Risk stratification of kidneys from donation after cardiac death donors and the utility of machine perfusion.

There has been a dramatic increase in the utilization of kidneys from donors after cardiac death (DCD). While these organs represent an opportunity to expand the donor pool, the assessment of risk and optimal perioperative management remains unclear. Our primary aim was to identify risk factors for objective outcomes, and secondarily, we sought to determine what impact pulsatile machine perfusion (PMP) had on these outcomes. From 1993 to November 2008, 6057 DCD kidney transplants were reported to the Organ Procurement and Transplantation Network database, with complete endpoints for delayed graft function (DGF) and graft survival (GS). Risk factors were identified using a multivariable regression analysis adjusted for recipient factors. Age (50 yr) [OR 1.81, p < 0.0001] and cold ischemia time (CIT) (>30 h) [OR 3.22, p < 0.0001] were the strongest predictors of DGF. The use of PMP decreased the incidence of DGF only when donor age was >60 yr and improved long-term graft survival when donor age was >50 yr. Donor warm ischemia time >20 min was also found to correlate with increased DGF. While the incidence of DGF in DCD kidneys is significantly higher, the only factors the transplant surgeon can control are CIT and the use of PMP. The data suggest that the use of PMP in DCD kidneys <50 yr old provides little clinical benefit and may increase CIT.

Fermented whey--an inexpensive feed source for a laboratory-scale selenium-bioremediation reactor system inoculated with Thauera selenatis.

It is critical that an inexpensive electrondonor/carbon-source be found for selenium bioremediation using the selenate-respiring bacterium, Thauera selenatis. Since acetate is a preferred substrate for growth of this organism, a method was developed for fermenting the lactose in whey to large amounts of acetate. Indigenous whey microorganisms fermented the whey lactose in this manner when grown in continuous culture at a very slow dilution rate (D = 0.05 h-1). The successful use of the fermented whey lactose as the carbon-source/electron-donor feed for a laboratory-scale selenium-bioremediation reactor system, inoculated with T. selenatis, treating selenium-contaminated drainage water was also demonstrated. Selenium oxyanions and nitrate were reduced by 98%.

Pilot-Scale Selenium Bioremediation of San Joaquin Drainage Water with Thauera selenatis.

This report describes a simple method for the bioremediation of selenium from agricultural drainage water. A medium-packed pilot-scale biological reactor system, inoculated with the selenate-respiring bacterium Thauera selenatis, was constructed at the Panoche Water District, San Joaquin Valley, Calif. The reactor was used to treat drainage water (7.6 liters/min) containing both selenium and nitrate. Acetate (5 mM) was the carbon source-electron donor reactor feed. Selenium oxyanion concentrations (selenate plus selenite) in the drainage water were reduced by 98%, to an average of 12 (plusmn) 9 (mu)g/liter. Frequently (47% of the sampling days), reactor effluent concentrations of less than 5 (mu)g/liter were achieved. Denitrification was also observed in this system; nitrate and nitrite concentrations in the drainage water were reduced to 0.1 and 0.01 mM, respectively (98% reduction). Analysis of the reactor effluent showed that 91 to 96% of the total selenium recovered was elemental selenium; 97.9% of this elemental selenium could be removed with Nalmet 8072, a new, commercially available precipitant-coagulant. Widespread use of this system (in the Grasslands Water District) could reduce the amount of selenium deposited in the San Joaquin River from 7,000 to 140 lb (ca. 3,000 to 60 kg)/year.