Development of plant-produced Bluetongue virus vaccines

Bluetongue is a disease of domestic and wild ruminants caused by Bluetongue virus (BTV). It has caused several serious outbreaks, the most recent occurring in Northern Europe in 2006 during which high mortality rates of livestock were reported. The only vaccines currently approved and commercially available for use are live-attenuated or inactivated virus strains and although these are effective, there is the risk of reversion in the case of live-attenuated strains to more virulent forms by recombination. Another drawback associated with the use of live-attenuated virus vaccines is that they are not DIVA (differentiate infected from vaccinated animals) compliant, this means that naturally infected animals cannot be distinguished from vaccinated animals. Recombinantly produced vaccines would be preferable to minimize the risks associated with live-attenuated virus vaccines and also enable the development of candidate vaccines that are DIVA-compliant. A number of recombinant vaccine candidates have been developed against BTV, with the most promising vaccine consisting of BTV virus-like particles (VLPs). BTV VLPs were successfully produced in insect cells by the co-expression of the four BTV capsid proteins (VP2, VP3, VP5 and VP7). Sheep vaccinated with insect cell-produced BTV VLPs were shown to be protected against challenge with wild type virus. However, the high costs associated with the production and scale-up of BTV VLPs in insect cells has possibly limited their widespread application. Plants – such as N. benthamiana – provides a safe, efficient and cost effective system for the production of recombinant proteins. In this study the best plant expression vector with which to co-express the four BTV serotype 8 (BTV-8) VPs – which direct formation of BTV-8 VLPs – was identified. Expression and purification of the BTV-8 VLPs was optimised with the aim of producing a VLP-based vaccine for BTV-8. It was further undertaken to develop two novel second generation plant-produced protein body (PB) vaccines that are DIVA compliant. Mice were immunised with the plantproduced VLP and PB vaccines in order to analyse their ability to elicit humoral immune responses

Agrarian structure in Poland : the myth of large-farm superiority

In Poland, present policies are aimed at promoting large, mechanized farms over smaller family farms. These policies are based on the perception that large farms offer real economies of scale. But international evidence indicates that such large, mechanized farms are generally less efficient and use less labor than small family farms. The authors analyzed the relationship between farm size and efficiency in Polish agriculture. They used two different methods to do so. First they determined differences in total factor productivity between small and large farms. They then used Data Envelope Analysis to estimate scale efficiencies. The results show that, for the sample of farms analyzed: 1) large farms are not more efficient than smaller farms; and 2) smaller farms are more labor-intensive than larger farms. These results have important policy implications for farm restructuring in Poland and other transition economies facing similar issues and conditions.Environmental Economics&Policies,Crops&Crop Management Systems,Agricultural Knowledge&Information Systems,Banks&Banking Reform,Economic Theory&Research,Banks&Banking Reform,Environmental Economics&Policies,Agricultural Knowledge&Information Systems,Crops&Crop Management Systems,Livestock&Animal Husbandry

Duality constructions from quantum state manifolds

The formalism of quantum state space geometry on manifolds of generalised coherent states is proposed as a natural setting for the construction of geometric dual descriptions of non-relativistic quantum systems. These state manifolds are equipped with natural Riemannian and symplectic structures derived from the Hilbert space inner product. This approach allows for the systematic construction of geometries which reflect the dynamical symmetries of the quantum system under consideration. We analyse here in detail the two dimensional case and demonstrate how existing results in the AdS_2/CFT_1 context can be understood within this framework. We show how the radial/bulk coordinate emerges as an energy scale associated with a regularisation procedure and find that, under quite general conditions, these state manifolds are asymptotically anti-de Sitter solutions of a class of classical dilaton gravity models. For the model of conformal quantum mechanics proposed by de Alfaro et. al. the corresponding state manifold is seen to be exactly AdS_2 with a scalar curvature determined by the representation of the symmetry algebra. It is also shown that the dilaton field itself is given by the quantum mechanical expectation values of the dynamical symmetry generators and as a result exhibits dynamics equivalent to that of a conformal mechanical system.Comment: 25 Pages, References Adde

Mechanisms of oedema formation: The minor role of hypoalbuminaemia

Objectives: Seriously ill patients often suffer from disorders of salt and water balance and present with clinical signs of either dehydration or oedema. The relationship of hypoalbuminaemia to oedema is complex and controversial and formed the central issue of this study. Design: Prospective study Setting: Medical wards of New Somerset Secondary Hospital, November 2004. Subjects: 50 patients admitted consecutively to the medical wards at New Somerset Hospital were evaluated. 26 males and 24 females participated. Outcome measures:. An attempt was made to correlate causes of salt and water imbalance with the clinical assessment of volume status, oedema formation, nutritional state and serum albumin levels. Results: Hypoalbuminaemia was not related to oedema in this study. From the 24 patients with serum albumin below 30 g/L, only 6 had oedema. These patients all had other abnormalities which could have resulted in the oedema: notably primary salt retention by failing kidneys, cor pulmonale and malignancy. None of the patients with serum albumin levels below 15 g/L had any signs of oedema. The combined insult of a chronic inflammatory disease and malnutrition had a marked effect on serum albumin levels. Conclusion: Significant hypoalbuminaemia was present in a substantial portion of the patients included in this study, yet oedema was detected infrequently and generally had an easily identifiable cause not related to low albumin levels. Most patients with hypoalbuminaemia presented with normal or positive water balance. This study supports the notion that hypoalbuminaemia is infrequently associated with oedema and plays a minor role in its formation

The use of vincristine in refractory auto-immune thrombocytopenic purpura

Two patients with auto-immune thrombocytopenic purpura are reported who continued to bleed despite high doses of corticosteroids, immunosuppressive therapy and splenectomy. The addition of vincristine to their therapeutic regimen produced a response in each case and both patients are now off all therapy without significant bleeding. It is suggested that this agent may be of value in selected cases where conventional regimens have failed or where splenectomy and corticosteroids are contra-indicated.S. Afr. Med. J., 48, 2039 (1974)