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1,403 results on '"Levitt M"'

1. Infrared spectroscopy of an endohedral water in fullerene.

Author

Shugai, A., Nagel, U., Murata, Y., Li, Yongjun, Mamone, S., Krachmalnicoff, A., Alom, S., Whitby, R. J., Levitt, M. H., and Rõõm, T.

Subjects
INFRARED spectroscopy, FULLERENES, ELECTRIC dipole moments, SPECTRAL lines, QUADRUPOLE moments, INFRARED spectra
Abstract

An infrared absorption spectroscopy study of the endohedral water molecule in a solid mixture of H2O@C60 and C60 was carried out at liquid helium temperature. From the evolution of the spectra during the ortho–para conversion process, the spectral lines were identified as para-H2O and ortho-H2O transitions. Eight vibrational transitions with rotational side peaks were observed in the mid-infrared: ω1, ω2, ω3, 2ω1, 2ω2, ω1 + ω3, ω2 + ω3, and 2ω2 + ω3. The vibrational frequencies ω2 and 2ω2 are lower by 1.6% and the rest by 2.4%, as compared to those of free H2O. A model consisting of a rovibrational Hamiltonian with the dipole and quadrupole moments of H2O interacting with the crystal field was used to fit the infrared absorption spectra. The electric quadrupole interaction with the crystal field lifts the degeneracy of the rotational levels. The finite amplitudes of the pure v1 and v2 vibrational transitions are consistent with the interaction of the water molecule dipole moment with a lattice-induced electric field. The permanent dipole moment of encapsulated H2O is found to be 0.50 ± 0.05 D as determined from the far-infrared rotational line intensities. The translational mode of the quantized center-of-mass motion of H2O in the molecular cage of C60 was observed at 110 cm−1 (13.6 meV). [ABSTRACT FROM AUTHOR]

Published
2021
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11. Nuclear singlet relaxation by scalar relaxation of the second kind in the slow-fluctuation regime.

Author

Elliott, S. J., Bengs, C., Brown, L. J., Hill-Cousins, J. T., O'Leary, D. J., Pileio, G., and Levitt, M. H.

Subjects
RADIOACTIVE decay, RELAXATION for health, DEUTERIUM, SINGLET state (Quantum mechanics)
Abstract

The singlet state of nuclear spin-1/2 pairs is protected against many common relaxation mechanisms. Singlet order, which is defined as the population difference between the nuclear singlet and triplet states, usually decays more slowly than the nuclear magnetization. Nevertheless, some decay mechanisms for nuclear singlet order persist. One such mechanism is called scalar relaxation of the second kind (SR2K) and involves the relaxation of additional nuclei ("third spins") which have scalar couplings to the spin-1/2 pair. This mechanism requires a difference between the couplings of at least one third spin with the two members of the spin-1/2 pair, and depends on the longitudinal relaxation time of the third spin. The SR2K mechanism of nuclear singlet relaxation has previously been examined in the case where the relaxation rate of the additional spins is on the time scale of the nuclear Larmor frequency. In this paper, we consider a different regime, in which the longitudinal relaxation of the third spins is on a similar time scale to the J-coupling between the members of the spin pair. This regime is often encountered when the spin-1/2 pair has scalar couplings to nearby deuterium nuclei. We show that the SR2K mechanism may be suppressed in this regime by applying a radiofrequency field which is resonant either with the members of the spin pair, or with the third spins. These phenomena are analyzed theoretically and by numerical simulations, and demonstrated experimentally on a diester of [13C2, 2H2]-labeled fumarate in solution. [ABSTRACT FROM AUTHOR]

Published
2019
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17. Development of a Pharmacokinetic Model That Accounts for the Plasma Concentrations of Conjugated and Unconjugated Bilirubin Observed in a Variety of Disease States

Author

Levitt DG and Levitt MD

Subjects
bilirubin, dubin-johnson, rotor, gilbert’s, oatp, Diseases of the digestive system. Gastroenterology, RC799-869
Abstract

David G Levitt,1,* Michael D Levitt2,* 1Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA; 2Research Service, Veterans Affairs Medical Center, Minneapolis, MN, USA*These authors contributed equally to this workCorrespondence: David G Levitt, Department of Integrative Biology and Physiology, University of Minnesota, 6-125 Jackson Hall, 321 Church St. S. E, Minneapolis, MN, 55455, USA, Tel +612 594 0272, Email levit001@umn.eduIntroduction: For a large variety of liver pathologies, the plasma unconjugated (UB) and conjugated (CB) bilirubin concentrations appear to be coupled. For example, in alcoholic cirrhosis, UB and CB are roughly the same over a large range of total bilirubin, requiring an initial massive increase (about 40-fold) in plasma CB to reach the level of UB and then similar increases in UB and CB as the disease progresses. This coupling has been either unrecognized or ignored and this paper is the first attempt to try to explain it quantitatively in terms of known hepatic cell metabolic and membrane transport properties.Methods: A simplified pharmacokinetic model is developed and applied to a variety of hyperbilirubinemic pathologies. A central feature of the model is based on the recent observation that double knockout of the rat OATP1A and OATP1B hepatic transporters produces a roughly 400-fold increase in plasma CB, indicating that there is a normal rapid recycling of CB from the cell to the plasma with reuptake via OATP. We use the experimental rat Km of OATP CB transport to show that OATP uptake becomes saturated at relatively low plasma CB concentrations, decreasing uptake, and producing massive (up to 1000-fold) increases in CB in some pathologies. It is assumed that UB and CB are competing for the OATP transporter, producing the increased plasma UB that is observed in “pure” CB pathologies.Results: The model accurately describes the clinically observed UB and CB for pure UB (Gilbert’s, hemolytic anemia) and CB (Dubin-Johnson, Rotor syndrome, biliary atresia) pathologies as well as in cirrhosis.Conclusion: This model is a preliminary, first attempt to quantitatively describe UB and CB pharmacokinetics. It is hoped that it will stimulate more detailed measurements and analysis.Keywords: bilirubin, Dubin-Johnson, Rotor, Gilbert’s, OATP

Published
2023

20. Differentiation of mouth versus gut as site of origin of odoriferous breath gases after garlic ingestion

Author

Suarez, F., Springfield, J., Furne, J., and Levitt, M.

Subjects
Breath, Offensive -- Physiological aspects, Mouth -- Physiological aspects, Stomach -- Physiological aspects, Dimethyl sulfide -- Physiological aspects, Garlic -- Physiological aspects, Biological sciences
Abstract

Experimental evidence shows that breath odor following garlic ingestion initially originates from the mouth and eventually from the gut. The gut versus mouth origin of odoriferous breath gases was investigated using the sulfur-containing gases of garlic as probes. Transient high concentrations of methanethiol and allyl mercaptan and lower concentrations of allyl methyl disulfide, allyl methyl sulfide and allyl disulfide were observed in the mouth immediately after garlic ingestion. Only allyl methyl sulfide was present in the gut as indicated by similar partial pressures in mouth, urine and alveolar air.

Published
1999

23. Production and elimination of sulfur-containing gases in the rat colon

Author

Suarez, F., Furne, J., Springfield, J., and Levitt, M.

Subjects
Sulfur compounds -- Physiological aspects, Colon (Anatomy) -- Physiological aspects, Biological sciences
Abstract

Sulfur-containing gas production and elimination in the unperturbed colon was investigated in permanently cannulated rats. The sulfur containing gases produced in the cecum of the test animals are hydrogen sulfide, methanethiol and dimethyl sulfide. The production rates of these gases demonstrate a dependence on the diet of the test animals. The absorption, metabolism and turnover of hydrogen sulfide in the rat colon are discussed.

Published
1998

26. Insights into human colonic physiology obtained from the study of flatus composition

Author

Suarez, F., Furne, J., Springfield, J., and Levitt, M.

Subjects
Gastrointestinal gas -- Analysis, Gases -- Physiological aspects, Microbiological synthesis -- Physiological aspects, Biological sciences
Abstract

Flatus samples passed by healthy subjects were analyzed to determine the presence of five quantitatively important gases such as carbon dioxide (CO2), hydrogen (H2) and methane (CH4). Analysis of the relationship between the excretion rates of the colonic gases in flatus samples indicated the predominance of flatus gases such as CO2, H2 and N2 in humans. Furthermore, flatus gases such as CO2 and H2 were characterized as the main products of bacterial synthesis in human colon.

Published
1997

27. Abstracts

Author

Rosen, L., Reed, J., Ufberg, D., Thorburn, H., Carter, K., Goldberg, J., Finlay, I. G., Church, J. M., Hill, G. L., Carter, F. M., Cohen, Z., McLeod, R. S., Bauer, J. J., Sher, M. E., Gelernt, I. M., Crim, R. W., Fazio, V. W., Lavery, I. C., Williams, J. G., Nemer, F. D., Rothenberger, D. A., Goldberg, S. M., Hyman, N. H., Tuckson, W. B., Deutsch, A. A., Gregoire, R., Cullen, J., Johnson, G. P., Wolff, B. G., Koltun, W., Schoetz, Jr., D. J., Roberts, P. L., Murray, J. J., Coller, J. A., Veidenheimer, M. C., Keighley, M. R. B., Hosie, K., Sakaguchi, M., Tudor, R., Kmiot, W., Ambroze, Jr., W. L., Dozois, R. R., Pemberton, J. H., Kelly, K. A., Wiltz, O., Hashmi, H., Fucini, C., Thayer, M. L., Madoff, R. D., Jacobs, D. M., Bubrick, M. P., Galandiuk, S., Tsao, J., Ilstrup, D. M., Duthie, G. S., Bartolo, D. C. C., Miller, R., Pinho, M., Kunin, J. D., Fleshman, J. W., Kodner, I. J., Fry, R. D., Wexner, S. D., Jagelman, D. G., Corredor, C., Salanga, V., Scholefield, J. H., Whatrup, C., Talbot, I. C., Northover, J. M. A., Sonnex, C., Safavi, A., Gottesman, L., Dailey, T., Moenning, S., Nightengale, S., Simonton, T., Huber, P., Odom, C., Kaplan, E., Strong, S. A., Milsom, J. W., Taylor, C. W., Cho, C. C., Stewart, W. R. C., Hartmann, R. F., Khanduja, K. S., Aguilar, P. S., Rahman, S. M., Arnold, M. W., Caushaj, P., Viratyosin, S., French, T., Madoff, R., Karamjit, S., Meesig, D. M., Macleod, C. A. H., Balcos, E. G., Buls, J. G., Nelson, H., Donohue, J. H., McKean, D. J., Leu, S. Y., Wang, S. R., Hsu, H., Ramanujam, P. S., Alberts, D. S., Clark, L., Ritenbaugh, C., Rowley, S., Kane, N., Jones, C., Davies, A., Baker, P., Neoptolemos, J. P., Devereux, D. F., Robertson, F. M., Spain, D. A., Cance, W. G., Cohen, A. M., Sigurdson, E. R., Enker, W. E., Konishi, F., Yasuda, Y., Ochiai, S., Kanazawa, K., Davis, M., Medina, V., Miller, D., Fielding, L. P., Prats, I., Berman, M., West, B., Savoca, P. E., Ballantyne, G. H., Flannery, J. T., Modlin, I. M., Tsukada, K., Jagelman, D. A., McGannon, E. M., Schroeder, T., Sakamoto, G. D., MacKeigan, J. M., Opelka, F., Timmcke, A., Gathright, J. B., Hicks, T., Ray, J., McKee, C. C., Ragland, J. J., Myers, J. O., Christie, J. P., Marrazzo, III, J., Flemming, F. X., Longo, W. E., Pollard, C. W., Nivatvongs, S., Rojanasakul, A., Jetmore, A. B., Baker, J., Wiltz, O. H., McKee, R. F., Lauder, J., Poon, F., Aitchison, M., Fleshman, James W., Dreznik, Zeev, Kodner, Ira J., Fry, Robert D., Kerner, B. A., Labow, S., Hoexter, B., Moseson, M., Cheape, J. D., Bowinkelman, K., Dziki, A. J., Malthaner, R. A., Harmon, J. W., Saini, N., Duncan, M. D., Fernicola, M. T., Fischer, B. A., Hakki, F. Z., Trad, K. S., Ugarte, R., Senagore, A. J., Mazier, W. P., Kilbride, M., Herrera, L., Goumas, W., Petrelli, N., Bailey, H. R., Huval, W. V., Max, E., Smith, K. W., Marks, G., Mohiuddin, M., Basile, M., Eitan, A., Wolff, B., Dozois, R., Devine, R., Beart, R., Kelly, A., Unti, J. A., Orsay, C. P., Pearl, R. K., Nelson, R. L., Duarte, B., Prasad, M. L., Abcarian, H., Senagore, A., Milson, J. W., Strong, S., Walshaw, R. K., Chaudry, I. H., Hojo, K., Sugihara, K., Katunuma, K., Vernava, A., Beart, R. W., Stewart, J., Diament, R. H., Salter, M., Brennan, T. G., Sheikh, F., Khubchandani, I. T., Miyajima, N., Uematsu, Y., Kodaira, S., Teramoto, T., Orrom, W. J., Duthie, G., Corne, H., Blatchford, G. J., Perry, R. E., Christensen, M. A., Thorson, A. G., Dreznik, Zeev, Wong, W. D., Jensen, L. L., Lee, K. H., Yoon, Choong, Joo, H. Z., Levien, D. H., Gibbons, S., Begos, D., Byrne, D. W., Gordon, P. H., Bégin, L. R., Mitmaker, B., Saclarides, T., Bhattacharyya, A., Britton, C., Stone, J. M., Lowry, A. C., Moran, M., Launer, D. P., McReynolds, D. G., Eastman, A. B., Peck, J. J., Rozycki, G. S., Ramanujam, Paravasthu S., Bellapravalu, Sharad, Venkatesh, Kurakurachi S., Griffin, Kathleen M., Vernava, A. M., Beckman, R., Andrus, C., Johnson, F., Herrmann, V., Kaminski, D. L., Wetter, L. A., Dinneen, M., Levitt, M., Motson, R. W., Rohrer, D. A., Bapna, M. S., Rotstein, L. E., Radhakrishnan, Jayant, Shrader, Charisse, Ravo, B., Frattaroli, F. M., Reggio, D., Litchy, W. J., Hanson, R. B., Morgado, Pedro J., Alfaro, Rodrigo, Alfonzo, Rafael, Vachon, D. A., Oliver, G. C., Eisenstat, T. E., Salvati, E. P., Rubin, R. J., Clay, R. P., Kumar, Sanath, Guillem, J. G., Levy, M. F., Hsieh, L. L., Johnson, M. D., Forde, K. A., Weinstein, I. B., Bilchik, A. J., Fleming, F. X., Pernikoff, B. J., Goldenring, J. R., Fozard, J. B., Lowndes, R. H., Young, H. L., Sackier, J., Leite, J. F. M. S., Fausto-Pontes, Martins, M. I., Kmiot, W. A., Youngs, D. J., Harding, L. K., Hesselwood, S. R., Smith, N., Hartley, M. G., Hudson, M. J., Hill, M. J., Gent, A. E., Grace, R. H., Swarbrick, E. T., Hellier, M. D., Procaccino, J. A., Oakley, J. R., Flanagan, Jr., R. A., Lapos, L., Riether, R. D., Stasik, J. J., Trostle, D. R., Sheets, J. A., Ferrara, A., Armstrong, D. N., Bjorck, S., McMillen, M. A., Nicholson, J. D., Halleran, D. R., Trivisonno, D. P., Ziegler, J. A., Lott, J., Saleeby, R., Sullivan, T., and Nelson, R.

Published
1990
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37. PRACTICE PARAMETERS FOR THE MANAGEMENT OF COLONIC CANCER II: OTHER ISSUES. RECOMMENDATIONS OF THE COLORECTAL SURGICAL SOCIETY OF AUSTRALIA

Author

Adams, W., Cartmill, J., Chapuis, P., Cunningham, I., Farmer, K. C., Hewett, P., Hoffmann, D., Jass, J., Jones, I., Killingback, M., Levitt, M., Lumley, J., Mcleish, A., Meagher, A., Moore, J., Newland, R., Newstead, G., Oakley, J., Olver, I., Platell, C., Polglase, A., Sarre, R., Schache, D., Solomon, M., Stewart, P., Stitz, R., Sweeney, J., Tjandra, J., and Waxman, B.

Published
1999

38. PRACTICE PARAMETERS FOR THE MANAGEMENT OF COLONIC CANCER I: SURGICAL ISSUES. RECOMMENDATIONS OF THE COLORECTAL SURGICAL SOCIETY OF AUSTRALIA

Author

Moore, J., Hewett, P., Penfold, J. C., Adams, W., Cartmill, J., Chapuis, P., Cunningham, I., Farmer, K. C., Hewett, P., Hoffmann, D., Jass, J., Jones, I., Killingback, M., Levitt, M., Lumley, J., Mcleish, A., Meagher, A., Moore, J., Newland, R., Newstead, G., Oakley, J., Olver, I., Platell, C., Polglase, A., Sarre, R., Schache, D., Solomon, M., Stewart, P., Stitz, R., Sweeney, J., Tjandra, J., and Waxman, B.

Published
1999

44. Singulett‐Kontrast‐Magnetresonanztomographie: Freisetzung der Hyperpolarisation durch den Metabolismus**.

Author

Eills, J., Cavallari, E., Kircher, R., Di Matteo, G., Carrera, C., Dagys, L., Levitt, M. H., Ivanov, K. L., Aime, S., Reineri, F., Münnemann, K., Budker, D., Buntkowsky, G., and Knecht, S.

Abstract

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2021
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45. Singlet‐Contrast Magnetic Resonance Imaging: Unlocking Hyperpolarization with Metabolism**.

Author

Eills, J., Cavallari, E., Kircher, R., Di Matteo, G., Carrera, C., Dagys, L., Levitt, M. H., Ivanov, K. L., Aime, S., Reineri, F., Münnemann, K., Budker, D., Buntkowsky, G., and Knecht, S.

Subjects
MAGNETIC resonance imaging, CHEMICAL precursors, CHEMICAL reactions, CELL nuclei, MALATE dehydrogenase
Abstract

Hyperpolarization‐enhanced magnetic resonance imaging can be used to study biomolecular processes in the body, but typically requires nuclei such as 13C, 15N, or 129Xe due to their long spin‐polarization lifetimes and the absence of a proton‐background signal from water and fat in the images. Here we present a novel type of 1H imaging, in which hyperpolarized spin order is locked in a nonmagnetic long‐lived correlated (singlet) state, and is only liberated for imaging by a specific biochemical reaction. In this work we produce hyperpolarized fumarate via chemical reaction of a precursor molecule with para‐enriched hydrogen gas, and the proton singlet order in fumarate is released as antiphase NMR signals by enzymatic conversion to malate in D2O. Using this model system we show two pulse sequences to rephase the NMR signals for imaging and suppress the background signals from water. The hyperpolarization‐enhanced 1H‐imaging modality presented here can allow for hyperpolarized imaging without the need for low‐abundance, low‐sensitivity heteronuclei. [ABSTRACT FROM AUTHOR]

Published
2021
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46. BEST PRACTICE PARAMETERS FOR MANAGEMENT OF RECTAL CANCER: RECOMMENDATIONS OF THE COLORECTAL SURGICAL SOCIETY OF AUSTRALIA

Author

Anseline, P. F., Bell, A. McK., Bokey, E. L., Chapuis, P. H., Cohen, J. R., Collopy, B. T., Ctercteko, G. C., Cunningham, I. G., Douglas, P. R., Eyers, A. A., Fazio, V. W., Findlay, M., Hoffmann, D. C., Jones, I. T., Killingback, M. J., Levitt, M. D., Lubowski, D. Z., McLeish, A. R., McNamara, M. J., Newstead, G. L., O'Connor, T. W., Penfold, J. C. B., Stewart, P. J., Stitz, R. W., Stuart, M., Sweeney, J. L., Young, J. F., Waxman, B. P., Woods, R. J., and Yuile, P. G.

Published
1996

50. Interaction potential and infrared absorption of endohedral H2 in C60.

Author

Ge, Min, Nagel, U., Hüvonen, D., Rõõm, T., Mamone, S., Levitt, M. H., Carravetta, M., Murata, Y., Komatsu, K., Chen, J. Y.-C., and Turro, N. J.

Subjects
HYDROGEN, ABSORPTION, INFRARED spectra, DIPOLE moments, FULLERENES, NUCLEAR magnetic resonance, NEUTRON scattering
Abstract

We have measured the temperature dependence of the infrared spectra of a hydrogen molecule trapped inside a C60 cage, H2@C60, in the temperature range from 6 to 300 K and analyzed the excitation spectrum by using a five-dimensional model of a vibrating rotor in a spherical potential. The electric dipole moment is induced by the translational motion of endohedral H2 and gives rise to an infrared absorption process where one translational quantum is created or annihilated, ΔN = ±1. Some fundamental transitions, ΔN = 0, are observed as well. The rotation of endohedral H2 is unhindered but coupled to the translational motion. The isotropic and translation-rotation coupling part of the potential are anharmonic and different in the ground and excited vibrational states of H2. The vibrational frequency and the rotational constant of endohedral H2 are smaller than those of H2 in the gas phase. The assignment of lines to ortho- and para-H2 is confirmed by measuring spectra of a para enriched sample of H2@C60 and is consistent with the earlier interpretation of the low temperature infrared spectra [Mamone et al., J. Chem. Phys. 130, 081103 (2009)]. [ABSTRACT FROM AUTHOR]

Published
2011
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