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Author Dirikolu, L.; Lehner, A.F.; Karpiesiuk, W.; Hughes, C.; Woods, W.E.; Boyles, J.; Harkins, J.D.; Troppmann, A.; Tobin, T.
Title (up) Detection, quantification, metabolism, and behavioral effects of selegiline in horses Type Journal Article
Year 2003 Publication Veterinary Therapeutics : Research in Applied Veterinary Medicine Abbreviated Journal Vet Ther
Volume 4 Issue 3 Pages 257-268
Keywords Administration, Oral; Animals; Behavior, Animal/drug effects; Female; Horses/*metabolism; Mass Spectrometry/veterinary; Monoamine Oxidase Inhibitors/administration & dosage/blood/*pharmacokinetics/pharmacology/urine; Selegiline/administration & dosage/blood/*pharmacokinetics/pharmacology/urine; Substance Abuse Detection/veterinary
Abstract Selegiline ([R]-[-]N,alpha-dimethyl-N-2- propynylphenethylamine or l-deprenyl), an irreversible inhibitor of monoamine oxidase, is a classic antidyskinetic and antiparkinsonian agent widely used in human medicine both as monotherapy and as an adjunct to levodopa therapy. Selegiline is classified by the Association of Racing Commissioners International (ARCI) as a class 2 agent, and is considered to have high abuse potential in racing horses. A highly sensitive LC/MS/MS quantitative analytical method has been developed for selegiline and its potential metabolites amphetamine and methamphetamine using commercially available deuterated analogs of these compounds as internal standards. After administering 40 mg of selegiline orally to two horses, relatively low (<60 ng/ml) concentrations of parent selegiline, amphetamine, and methamphetamine were recovered in urine samples. However, relatively high urinary concentrations of another selegiline metabolite were found, tentatively identified as N- desmethylselegiline. This metabolite was synthesized and found to be indistinguishable from the new metabolite recovered from horse urine, thereby confirming the chemical identity of the equine metabolite. Additionally, analysis of urine samples from four horses dosed with 50 mg of selegiline confirmed that N-desmethylselegiline is the major urinary metabolite of selegiline in horses. In related behavior studies, p.o. and i.v. administration of 30 mg of selegiline produced no significant changes in either locomotor activities or heart rates.
Address Department of Biomedical Sciences, College of Veterinary Medicine, Nursing and Allied Health, Tuskegee University, Tuskegee, AL 36088, USA
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1528-3593 ISBN Medium
Area Expedition Conference
Notes PMID:15136987 Approved no
Call Number Serial 1901
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Author Ballew, R.M.; Sabelko, J.; Gruebele, M.
Title (up) Direct observation of fast protein folding: the initial collapse of apomyoglobin Type Journal Article
Year 1996 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc. Natl. Acad. Sci. U.S.A.
Volume 93 Issue 12 Pages 5759-5764
Keywords Animals; Apoproteins/*chemistry; Circular Dichroism; Horses; Kinetics; Muscle, Skeletal/chemistry; Myoglobin/*chemistry; *Protein Folding; Spectrometry, Fluorescence; Spectrophotometry, Infrared; Temperature
Abstract The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiments on mutants and consideration of steady-state CD and fluorescence spectra indicate that the observed microsecond phase monitors assembly of an A x (H x G) helix subunit. Measurements at different viscosities indicate diffusive behavior even at low viscosities, in agreement with motions of a solvent-exposed protein during the initial collapse.
Address School of Chemical Sciences and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, 61801, USA
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0027-8424 ISBN Medium
Area Expedition Conference
Notes PMID:8650166 Approved no
Call Number Equine Behaviour @ team @ Serial 3798
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Author Andersson, P.; Kvassman, J.; Lindstrom, A.; Olden, B.; Pettersson, G.
Title (up) Effect of NADH on the pKa of zinc-bound water in liver alcohol dehydrogenase Type Journal Article
Year 1981 Publication European Journal of Biochemistry / FEBS Abbreviated Journal Eur J Biochem
Volume 113 Issue 3 Pages 425-433
Keywords Alcohol Oxidoreductases/*metabolism; Aldehydes/metabolism; Animals; Binding Sites; Cinnamates/metabolism; Horses; Hydrogen-Ion Concentration; Kinetics; Ligands; Liver/*metabolism; NAD/*metabolism; Water/metabolism; Zinc/metabolism
Abstract Equilibrium constants for coenzyme binding to liver alcohol dehydrogenase have been determined over the pH range 10--12 by pH-jump stop-flow techniques. The binding of NADH or NAD+ requires the protonated form of an ionizing group (distinct from zinc-bound water) with a pKa of 10.4. Complex formation with NADH exhibits an additional dependence on the protonation state of an ionizing group with a pKa of 11.2. The binding of trans-N,N-dimethylaminocinnamaldehyde to the enzyme . NADH complex is prevented by ionization of the latter group. It is concluded from these results that the pKa-11.2-dependence of NADH binding most likely derives from ionization of the water molecule bound at the catalytic zinc ion of the enzyme subunit. The pKa value of 11.2 thus assigned to zinc-bound water in the enzyme . NADH complex appears to be typical for an aquo ligand in the inner-sphere ligand field provided by the zinc-binding amino acid residues in liver alcohol dehydrogenase. This means that the pKa of metal-bound water in zinc-containing enzymes can be assumed to correlate primarily with the number of negatively charged protein ligands coordinated by the active-site zinc ion.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0014-2956 ISBN Medium
Area Expedition Conference
Notes PMID:7011796 Approved no
Call Number Equine Behaviour @ team @ Serial 3810
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Author Touma, C.; Sachser, N.; Mostl, E.; Palme, R.
Title (up) Effects of sex and time of day on metabolism and excretion of corticosterone in urine and feces of mice Type Journal Article
Year 2003 Publication General and Comparative Endocrinology Abbreviated Journal Gen Comp Endocrinol
Volume 130 Issue 3 Pages 267-278
Keywords Animals; Chromatography, High Pressure Liquid; Circadian Rhythm/*physiology; Corticosterone/*metabolism/urine; Feces/*chemistry; Female; Immunoenzyme Techniques; Kinetics; Male; Mice; Mice, Inbred C57BL; Reference Values; Sex Factors; Stress/metabolism; Time Factors; Tritium
Abstract Non-invasive techniques to monitor stress hormones in small animals like mice offer several advantages and are highly demanded in laboratory as well as in field research. Since knowledge about the species-specific metabolism and excretion of glucocorticoids is essential to develop such a technique, we conducted radiometabolism studies in mice (Mus musculus f. domesticus, strain C57BL/6J). Each mouse was injected intraperitoneally with 740 kBq of 3H-labelled corticosterone and all voided urine and fecal samples were collected for five days. In a first experiment 16 animals (eight of each sex) received the injection at 9 a.m., while eight mice (four of each sex) were injected at 9 p.m. in a second experiment. In both experiments radioactive metabolites were recovered predominantly in the feces, although males excreted significantly higher proportions via the feces (about 73%) than females (about 53%). Peak radioactivity in the urine was detected within about 2h after injection, while in the feces peak concentrations were observed later (depending on the time of injection: about 10h postinjection in experiment 1 and about 4h postinjection in experiment 2, thus proving an effect of the time of day). The number and relative abundance of fecal [3H]corticosterone metabolites was determined by high performance liquid chromatography (HPLC). The HPLC separations revealed that corticosterone was extensively metabolized mainly to more polar substances. Regarding the types of metabolites formed, significant differences were found between males and females, but not between the experiments. Additionally, the immunoreactivity of these metabolites was assessed by screening the HPLC fractions with four enzyme immunoassays (EIA). However, only a newly established EIA for 5alpha-pregnane-3beta,11beta,21-triol-20-one (measuring corticosterone metabolites with a 5alpha-3beta,11beta-diol structure) detected several peaks of radioactive metabolites with high intensity in both sexes, while the other EIAs showed only minor immunoreactivity. Thus, our study for the first time provides substantial information about metabolism and excretion of corticosterone in urine and feces of mice and is the first demonstrating a significant impact of the animals' sex and the time of day. Based on these data it should be possible to monitor adrenocortical activity non-invasively in this species by measuring fecal corticosterone metabolites with the newly developed EIA. Since mice are extensively used in research world-wide, this could open new perspectives in various fields from ecology to behavioral endocrinology.
Address Department of Behavioral Biology, Institute of Neuro and Behavioral Biology, University of Muenster, Badestrasse 9, D-48149 Muenster, Germany. touma@uni-muenster.de
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0016-6480 ISBN Medium
Area Expedition Conference
Notes PMID:12606269 Approved no
Call Number Equine Behaviour @ team @ Serial 4086
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Author Wilson, M.T.; Silvestrini, M.C.; Morpurgo, L.; Brunori, M.
Title (up) Electron transfer kinetics between Rhus vernicifera stellacyanin and cytochrome c (horse heart cytochrome c and Pseudomonas cytochrome c551) Type Journal Article
Year 1979 Publication Journal of Inorganic Biochemistry Abbreviated Journal J Inorg Biochem
Volume 11 Issue 2 Pages 95-100
Keywords Animals; Copper; Cytochrome c Group/*metabolism; Electron Transport; Kinetics; Metalloproteins/*metabolism; Plant Proteins/*metabolism; *Plants, Toxic; Pseudomonas aeruginosa/*metabolism; Toxicodendron/*metabolism
Abstract The electron transfer reactions between Rhus vernicifera stellacyanin and either horse heart cytochrome c or Pseudomonas aeruginosa cytochrome c551 were investigated by rapid reaction techniques. The time course of electron transfer is monophasic under all conditions, and thus consistent with a simple formulation of the reaction. Both stopped-flow and temperature-jump experiments yield equilibrium constants in reasonable agreement with values calculated from the redox potentials. The differences in reaction rate between the two cytochromes and stellacyanin are discussed in terms of the Marcus theory.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0162-0134 ISBN Medium
Area Expedition Conference
Notes PMID:228006 Approved no
Call Number refbase @ user @ Serial 3879
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Author Guo, G.L.; Moffit, J.S.; Nicol, C.J.; Ward, J.M.; Aleksunes, L.A.; Slitt, A.L.; Kliewer, S.A.; Manautou, J.E.; Gonzalez, F.J.
Title (up) Enhanced acetaminophen toxicity by activation of the pregnane X receptor Type Journal Article
Year 2004 Publication Toxicological sciences : an official journal of the Society of Toxicology Abbreviated Journal Toxicol Sci
Volume 82 Issue 2 Pages 374-380
Keywords Acetaminophen/pharmacokinetics/*toxicity; Analgesics, Non-Narcotic/pharmacokinetics/*toxicity; Animals; Aryl Hydrocarbon Hydroxylases/biosynthesis; Biotransformation; Blotting, Northern; Chromatography, High Pressure Liquid; Cytochrome P-450 CYP3A; Membrane Proteins; Mice; Mice, Knockout; Oxidoreductases, N-Demethylating/biosynthesis; Pregnenolone Carbonitrile/pharmacology; Receptors, Cytoplasmic and Nuclear/*drug effects; Receptors, Steroid/*drug effects; Sulfhydryl Compounds/metabolism
Abstract The pregnane X receptor (PXR) is a ligand-activated transcription factor and member of the nuclear receptor superfamily. Activation of PXR represents an important mechanism for the induction of cytochrome P450 3A (CYP3A) enzymes that can convert acetaminophen (APAP) to its toxic intermediate metabolite, N-acetyl-p-benzoquinone imine (NAPQI). Therefore, it was hypothesized that activation of PXR plays a major role in APAP-induced hepatotoxicity. Pretreatment with the PXR activator, pregnenolone 16alpha-carbonitrile (PCN), markedly enhanced APAP-induced hepatic injury, as revealed by increased serum ALT levels and hepatic centrilobular necrosis, in wild-type but not in PXR-null mice. Further analysis showed that following PCN treatment, PXR-null mice had lower CYP3A11 expression, decreased NAPQI formation, and increased maintenance of hepatic glutathione content compared to wild-type mice. Thus, these results suggest that PXR plays a critical role in APAP-induced hepatic toxicity, probably by inducing CYP3A11 expression and hence increasing bioactivation.
Address Laboratory of Metabolism, CCR, NCI, NIH, Bethesda, Maryland 20892, USA
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1096-6080 ISBN Medium
Area Expedition Conference
Notes PMID:15456926 Approved no
Call Number refbase @ user @ Serial 71
Permanent link to this record
 
 
Author Gonzalez-Fernandez, J.M.; Atta, S.E.
Title (up) Facilitated transport of oxygen in the presence of membranes in the diffusion path Type Journal Article
Year 1982 Publication Biophysical Journal Abbreviated Journal Biophys J
Volume 38 Issue 2 Pages 133-141
Keywords Animals; Biological Transport, Active; Cell Membrane/*metabolism; Diffusion; Dogs; Horses; Humans; Kinetics; Mathematics; *Models, Biological; Muscles/*metabolism; Oxygen/*metabolism
Abstract Most of the experimental observations on facilitated transport have been done with millipore filters, and all the theoretical studies have assumed homogeneous spatial properties. In striated muscle there exist membranes that may impede the diffusion of the carrier myoglobin. In this paper a theoretical study is undertaken to analyze the transport in the presence of membranes in the diffusion path. For the numerical computations physiologically relevant values of the parameters were chosen. The numerical results indicate that the presence of membranes tends to decrease the facilitation. For the nonlinear chemical kinetics of the reaction of oxygen with the carrier, this decrement also depends on the location of the membranes. At the higher oxygen concentration side of each membrane the flow of combined oxygen is transferred to the flow of dissolved oxygen. The reverse process occurs at the lower concentration side. Jump discontinuities of the concentration of the oxygen-carrier compound at each membrane are associated with these transfers. The decrement of facilitation is due to the cumulative effect of these jump discontinuities.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0006-3495 ISBN Medium
Area Expedition Conference
Notes PMID:7093418 Approved no
Call Number Equine Behaviour @ team @ Serial 3806
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Author Abbruzzetti, S.; Crema, E.; Masino, L.; Vecli, A.; Viappiani, C.; Small, J.R.; Libertini, L.J.; Small, E.W.
Title (up) Fast events in protein folding: structural volume changes accompanying the early events in the N-->I transition of apomyoglobin induced by ultrafast pH jump Type Journal Article
Year 2000 Publication Biophysical Journal Abbreviated Journal Biophys J
Volume 78 Issue 1 Pages 405-415
Keywords Animals; Apoproteins/*chemistry; Horses; *Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; Protein Conformation; *Protein Folding; Protein Structure, Secondary; Spectrometry, Fluorescence
Abstract Ultrafast, laser-induced pH jump with time-resolved photoacoustic detection has been used to investigate the early protonation steps leading to the formation of the compact acid intermediate (I) of apomyoglobin (ApoMb). When ApoMb is in its native state (N) at pH 7.0, rapid acidification induced by a laser pulse leads to two parallel protonation processes. One reaction can be attributed to the binding of protons to the imidazole rings of His24 and His119. Reaction with imidazole leads to an unusually large contraction of -82 +/- 3 ml/mol, an enthalpy change of 8 +/- 1 kcal/mol, and an apparent bimolecular rate constant of (0.77 +/- 0.03) x 10(10) M(-1) s(-1). Our experiments evidence a rate-limiting step for this process at high ApoMb concentrations, characterized by a value of (0. 60 +/- 0.07) x 10(6) s(-1). The second protonation reaction at pH 7. 0 can be attributed to neutralization of carboxylate groups and is accompanied by an apparent expansion of 3.4 +/- 0.2 ml/mol, occurring with an apparent bimolecular rate constant of (1.25 +/- 0.02) x 10(11) M(-1) s(-1), and a reaction enthalpy of about 2 kcal/mol. The activation energy for the processes associated with the protonation of His24 and His119 is 16.2 +/- 0.9 kcal/mol, whereas that for the neutralization of carboxylates is 9.2 +/- 0.9 kcal/mol. At pH 4.5 ApoMb is in a partially unfolded state (I) and rapid acidification experiments evidence only the process assigned to carboxylate protonation. The unusually large contraction and the high energetic barrier observed at pH 7.0 for the protonation of the His residues suggests that the formation of the compact acid intermediate involves a rate-limiting step after protonation.
Address Dipartimento di Fisica, Universita di Parma, 43100 Parma, Italia
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0006-3495 ISBN Medium
Area Expedition Conference
Notes PMID:10620304 Approved no
Call Number Equine Behaviour @ team @ Serial 3792
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Author Hoang, L.; Maity, H.; Krishna, M.M.G.; Lin, Y.; Englander, S.W.
Title (up) Folding units govern the cytochrome c alkaline transition Type Journal Article
Year 2003 Publication Journal of Molecular Biology Abbreviated Journal J Mol Biol
Volume 331 Issue 1 Pages 37-43
Keywords Animals; Cytochrome c Group/*chemistry; Horses; Hydrogen/chemistry; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; *Protein Folding; Protein Structure, Tertiary; Spectrum Analysis; Titrimetry
Abstract The alkaline transition of cytochrome c is a model for protein structural switching in which the normal heme ligand is replaced by another group. Stopped flow data following a jump to high pH detect two slow kinetic phases, suggesting two rate-limiting structure changes. Results described here indicate that these events are controlled by the same structural unfolding reactions that account for the first two steps in the reversible unfolding pathway of cytochrome c. These and other results show that the cooperative folding-unfolding behavior of protein foldons can account for a variety of functional activities in addition to determining folding pathways.
Address Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA. lhoang@mail.upenn.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2836 ISBN Medium
Area Expedition Conference
Notes PMID:12875834 Approved no
Call Number Equine Behaviour @ team @ Serial 3781
Permanent link to this record
 
 
Author Geutjens, C.A.; Clayton, H.M.; Kaiser, L.J.
Title (up) Forces and pressures beneath the saddle during mounting from the ground and from a raised mounting platform Type Journal Article
Year 2008 Publication The Veterinary Journal Abbreviated Journal
Volume 175 Issue 3 Pages 332-337
Keywords Electronic saddle mat; Total force; Peak pressure; Equestrian; Kinetics
Abstract The objective was to use an electronic pressure mat to measure and compare forces and pressures of the saddle on a horse's back when riders mounted from the ground and with the aid of a mounting platform. Ten riders mounted a horse three times each from the ground and from a 35 cm high mounting platform in random order. Total force (summation of forces over all 256 sensors) was measured and compared at specific points on the force-time curve. Total force was usually highest as the rider's right leg was swinging upwards and was correlated with rider mass. When normalized to rider mass, total force and peak pressure were significantly higher when mounting from the ground than from a raised platform (P < 0.05). The area of highest pressure was on the right side of the withers in 97% of mounting efforts, confirming the importance of the withers in stabilizing the saddle during mounting.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Admin @ knut @ Serial 4344
Permanent link to this record