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Abbruzzetti, S., Crema, E., Masino, L., Vecli, A., Viappiani, C., Small, J. R., et al. (2000). Fast events in protein folding: structural volume changes accompanying the early events in the N-->I transition of apomyoglobin induced by ultrafast pH jump. Biophys J, 78(1), 405–415.
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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Abbruzzetti, S., Viappiani, C., Sinibaldi, F., & Santucci, R. (2004). Kinetics of histidine dissociation from the heme Fe(III) in N-fragment (residues 1-56) of cytochrome c. Protein J, 23(8), 519–527.
Abstract: We have here investigated the dissociation kinetics of the His side chains axially ligated to the heme-iron in the ferric (1-56 residues) N-fragment of horse cyt c. The ligand deligation induced by acidic pH-jump occurs as a biexponential process with different pre-exponential factors, consistent with a structural heterogeneity in solution and the presence of two differently coordinated species. In analogy with GuHCl-denatured cyt c, our data indicate the presence in solution of two ferric forms of the N-fragment characterized by bis-His coordination, as summarized in the following scheme: His18-Fe(III)-His26 <==> His18-Fe(III)-His33. We have found that the pre-exponential factors depend on the extent of the pH-jump. This may be correlated with the different pKa values shown by His26 and His33; due to steric factors, His26 binds to the heme-Fe(III) less strongly than His33, as recently shown by studies on denatured cyt c. Interestingly, the two lifetimes are affected by temperature but not by the extent of the pH-jump. The lower pKa for the deligation reaction required the use of an improved laser pH-jump setup, capable of inducing changes in H+ concentration as large as 1 mM after the end of the laser pulse. For the ferric N-fragment, close activation entropy values have been determined for the two histidines coordinated to the iron; this result significantly differs from that for GuHCl-denatured cyt c, where largely different values of activation entropy were calculated. This underlines the role played by the missing segment (residues 57-104) peptide chain in discriminating deligation of the “nonnative” His from the sixth coordination position of the metal.
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Abbruzzetti, S., Viappiani, C., Small, J. R., Libertini, L. J., & Small, E. W. (2001). Kinetics of histidine deligation from the heme in GuHCl-unfolded Fe(III) cytochrome C studied by a laser-induced pH-jump technique. J Am Chem Soc, 123(27), 6649–6653.
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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Anderson, W. D., & Summers, C. H. (2007). Neuroendocrine Mechanisms, Stress Coping Strategies, and Social Dominance: Comparative Lessons about Leadership Potential. Ann Am Acad Polit Soc Sci, 614(1), 102–130.
Abstract: The authors examine dominance and subordination in the social psychology, political science, and biology literatures. Using Summers and Winberg (2006) as a guide, the authors suggest that extreme dominance or subordination phenotypes--including social dominance orientation and right-wing authoritarianism--are determined by an organism's genetic predispositions, motivations, stress responses, and long-term hormone release and uptake states. The authors offer hypotheses about the likely neurochemical profiles for each of these extreme dominance and subordination phenotypes and suggest two designs that begin to test these hypotheses.
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Aviad, A. D., & Houpt, J. B. (1994). The molecular weight of therapeutic hyaluronan (sodium hyaluronate): how significant is it? J Rheumatol, 21(2), 297–301.
Abstract: Various molecular weight hyaluronic acid (HA) preparations have been injected into joints for the treatment of human and equine osteoarthritis. A therapeutic advantage has been claimed for commercial products with a molecular weight in the range found in normal synovial fluid (SF), compared to lower molecular weight products. But a correlation between molecular weight and efficacy is not borne out by an analysis of the available literature on clinical results. SF viscosity, HA concentration, HA molecular weight and rate of synthesis in joint disease. It is proposed that the beneficial effect of injected HA in joint disease may be due to pharmacological rather than to physical properties.
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Ballew, R. M., Sabelko, J., & Gruebele, M. (1996). Direct observation of fast protein folding: the initial collapse of apomyoglobin. Proc. Natl. Acad. Sci. U.S.A., 93(12), 5759–5764.
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.
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Baltic, M., Jenni-Eiermann, S., Arlettaz, R., & Palme, R. (2005). A noninvasive technique to evaluate human-generated stress in the black grouse. Ann N Y Acad Sci, 1046, 81–95.
Abstract: The continuous development of tourism and related leisure activities is exerting an increasingly intense pressure on wildlife. In this study, a novel noninvasive method for measuring stress in the black grouse, an endangered, emblematic species of European ecosystems that is currently declining in several parts of its European range, is tested and physiologically validated. A radiometabolism study and an ACTH challenge test were performed on four captive black grouse (two of each sex) in order to get basic information about the metabolism and excretion of corticosterone and to find an appropriate enzyme-immunoassay (EIA) to measure its metabolites in the feces. Peak radioactivity in the droppings was detected within 1 to 2 hours. Injected (3)H-corticosterone was excreted as polar metabolites and by itself was almost absent. A cortisone-EIA was chosen from among seven tested EIAs for different groups of glucocorticoid metabolites, because it cross-reacted with some of the formed metabolites and best reflected the increase of excreted corticosterone metabolites, after the ACTH challenge test. Concentrations of the metabolites from fecal samples collected from snow burrows of free-ranging black grouse were within the same range as in captive birds. The noninvasive method described may be appropriate for evaluating the stress faced by free-living black grouse populations in the wild, particularly in mountain ecosystems where human disturbance, especially by winter sports, is of increasing conservation concern.
Keywords: Adrenocorticotropic Hormone/metabolism; Animals; Bird Diseases/*metabolism; Conservation of Natural Resources; Corticosterone/*metabolism; Ecosystem; Feces/*chemistry; Female; Galliformes/*metabolism; Immunoenzyme Techniques/methods/veterinary; Male; Reproducibility of Results; Stress/metabolism/*veterinary; Tritium/diagnostic use
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Birch, H. L., Bailey, A. J., & Goodship, A. E. (1998). Macroscopic 'degeneration' of equine superficial digital flexor tendon is accompanied by a change in extracellular matrix composition. Equine Vet J, 30(6), 534–539.
Abstract: Injuries to the superficial digital flexor tendon are common in horses required to gallop and jump at speed. Partial rupture of this tendon usually occurs in the central core of the midmetacarpal region and may be preceded by localised degenerative changes. Post mortem examination of apparently normal equine flexor tendons has revealed an abnormal macroscopic appearance in the central core, characterised by a reddish discolouration. We have previously shown that there is also physical damage to the collagen fibres. In the present study we tested the hypothesis that the abnormal appearance is accompanied by changes in the composition of the extracellular matrix of the tendon. Biochemical analysis of the extracellular matrix demonstrated an increase in total sulphated glycosaminoglycan content, increase in the proportion of type III collagen and decrease in collagen linked fluorescence in the central core of 'degenerated' tendons relative to tissue from the peripheral region of the same tendon. Dry matter content and total collagen content were not significantly different between tendon zones or normal and 'degenerated' tendons. These changes suggest a change in cell metabolism and matrix turnover in the central core of the tendon and are likely to contribute to a decrease in mechanical properties in this part of the tendon, predisposing to the characteristic partial rupture of the tendon.
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Boucher, J. M., Hanosset, R., Augot, D., Bart, J. M., Morand, M., Piarroux, R., et al. (2005). Detection of Echinococcus multilocularis in wild boars in France using PCR techniques against larval form. Vet Parasitol, 129(3-4), 259–266.
Abstract: Recently, new data have been collected on the distribution and ecology of Echinococcus multilocularis in European countries. Different ungulates species such as pig, goat, sheep, cattle and horse are known to host incomplete development of larval E. multilocularis. We report a case of E. multilocularis portage in two wild boars from a high endemic area in France (Department of Jura). Histological examination was performed and the DNA was isolated from hepatic lesions then amplified by using three PCR methods in two distinct institutes. Molecular characterisation of PCR products revealed 99% nucleotide sequence homology with the specific sequence of the U1 sn RNA gene of E. multilocularis, 99 and 99.9% nucleotide sequence homology with the specific sequence of the cytochrome oxydase gene of Echinococcus genus and 99.9% nucleotide sequence homology with a genomic DNA sequence of Echinococcus genus for the first and the second wild boar, respectively.
Keywords: Animals; Base Sequence; DNA, Helminth/chemistry/genetics; Echinococcosis/parasitology/pathology/*veterinary; Echinococcus multilocularis/*isolation & purification; Electron Transport Complex IV/chemistry/genetics; France; Histocytochemistry/veterinary; Liver/parasitology/pathology; Male; Molecular Sequence Data; Polymerase Chain Reaction/veterinary; Sequence Alignment; Sus scrofa/*parasitology; Swine Diseases/*parasitology/pathology
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Carroll, J., Murphy, C. J., Neitz, M., Hoeve, J. N., & Neitz, J. (2001). Photopigment basis for dichromatic color vision in the horse. J Vis, 1(2), 80–87.
Abstract: Horses, like other ungulates, are active in the day, at dusk, dawn, and night; and, they have eyes designed to have both high sensitivity for vision in dim light and good visual acuity under higher light levels (Walls, 1942). Typically, daytime activity is associated with the presence of multiple cone classes and color-vision capacity (Jacobs, 1993). Previous studies in other ungulates, such as pigs, goats, cows, sheep and deer, have shown that they have two spectrally different cone types, and hence, at least the photopigment basis for dichromatic color vision (Neitz & Jacobs, 1989; Jacobs, Deegan II, Neitz, Murphy, Miller, & Marchinton, 1994; Jacobs, Deegan II, & Neitz, 1998). Here, electroretinogram flicker photometry was used to measure the spectral sensitivities of the cones in the domestic horse (Equus caballus). Two distinct spectral mechanisms were identified and are consistent with the presence of a short-wavelength-sensitive (S) and a middle-to-long-wavelength-sensitive (M/L) cone. The spectral sensitivity of the S cone was estimated to have a peak of 428 nm, while the M/L cone had a peak of 539 nm. These two cone types would provide the basis for dichromatic color vision consistent with recent results from behavioral testing of horses (Macuda & Timney, 1999; Macuda & Timney, 2000; Timney & Macuda, 2001). The spectral peak of the M/L cone photopigment measured here, in vivo, is similar to that obtained when the gene was sequenced, cloned, and expressed in vitro (Yokoyama & Radlwimmer, 1999). Of the ungulates that have been studied to date, all have the photopigment basis for dichromatic color vision; however, they differ considerably from one another in the spectral tuning of their cone pigments. These differences may represent adaptations to the different visual requirements of different species.
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