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Meershoek, L. S., Schamhardt, H. C., Roepstorff, L., & Johnston, C. (2001). Forelimb tendon loading during jump landings and the influence of fence height. Equine Vet J Suppl, (33), 6–10.
Abstract: Lameness in athletic horses is often caused by forelimb tendon injuries, especially in the interosseus tendon (TI) and superficial digital flexor tendon (SDF), but also in the accessory ligament (AL) of the deep digital flexor tendon (DDF). In an attempt to explain the aetiology of these injuries, the present study investigated the loading of the tendons during landing after a jump. In jumping horses, the highest forces can be expected in the trailing limb during landing. Therefore, landing kinematics and ground reaction forces of the trailing forelimb were measured from 6 horses jumping single fences with low to medium heights of 0.80, 1.00 and 1.20 m. The tendon forces were calculated using inverse dynamics and an in vitro model of the lower forelimb. Calculated peak forces in the TI, SDF and DDF + AL during landing were 15.8, 13.9 and 11.7 kN respectively. The relative loading of the tendons (landing forces compared with failure forces determined in a separate study) increased from DDF to TI to SDF and was very high in SDF. This explains the low injury incidence of the DDF and the high injury incidence of the SDF. Fence height substantially influenced SDF forces, whereas it hardly influenced TI forces and did not influence AL strain. Reduction of fence height might therefore limit the risks for SDF injuries, but not for TI and AL injuries.
Keywords: Animals; Biomechanics; Forelimb/injuries/physiology; Horses/injuries/*physiology; Lameness, Animal/etiology; Ligaments, Articular/*physiology; Locomotion/*physiology; Physical Conditioning, Animal; Tendon Injuries/complications/physiopathology/veterinary; Tendons/*physiology; Weight-Bearing/physiology
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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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Dyson, H. J., & Beattie, J. K. (1982). Spin state and unfolding equilibria of ferricytochrome c in acidic solutions. J Biol Chem, 257(5), 2267–2273.
Abstract: Equilibrium, stopped flow, and temperature-jump spectrophotometry have been used to identify processes in the unfolding of ferricytochrome c in acidic aqueous solutions. A relaxation occurring in approximately 100 microseconds involves perturbation of a spin-equilibrium between two folded conformers of the protein with methionine-80 coordinated or dissociated from the heme iron. The protein unfolds more slowly, in milliseconds, with dissociation and protonation of histidine-18. These two transitions appear cooperative in equilibrium measurements at low (0.01 M) ionic strength, but are separated at higher (0.10 M) ionic strength. They are resolved under both conditions in the dynamic measurements. The spin-equilibrium description permits a unified explanation of a number of properties of ferricytochrome c in acidic aqueous solutions.
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Andersson, P., Kvassman, J., Lindstrom, A., Olden, B., & Pettersson, G. (1981). Effect of NADH on the pKa of zinc-bound water in liver alcohol dehydrogenase. Eur J Biochem, 113(3), 425–433.
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.
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Singer, E. R., Barnes, J., Saxby, F., & Murray, J. K. (2008). Injuries in the event horse: Training versus competition. The Veterinary Journal, 175(1), 76–81.
Abstract: Two related studies on injuries sustained by event horses during competition and during training are reported. During the cross-country phase of competition, the most common injuries were lacerations and abrasions to the carpus and stifle. Superficial digital flexor tendonitis and exertional rhabdomyolysis were significantly more common during Cours Complete Internationale (CCI) competitions compared to one-day event (ODE) competitions. The difference in injury types at ODEs and CCI competitions probably relates to the increased athletic demands of the CCI and the closer veterinary observation at these competitions. The results of the training study indicate that 21% of horses intending to compete in a CCI did not start due to injury. Forty-three percent of these injuries involved soft tissue structures with injuries to the superficial digital flexor tendon and the suspensory ligament each accounting for 33%. The most important area for future research is investigation of the risk factors for these career-threatening soft tissue injuries.
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Thor, D. H., & Holloway, W. R. (1982). Social memory of the male laboratory rat. J. Comp. Physiol. Psychol., 96(6), 1000–1006.
Abstract: Used duration of social-investigatory behavior by 36 mature male Long-Evans rats as a measure of individual recognition in 5 experiments to assess social memory. In Exp I, the duration of social investigation during a 2nd exposure to the same juvenile (n[en space]=[en space]12) was directly related to the length of the interexposure interval. In Exp II, Ss were exposed to the same or different juvenile 10 min after an initial 5-min exposure to a novel juvenile; reexposure to the same juvenile elicited significantly less social investigation than an exposure to a different juvenile. Exps III and IV demonstrated that following a 5-min introductory exposure, social memory of the juvenile was relatively brief in comparison with that of mature Ss. Exp V revealed a retroactive interference effect on recently acquired memory for an individual: 12 mature Ss exposed to interpolated social experience engaged in significantly longer investigation of a juvenile than those with no interpolated social experience. The combined results suggest that (1) the rat normally engages in spontaneous learning of individual identity and (2) social memory may be a significant aspect of complex social interactions. (16 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)
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Ahrendt, L. P., Christensen, J. W., & Ladewig, J. (2012). The ability of horses to learn an instrumental task through social observation. In Applied Animal Behaviour Science (Vol. 139, pp. 105–113).
Abstract: The ability of horses to learn through social observation may ease the implementation of new management systems, because the use of automatic feeders etc. by naive horses could be facilitated by observation of experienced horses. However, previous studies found no documentation for observational learning abilities in horses. This study aimed to investigate the ability of horses to learn an instrumental task from a familiar conspecific when social interaction was allowed during the demonstration. Two similar experiments were performed. In the first experiment, Observer horses (n=11) participated in ten successive demonstrations, where a trained Demonstrator opened an operant device by pushing a sliding lid aside with the muzzle in order to obtain a food reward. Immediately after the demonstrations the Observer horses were given the opportunity to operate the device alone. Control horses (n=11) were aware that the device contained food but were presented to the operant device without demonstration of the task. The learning criterion was at least two openings. Accomplishment of and latency to accomplish the learning criterion, and investigative behaviour towards the operant device were recorded. Five Observers and one Control, out of the eleven horses in each treatment group, accomplished the learning criterion. Even though this presents a high odds ratio (OR) in favour of the Observer treatment (OR=7.6), there was no significant difference between the treatment groups (P=0.15). Analysis of investigative behaviour showed, however, that the demonstrations increased the motivation of the Observer horses to investigate the device. Subsequently, a similar experiment was performed in a practical setting with 44 test horses (mixed age, gender and breed). We used the same operant device and the same number and type of demonstrations, although the horses were held on a loose rope to minimise aggression. In this second experiment, six of 23 Observer horses and five of 21 Control horses learned the instrumental task, representing no influence of the demonstration. Thus, this study did not demonstrate an ability of horses to learn an instrumental task through observation.
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Massen, J., Sterck, E., & de Vos, H. (2010). Close social associations in animals and humans: functions and mechanisms of friendship (Vol. 147).
Abstract: Both humans and group-living animals associate and behave affiliatively more with some individuals than others. Human friendship has long been acknowledged, and recently scientists studying animal behaviour have started using the term friendship for close social associates in animals. Yet, while biologists describe friends as social tools to enhance fitness, social scientists describe human friendship as unconditional. We investigate whether these different descriptions reflect true differences in human friendship and animal close social associations or are a by-product of different research approaches: namely social scientists focussing on proximate and biologists on ultimate explanations. We first stress the importance of similar measures to determine close social associations, thereafter examine their ultimate benefits and proximate motivations, and discuss the latest findings on the central-neural regulation of social bonds. We conclude that both human friendship and animal close social associations are ultimately beneficial. On the proximate level, motivations for friendship in humans and for close social associations in animals are not necessarily based on benefits and are often unconditional. Moreover, humans share with many animals a similar physiological basis of sociality. Therefore, biologists and social scientist describe the same phenomenon, and the use of the term friendship for animals seems justified.
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Skandakumar, S., Stodulski, G., & Hau, J. (1995). Salivary IgA: a Possible Stress Marker In Dogs. In Animal Welfare (Vol. 4, pp. 339–350).
Abstract: Stress in humans has been reported to be associated with a decrease in the salivary immunoglobulin A (s-IgA) levels enabling the possible use of s-IgA to assess stress. Prolonged stress, if reliably assessed in a non-invasive manner, may be used to assess animal welfare. This study analysed groups of dogs undergoing physical and temperamental training and s-IgA levels were measured by rocket immunoelectrophoresis in prospective samples. Behavioural assessment was carried out and cortisol levels in saliva were measured by ELISA. A significant negative correlation (P < 0.007) between the logarithmic cortisol concentrations and s-IgA levels in saliva was recorded. The behavioural assessment of the dogs agreed well with the biochemical markers. It is concluded that IgA levels in saliva may be a useful marker of dog well-being and that stress results in decreased s-IgA levels.
Keywords: Animal Welfare; Behaviour; Cortisol; Dog; Salivary Iga (S-Iga); Stress; Well-Being
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Reyna-Garfias, H., Miliar, A., Jarillo-Luna, A., Rivera-Aguilar, V., Pacheco-Yepez, J., Baeza, I., et al. (2010). Repeated restraint stress increases IgA concentration in rat small intestine. Brain, Behavior, and Immunity, 24(1), 110–118.
Abstract: The most abundant intestinal immunoglobulin and first line of specific immunological defense against environmental antigens is secretory immunoglobulin A. To better understand the effect of repeated stress on the secretion of intestinal IgA, the effects of restraint stress on IgA concentration and mRNA expression of the gene for the alpha-chain of IgA was assessed in both the duodenum and ileum of the rats. Restraint stress induced an increase in intestinal IgA, which was blocked by an adrenalectomy, suggesting a role of catecholamines and glucocorticoids. Whereas the blocking of glucocorticoid receptors by RU-486 did not affect the increased IgA concentration, it did reduce IgA alpha-chain mRNA expression in both segments, indicating a possible mediation on the part of glucocorticoids in IgA secretion by individual cells. Treatment with corticosterone significantly increased both the IgA concentration and IgA alpha-chain mRNA expression in ileum but not in duodenum, suggesting that glucocorticoids may act directly on IgA-antibody forming cells to increase IgA secretion in the former segment. A probable role by catecholamines was evidenced by the reduction in IgA concentration and IgA alpha-chain mRNA expression in both segments after a chemical sympathectomy with 6-hydroxydopamine (6-OHDA). Additionally, norepinephrine significantly reduced IgA alpha-chain mRNA levels but increased pIgR mRNA expression and IgA concentration in both intestinal segments. We propose that the increased intestinal IgA levels caused by repeated restraint stress is likely due to the effects of catecholamines on the transport of plgA across the epithelium.
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