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    Endocrine fibroblast growth factors in domestic animals.
    (Elsevier B.V., 2024-07-09) Brinker EJ; Hardcastle MR; Dittmer KE; Graff EC
    Fibroblast growth factors (FGFs) are a group of structurally homologous yet functionally pleiotropic proteins. Canonical and intracellular FGFs have primarily autocrine or paracrine effects. However, the FGF19 subfamily, composed of FGF15/19, FGF21, and FGF23, act as endocrine hormones that regulate bile acid, metabolic, and phosphorus homeostasis, respectively. Current research in human and rodent models demonstrates the potential of these endocrine FGFs to target various diseases, including disorders of inherited hypophosphatemia, chronic liver disease, obesity, and insulin resistance. Many diseases targeted for therapeutic use in humans have pathophysiological overlaps in domestic animals. Despite the potential clinical and economic impact, little is known about endocrine FGFs and their signaling pathways in major domestic animal species compared with humans and laboratory animals. This review aims to describe the physiology of these endocrine FGFs, discuss their current therapeutic use, and summarize the contemporary literature regarding endocrine FGFs in domestic animals, focusing on potential future directions.
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    Steps towards operationalizing One Health approaches.
    (Elsevier B.V., 2024-04-27) Pepin KM; Carlisle K; Anderson D; Baker MG; Chipman RB; Benschop J; French NP; Greenhalgh S; McDougall S; Muellner P; Murphy E; O'Neale DRJ; Plank MJ; Hayman DTS
    One Health recognizes the health of humans, agriculture, wildlife, and the environment are interrelated. The concept has been embraced by international health and environmental authorities such as WHO, WOAH, FAO, and UNEP, but One Health approaches have been more practiced by researchers than national or international authorities. To identify priorities for operationalizing One Health beyond research contexts, we conducted 41 semi-structured interviews with professionals across One Health sectors (public health, environment, agriculture, wildlife) and institutional contexts, who focus on national-scale and international applications. We identify important challenges, solutions, and priorities for delivering the One Health agenda through government action. Participants said One Health has made progress with motivating stakeholders to attempt One Health approaches, but achieving implementation needs more guidance (action plans for how to leverage or change current government infrastructure to accommodate cross-sector policy and strategic mission planning) and facilitation (behavioral change, dedicated personnel, new training model).
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    Characterising the responses of farm mammals to a thoracic squeeze and the relationship to tonic immobility : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand
    (Massey University, 2023) Holdsworth, Sophia Ellen
    Applying compression to the thorax of newborn farm mammals causes immobility accompanied by reduced responsiveness. Traditionally, this response was proposed to arise in neonatal foals due to the ‘thoracic squeeze’ mimicking the compression occurring during birth. Recent findings regarding the responses to the squeeze suggest a link to Tonic Immobility (TI). TI is a temporary and reversible state of reduced responsiveness and immobility with characteristic physiological changes. It is elicited by the collective actions of handling and sustained physical contact with additional pressure (restraint) and may be facilitated by inversion. TI is reported in young and adult animals of numerous species. The aim of this thesis was to examine whether responses to the thoracic squeeze are consistent with TI. First, behavioural responses to a squeeze were explored in lambs, with a focus on determining whether responses persisted beyond the neonatal period. Cortisol responses of healthy neonatal piglets to the squeeze were then investigated to explore similarities in Hypothalamic-Pituitary-Adrenal responses between the squeeze and TI. The final study examined electroencephalographic (EEG) responses of healthy neonatal piglets to a thoracic squeeze under light anaesthesia, to determine whether the squeeze causes changes in brain activity or exerts anti-nociceptive effects such as those reported during TI. The results demonstrated that responses to a thoracic squeeze persist beyond the neonatal period in lambs, and responses are generalised across multiple mammalian species. Furthermore, cortisol responses of piglets to a thoracic squeeze followed a similar pattern to that previously observed during TI in other species. Also consistent with some TI studies, the initial handling and restraint required to apply the squeeze appeared to induce the cortisol response in piglets. No inferences could be made about the effects of a thoracic squeeze on state of awareness in neonatal piglets, or the squeeze’s effect on nociception due to methodological limitations. Nevertheless, the results of this research support the hypothesis that the thoracic squeeze may be classified as a stimulus for inducing TI. Further work is required to characterise the effects of the squeeze on awareness and nociception and to explore the affective experiences of animals subjected to the squeeze.
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    Sarcocystis gigantea : studies on sporocyst production, excystation and viability : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science
    (Massey University, 1984) McKenna, Philip Bernard
    Recent advances in knowledge about the sporozoan genus Sacocystis (Protozoa: Apicomplexa) are reviewed and studies on the production, excystation and viability of sporocysts of Sarcocystis gigantea, undertaken. Investigation of a sedimentation/floatation procedure for the mass recovery of S. gigantea sporocysts from cat faeces showed that the greatest yields were obtained when a proportion of faeces to floatation medium of 5% and a centrifugal force of 6000 x g for at least 5 min were used. Ninety-six percent of the sporocysts recovered were obtained from the first centrifugation in aqueous NaCl solution, specific gravity 1.2. Although neither sieving nor additional washing of homogenised samples prior to floatation significantly affected sporocyst recovery both reduced the amount of debris present. A considerable reduction in the amount of debris resulted from feeding infected cats on tinned fish rather than tinned meat. The addition of CCl4 to the NaCl solution also improved sporocyst purity but with a marked reduction in the numbers recovered. A technique for determining the concentration of sporocysts in faeces, using a modification of the mass recovery procedure and a haemocytometer, was developed. This was shown to be more accurate and reliable than the McMaster method for performing faecal sporocyst counts. It resulted in a mean sporocyst recovery of 75.5% and was used to obtain information about patterns of sporocyst excretion and numbers of S. gigantea sporocysts shed by 28 experimentally infected cats. In all cats, sporocyst excretion commenced 10 or 11 days post-infection(PI). Peak production occurred between 13 and 22 days PI, in most instances on days 17 and 18. Peak numbers (rounded) ranged from 550 to 260,000 (mean = 53,000) sporocysts per gram of faeces or from 38,000 to 6.6. million (mean = 1.7 million) sporocysts per day. The number of days sporocysts were shed ranged from 26 to at least 60 days PI but in 26 of the 28 infections examined, more than 80% of the total sporocyst yield was produced within 30 days of infection. The total numbers of sporocysts produced by individual cats over the patent period ranged from 164,000 to 56.6 million (mean = 12.7 million). These numbers tended to increase with increasing infective dose and to be greater in those cats receiving multiple rather than equivalent single doses. Neither the sex of the cat, nor experience of one or two previous infections, had any significant effect on the numbers of sporocysts shed. Studies on the in vitro excystation of S.gigantea sporocysts revealed that pretreatment before exposure to trypsin and bile was an essential pre-requisite. However, in contrast to S. tenella and S. capracanis, incubation in cysteine hydrochloride under CO2 was largely unsuccessful for excysting S. gigantea: of the pretreatments tested only exposure to sodium hypochlorite proved effective. Excystation from sodium hypochlorite-pretreated S. gigantea sporocysts took place in trypsin and bile between temperatures of 30° and 43°C and occurred rapidly at 39°C. While the presence of bile or bile salts was essential for this process, that of trypsin was not although more sporocysts excysted in its presence than in its absence. Excystation occurred in the presence of all bile types tested but not when 'Tween 80' was substituted for bile. The highest levels of excystation were recorded when cattle or sheep bile or sodium taurocholate were used and the lowest when chicken or pig bile were employed. Neither the concentration of sheep bile above 2.5%, nor hydrogen ion concentration (pH range 5.0 to 10.0) appeared to have any marked effect on the level of excystation obtained. The excystation process for S. gigantea was similar to that described for other Sarcocystis species and for other coccidian genera that lack sporocyst Stieda bodies. Sporozoites escaped following the collapse of the sporocyst wall and its eventual separation into four elongated pieces. In vivo studies on excystation of S. gigantea indicated that this process was, as in vitro, diphasic involving pretreatment and treatment phases. They also tended to support in vitro observations that the requirements for the excystation of S. gigantea and S. tenella sporocysts were quite different. Although the results suggested that for neither species was the pretreatment stimulus likely to be provided by conditions in the rumen alone, exposure to abomasal conditions only, induced moderate levels of excystation in both when they were subsequently treated with trypsin and bile. For S. gigantea, 0.25 to 4 hr abomasal exposure was most effective,for S. tenella 24 hours. The stimuli necessary to complete the excystation process could, apparently, be provided by 1 hr placement in the duodenum for S. gigantea but not for S. tenella. Using in vitro excystation as a measure of viability, it was found that at 4°C, S. gigantea sporocysts survived considerably better in tap water (85% excystation after 174 days) than in either 2.5% potassium dichromate (15% excystation after 174 days) or 2% sulphuric acid (0% excystation after 5 days). Although they were able to resist 48 hr suspension at room temperature in most laboratory reagents, disinfectants and anti-coccidial drugs tested, six (sulphuric acid, ammonia, methanol, ethanol, potassium hydroxide, sodium hydroxide, 16% synergistic mixture of five chlorinated phenols.) had major sporocysticidal properties. Further investigation with three of these, showed that sporocyst excystation was reduced from 65% to less than 10% following contact with 2.5% sulphuric acid for 1 hr or with 2% ammonia or 4% Medol for 4 hours. Sporocysts were either killed, or their ability to excyst severely impaired, by heating to 60° and 55°C for 5 and 60 min, respectively, by exposure to ultraviolet radiation at a dose of 4000 ET, or by prolonged storage in water at 24°C. Sporocysts exposed to either constant or intermittent freezing at -18°C suffered a comparatively slow decline in excystation rate with time as did those subjected to desiccation. The duration of survival of desiccated sporocysts was inversely related to relative humidity and after 245 days at 33% RH and temperatures of 15 or 24°C, 60% of such sporocysts excysted. Studies on the survival of S. gigantea sporocysts in faeces outdoors showed that, viability declined most rapidly over the summer months and suggested that they were unlikely to remain infective for more than one year. Possible associations between the reported findings and both the epidemiology of S. gigantea infection and some of the previous unsuccessful or equivocal attempts to experimentally infect sheep with this species, are discussed.