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Author |
Ziegler, W.H. |
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Title |
[Endocrinological studies in arterial hypertension. Search for phaeochromocytoma] |
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Journal Article |
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Year |
1976 |
Publication |
Schweizerische Medizinische Wochenschrift |
Abbreviated Journal |
Schweiz Med Wochenschr |
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Volume |
106 |
Issue |
34 |
Pages |
1148-1150 |
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Keywords |
Angiography; Blood Volume; Catecholamines/urine; Glucagon/diagnostic use; Histamine/diagnostic use; Humans; Hydrogen-Ion Concentration; Hypertension/*etiology; Methods; Pheochromocytoma/*complications/diagnosis; Tyramine/diagnostic use |
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Abstract |
Elevated urinary catecholamines and their metabolites are the only findings which confirm the presence of pheochromocytoma. This examination is of particular interest if carried out in urine produced after spontaneous hypertensive episodes. Pharmacologic tests when carried out under standard conditions have proven to be a reliable aid in cases of suspected pheochromocytoma. Roentgenographic studies, determination of local plasma catecholamine concentrations and blood volume control should be undertaken in these patients before surgical procedure. |
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German |
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Endokrinologische Untersuchungen bei arterieller Hypertonie. Suche nach Phaochromozytom |
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0036-7672 |
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PMID:12561 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4047 |
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Author |
Nicol, C.J.; Davidson, H.P.D.; Harris, P.A.; Waters, A.J.; Wilson, A.D. |
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Title |
Study of crib-biting and gastric inflammation and ulceration in young horses |
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Journal Article |
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Year |
2002 |
Publication |
The Veterinary record |
Abbreviated Journal |
Vet. Rec. |
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Volume |
151 |
Issue |
22 |
Pages |
658-662 |
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Keywords |
Animal Husbandry/methods; Animals; Antacids/therapeutic use; *Behavior, Animal; Diet/veterinary; Endoscopy, Gastrointestinal/veterinary; Feces/chemistry; Female; Gastritis/diet therapy/physiopathology/*veterinary; Horse Diseases/diet therapy/*physiopathology/psychology; Horses; Hydrogen-Ion Concentration; Male; Random Allocation; Stereotyped Behavior/*physiology; Stomach Ulcer/diet therapy/physiopathology/*veterinary; Treatment Outcome; Weaning |
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Nineteen young horses that had recently started to perform the stereotypy of crib-biting were compared with 16 non-stereotypic horses for 14 weeks. After initial observations of their behaviour and an endoscopic examination of the condition of their stomachs, the horses were randomly allocated to a control or an antacid diet At the start of the trial, the stomachs of the crib-biting foals were significantly more ulcerated and inflamed than the stomachs of the normal foals. In addition, the faecal pH of the crib-biting foals (6.05) was significantly lower than that of the normal foals (6.58). The antacid diet resulted in a significant improvement in the condition of the horses' stomachs. The crib-biting behaviour declined in most of the foals, regardless of their diet, but tended to decline to a greater extent in the foals on the antacid diet. |
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Department of Clinical Veterinary Science, University of Bristol, Langford House, Bristol BS40 5DU |
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0042-4900 |
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PMID:12498408 |
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Call Number |
refbase @ user @ |
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83 |
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Author |
Haruta, N.; Kitagawa, T. |
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Title |
Time-resolved UV resonance Raman investigation of protein folding using a rapid mixer: characterization of kinetic folding intermediates of apomyoglobin |
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Journal Article |
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Year |
2002 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
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Volume |
41 |
Issue |
21 |
Pages |
6595-6604 |
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Keywords |
Animals; Apoproteins/*chemistry; Circular Dichroism; Holoenzymes/chemistry; Horses; Hydrochloric Acid/chemistry; Hydrogen-Ion Concentration; Imidazoles/chemistry; Kinetics; Models, Molecular; Myoglobin/*chemistry; Peptide Fragments/chemistry; *Protein Folding; Protein Structure, Secondary; Spectrum Analysis, Raman/*methods; Tryptophan/*chemistry; Ultraviolet Rays; Whales |
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Abstract |
The 244-nm excited transient UV resonance Raman spectra are observed for the refolding intermediates of horse apomyoglobin (h-apoMb) with a newly constructed mixed flow cell system, and the results are interpreted on the basis of the spectra observed for the equilibrium acid unfolding of the same protein. The dead time of mixing, which was determined with the appearance of UV Raman bands of imidazolium upon mixing of imidazole with acid, was 150 micros under the flow rate that was adopted. The pH-jump experiments of h-apoMb from pH 2.2 to 5.6 conducted with this device demonstrated the presence of three folding intermediates. On the basis of the analysis of W3 and W7 bands of Trp7 and Trp14, the first intermediate, formed before 250 micros, involved incorporation of Trp14 into the alpha-helix from a random coil. The frequency shift of the W3 band of Trp14 observed for this process was reproduced with a model peptide of the A helix when it forms the alpha-helix. In the second intermediate, formed around 1 ms after the start of refolding, the surroundings of both Trp7 and Trp14 were significantly hydrophobic, suggesting the formation of the hydrophobic core. In the third intermediate appearing around 3 ms, the hydrophobicity was relaxed to the same level as that of the pH 4 equilibrium intermediate, which was investigated in detail with the stationary state technique. The change from the third intermediate to the native state needs more time than 40 ms, while the appearance of the native spectrum after the mixing of the same solutions was confirmed separately. |
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School of Mathematical and Physical Sciences, The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan |
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0006-2960 |
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Notes |
PMID:12022863 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3785 |
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Author |
Abbruzzetti, S.; Viappiani, C.; Small, J.R.; Libertini, L.J.; Small, E.W. |
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Title |
Kinetics of histidine deligation from the heme in GuHCl-unfolded Fe(III) cytochrome C studied by a laser-induced pH-jump technique |
Type |
Journal Article |
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Year |
2001 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
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Volume |
123 |
Issue |
27 |
Pages |
6649-6653 |
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Keywords |
Animals; *Bacterial Proteins; Cytochrome c Group/*chemistry; Guanidine/*chemistry; Heme/*chemistry; Histidine/*chemistry; Horses; Hydrogen-Ion Concentration; Kinetics; *Lasers; Ligands; Protein Folding |
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Abstract |
We have developed an instrumental setup that uses transient absorption to monitor protein folding/unfolding processes following a laser-induced, ultrafast release of protons from o-nitrobenzaldehyde. The resulting increase in [H(+)], which can be more than 100 microM, is complete within a few nanoseconds. The increase in [H(+)] lowers the pH of the solution from neutrality to approximately 4 at the highest laser pulse energy used. Protein structural rearrangements can be followed by transient absorption, with kinetic monitoring over a broad time range (approximately 10 ns to 500 ms). Using this pH-jump/transient absorption technique, we have examined the dissociation kinetics of non-native axial heme ligands (either histidine His26 or His33) in GuHCl-unfolded Fe(III) cytochrome c (cyt c). Deligation of the non-native ligands following the acidic pH-jump occurs as a biexponential process with different pre-exponential factors. The pre-exponential factors markedly depend on the extent of the pH-jump, as expected from differences in the pK(a) values of His26 and His33. The two lifetimes were found to depend on temperature but were not functions of either the magnitude of the pH-jump or the pre-pulse pH of the solution. The activation energies of the deligation processes support the suggestion that GuHCl-unfolded cyt c structures with non-native histidine axial ligands represent kinetic traps in unfolding. |
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Dipartimento di Fisica, Universita di Parma, Istituto Nazionale per la Fisica della Materia, 43100 Parma, Italy |
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0002-7863 |
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Notes |
PMID:11439052 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3788 |
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Author |
Gulotta, M.; Gilmanshin, R.; Buscher, T.C.; Callender, R.H.; Dyer, R.B. |
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Title |
Core formation in apomyoglobin: probing the upper reaches of the folding energy landscape |
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Journal Article |
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Year |
2001 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
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Volume |
40 |
Issue |
17 |
Pages |
5137-5143 |
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Keywords |
Animals; Apoproteins/*chemistry; Computer Simulation; Horses; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; *Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Spectrometry, Fluorescence/instrumentation/methods; Thermodynamics; Tryptophan/chemistry |
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Abstract |
An acid-destabilized form of apomyoglobin, the so-called E state, consists of a set of heterogeneous structures that are all characterized by a stable hydrophobic core composed of 30-40 residues at the intersection of the A, G, and H helices of the protein, with little other secondary structure and no other tertiary structure. Relaxation kinetics studies were carried out to characterize the dynamics of core melting and formation in this protein. The unfolding and/or refolding response is induced by a laser-induced temperature jump between the folded and unfolded forms of E, and structural changes are monitored using the infrared amide I' absorbance at 1648-1651 cm(-1) that reports on the formation of solvent-protected, native-like helix in the core and by fluorescence emission changes from apomyoglobin's Trp14, a measure of burial of the indole group of this residue. The fluorescence kinetics data are monoexponential with a relaxation time of 14 micros. However, infrared kinetics data are best fit to a biexponential function with relaxation times of 14 and 59 micros. These relaxation times are very fast, close to the limits placed on folding reactions by diffusion. The 14 micros relaxation time is weakly temperature dependent and thus represents a pathway that is energetically downhill. The appearance of this relaxation time in both the fluorescence and infrared measurements indicates that this folding event proceeds by a concomitant formation of compact secondary and tertiary structures. The 59 micros relaxation time is much more strongly temperature dependent and has no fluorescence counterpart, indicating an activated process with a large energy barrier wherein nonspecific hydrophobic interactions between helix A and the G and H helices cause some helix burial but Trp14 remains solvent exposed. These results are best fit by a multiple-pathway kinetic model when U collapses to form the various folded core structures of E. Thus, the results suggest very robust dynamics for core formation involving multiple folding pathways and provide significant insight into the primary processes of protein folding. |
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Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA |
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0006-2960 |
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Notes |
PMID:11318635 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3789 |
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Author |
Pierce, M.M.; Nall, B.T. |
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Title |
Coupled kinetic traps in cytochrome c folding: His-heme misligation and proline isomerization |
Type |
Journal Article |
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Year |
2000 |
Publication |
Journal of Molecular Biology |
Abbreviated Journal |
J Mol Biol |
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Volume |
298 |
Issue |
5 |
Pages |
955-969 |
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Keywords |
Amino Acid Sequence; Amino Acid Substitution/genetics; Binding Sites; Cytochrome c Group/*chemistry/genetics/*metabolism; *Cytochromes c; Enzyme Stability/drug effects; Fluorescence; Guanidine/pharmacology; Heme/*metabolism; Histidine/genetics/*metabolism; Hydrogen-Ion Concentration; Isomerism; Kinetics; Models, Molecular; Molecular Sequence Data; Mutation/genetics; Proline/*chemistry/metabolism; Protein Conformation/drug effects; Protein Denaturation/drug effects; *Protein Folding; Protein Renaturation; Saccharomyces cerevisiae/enzymology/genetics; Sequence Alignment; Thermodynamics |
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Abstract |
The effect of His-heme misligation on folding has been investigated for a triple mutant of yeast iso-2 cytochrome c (N26H,H33N,H39K iso-2). The variant contains a single misligating His residue at position 26, a location at which His residues are found in several cytochrome c homologues, including horse, tuna, and yeast iso-1. The amplitude for fast phase folding exhibits a strong initial pH dependence. For GdnHCl unfolded protein at an initial pH<5, the observed refolding at final pH 6 is dominated by a fast phase (tau(2f)=20 ms, alpha(2f)=90 %) that represents folding in the absence of misligation. For unfolded protein at initial pH 6, folding at final pH 6 occurs in a fast phase of reduced amplitude (alpha(2f) approximately 20 %) but the same rate (tau(2f)=20 ms), and in two slower phases (tau(m)=6-8 seconds, alpha(m) approximately 45 %; and tau(1b)=16-20 seconds, alpha(1b) approximately 35 %). Double jump experiments show that the initial pH dependence of the folding amplitudes results from a slow pH-dependent equilibrium between fast and slow folding species present in the unfolded protein. The slow equilibrium arises from coupling of the His protonation equilibrium to His-heme misligation and proline isomerization. Specifically, Pro25 is predominantly in trans in the unligated low-pH unfolded protein, but is constrained in a non-native cis isomerization state by His26-heme misligation near neutral pH. Refolding from the misligated unfolded form proceeds slowly due to the large energetic barrier required for proline isomerization and displacement of the misligated His26-heme ligand. |
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Center for Biomolecular Structure, Department of Biochemistry, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA |
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0022-2836 |
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Notes |
PMID:10801361 |
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no |
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Call Number |
refbase @ user @ |
Serial |
3853 |
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Author |
Abbruzzetti, S.; Crema, E.; Masino, L.; Vecli, A.; Viappiani, C.; Small, J.R.; Libertini, L.J.; Small, E.W. |
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Title |
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 |
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Year |
2000 |
Publication |
Biophysical Journal |
Abbreviated Journal |
Biophys J |
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Volume |
78 |
Issue |
1 |
Pages |
405-415 |
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Keywords |
Animals; Apoproteins/*chemistry; Horses; *Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; Protein Conformation; *Protein Folding; Protein Structure, Secondary; Spectrometry, Fluorescence |
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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. |
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Dipartimento di Fisica, Universita di Parma, 43100 Parma, Italia |
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0006-3495 |
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Notes |
PMID:10620304 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3792 |
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