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Tartaglia G, Fuentes I, Patel N, Varughese A, Israel LE, Park PH, Alexander MH, Poojan S, Cao Q, Solomon B, Padron ZM, Dyer JA, Mellerio JE, McGrath JA, Palisson F, Salas-Alanis J, Han L, South AP. Antiviral drugs prolong survival in murine recessive dystrophic epidermolysis bullosa. EMBO Mol Med 2024; 16:870-884. [PMID: 38462666 PMCID: PMC11018630 DOI: 10.1038/s44321-024-00048-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 03/12/2024] Open
Abstract
Recessive dystrophic epidermolysis bullosa (RDEB) is a rare inherited skin disease characterized by defects in type VII collagen leading to a range of fibrotic pathologies resulting from skin fragility, aberrant wound healing, and altered dermal fibroblast physiology. Using a novel in vitro model of fibrosis based on endogenously produced extracellular matrix, we screened an FDA-approved compound library and identified antivirals as a class of drug not previously associated with anti-fibrotic action. Preclinical validation of our lead hit, daclatasvir, in a mouse model of RDEB demonstrated significant improvement in fibrosis as well as overall quality of life with increased survival, weight gain and activity, and a decrease in pruritus-induced hair loss. Immunohistochemical assessment of daclatasvir-treated RDEB mouse skin showed a reduction in fibrotic markers, which was supported by in vitro data demonstrating TGFβ pathway targeting and a reduction of total collagen retained in the extracellular matrix. Our data support the clinical development of antivirals for the treatment of patients with RDEB and potentially other fibrotic diseases.
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Affiliation(s)
- Grace Tartaglia
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ignacia Fuentes
- DEBRA Chile, Santiago, Chile
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Genética y Genómica, Facultad de Medicina Clínica Alemana, Universidad de Desarrollo, Santiago, Chile
| | - Neil Patel
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Abigail Varughese
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Lauren E Israel
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Pyung Hun Park
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael H Alexander
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Shiv Poojan
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Qingqing Cao
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Brenda Solomon
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Zachary M Padron
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jonathan A Dyer
- Department of Dermatology, University of Missouri School of Medicine, Columbia, MO, USA
| | - Jemima E Mellerio
- St. John's Institute of Dermatology, King's College London (Guy's Campus), London, UK
| | - John A McGrath
- St. John's Institute of Dermatology, King's College London (Guy's Campus), London, UK
| | - Francis Palisson
- DEBRA Chile, Santiago, Chile
- Servicio de Dermatologia, Facultad de Medicina Clínica Alemana-Universidad de Desarrollo, Santiago, Chile
| | | | - Lin Han
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Andrew P South
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, PA, USA.
- The Joan and Joel Rosenbloom Research Center for Fibrotic Diseases, Thomas Jefferson University, Philadelphia, PA, USA.
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA.
- Department of Otolaryngology Head and Neck Surgery, Thomas Jefferson University, Philadelphia, PA, USA.
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Alexander MH, Cousins WJ, Ewen T, South AP, Lovat P, Stefanos N. The combined immunohistochemical expression of AMBRA1 and SQSTM1 identifies patients with poorly differentiated cutaneous squamous cell carcinoma at risk of metastasis: A proof of concept study. J Cutan Pathol 2024. [PMID: 38421158 DOI: 10.1111/cup.14590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 12/22/2023] [Accepted: 01/09/2024] [Indexed: 03/02/2024]
Abstract
BACKGROUND Cutaneous squamous cell carcinoma (cSCC) incidence continues to increase globally with, as of yet, an unmet need for reliable prognostic biomarkers to identify patients at increased risk of metastasis. The aim of the present study was to test the prognostic potential of the combined immunohistochemical expression of the autophagy regulatory biomarkers, AMBRA1 and SQSTM1, to identify high-risk patient subsets. METHODS A retrospective cohort of 68 formalin-fixed paraffin-embedded primary cSCCs with known 5-year metastatic outcomes were subjected to automated immunohistochemical staining for AMBRA1 and SQSTM1. Digital images of stained slides were annotated to define four regions of interest: the normal and peritumoral epidermis, the tumor mass, and the tumor growth front. H-score analysis was used to semi-quantify AMBRA1 or SQSTM1 expression in each region of interest using Aperio ImageScope software, with receiver operator characteristics and Kaplan-Meier analysis used to assess prognostic potential. RESULTS The combined loss of expression of AMBRA1 in the tumor growth front and SQSTM1 in the peritumoral epidermis identified patients with poorly differentiated cSCCs at risk of metastasis (*p < 0.05). CONCLUSIONS Collectively, these proof of concept data suggest loss of the combined expression of AMBRA1 in the cSCC growth front and SQSTM1 in the peritumoral epidermis as a putative prognostic biomarker for poorly differentiated cSCC.
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Affiliation(s)
- Michael H Alexander
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- AMLo Biosciences, Newcastle Helix, Newcastle upon Tyne, Newcastle upon Tyne, UK
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - William J Cousins
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- AMLo Biosciences, Newcastle Helix, Newcastle upon Tyne, Newcastle upon Tyne, UK
| | - Tom Ewen
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- AMLo Biosciences, Newcastle Helix, Newcastle upon Tyne, Newcastle upon Tyne, UK
| | - Andrew P South
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Penny Lovat
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- AMLo Biosciences, Newcastle Helix, Newcastle upon Tyne, Newcastle upon Tyne, UK
| | - Niki Stefanos
- Cellular Pathology, Addenbrookes Hospital, Cambridge, UK
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Tartaglia G, Park PH, Alexander MH, Nyström A, Rosenbloom J, South AP. Trametinib-Induced Epidermal Thinning Accelerates a Mouse Model of Junctional Epidermolysis Bullosa. Biomolecules 2023; 13:biom13050740. [PMID: 37238610 DOI: 10.3390/biom13050740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/20/2023] [Accepted: 04/23/2023] [Indexed: 05/28/2023] Open
Abstract
Junctional epidermolysis bullosa (JEB) patients experience skin and epithelial fragility due to a pathological deficiency in genes associated with epidermal adhesion. Disease severity ranges from post-natal lethality to localized skin involvement with persistent blistering followed by granulation tissue formation and atrophic scarring. We evaluated the potential of utilizing Trametinib, an MEK inhibitor previously shown to target fibrosis, with and without the documented EB-anti-fibrotic Losartan for reducing disease severity in a mouse model of JEB; Lamc2jeb mice. We found that Trametinib treatment accelerated disease onset and decreased epidermal thickness, which was in large part ameliorated by Losartan treatment. Interestingly, a range of disease severity was observed in Trametinib-treated animals that tracked with epidermal thickness; those animals grouped with higher disease severity had thinner epidermis. To examine if the difference in severity was related to inflammation, we conducted immunohistochemistry for the immune cell markers CD3, CD4, CD8, and CD45 as well as the fibrotic marker αSMA in mouse ears. We used a positive pixel algorithm to analyze the resulting images and demonstrated that Trametinib caused a non-significant reduction in CD4 expression that inversely tracked with increased fibrotic severity. With the addition of Losartan to Trametinib, CD4 expression was similar to control. Together, these data suggest that Trametinib causes a reduction in both epidermal proliferation and immune cell infiltration/proliferation, with concurrent acceleration of skin fragility, while Losartan counteracts Trametinib's adverse effects in a mouse model of JEB.
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Affiliation(s)
- Grace Tartaglia
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Pyung Hun Park
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Michael H Alexander
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Alexander Nyström
- Department of Dermatology, Medical Faculty, Medical Center-University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Joel Rosenbloom
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
- The Joan and Joel Rosenbloom Research Center for Fibrotic Diseases, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Andrew P South
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
- The Joan and Joel Rosenbloom Research Center for Fibrotic Diseases, Thomas Jefferson University, Philadelphia, PA 19107, USA
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Laskowski MR, Michael TJ, Ogden HM, Alexander MH, Mullin AS. Rotational energy transfer kinetics of optically centrifuged CO molecules investigated through transient IR spectroscopy and master equation simulations. Faraday Discuss 2022; 238:87-102. [DOI: 10.1039/d2fd00068g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A combined experimental and theoretical study of quantum state-resolved rotational energy transfer kinetics of optically centrifuged CO molecules is presented. In the experiments, inverted rotational distributions of CO in rotational...
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Nichols B, Chadwick H, Gordon SDS, Eyles CJ, Hornung B, Brouard M, Alexander MH, Aoiz FJ, Gijsbertsen A, Stolte S. Steric effects and quantum interference in the inelastic scattering of NO(X) + Ar. Chem Sci 2015; 6:2202-2210. [PMID: 28694950 PMCID: PMC5485563 DOI: 10.1039/c4sc03842h] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 02/03/2015] [Indexed: 11/21/2022] Open
Abstract
New measurements of the differential steric effect for NO + Ar inelastic scattering highlight the importance of quantum interference.
Rotationally inelastic collisions of NO(X) with Ar are investigated in unprecedented detail using state-to-state, crossed molecular beam experiments. The NO(X) molecules are selected in the Ω = 0.5, j = 0.5, f state and then oriented such that either the ‘N’ or ‘O’ end of the molecule is directed towards the incoming Ar atom. Velocity map ion imaging is then used to probe the scattered NO molecules in well-defined quantum states. We show that the fully quantum state-resolved differential steric asymmetry, which quantifies how the relative efficiency for scattering off the ‘O’ and the ‘N’ ends of the molecule varies with scattering angle, is strongly affected by quantum interference. Significant changes in both integral and differential cross sections are found depending on whether collisions occur with the N or O ends of the molecule. The results are well accounted for by rigorous quantum mechanical calculations, in contrast to both classical trajectory calculations and more simplistic models that provide, at best, an incomplete picture of the dynamics.
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Affiliation(s)
- B Nichols
- The Department of Chemistry , University of Oxford , The Physical and Theoretical Chemistry Laboratory , South Parks Road , Oxford , OX1 3QZ , United Kingdom .
| | - H Chadwick
- The Department of Chemistry , University of Oxford , The Physical and Theoretical Chemistry Laboratory , South Parks Road , Oxford , OX1 3QZ , United Kingdom .
| | - S D S Gordon
- The Department of Chemistry , University of Oxford , The Physical and Theoretical Chemistry Laboratory , South Parks Road , Oxford , OX1 3QZ , United Kingdom .
| | - C J Eyles
- The Department of Chemistry , University of Oxford , The Physical and Theoretical Chemistry Laboratory , South Parks Road , Oxford , OX1 3QZ , United Kingdom .
| | - B Hornung
- The Department of Chemistry , University of Oxford , The Physical and Theoretical Chemistry Laboratory , South Parks Road , Oxford , OX1 3QZ , United Kingdom .
| | - M Brouard
- The Department of Chemistry , University of Oxford , The Physical and Theoretical Chemistry Laboratory , South Parks Road , Oxford , OX1 3QZ , United Kingdom .
| | - M H Alexander
- Department of Chemistry and Biochemistry and Institute of Physical Science and Technology , University of Maryland , College Park , MD 20742 , USA .
| | - F J Aoiz
- Departamento de Química Física , Facultad de Química , Universidad Complutense , 28040 Madrid , Spain .
| | - A Gijsbertsen
- Institute for Lasers, Life and Biophotonics , Vrije Universiteit , de Boelelaan 1083 , Amsterdam 1081 HV , The Netherlands
| | - S Stolte
- Institute of Atomic and Molecular Physics , Jilin University , Changchun 130012 , China . .,Department of Physics and Astronomy , LaserLaB , Vrije Universiteit , de Boelelaan 1083 , Amsterdam 1081 HV , The Netherlands.,Laboratoire Francis Perrin , Bâtiment 522, DRECEM/SPAM/CEA Saclay , 91191 Gif sur Yvette , France
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Abstract
Employing the method of constant photon energy sum (CONPHOENERS) scans, we measure the near-IR spectrum of NO-Xe in the region of the first vibrational overtone of the NO monomer. Three bands are detected, which are assigned as the origin band located at 3722.60 cm(-1) and as bands with excitation of one quantum of z-axis rotation (3726.07 cm(-1)) and one quantum of bending vibration (3739.02 cm(-1)), respectively. The partially resolved rotational and electronic fine structures of the bands are analyzed with the help of a full quantum mechanical bound-state calculation using the ab initio potential energy surfaces of Kłos et al. (J. Chem. Phys. 2012, 137, 014312/1-014312/14). We perform a linear least-squares fit to the calculated energy levels to determine a set of spectroscopic constants that describe not only the overall rotation of the complex but also the electrostatic splitting due to the sum potential and the P-type doubling due to the difference potential. Using these results as guidance, we are able to simulate the experimental spectra. The comparison with the results from the theoretical treatment confirms the high quality of the ab initio treatment. The position of the excited bands is predicted with sub-wavenumber accuracy. Also, the rotational constants for all bands are found within less than 5%. Some differences are found for the amount of P-type doubling, which is overestimated by the theoretical treatment. Constants for the electrostatic splitting are in reasonable agreement for the origin band. Larger deviations are found for the vibrationally excited band, which points toward some inaccuracies in the potential energy surfaces.
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Affiliation(s)
- H Meyer
- Department of Physics and Astronomy, The University of Georgia , Athens, Georgia 30602-2451, United States
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McGurk SJ, McKendrick KG, Costen ML, Alexander MH, Dagdigian PJ. Parity-dependent oscillations in collisional polarization transfer: CN(A²Π, v = 4) + Ar. J Chem Phys 2013; 139:124304. [PMID: 24089764 DOI: 10.1063/1.4821602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report the first systematic experimental and theoretical study of the state-to-state transfer of rotational angular momentum orientation in a (2)Π-rare gas system. CN(X(2)Σ(+)) was produced by pulsed 266 nm photolysis of ICN in a thermal bath (296 K) of Ar collider gas. A pulsed circularly polarized tunable dye laser prepared CN(A(2)Π, v = 4) in two fully state-selected initial levels, j = 6.5 F1e and j = 10.5 F2f, with a known laboratory-frame orientation. Both the prepared levels and a range of product levels, j' F1e and j' F2f, were monitored using the circular polarized output of a tunable diode laser via cw frequency-modulated (FM) spectroscopy in stimulated emission on the CN(A-X) (4,2) band. The FM Doppler lineshapes for co-rotating and counter-rotating pump-and-probe geometries reveal the time-dependence of the populations and orientations. Kinetic fitting was used to extract the state-to-state population transfer rate constants and orientation multipole transfer efficiencies (MTEs), which quantify the degree of conservation of initially prepared orientation in the product level. Complementary full quantum scattering (QS) calculations were carried out on recently computed ab initio potential energy surfaces. Collision-energy-dependent tensor cross sections for ranks K = 0 and 1 were computed for transitions from both initial levels to all final levels. These quantities were integrated over the thermal collision energy distribution to yield predictions of the experimentally observed state-to-state population transfer rate constants and MTEs. Excellent agreement between experiment and theory is observed for both measured quantities. Dramatic oscillations in the MTEs are observed, up to and including changes in the sign of the orientation, as a function of even/odd Δj within a particular spin-orbit and e/f manifold. These oscillations, along with those also observed in the state-to-state rate constants, reflect the rotational parity of the final level. In general, parity-conserving collisions conserve rotational orientation, while parity-changing collisions result in large changes in the orientation. The QS calculations show that the dynamics of the collisions leading to these different outcomes are fundamentally different. We propose that the origin of this behavior lies in interferences between collisions that sample the even and odd-λ terms in the angular expansions of the PESs.
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Affiliation(s)
- S J McGurk
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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Steill JD, Kay JJ, Paterson G, Sharples TR, Kłos J, Costen ML, Strecker KE, McKendrick KG, Alexander MH, Chandler DW. Rotational alignment of NO (A2Σ+) from collisions with Ne. J Phys Chem A 2013; 117:8163-74. [PMID: 23611173 DOI: 10.1021/jp402019s] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the direct angle-resolved measurement of collision-induced alignment of short-lived electronically excited molecules using crossed atomic and molecular beams. Utilizing velocity-mapped ion imaging, we measure the alignment of NO in its first electronically excited state (A(2)Σ(+)) following single collisions with Ne atoms. We prepare A(2)Σ(+) (v = 0, N = 0, j = 0.5) and by comparing images obtained using orthogonal linear probe laser polarizations, we experimentally determine the degree of alignment induced by collisional rotational excitation for the final rotational states N' = 4, 5, 7, and 9. The experimental results are compared to theoretical predictions using both a simple classical hard-shell model and quantum scattering calculations on an ab initio potential energy surface (PES). The experimental results show overall trends in the scattering-angle dependent polarization sensitivity that are accounted for by the simple classical model, but structure in the scattering-angle dependence that is not. The quantum scattering calculations qualitatively reproduce this structure, and we demonstrate that the experimental measurements have the sensitivity to critique the best available potential surfaces. This sensitivity to the PES is in contrast to that predicted for ground-state NO(X) alignment.
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Affiliation(s)
- Jeffrey D Steill
- Sandia National Laboratories, Livermore, California 94550, United States
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McGurk SJ, McKendrick KG, Costen ML, Bennett DIG, Kłos J, Alexander MH, Dagdigian PJ. Depolarization of rotational angular momentum in CN(A2Π, v = 4) + Ar collisions. J Chem Phys 2012; 136:164306. [PMID: 22559481 DOI: 10.1063/1.4705118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Angular momentum depolarization and population transfer in CN(A(2)Π, v = 4, j, F(1)e) + Ar collisions have been investigated both experimentally and theoretically. Ground-state CN(X(2)Σ(+)) molecules were generated by pulsed 266-nm laser photolysis of ICN in a thermal (nominally 298 K) bath of the Ar collision partner at a range of pressures. The translationally thermalized CN(X) radicals were optically pumped to selected unique CN(A(2)Π, v = 4, j = 2.5, 3.5, 6.5, 11.5, 13.5, and 18.5, F(1)e) levels on the A-X (4,0) band by a pulsed tunable dye laser. The prepared level was monitored in a collinear geometry by cw frequency-modulated (FM) spectroscopy in stimulated emission on the CN(A-X) (4,2) band. The FM lineshapes for co- and counter-rotating circular pump and probe polarizations were analyzed to extract the time dependence of the population and (to a good approximation) orientation (tensor rank K = 1 polarization). The corresponding parallel and perpendicular linear polarizations yielded population and alignment (K = 2). The combined population and polarization measurements at each Ar pressure were fitted to a 3-level kinetic model, the minimum complexity necessary to reproduce the qualitative features of the data. Rate constants were extracted for the total loss of population and of elastic depolarization of ranks K = 1 and 2. Elastic depolarization is concluded to be a relatively minor process in this system. Complementary full quantum scattering (QS) calculations were carried out on the best previous and a new set of ab initio potential energy surfaces for CN(A)-Ar. Collision-energy-dependent elastic tensor and depolarization cross sections for ranks K = 1 and 2 were computed for CN(A(2)Π, v = 4, j = 1.5-10.5, F(1)e) rotational/fine-structure levels. In addition, integral cross sections for rotationally inelastic transitions out of these levels were computed and summed to yield total population transfer cross sections. These quantities were integrated over a thermal collision-energy distribution to yield the corresponding rate constants. A complete master-equation simulation using the QS results for the selected initial level j = 6.5 gave close, but not perfect, agreement with the near-exponential experimental population decays, and successfully reproduced the observed multimodal character of the polarization decays. On average, the QS population removal rate constants were consistently 10%-15% higher than those derived from the 3-level fit to the experimental data. The QS and experimental depolarization rate constants agree within the experimental uncertainties at low j, but the QS predictions decline more rapidly with j than the observations. In addition to providing a sensitive test of the achievable level of agreement between state-of-the art experiment and theory, these results highlight the importance of multiple collisions in contributing to phenomenological depolarization using any method sensitive to both polarized and unpolarized molecules in the observed level.
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Affiliation(s)
- S J McGurk
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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10
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Paterson G, Relf A, Costen ML, McKendrick KG, Alexander MH, Dagdigian PJ. Rotationally elastic and inelastic dynamics of NO(X2Π, v = 0) in collisions with Ar. J Chem Phys 2011; 135:234304. [PMID: 22191872 DOI: 10.1063/1.3665135] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A combined theoretical and experimental study of the depolarization of selected NO(X(2)Π, v = 0, j, F, ɛ) levels in collisions with a thermal bath of Ar has been carried out. Rate constants for elastic depolarization of rank K = 1 (orientation) and K = 2 (alignment) were extracted from collision-energy-dependent quantum scattering calculations, along with those for inelastic population transfer to discrete product levels. The rate constants for total loss of polarization of selected initial levels, which are the sum of elastic depolarization and population transfer contributions, were measured using a two-color polarization spectroscopy technique. Theory and experiment agree qualitatively that the rate constants for total loss of polarization decline modestly with j, but the absolute values differ by significantly more than the statistical uncertainties in the measurements. The reasons for this discrepancy are as yet unclear. The lack of a significant K dependence in the experimental data is, however, consistent with the theoretical prediction that elastic depolarization makes only a modest contribution to the total loss of polarization. This supports a previous conclusion that elastic depolarization for NO(X(2)Π) + Ar is significantly less efficient than for the electronically closely related system OH(X(2)Π) + Ar [P. J. Dagdigian and M. H. Alexander, J. Chem. Phys. 130, 204304 (2009)].
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Affiliation(s)
- G Paterson
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
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Lique F, Jorfi M, Honvault P, Halvick P, Lin SY, Guo H, Xie DQ, Dagdigian PJ, Kłos J, Alexander MH. O+OH-->O(2)+H: A key reaction for interstellar chemistry. New theoretical results and comparison with experiment. J Chem Phys 2010; 131:221104. [PMID: 20001016 DOI: 10.1063/1.3274226] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report extensive, fully quantum, time-independent (TID) calculations of cross sections at low collision energies and rate constants at low temperatures for the O+OH reaction, of key importance in the production of molecular oxygen in cold, dark, interstellar clouds and in the chemistry of the Earth's atmosphere. Our calculations are compared with TID calculations within the J-shifting approximation, with wave-packet calculations, and with quasiclassical trajectory calculations. The fully quantum TID calculations yield rate constants higher than those from the more approximate methods and are qualitatively consistent with a low-temperature extrapolation of earlier experimental values but not with the most recent experiments at the lowest temperatures.
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Affiliation(s)
- F Lique
- LOMC, Universite du Havre, 25 Rue Philippe Lebon, BP 540, 76 058 Le Havre Cedex, France
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Abstract
The collision dynamics of the NO+Ne system is investigated in a molecular beam scattering experiment at a collision energy of 1055 cm(-1). Employing resonance enhanced multiphoton ionization of NO, we measured state-resolved integral and differential cross sections for the excitation to various levels of both spin-orbit manifolds. The dependence of the scattered intensity on the laser polarization is used to extract differential quadrupole moments for the collision induced angular momentum alignment. The set of cross section data is compared with results of a full quantum mechanical close coupling calculation using the set of ab initio potential energy surfaces of Alexander et al. [J. Chem. Phys. 114, 5588 (2001)]. In previous work, it was found that the positions and rotational substructures for the lowest bend-stretch vibrational states derived from these surfaces agree very well with the observed spectrum of the NO-Ne complex. For the same potential, we find that the calculated cross sections show a less satisfactory agreement with the experimental data. While the overall Jf dependence and magnitude of the integral and differential cross sections are in good agreement, noticeable discrepancies exist for the angle dependence of the differential cross sections. In general, the calculated rotational rainbow structures are shifted towards larger scattering angles indicating that the anisotropy of the potential is overestimated in the fit to the ab initio points or in the ab initio calculation itself. For most states, we find the measured alignment moments to be in excellent agreement with the results of the calculation as well as with predictions of sudden models. Significant deviations from the sudden models are observed only for those fine-structure changing collisions which are dominated by forward scattering. Results of the full quantum calculation confirm the deviations for these states.
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Affiliation(s)
- Y Kim
- Department of Physics and Astronomy, The University of Georgia, Athens, Georgia 30602-2451, USA
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Balucani N, Skouteris D, Cartechini L, Capozza G, Segoloni E, Casavecchia P, Alexander MH, Capecchi G, Werner HJ. Differential cross sections from quantum calculations on coupled Ab initio potential energy surfaces and scattering experiments for Cl(2P)+H2 reactions. Phys Rev Lett 2003; 91:013201. [PMID: 12906538 DOI: 10.1103/physrevlett.91.013201] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2003] [Indexed: 05/24/2023]
Abstract
To assess the relative reactivity of the spin-orbit excited state of atomic Cl with molecular hydrogen, we have measured differential cross sections using an atomic Cl beam with a known concentration of the ground and excited spin-orbit states. These are compared with the first determination of the cross sections from quantum mechanical scattering calculations on a set of coupled ab initio potential energy surfaces. The comparison suggests that these surfaces may underestimate the degree of rotational excitation of the HCl products and that the excited spin-orbit state plays a minor role in the reaction.
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Affiliation(s)
- N Balucani
- Dipartimento di Chimica, Università di Perugia, 06123 Perugia, Italy
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Kohguchi H, Suzuki T, Alexander MH. Fully state-resolved differential cross sections for the inelastic scattering of the open-shell NO molecule by Ar. Science 2001; 294:832-4. [PMID: 11679664 DOI: 10.1126/science.1063774] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
State-resolved differential cross sections (DCSs) for the inelastic scattering of NO(j" = 0.5, Omega" = 1/2) + Ar --> NO(j', Omega' = 1/2, 3/2) + Ar were obtained at a collision energy of 516 cm(-1), both experimentally and theoretically. A crossed molecular beam ion-imaging apparatus was used to measure DCSs for 20 final (j', Omega') states, including spin-orbit conserving (DeltaOmega = 0) and changing (DeltaOmega = 1) transitions. Quantum close-coupling scattering calculations on ab initio coupled-cluster CCSD(T) and CEPA (correlated electron pair approximation) potential energy surfaces were also performed. Although small discrepancies were found for the DeltaOmega = 1 transitions, we find marked agreement between theory and experiment for the collision dynamics of this system, which is the paradigm for the collisional relaxation of a molecular radical.
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Affiliation(s)
- H Kohguchi
- Institute for Molecular Science and Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan
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Tan X, Dagdigian PJ, Alexander MH. Electronic spectroscopy and excited state dynamics of the Al-H2/D2 complex. Faraday Discuss 2001:387-404; discussion 419-31. [PMID: 11605277 DOI: 10.1039/b008488n] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electronic spectra of the Al-H2 and Al-D2 complexes are investigated in a collaborative experimental and theoretical study. The complexes were prepared in a pulsed supersonic beam and detected with laser fluorescence excitation spectroscopy. Transitions to bound vibrational levels in electronic states correlating with the excited-state Al(3d, 4p, 4d) + H2/D2 asymptotes were observed by monitoring emission from lower excited Al atomic levels, formed in the non-radiative decay of the excited complex. Fluorescence depletion has also been used to verify that the observed Al-H2 bands all involve the same molecular carrier. The bands have been assigned to the more strongly bound Al-oH2 and Al-pD2 nuclear spin modifications. In contrast to our previous observations for Al(5s)-H2 [X. Yang and P. J. Dagdigian, J. Chem. Phys., 1998, 109, 8920], for which only one potential energy surface (PES) emanates from the dissociation asymptote, the Lorentzian widths of the different vibrational bands in the 3d, 4p, 4d<--3p transitions vary widely, in some cases allowing resolution of the rotational structure of the bands. With the help of the calculated Al(3p)-oH2/pD2 dissociation energies, binding energies of the observed excited vibronic levels are reported. The mechanism of predissociation is investigated theoretically through ab initio calculation of C2 nu cuts of the excited PESs. It is concluded that predissociation occurs through coupling with the repulsive Al(4s)-H2 PES. With these calculations, a qualitative interpretation of the observed bands could be made.
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Affiliation(s)
- X Tan
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218-2685, USA
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DePristo AE, Alexander MH. Decoupling approximations for rotationally inelastic collisions between ions and polar molecules: H+-CN. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/0022-3700/9/15/020] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Tobacco use continues to occur in epidemic proportions and with it, significant morbidity and mortality. One third of smokers will die prematurely of a smoking-related disease. This article reviews the adverse health effects of tobacco use so that clinicians can be aware of the benefits patients will reap when they stop using this lethal substance.
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Affiliation(s)
- B E Mitchell
- Resident, General Preventive Medicine Residency, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland 21205, USA
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Pouilly B, Orlikowski T, Alexander MH. Fully ab initio dynamics of fine-structure-changing transitions in collisions of Mg(3s3p3P) with He. ACTA ACUST UNITED AC 1999. [DOI: 10.1088/0022-3700/18/10/013] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Alexander MH. Mechanism and pattern of injury associated with use of seat belts. J Emerg Nurs 1988; 14:214-6. [PMID: 3045383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Abstract
To assess the effect of chronic protein-energy malnutrition on fecundability (ovulation rate), fecundity (percentage of animals bred that conceived) and fertility (live fetuses at d 18 of pregnancy), 42-d-old female rats were assigned to six groups: two dietary treatment groups and, within each treatment group, three outcome groups. Rats were fed ad libitum (AL) or were chronically restricted (CR) to 50% of AL intake for 28 d before ovulation was assessed and then until implantation and fetal viability were measured. In the ovulation groups, corpora lutea were counted at estrus. In the implantation groups, blastocyst implantation sites were quantified by using Pontamine Blue dye at d 5 of pregnancy. In the viability groups, live and dead fetuses and metrial nodes were counted at d 18 of pregnancy. CR rats had 74% as many corpora lutea as AL rats; however, fecundity did not differ between dietary treatments. CR rats had 71% as many blastocyst implantation sites and 65% as many viable fetuses as AL rats. Chronic malnutrition negatively affected weight gain before and during pregnancy as well as reproductive performance. These findings help to explain why CR rats have fewer progeny.
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Affiliation(s)
- M H Alexander
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853
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