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Serum Erythropoietin Levels after Renal Transplantation
We measured serum erythropoietin levels serially in 31 renal-transplant recipients treated with cyclosporine, using the recently developed recombinant human erythropoietin-based radioimmunoassay.
The mean (±SEM) serum erythropoietin concentration in these patients before transplantation (14±2 U per liter) was similar to that in normal subjects who did not have anemia. A transient postoperative 9-fold increase (range, 0- to 74-fold) in the serum erythropoietin levels was followed by a smaller (3-fold) and sustained (28±3 days) second elevation. The initial increase occurred in the absence of graft function and was not accompanied by an erythropoietic response, whereas the second increase was associated with graft recovery and the complete resolution of the anemia. Serum erythropoietin levels returned to normal as the hematocrit rose above 0.32. Thereafter, the hematocrit continued to rise toward normal, while the serum erythropoietin levels remained normal. The patients in whom erythrocytosis or iron-deficiency anemia developed had persistently elevated serum erythropoietin levels.
We conclude that in patients who have undergone renal transplantation, slight increases in endogenous erythropoietin levels induce erythropoiesis to the same extent as do large doses of exogenous erythropoietin in patients with uremia. Moreover, once initiated, erythropoiesis in renal-transplant recipients may be sustained by normal serum erythropoietin levels. These results suggest that the restoration of renal function improves the erythropoietic response to erythropoietin. (N Engl J Med 1989;321:151–7.)
THE recent availability of purified recombinant human erythropoietin in large quantities has allowed clinical trials of its efficacy in treating anemia.
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With the use of this recombinant hormone as a tracer and immunogen, it has also been possible to develop specific and sensitive radioimmunoassays to measure the levels of natural hormone in the serum of healthy subjects and patients with various disorders.
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Several investigators have found that the intravenous administration of recombinant erythropoietin (0.15 to 0.50 U per kilogram of body weight, three times a week) successfully treats anemia in patients undergoing hemodialysis.
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On the basis of available pharmacokinetic data, . . .
Journal Article
Applications of the periodic electrostatic embedded cluster method to solid state actinide chemistry
The work described in this thesis uses density functional theory (DFT) with an embedded cluster method, known as the periodic electrostatic embedded cluster method (PEECM) to study solid state actinide systems. The theoretical background of electronic structure calculations is discussed in the first chapter, while the remaining chapters deal with results of the studies. In Chapter 2 the PEECM is used to include long-range electrostatic interactions in calculations of Quantum Theory of Atoms in Molecules (QTAIM) bond critical point and delocalisation index metrics for the actinide-element bonds in Cs2UO2Cl4, U(Se2PPh2)4 and Np(Se2PPh2)4. The effects of the environment are seen to be minor, suggesting they do not account for the differences previously observed between the experimental and theoretical QTAIM data. In Chapter 3 the electronic structure of actinide dioxide systems has been investigated by examining the projected density of states (PDOS). While PBE incorrectly predicts these systems to be metallic, PBE0 finds them to be insulators, with the composition of the valence and conduction levels agreeing well with experiment. In Chapter 4 molecular and dissociative water adsorption on the (111) and (110) surfaces of UO2 and PuO2 has been investigated, with that on the (110) surface being stronger than on the (111). Similar energies are found for molecular and dissociative adsorption on the (111) surfaces, while on the (110) there is a clear preference for dissociative adsorption. Adsorption energies and geometries on the (111) surface of UO2 are in good agreement with recent periodic DFT studies using the GGA+U approach. In Chapter 5 oxygen vacancies are investigated on the actinide oxide surfaces. Oxygen vacancy formation energies are found to be much greater on UO2 than PuO2 surfaces. Oxygen vacancies lead to a preference for dissociative adsorption of water on both the (111) and (110) surfaces, with adsorption energies being much greater on PuO2 than UO2 surfaces.
Dissertation
Composite cutting tip and materials for mining tools
100M tons of rock and coal are cut per annum by the National Coal Board at a cost of about £10M in cutting picks alone. Existing tool materials are sufficient for cutting coal alone but are easily abraded and chipped during necessary rock cutting. The project is aimed at reducing this cost. Tools of a simple geometry were used for abrasive wear tests in order to gain a fuller understanding of the process of tip wear. Analysis of the change in geometry of the tips of these tools has enabled relationships between the wear parameters to be found. These led to the proposal of a simple analytical model of abrasive wear in rock cutting tools and to a much fuller understanding of the progression of wear. It was found that the major sites of abrasive wear and impact on the tip are not coincident. A new tip design has been proposed based on the understanding of tip wear that has been gained. Strategic placement of materials or local modification of materials properties is required for the new tips proposed. A search for new tip materials and alternative methods of increasing rock cutting tool life has been done. Many new materials and novel ways of increasing tool life have been considered. Two tip modifications have been tested, namely prototypes of the new composite tip and tips with chemical vapour deposited (CVD) coatings. The new composite tip design halves the tip wear rate. Coatings reduce the wear rate slightly. Production of the new tips will require a modified process. Several alternative production routes have been considered. Direct pressing of the composite tip is the favoured route although this will require a slightly modified die filling operation.
Dissertation
Brazil, Ethiopia, and New Zealand lead the way on climate-smart agriculture
As countries around the world face urgent agricultural challenges, the concept of ‘climate-smart’ agriculture (CSA) has been put forward to achieve climate change adaptation, mitigation, and food security synergistically. A new report explores how three countries are using integrated policy approaches to CSA and offers insights for how other countries can build CSA into their policy mix. Brazil has invested in research to support sustainable intensification while creating legal and enforcement mechanisms to protect forest areas as a response to unrestrained agricultural expansion driven by market demand. Ethiopia initiated innovative participatory watershed development programs, in partnership with numerous international institutions, which helped smallholder farmers to rehabilitate marginal land and break out of a poverty cycle. New Zealand has removed agricultural subsidies while partnering on research and development with the private sector as a way to ensure efficiency and resilience in an agricultural sector influenced by climate change and international trade dynamics. To assemble an integrated set of national policies that fosters CSA, governments will need context-specific assessments, strong multi-stakeholder institutions, coordination frameworks, and multi-scale information systems. Governments can select from an array of policy instruments ranging from regulatory mechanisms and economic incentives to public investments and educational campaigns. Many existing national policy goals and public programs designed to increase agricultural production, improve livelihoods, and reduce environmental risks can become important pillars of a national CSA strategy. Countries have obvious interests in fostering an agriculture sector that is climate-resilient, provides national needs for food, fiber, and fuel, and supports farm livelihoods. However, the incentives for national-level action toward reducing global greenhouse gas (GHG) levels are less clear in the absence of serious and shared international commitment. Integrated national CSA policies will be encouraged by clear, consistent signals from multilateral agencies, global donors, and international conventions and trade agreements that promote agriculture as a pathway for poverty reduction and food security.
Journal Article
