Fuel Cycle Costs for a Plutonium Recycle System

The costs of the chemical and metallurgical steps in the fuel cycle for large desalination reactors are estimated. Both capital and operating costs are presented at varying plant capacities for a Zircaloy-clad fuel element containing depleted uranium and recycled plutonium as the oxides. UO/sup 2/-0.5% PuO/sub 2/. The chemical steps are reported at throughputs of 1, 10, and 30 short tons of uranium per day; and the metallurgical or fabrication step at throughputs of 1, 3, 5, and 10 tons per day, as specified by the Office of Science and Technology. The total estimated cost of all the chemical and metallurgical steps drops from .17 to .68 per kilogram of uranium as the cycle throughput is increased from 1 to 10 tons of uranium per day. All steps decrease in cost as plant capacity is increased, with the most impressive decrease in the irradiated assembly processing step, which decreases from .19 to 10 to 07 per kilogram of uranium as throughput is changed from 1 to 10 to 30 tons of uranium per day. The contained data in conjunction with previous studies of a natural uranium fuel cycle and results of a current reactor optimization study will yield complete fuel cycle costs and plutonium value in recycle. (auth

Application of effect-compartment model to bumetanide-indomethacin interaction in dogs

Analyses of bumetanide's dose-response relationship have been complicated by the hysteresis observed between the drug's urinary excretion rate and its sodium excretion. This apparent time lag reflects the disequilibrium between the urine concentration and effect compartment (biophase) which occurs during the early distribution phase. In the present article, an expanded pharmaco-dynamic model has been introduced in which the hypothetical effect compartment is linked, by a first-order process (K ue ), to the urine compartment. Drug dissipation from the effect compartment occurs by means of the first-order rate constant , K eo . This representation accommodates bumetanide's luminal site of action in the kidney tubule as well as the drug's temporal component. Application of this model to the bumetanide-indomethacin interaction in dogs is examined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45030/1/10928_2005_Article_BF01058955.pd

Developing a Professional Studies Curriculum to Support Veterinary Professional Identity Formation

Professional studies teaching in medical and veterinary education is undergoing a period of change. Traditional approaches, aiming to teach students professional values and behaviors, are being enhanced by curricula designed to support students' professional identity formation. This development offers the potential for improving student engagement and graduates' mental well-being. The veterinary professional identity associated with emotional resilience and success in practice incorporates complexity in professional decision making and the importance of context on behaviors and actions. The veterinarian must make decisions that balance the sometimes conflicting needs of patient, clients, veterinarian, and practice; their subsequent actions are influenced by environmental challenges such as financial limitations, or stress and fatigue caused by a heavy workload. This article aims to describe how curricula can be designed to support the development of such an identity in students. We will review relevant literature from medical education and the veterinary profession to describe current best practices for supporting professional identity formation, and then present the application of these principles using the curriculum at the Royal Veterinary College (RVC) as a case study. Design of a “best practice” curriculum includes sequential development of complex thinking rather than notions of a single best solution to a problem. It requires managing a hidden curriculum that tends to reinforce a professional identity conceived solely on clinical diagnosis and treatment. It includes exposure to veterinary professionals with different sets of professional priorities, and those who work in different environments. It also includes the contextualization of taught content through reflection on workplace learning opportunities

Removing the Threat of Diclofenac to Critically Endangered Asian Vultures

Veterinary use of the nonsteroidal anti-inflammatory (NSAID) drug diclofenac in South Asia has resulted in the collapse of populations of three vulture species of the genusGyps to the most severe category of global extinction risk. Vultures are exposed to diclofenac when scavenging on livestock treated with the drug shortly before death. Diclofenac causes kidney damage, increased serum uric acid concentrations, visceral gout, and death. Concern about this issue led the Indian Government to announce its intention to ban the veterinary use of diclofenac by September 2005. Implementation of a ban is still in progress late in 2005, and to facilitate this we sought potential alternative NSAIDs by obtaining information from captive bird collections worldwide. We found that the NSAID meloxicam had been administered to 35 captiveGyps vultures with no apparent ill effects. We then undertook a phased programme of safety testing of meloxicam on the African white-backed vultureGyps africanus, which we had previously established to be as susceptible to diclofenac poisoning as the endangered AsianGyps vultures. We estimated the likely maximum level of exposure (MLE) of wild vultures and dosed birds by gavage (oral administration) with increasing quantities of the drug until the likely MLE was exceeded in a sample of 40G. africanus. Subsequently, sixG. africanus were fed tissues from cattle which had been treated with a higher than standard veterinary course of meloxicam prior to death. In the final phase, ten Asian vultures of two of the endangered species(Gyps bengalensis,Gyps indicus) were dosed with meloxicam by gavage; five of them at more than the likely MLE dosage. All meloxicam-treated birds survived all treatments, and none suffered any obvious clinical effects. Serum uric acid concentrations remained within the normal limits throughout, and were significantly lower than those from birds treated with diclofenac in other studies. We conclude that meloxicam is of low toxicity toGyps vultures and that its use in place of diclofenac would reduce vulture mortality substantially in the Indian subcontinent. Meloxicam is already available for veterinary use in India

Financing U.S. Graduate Medical Education: A Policy Position Paper of the Alliance for Academic Internal Medicine and the American College of Physicians

In this position paper, the Alliance for Academic Internal Medicine and the American College of Physicians examine the state of graduate medical education (GME) financing in the United States and recent proposals to reform GME funding. They make a series of recommendations to reform the current funding system to better align GME with the needs of the nation's health care workforce. These recommendations include using Medicare GME funds to meet policy goals and to ensure an adequate supply of physicians, a proper specialty mix, and appropriate training sites; spreading the costs of financing GME across the health care system; evaluating the true cost of training a resident and establishing a single per-resident amount; increasing transparency and innovation; and ensuring that primary care residents receive training in well-functioning ambulatory settings that are financially supported for their training roles

Effect of angiotensin II-induced changes in perfusion flow rate on chlorothiazide transport in the isolated perfused rat kidney

Angiotensin II was used as a probe to study the effect of changes in perfusate flow rate on the renal clearance parameters of chlorothiazide in the isolated perfused rat kidney. Perfusion studies were performed in five rats with no angiotensin II present in the perfusate and in five rats with a 1–4 ng/min infusion of angiotensin II into the perfusate. Angiotensin II had a dramatic effect on the renal hemodynamics, resulting in a 43% decrease in perfusate flow, a 16% decrease in glomerular filtration rate (GFR), and a 45% increase in filtration fraction. Values for the fractional excretion of glucose were low and consistent, with or without angiotensin II. Although the unbound fraction (fu) of chlorothiazide was unchanged between treatments, the renal (CL r ) and the secretion clearances were reduced by about 50% in the presence of angiotensin II; the excretion ratio [ER=CL r /(fu·GFR)] was reduced by 38% with angiotensin II present in the perfusate. Analysis of the data was complicated by the presence of a capacity-limited transport for renal tubular secretion. Transport parameters (±SD) were obtained and the corrected intrinsic secretory clearance [(V max /GFR)/K m ] of chlorothiazide was 123 ± 18 without angiotensin II vs. 72.8 ± 30.0 with angiotensin II. These results demonstrate that alterations in organ perfusion can significantly reduce the clearance parameters of chlorothiazide in the rat IPK. These flow-induced changes in intrinsic secretory transport may reflect perturbations other than that of perfusion flow rate alone .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45047/1/10928_2005_Article_BF01071001.pd

Determinants of bumetanide response in the dog: Effect of probenecid

The pharmacokinetics and pharmacodynamics of intravenous bumetanide (0.250 mg/kg), alone (treatment I) and after probenecid pretreatment (treatment II), were studied in four mongrel dogs. Lactated Ringer's solution was administered by vein throughout both treatments at a flow rate of 2 ml/min to avoid fluid and electrolyte depletion. Bumetanide and probenecid concentrations were analyzed by HPLC, sodium by flame photometry, and creatinine by colorimetry. Although the probenecid markedly reduced the plasma and renal clearances of bumetanide, as well as the fraction excreted unchanged in the urine, there was no significant difference between treatments I and II in the 4-hr natriuretic and diuretic responses. However, analysis of the dose-response curves between treatments I and II showed that sodium, excretion was better correlated with bumetanide urinary excretion rate than with plasma concentration. The reasons for a poor correlation between treatments during the early time periods are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45029/1/10928_2005_Article_BF01061766.pd

Renal transport kinetics of furosemide in the isolated perfused rat kidney

Direct quantitative data and corresponding theory are provided for the effect of protein binding on the renal transport of furosemide. Drug studies were performed with various combinations of bovine serum albumin and dextran. This resulted in a percent unbound ( fu ) of furosemide ranging from 0.785 to 85.8%. The corrected renal ( CLr/GFR ) and secretion ( CLs/GFR ) clearances of furosemide were observed to increase with percent free, but in a nonproportional manner. Plots of CLr/GFR or CLs/GFR vs. fu appeared to have a prominent y intercept as well as a convex ascending curve. In addition, the excretion ratio [ ER=CLr/ (fu · GFR) ] was reduced from 60.8 to 8.72 as fu increased. Overall, the data were best fitted to a model in which two Michaelis-Menten terms wre used to describe renal tubular transport, and secretion was dependent upon free drug concentrations in the perfusate. The results demonstrate that the renal mechanisms of furosemide excretion are more complex than previously reported and that active secretion may involve two different transport systems over the concentration range studied.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45036/1/10928_2005_Article_BF01065259.pd