Sheep Updates 2005 - Part 5

This session covers eleven papers from different authors; MARKET INFORMATION 1. Crystal Spring - Crystal clear and consistant, Geoff Duddy, Livestock Officer (Sheep & Wool) Yanco, NSW, Brent McLoud, (Product Development Officer) Cowra, NSW, John Sullivan, J.J Dresser and Co (Agent), Woodstock, NSW 2. An overview of Recent Developments in Dark and Medullated Fibre Testing, T.J. Mahar, A. Balasingam, AWTA Ltd 3. Opportunities and Implications for Wool Producers of the TEAM3 Prediction Equations, J.H. Stanton12 K.M.S. Curtis1 , 1Department of Agriculture Western Australia, 2 Curtin University, WA 4. Premiums and Discounts for Fibre Properties in Superfine Wool, Now and in the Future?, K.M.S. Curtis1, P.R. Lamb2, 1 Department of Agriculture Western Australia, 2Lambshift Consulting, Geelong VIC FEEDLOTTING 5. Manure in sheep feedlots: problem or opportunity?, Eliza Dowling, Ned Crossley Department of Agriculture , Western Australia, Surrender Mann, Chemistry Centre (WA), East Perth WA, 6. The State of Lamb Confinement Feeding in WA, Ned Crossley, Department of Agriculture, Western Australia 7. Finishing lambs in a feed lot - Is it profitable?, Lucy Anderton, Department of Agriculture, Western Australia 8. Repeated live weights can mardinally improve prediction of compliance to markey specifications, Mattew Kelly, Andrew Swan, CSIRO livestock industries, Ian McFarland, Department of Agriculture Western Australia. WELFARE 9. Mulesing accreditation - to be or not to be? Di Evans, Department of Agriculture, Western Australia. 10. The Economic and Research Implications of managing Merino Sheep with out Mulesing, K. Bell, Sheep Management and Production Consultants, North Fremantle WA, D. Sackett, Homes Sackett and Associates, Wagga Wagga NSW 11. How do lambs fare during curfew, Dr Robin Jacob, Department of Agriculture, Western Australi

Developmental Hippocampal Neuroplasticity in a Model of Nicotine Replacement Therapy during Pregnancy and Breastfeeding

The influence of developmental nicotine exposure on the brain represents an important health topic in light of the popularity of nicotine replacement therapy (NRT) as a smoking cessation method during pregnancy.In this study, we used a model of NRT during pregnancy and breastfeeding to explore the consequences of chronic developmental nicotine exposure on cerebral neuroplasticity in the offspring. We focused on two dynamic lifelong phenomena in the dentate gyrus (DG) of the hippocampus that are highly sensitive to the environment: granule cell neurogenesis and long-term potentiation (LTP).Pregnant rats were implanted with osmotic mini-pumps delivering either nicotine or saline solutions. Plasma nicotine and metabolite levels were measured in dams and offspring. Corticosterone levels, DG neurogenesis (cell proliferation, survival and differentiation) and glutamatergic electrophysiological activity were measured in pups.Juvenile (P15) and adolescent (P41) offspring exposed to nicotine throughout prenatal and postnatal development displayed no significant alteration in DG neurogenesis compared to control offspring. However, NRT-like nicotine exposure significantly increased LTP in the DG of juvenile offspring as measured in vitro from hippocampal slices, suggesting that the mechanisms underlying nicotine-induced LTP enhancement previously described in adult rats are already functional in pups.These results indicate that synaptic plasticity is disrupted in offspring breastfed by dams passively exposed to nicotine in an NRT-like fashion

Examining the generalizability of research findings from archival data

This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability—for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples

Food restriction reduces neurogenesis in the avian hippocampal formation

The mammalian hippocampus is particularly vulnerable to chronic stress. Adult neurogenesis in the dentate gyrus is suppressed by chronic stress and by administration of glucocorticoid hormones. Post-natal and adult neurogenesis are present in the avian hippocampal formation as well, but much less is known about its sensitivity to chronic stressors. In this study, we investigate this question in a commercial bird model: the broiler breeder chicken. Commercial broiler breeders are food restricted during development to manipulate their growth curve and to avoid negative health outcomes, including obesity and poor reproductive performance. Beyond knowing that these chickens are healthier than fully-fed birds and that they have a high motivation to eat, little is known about how food restriction impacts the animals' physiology. Chickens were kept on a commercial food-restricted diet during the first 12 weeks of life, or released from this restriction by feeding them ad libitum from weeks 7-12 of life. To test the hypothesis that chronic food restriction decreases the production of new neurons (neurogenesis) in the hippocampal formation, the cell proliferation marker bromodeoxyuridine was injected one week prior to tissue collection. Corticosterone levels in blood plasma were elevated during food restriction, even though molecular markers of hypothalamic-pituitary-adrenal axis activation did not differ between the treatments. The density of new hippocampal neurons was significantly reduced in the food-restricted condition, as compared to chickens fed ad libitum, similar to findings in rats at a similar developmental stage. Food restriction did not affect hippocampal volume or the total number of neurons. These findings indicate that in birds, like in mammals, reduction in hippocampal neurogenesis is associated with chronically elevated corticosterone levels, and therefore potentially with chronic stress in general. This finding is consistent with the hypothesis that the response to stressors in the avian hippocampal formation is homologous to that of the mammalian hippocampus

Neuregulin-1/ErbB activity in hippocampal plasticity and psychopathology

We initially sought to examine the effects of neuregulin-1 (NRG1) administration on adult hippocampal neuroplasticity, and determined that this paradigm increases cell proliferation and neurogenesis in the ventral (but not dorsal) hippocampus. This neurogenic increase was accompanied by antidepressant-like behaviour that was present when these cells became functional neurons, but not acutely after administration. We also identified ErbB3 as a candidate mechanistic receptor in this phenomenon. Next we completed our characterization of the neurogenic effects of NRG1, and determined that they are limited to proliferation and neurogenesis in the ventral hippocampus. We also discovered morphological differences between immature neurons in the dorsal and ventral dentate gyrus (DG). Having determined that NRG1-ErbB3 signaling has antidepressant-like properties, we then sought to investigate whether the converse was also true, in that psychopathological samples and animal models might show deficits in NRG1-ErbB3 signaling. As hypothesized, we found decreased hippocampal ErbB3 expression in suicide completers, as well as deficits in anterior DG granule neurons (which we and others show ubiquitously express ErbB3), with the latter phenotype being reversed with antidepressant treatment, as well as cell body hypertrophy in the posterior DG granule cell layer. Together these results identify a pathway that is putatively involved in both psychopathology and its amelioration, ostensibly through its effects in the DG.Nous avons d'abord cherché à examiner les effets d'une administration de la NRG1 sur la neuroplasticité hippocampique et déterminé que ce traitement augmente la prolifération cellulaire ainsi que la neurogenèse au sein de l'hippocampe ventral (mais non dorsal). Cette neurogenèse accrue fut accompagnée, dès lors que les cellules devinrent des neurones fonctionnels, d'un comportement typique d'un effet antidépresseur. Nous avons également identifié le récepteur ErbB3 comme étant le récepteur pouvant médier ces effets. Nous avons par la suite complété la caractérisation des effets neurogéniques de NRG1 et déterminé ainsi que ces effets se limitent à la prolifération et à la neurogenèse au sein de l'hippocampe ventral. Nous avons aussi découvert des différences morphologiques entre les neurones immatures localisés dans l'hippocampe ventral et ceux de l'hippocampe dorsal. Ayant déterminé que la signalisation NRG1-ErbB3 présente des propriétés antidépressives, nous avons ensuite cherché à savoir si des déficits dans cette signalisation étaient détectables au sein d'échantillons cérébraux humains et de modèles animaux de psychopathologies. Notre hypothèse fut vérifiée par la démonstration d'une forte régulation à la baisse de l'espression d'ErbB3 dans l'hippocampe de suicidés, ainsi que de déficits dramatiques au niveau des neurones granulaires du gyrus denté antérieur (phénomène renversé par le traitement aux antidépreseurs), connus pour leur expression de ce récepteur. De plus, nous avons observé une hypertrophie du corps cellulaire dans la couche de cellules granulaires du gyrus denté postérieur. Dans leur ensemble, ces résultats identifient une nouvelle voie pouvant être impliquée, par ses actions au sein du gyrus denté, dans la psychopathologie ainsi que dans son traitement

Regional and sub-regional differences in hippocampal GABAergic neuronal vulnerability in the TgCRND8 mouse model of Alzheimer's disease

International audienceHippocampal network activity is predominantly coordinated by γ-amino-butyric acid (GABA)ergic neurons. We have previously hypothesized that the altered excitability of hippocampal neurons in Alzheimer's disease (AD), which manifests as increased in vivo susceptibility to seizures in the TgCRND8 mouse model of AD, may be related to disruption of hippocampal GABAergic neurons. In agreement, our previous study in TgCRND8 mice has shown that hippocampal GABAergic neurons are more vulnerable to AD-related neuropathology than other types of neurons. To further explore the mechanisms behind the observed decrease of GABAergic neurons in 6 month-old TgCRND8 mice, we assessed the relative proportion of somatostatin (SOM), neuropeptide Y (NPY) and paravalbumin (PV) sub-types of GABAergic neurons at the regional and sub-regional level of the hippocampus. We found that NPY expressing GABAergic neurons were the most affected, as they were decreased in CA1-CA2 (pyramidal-, stratum oriens, stratum radiatum and molecular layers), CA3 (specifically in the stratum oriens) and dentate gyrus (specifically in the polymorphic layer) in TgCRND8 mice as compared to non-transgenic controls. SOM expressing GABAergic neurons were decreased in CA1-CA2 (specifically in the stratum oriens) and in the stratum radiatum of CA3, whereas PV neurons were significantly altered in stratum oriens sub-region of CA3. Taken together, these data provide new evidence for the relevance of hippocampal GABAergic neuronal network disruption as a mechanism underlying AD sequelae such as aberrant neuronal excitability, and further point to complex hippocampal regional and sub-regional variation in susceptibility to AD-related neuronal loss

Subchronic peripheral neuregulin-1 increases ventral hippocampal neurogenesis and induces antidepressant-like effects.

BACKGROUND: Adult hippocampal neurogenesis has been implicated in the mechanism of antidepressant action, and neurotrophic factors can mediate the neurogenic changes underlying these effects. The neurotrophic factor neuregulin-1 (NRG1) is involved in many aspects of brain development, from cell fate determination to neuronal maturation. However, nothing is known about the influence of NRG1 on neurodevelopmental processes occurring in the mature hippocampus. METHODS: Adult male mice were given subcutaneous NRG1 or saline to assess dentate gyrus proliferation and neurogenesis, as well as cell fate determination. Mice also underwent behavioral testing. Expression of ErbB3 and ErbB4 NRG1 receptors in newborn dentate gyrus cells was assessed at various time points between birth and maturity. The phenotype of ErbB-expressing progenitor cells was also characterized with cell type-specific markers. RESULTS: The current study shows that subchronic peripheral NRG1β administration selectively increased cell proliferation (by 71%) and neurogenesis (by 50%) in the caudal dentate gyrus within the ventral hippocampus. This pro-proliferative effect did not alter neuronal fate, and may have been mediated by ErbB3 receptors, which were expressed by newborn dentate gyrus cells from cell division to maturity and colocalized with SOX2 in the subgranular zone. Furthermore, four weeks after cessation of subchronic treatment, animals displayed robust antidepressant-like behavior in the absence of changes in locomotor activity, whereas acute treatment did not produce antidepressant effects. CONCLUSIONS: These results show that neuregulin-1β has pro-proliferative, neurogenic and antidepressant properties, further highlight the importance of peripheral neurotrophic factors in neurogenesis and mood, and support the role of hippocampal neurogenesis in mediating antidepressant effects

The interstitial lung disease multidisciplinary meeting: A position statement from the Thoracic Society of Australia and New Zealand and the Lung Foundation Australia

Interstitial lung diseases (ILD) are a diverse group of pulmonary diseases for which accurate diagnosis is critical for optimal treatment outcomes. Diagnosis of ILD can be challenging and a multidisciplinary approach is recommended in international guidelines. The purpose of this position paper is to review the evidence for the use of the multidisciplinary meeting (MDM) in ILD and suggest an approach to its governance and constitution, in an attempt to provide a standard methodology that could be applied across Australia and New Zealand. This position paper is endorsed by the Thoracic Society of Australia and New Zealand (TSANZ) and the Lung Foundation Australia (LFA)