar to an evolved star and a young stellar object (YSO). To help determine its true nature, we obtained infrared spectra of IRAS 19312+1950 in the range 5–550 μm using the Herschel and Spitzer space observatories. The Herschel PACS maps exhibit a compact, slightly asymmetric continuum source at 170 μm, indicative of a large, dusty circumstellar envelope. The far-IR CO emission line spectrum reveals two gas temperature components: ≈0.22 solar masses of material at 280 ± 18 K, and ≈1.6 solar masses of material at 157 ± 3 K. The O i 63 μm line is detected on-source but no significant emission from atomic ions was found. The HIFI observations display shocked, high-velocity gas with outflow speeds up to 90 km/s along the line of sight. From Spitzer spectroscopy, we identify ice absorption bands due to H2O at 5.8 μm and CO2 at 15 μm. The spectral energy distribution is consistent with a massive, luminous (~2 × 10^4 solar luminosities) central source surrounded by a dense, warm circumstellar disk and envelope of total mass ~500–700 solar masses, with large bipolar outflow cavities. The combination of distinctive far-IR spectral features suggest that IRAS 19312+1950 should be classified as an accreting, high-mass YSO rather than an evolved star. In light of this reclassification, IRAS 19312+1950 becomes only the fifth high-mass protostar known to exhibit SiO maser activity, and demonstrates that 18 cm OH maser line ratios may not be reliable observational discriminators between evolved stars and YSOs.
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| 6. |
- Cordiner, M. A., et al.
(författare)
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Organic chemistry of low-mass star-forming cores I: 7 mm spectroscopy of Chamaeleon MMS1
- 2012
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 744, s. 131-
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Tidskriftsartikel (refereegranskat)abstract
- Observations are presented of emission lines from organic molecules at frequencies 32-50 GHz in the vicinity of Chamaeleon MMS1. This chemically rich dense cloud core harbors an extremely young, very low luminosity protostellar object and is a candidate first hydrostatic core. Column densities are derived and emission maps are presented for species including polyynes, cyanopolyynes, sulphuretted carbon chains, and methanol. The polyyne emission peak lies about 5000 AU from the protostar, whereas methanol peaks about 15,000 AU away. Averaged over the telescope beam, the molecular hydrogen number density is calculated to be 106 cm–3 and the gas kinetic temperature is in the range 5-7 K. The abundances of long carbon chains are very large and are indicative of a non-equilibrium carbon chemistry; C6H and HC7N column densities are 5.9+2.9 –1.3 × 1011 cm–2 and 3.3+8.0 –1.5 × 1012 cm–2, respectively, which are similar to the values found in the most carbon-chain-rich protostars and prestellar cores known, and are unusually large for star-forming gas. Column density upper limits were obtained for the carbon-chain anions C4H– and C6H–, with anion-to-neutral ratios [C4H–]/[C4H]
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| 7. |
- Zhang, Chenghui, et al.
(författare)
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Circulating Tissue Factor-Positive Procoagulant Microparticles in Patients with Type 1 Diabetes
- 2019
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Ingår i: Diabetes, Metabolic Syndrome and Obesity. - : DOVE MEDICAL PRESS LTD. - 1178-7007. ; 12, s. 2819-2828
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To investigate the count of circulating tissue factor-positive (TF+) procoagulant microparticles (MPs) in patients with type 1 diabetes mellitus (T1DM).Methods: This case-control study included patients with T1DM and age and sex-matched healthy volunteers. The counts of phosphatidylserine-positive (PS+) MPs and TF(+)PS(+)MPs and the subgroups derived from different cell types were measured in the peripheral blood sample of the two groups using multicolor flow cytometric assay. We compared the counts of each MP between groups as well as the ratio of the TF(+)PS(+)MPs and PS(+)MPs (TF(+)PS(+)MPs/PS(+)MPs).Results: We recruited 36 patients with T1DM and 36 matched healthy controls. Compared with healthy volunteers, PS(+)MPs, TF(+)PS(+)MPs and TF(+)PS(+)MPs/PS(+)MPs were elevated in patients with T1DM (PS(+)MPs: 1078.5 +/- 158.08 vs 686.84 +/- 122.04/mu L, P <0.001; TF(+)PS(+)MPs: 202.10 +/- 47.47 vs 108.33 +/- 29.42/mu L, P <0.001; and TF(+)PS(+)MPs/PS(+)MPs: 0.16 +/- 0.04 vs 0.19 +/- 0.05, P = 0.004), mostly derived from platelet, lymphocytes and endothelial cells. In the subgroup analysis, the counts of total and platelet TF(+)PS(+)MPs were increased in patients with diabetic retinopathy (DR) and with higher HbA1c, respectively.Conclusion: Circulating TF(+)PS(+)MPs and those derived from platelet, lymphocytes and endothelial cells were elevated in patients with T1DM.
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