Untreated Units Research Articles

Randomization Under Permutation Invariance

This paper studies finite sample minimax optimal randomization schemes and estimation schemes in estimating parameters including the average treat- ment effect, when treatment effects are heterogeneous. A randomization scheme is a distribution over a group of permutations of a given treatment assignment vector. An estimation scheme is a joint distribution over assignment vectors, linear estimators, and permutations of assignment vectors. The key element in the minimax problem is that the worst case is over a class of distributions of the data which is invariant to a group of permutations. First, I show that given any assignment vector and any estimator, the uniform distribution over the same group of permutations, namely the complete randomization scheme, is minimax optimal. Second, under further assumptions on the class of distributions and the objective function, I show the minimax optimal estimation scheme involves completely randomizing an assignment vector, while the optimal estimator is the difference-in-means under complete invariance and a weighted average of within-block differences under a block structure, and the numbers of treated and untreated units are determined by Neyman allocations.

ArCo: An artificial counterfactual approach for high-dimensional panel time-series data

We consider a new, flexible and easy-to-implement method to estimate thecausal effects of an intervention on a single treated unit when a control group is not available and which nests previous proposals in the literature. It is a two-step methodology where in the first stage, a counterfactual is estimated based on a large-dimensional set of variables from a pool of untreated units by means of shrinkage methods, such as the least absolute shrinkage and selection operator (LASSO). In the second stage, we estimate the average intervention effect on a vector of variables, which is consistent and asymptotically normal. Our results are valid uniformly over a wide class of probability laws. We show that these results hold even when the exact date of the intervention is unknown. Tests for multiple interventions and for contamination effects are derived. By a simple transformation of the variables, it is possible to test for multivariate intervention effects on several moments of the variables of interest. Existing methods in the literature usually test for intervention effects on a single variable and assume that the time of the intervention is known. In addition, high-dimensionality is frequently ignored and inference is either conducted under a set of more stringent hypotheses and/or by permutation tests. A Monte Carlo experiment evaluates the properties of the method in finite samples and compares it with other alternatives. As an application, we evaluate the effects on inflation, GDP growth, retail sales and credit of an anti tax-evasion program.

Plant community dynamics following hazardous fuel treatments and mega-wildfire in a warm-dry mixed-conifer forest of the USA

The greater than 200,000 ha Wallow Fire of May-July 2011 burned through mixed-conifer and ponderosa pine forests in Arizona and New Mexico in the southwestern U.S. This “mega-fire” set the stage for an opportunistic study to examine understory plant community responses to pre-fire fuel reduction treatments in areas dominated by dry mixed-conifer forests. In 2016, five years after the fire, we remeasured nine pairs of treated and untreated sites that were installed in 2012 and compared understory characteristics including species cover, richness and community composition. Native plant cover was significantly higher (20% total cover) in areas that were treated for fuel reduction before the fire compared with untreated areas (17% cover), despite the variability in fire severity and tree mortality. Non-native plant cover was not significantly different between treated and untreated units. Herbaceous understory cover was negatively correlated (p < 0.05) with total tree basal area and tree canopy cover in treated as well as untreated units, and positively correlated with tree mortality and basal area mortality in the untreated units. In the treated units, species richness and diversity were negatively (r = −0.62 to −0.63) correlated with insolation and elevation. Non-metric multidimensional scaling ordinations along with univariate results suggested that community composition was driven by increased insolation following loss of tree canopy. Cover of species that benefit from high light and warmer temperatures, such as some shrubs and perennial graminoids, increased from 2012 to 2016. Overall, fuel reduction treatments led to persistent increases in cover of native species, lending weight to the usefulness of hazardous fuel reduction treatments in promoting native plant cover.

Delayed tree mortality, bark beetle activity, and regeneration dynamics five years following the Wallow Fire, Arizona, USA: Assessing trajectories towards resiliency

Warm/dry mixed conifer forests have undergone changes in disturbance regimes, forest structure, species composition, and surface fuel accumulation which have led to increased susceptibility to large, uncharacteristically severe wildfires and pathogenic outbreaks. Ecosystems resilient to fire events return to a similar set of structures (e.g., forest and understory composition and density) or processes (e.g., fire, decomposition rates); however, when exposed to disturbances outside the evolutionary envelope, may transition to a different state (e.g., type conversion). We sampled warm/dry mixed conifer forest stands treated prior to the 2011 Wallow Fire and paired untreated sites five years following the fire. Our objective was to evaluate mid-term ecosystem resiliency in terms of forest structure, bark beetle activity, and tree regeneration. We hypothesized that treated units would have higher mid-term post-fire resiliency compared to untreated units. In 2016, average total tree density remained significantly lower in treated compared to paired untreated units; conifer density and BA decreased in both treated and untreated units. Diameter distributions in 2016 treated units remained similar to those observed in 2012 with the exception of increased density in the smallest diameter class. In untreated units, the majority of tree density reductions occurred in the 10–30 cm dbh classes. Post-fire tree mortality was stable across treated and untreated units, with no significant differences; however, abundant ingrowth of small hardwoods occurred throughout the study area. Large-tree density decreased by about 20% in both treated and untreated units between 2012 and 2016. Evidence of post-fire bark beetles was generally low and patchy throughout the study site; however, beetle activity was more widespread in untreated units. Twice as many trees were attacked by bark beetles in untreated versus treated units suggesting treatments may have reduced post-fire beetle activity. Following wildfire, observed conifer regeneration was lower and hardwood regeneration was higher with increasing burn severity; conifer regeneration was nearly three times higher in treated units. This study suggests that pre-fire fuel reduction treatments contribute less to mid-term resiliency than to short-term resiliency of forested ecosystems. We observed trends of higher resilience to insect outbreaks and potential implications for type change from conifer to deciduous forest. Furthermore, our study underscores the importance of understanding mid-term post-fire recovery, and while it provides insights regarding recovery of these ecosystems, additional monitoring and research is needed to fully understand the implications toward long-term resiliency.

A simple approximation to the average effect of the treatment on the treated in panel settings with selective enrolment

ABSTRACTThis article shows that, in panel settings when the probability of receiving a treatment is low, simple comparisons of outcomes between those who are treated in a given period and those who are untreated in that period, but receive the treatment in some other period, approximately identify the average effect of the treatment on the treated. Monte Carlo simulations reveal that this approximate selection-correction substantially reduces selection bias relative to naive comparisons of outcomes between treated and untreated units.

ARCO: An Artificial Counterfactual Approach For High-Dimensional Panel Time-Series Data

We consider a new method to estimate causal effects when a treated unit suffers a shock or an intervention, such as a policy change, but there is not a readily available control group or counterfactual. We propose a two-step approach where in the first stage an artificial counterfactual is estimated from a large-dimensional set of variables from pool of untreated units (donors pool) using shrinkage methods, such as the Least Absolute Shrinkage Operator (LASSO). In the second stage, we estimate the average intervention effect on a vector of variables belonging to the treated unit, which is consistent and asymptotically normal. Our results are valid uniformly over a wide class of probability laws. Furthermore, we show that these results still hold when the date of the intervention is unknown and must be estimated from the data. Tests for multiple interventions and for contamination effects are also derived. By a simple transformation of the variables of interest, it is also possible to test for intervention effects on several moments (such as the mean or the variance) of the variables of interest. Finally, we can disentangle the actual intervention effects from confounding factors that usually bias before-and-after estimators. A detailed Monte Carlo experiment evaluates the properties of the method in finite samples and compares our proposal with other alternatives such as the differences-in-differences, factor models and the synthetic control method. An empirical application to evaluate the effects on inflation of a new anti tax evasion program in Brazil is considered. Our methodology is inspired by different branches of the literature such as: the Synthetic Control method, the Global Vector Autoregressive models, the econometrics of structural breaks, and the counterfactual analysis based on macro-econometric and panel data models.

Impacts of Short-Rotation Early-Growing Season Prescribed Fire on a Ground Nesting Bird in the Central Hardwoods Region of North America.

Landscape-scale short-rotation early-growing season prescribed fire, hereafter prescribed fire, in upland hardwood forests represents a recent shift in management strategies across eastern upland forests. Not only does this strategy depart from dormant season to growing season prescriptions, but the strategy also moves from stand-scale to landscape-scale implementation (>1,000 ha). This being so, agencies are making considerable commitments in terms of time and resources to this management strategy, but the effects on wildlife in upland forests, especially those dominated by hardwood canopy species, are relatively unknown. We initiated our study to assess whether this management strategy affects eastern wild turkey reproductive ecology on the Ozark-St. Francis National Forest. We marked 67 wild turkey hens with Global Positioning System (GPS) Platform Transmitting Terminals in 2012 and 2013 to document exposure to prescribed fire, and estimate daily nest survival, nest success, and nest-site selection. We estimated these reproductive parameters in forest units managed with prescribed fire (treated) and units absent of prescribed fire (untreated). Of 60 initial nest attempts monitored, none were destroyed or exposed to prescribed fire because a majority of fires occurred early than a majority of the nesting activity. We found nest success was greater in untreated units than treated units (36.4% versus 14.6%). We did not find any habitat characteristic differences between successful and unsuccessful nest-sites. We found that nest-site selection criteria differed between treated and untreated units. Visual concealment and woody ground cover were common selection criteria in both treated and untreated units. However, in treated units wild turkey selected nest-sites with fewer small shrubs (<5 cm ground diameter) and large trees (>20 cm DBH) but not in untreated units. In untreated units wild turkey selected nest-sites with more large shrubs (≥5cm ground diameter) but did not select for small shrubs or large trees. Our findings suggest that wild turkey have not benefited from the reintroduction of prescribed fire to the WRERA.

Pathogen inactivation of double-dose buffy-coat platelet concentrates photochemically treated with amotosalen and UVA light: preservation of in vitro function.

The INTERCEPT Blood System for Platelets (PLT) utilizes amotosalen (S-59) in combination with ultraviolet A (UVA) light to inactivate viruses, bacteria, protozoa and leucocytes that may contaminate PLT concentrates. However, limited data are available on the quality of INTERCEPT-treated double-dose (DD) buffy-coat (BC) PLT units allowing a single treatment procedure to produce two pathogen-inactivated PLT units for transfusion. The objective of this study was to evaluate potential in vitro effects of the INTERCEPT treatment on pools of 7 BCs as compared to untreated units. Functional, phenotypic and mitochondrial properties of DD BC PLTs during storage over 7days were studied. For some parameters measured, small yet significant differences were observed including PLT count (P<0·05), pH, pCO2 and glucose concentration. Throughout storage, no significant differences were observed in ATP levels, ESC, HSR reactivity and CD62P expression. Similarly, no differences were observed in the expression of PAC-1, CD42b and PECAM-1 at any time-points. The mitochondrial membrane potential (MMP) determined by JC-1-labelling was well maintained until day 7 in all treated and untreated units (>90%). The release of sCD40L increased over time (P<0·01) in all units but without any significant differences between treated and untreated PLTs. Our data demonstrate that photochemical pathogen inactivation of DD-BC PLT concentrates with the INTERCEPT Blood System had no influence on the PLT in vitro quality over the 7day of storage. However, whether in vivo efficacy of INTERCEPT-treated PLTs is affected may require clinical evaluation.

Propensity Score-Based Methods versus MTE-Based Methods in Causal Inference: Identification, Estimation, and Application.

Since the seminal introduction of the propensity score by Rosenbaum and Rubin, propensity-score-based (PS-based) methods have been widely used for drawing causal inferences in the behavioral and social sciences. However, the propensity score approach depends on the ignorability assumption: there are no unobserved confounders once observed covariates are taken into account. For situations where this assumption may be violated, Heckman and his associates have recently developed a novel approach based on marginal treatment effects (MTE). In this paper, we (1) explicate consequences for PS-based methods when aspects of the ignorability assumption are violated; (2) compare PS-based methods and MTE-based methods by making a close examination of their identification assumptions and estimation performances; (3) apply these two approaches in estimating the economic return to college using data from NLSY 1979 and discuss their discrepancies in results. When there is a sorting gain but no systematic baseline difference between treated and untreated units given observed covariates, PS-based methods can identify the treatment effect of the treated (TT). The MTE approach performs best when there is a valid and strong instrumental variable (IV). In addition, this paper introduces the "smoothing-difference PS-based method," which enables us to uncover heterogeneity across people of different propensity scores in both counterfactual outcomes and treatment effects.

Whole blood treated with riboflavin and ultraviolet light: quality assessment of all blood components produced by the buffy coat method.

Pathogen inactivation (PI) technologies are currently licensed for use with platelet (PLT) and plasma components. Treatment of whole blood (WB) would be of benefit to the blood banking community by saving time and costs compared to individual component treatment. However, no paired, pool-and-split study directly assessing the impact of WB PI on the subsequently produced components has yet been reported. In a "pool-and-split" study, WB either was treated with riboflavin and ultraviolet (UV) light or was kept untreated as control. The buffy coat (BC) method produced plasma, PLT, and red blood cell (RBC) components. PLT units arising from the untreated WB study arm were treated with riboflavin and UV light on day of production and compared to PLT concentrates (PCs) produced from the treated WB units. A panel of common in vitro variables for the three types of components was used to monitor quality throughout their respective storage periods. PCs derived from the WB PI treatment were of significantly better quality than treated PLT components for most variables. RBCs produced from the WB treatment deteriorated earlier during storage than untreated units. Plasma components showed a 3% to 44% loss in activity for several clotting factors. Treatment of WB with riboflavin and UV before production of components by the BC method shows a negative impact on all three blood components. PLT units produced from PI-treated WB exhibited less damage compared to PLT component treatment.

Effectiveness of fuel reduction treatments: Assessing metrics of forest resiliency and wildfire severity after the Wallow Fire, AZ

Landscape-scale wildfire has occurred in higher frequencies across the planet. Fuel reduction treatments to fire-adapted systems have been shown to reduce the impact to human values-at-risk. However, few studies have examined if these treatments contribute to ecosystem resilience, or the capacity of a system to absorb perturbation and return to a similar set of structures or processes. We defined short-term metrics of resiliency to test the hypothesis that fuel reduction treatments in mixed conifer forests increased a fire-adapted system’s resiliency to uncharacteristically severe wildfire. In addition, we tested the hypothesis that fuel reduction treatments reduced burn severity, thereby increasing protection for adjacent human communities. We examined a mixed conifer forested landscape in the southwestern U.S. that was burned by a landscape-scale “mega-fire” in 2011; fuel reduction treatments had been established around communities in the 10years prior to the fire. Fire effects were highly variable in both treated and untreated forests. However, analysis of resiliency metrics showed that: (a) treated units retained a higher proportion of large trees and had post-fire tree densities within the natural range of variability; (b) the understory herbaceous community had significantly higher cover of native grasses in the treated units, but no significant differences in nonnative cover between treated and untreated units; and (c) high-severity patch sizes were significantly larger in untreated stands and covered a larger proportion of the landscape than historical reference conditions. Fire severity, as defined by overstory mortality and basal area loss, was significantly lower in treated units; on average, trees killed per hectare in untreated units was six times the number of trees killed in treated units. Fuel reduction treatments simultaneously reduced fire severity and enhanced short-term metrics of ecosystem resiliency to uncharacteristically severe fire.

Reducing the risk of hyperammonemia from transfusion of stored red blood cells

Ammonia concentration increases in red cell units (RBCs) during storage. We measured absolute amounts of ammonia (AA) per unit serially in stored RBCs and before and after removal of the supernatant by volume reduction (VR) or washing. Ammonia increased 6.4-fold in untreated units over 31 days. VR decreased AA 3.7-fold, whereas washing decreased it 38-fold (p<0.0001). At least for certain patients, e.g., infants receiving large volume transfusions and patients in liver failure, it may be advisable to use RBCs as fresh as possible and to limit infusion (by VR or washing) of ammonia in the supernatant.

Model Feedback in Bayesian Propensity Score Estimation

Methods based on the propensity score comprise one set of valuable tools for comparative effectiveness research and for estimating causal effects more generally. These methods typically consist of two distinct stages: (1) a propensity score stage where a model is fit to predict the propensity to receive treatment (the propensity score), and (2) an outcome stage where responses are compared in treated and untreated units having similar values of the estimated propensity score. Traditional techniques conduct estimation in these two stages separately; estimates from the first stage are treated as fixed and known for use in the second stage. Bayesian methods have natural appeal in these settings because separate likelihoods for the two stages can be combined into a single joint likelihood, with estimation of the two stages carried out simultaneously. One key feature of joint estimation in this context is "feedback" between the outcome stage and the propensity score stage, meaning that quantities in a model for the outcome contribute information to posterior distributions of quantities in the model for the propensity score. We provide a rigorous assessment of Bayesian propensity score estimation to show that model feedback can produce poor estimates of causal effects absent strategies that augment propensity score adjustment with adjustment for individual covariates. We illustrate this phenomenon with a simulation study and with a comparative effectiveness investigation of carotid artery stenting versus carotid endarterectomy among 123,286 Medicare beneficiaries hospitlized for stroke in 2006 and 2007.

Expression of Platelet (PLT) P-Selectin and PLT-Neutrophil (PMN) Interaction After Treatment of Whole Blood with Mirasol® PRT.

AbstractAbstract 2288 IntroductionPlatelet concentrates develop biologically active compounds during storage which may play a role in adverse events of transfusion. Although many studies have focused on release of soluble pro-inflammatory compounds, changes in cells such as platelets may contribute to the response or pro-inflammatory effects of transfusion products. In previous studies we have shown that pathogen reduction with Mirasol PRT of apheresis PLT concentrates induced changes in PLTs which increased during storage including expression of P-selectin and the capacity to form PLT-PMN aggregates. These changes were also associated with increased adherence of stored PLTs in a microfluidic chamber. In the current study we evaluated P-selectin and PLT-PMN aggregate formation in whole blood after treatment with Mirasol PRT. MethodsTen units of whole blood from healthy donors were drawn into CPD under an IRB approved protocol. Five units where treated with Mirasol PRT and five units remained untreated. Aliquots were taken before and after treatment (or at same times for untreated units) on Day 0 and 24–27 hours after draw on Day 1 after storage at 22–24°C. Platelet rich plasma (PRP) was produced by standard technique and PLTs isolated on a Sepharose 2B column. PLTs were incubated with APC-CD62P and FITC-CD41a for comparison with P-selectin expressed as percent positive increase over isotype control. PMNs were isolated from 50 ml of heparinized peripheral blood drawn from healthy, ABO-matched donors. After a 5 min pre-incubation at 37°C in a shaking water bath, untreated, treated PLTs, and PMNs were incubated separately or together for 3 min then quenched at 4°C. FITC-CD41a and FITC-IgG1 isotype for platelet-PMN aggregate quantitation or PE-CD11b for CD11b expression on neutrophils were added. Platelet-PMN aggregates was expressed as percent of all PMN events above CD41a isotype control. CD11b expression was determined for PMNs after exposure to PLTs by flow cytometry. ResultsP-selectin positive cells did not change significantly over time in samples from untreated products (Table 1). After Mirasol PRT treatment, cells positive for P-selectin increased on Day 0 and 1 (p<0.005, two-tailed t-test). Treated products, compared to untreated products demonstrated significantly increased P-selectin expression on Day 1.Table 1P-selectin Expression on PLTsSample% PLTs positive for P-selectinUntreated WBDay 0, earlyDay 0, lateDay 110.2 ± 2.2*15.2 ± 3.312.3 ± 2.3Mirasol PRT treatedDay 0, preDay 0, postDay 17.6 ± 1.119.0 ± 2.521.7 ± 2.6***Numbers represent mean ± SEM for 5 separate products each**Treated cells different than untreated cells, p<0.05Results for PMN-PLT aggregates parallel expression of P-selectin (Table 2). No increase in aggregate formation was seen for untreated samples; however, treated samples showed increased aggregates at Day 0 and 1 (p<0.005). Aggregates with PMNs were increased in treated samples in comparison to untreated samples on Day 1.Table 2PLT-PMN AggregatesSample% PMNs with associated PLTsUntreated WBDay 0, earlyDay 0, lateDay 17.8 ± 4.49.8 ± 3.37.1 ± 3.8Mirasol PRT treatedDay 0, preDay 0, postDay 14.8 ± 3.015.5 ± 3.519.3 ± 6.9**No differences were seen with CD11b expression on PMNs after exposure of treated or untreated PLTs at any of the times studied.*Numbers represent mean ± SEM for 5 separate products each**Treated cells different than untreated cells, p<0.05 ConclusionTreatment of whole blood with Mirasol PRT results in increased expression of P-selectin on PLTs and capability of forming aggregates with PMNs. The changes occur soon after initiation of treatment, and the implications for clinical response to of platelet infusion and adverse events of transfusion need to be established. Disclosures:Ambruso:Terumo BCT: Research Funding. Seewald:Terumo BCT: Research Funding. Marschner:Terumo BCT: Employment. Goodrich:Terumo BCT: Employment.

Surface fuel treatments in young, regenerating stands affect wildfire severity in a mixed conifer forest, eastside Cascade Range, Washington, USA

Previous studies have debated the flammability of young regenerating stands, especially those in a matrix of mature forest, and no consensus has emerged as to whether young stands are inherently prone to high-severity wildfire. This topic has recently been addressed using spatial imagery, and weak inferences were made given the scale mismatch between the coarse resolution of spatial imagery and the fine resolution of mechanisms driving fire severity. We collected empirical stand and fire-severity data from 44 regenerating stands that are interspersed in mature, mid-elevation forests in the Okanogan-Wenatchee National Forest (OWNF) on the eastside of the Cascade Range in Washington, USA. These stands are mixed-species plantations that were established to promote regeneration of seral to late-seral tree species (Douglas-fir, subalpine fir, Engelmann spruce, western larch) in small patches within a larger lodgepole pine forest. In 2006, the 70,925ha Tripod Fire burned through all the plantations and the surrounding lodgepole pine matrix. To understand what drives fire effects in plantations, especially those that exist in spatially heterogeneous forests, we compared fire severity in plantations with and without fuels-reducing site preparation (i.e., fuel treatments), using three metrics to quantify severity: mortality (%), exposed mineral soil (%), and char height (m). We built generalized linear models for each severity metric and tested for a difference in all severity metrics between treated and untreated units using Permutational Multivariate Analysis of Variance. Units without fuel treatments have more severe fire effects: mortality is 77% in untreated units and 37% in treated units (p=0.0005). Other variables contribute to differences in fire severity, including species composition, canopy closure, and canopy base height. Canopy base height and canopy closure both exhibit a reverse relationship with mortality from what was expected: the higher the canopy closure and the lower the canopy base height, the lower the mortality. In other words, stands that have trees closer together with crowns near the ground are more likely to have lower mortality. Overall, the results suggest that young stands in some dry mixed conifer forests can be resilient to wildfire if surface fuel loading is low upon stand establishment.

Platelet derived cytokine accumulation in platelet concentrates treated for pathogen reduction

BackgroundPathogen reduction technologies (PRTs) prevent replication and proliferation of pathogens in platelet (PLT) concentrates (PCs) by modifying nucleic acids. Due to increased cell activation, PRT may also lead to increased cytokine release from α granules and promote adverse transfusion reactions in the recipient. DesignFifteen double-dose leukoreduced apheresis PCs were collected on the Trima Accel platform (vs. 5.2.) allowing for the resuspension in PLT additive solution (PAS) immediately after collection. After a 2-h resting period (1st hour without, 2nd hour with agitation), splitting was performed: one unit remained untreated to serve as control (C), while the other was riboflavin-UVB treated using the Mirasol-PRT system according to the manufacturer’s instructions (M). During 8days of storage, PCs were analyzed for contaminating white and red blood cells, bacterial growth, PLT activation, LDH and cytokine release (MIP-1 α, RANTES, PF4, and TGF-β-1). Results obtained were opposed to a former study, where triple-dose PCs underwent Mirasol-PRT prior to resuspension or the INTERCEPT BLOOD SYSTEM (psoralen-UVA) or remained untreated. ResultsDespite similar LDH release, PRT treatment was associated with significantly higher (p<0.05) cell activation but only slightly higher cytokine accumulation during storage. Differences became significant only for PF4 and RANTES at day 8 of storage. On the other hand, in the investigation on triple-dose PCs (yielding higher cytokine levels), TGF beta-1 and RANTES remained significantly (p<0.05) lower after PRT treatment compared to untreated units. ConclusionFactors, such as collection modality, onset of resuspension and additional amounts of magnesium/potassium in the PAS used may be of equal or even greater impact for cytokine accumulation in stored PCs than PRT treatment.

Protein stability of previously frozen plasma, riboflavin and UV light-treated, refrozen and stored for up to 2 years at −30 °C

Background The Mirasol pathogen reduction technology system for plasma is based on a riboflavin and UV light treatment process resulting in pathogen inactivation due to irreversible, photochemically induced damage of nucleic acids. The objective of this study was to evaluate the in vitro protein quality of previously frozen FFP, thawed, Mirasol-treated and refrozen for a final storage period of up to 2 years at −30 °C. Materials and methods All plasma products were held at 4 ± 2 °C, and frozen within 8 h after the start of collection. FFP was stored frozen at −30 °C for eight time intervals before riboflavin and UV light treatment and refrozen to −30 °C and stored for varying time intervals for a total storage period of up to 2 years at −30 °C. Results were compared to paired, untreated units thawed and stored for the same time intervals. Results The overall mean values for all time points in riboflavin and UV light treated plasma samples indicates that all proteins were well preserved following a period of frozen storage for 2 years at −30 °C. Factors V, VII and XI, retained 70%, 65% and 53% activity, respectively. All other protein factors, anticoagulant and inhibitor proteins demonstrated retention between 74% and 100%. Conclusion Riboflavin and UV light-treated FFP maintained both coagulant and anticoagulant in vitro protein quality after double freeze/thaw storage at −30 °C for up to 2 years, a finding that may offer processing flexibility to blood centers.

Effects on renal function of obstructive and nonobstructive dilatation of the upper urinary tract in ileal neobladders with refluxing ureteroenteric anastomoses

Aims To investigate the incidence and long-term effects on kidney function of obstructive and nonobstructive dilatation of the upper urinary tract in patients with ileal neobladder with refluxing ureterointestinal anastomoses. Methods We retrospectively analyzed a prospectively derived database of 110 patients with bladder cancer and who were treated with an ileal neobladder between 1996 and 2007 using refluxing end-to-side ureterointestinal anastomoses on a short afferent limb. The mean follow up was 65 months. At every follow up visit the patients had an analysis of serum creatinine, urine culture, abdominal CT or ultrasonography, and, if there was dilatation of the upper urinary tract, 99mTc-DTPA renal scintigraphy was requested. Results In all, 206 renoureteral units were included in the study. Overall, seven had anastomotic stricture and of those, three were symptomatic and were corrected; while four were asymptomatic and of those, only two, with preserved split GFR, were surgically treated, while the remaining two, with a poor split GFR, were followed up. The last 99mTc-DTPA showed a preserved split GFR in the reimplanted units and further split renal function decrease in untreated units. Nonobstructive dilatation of the upper urinary tract, caused by reflux, was diagnosed in 13 units. The dilatation was bilateral in three patients with recurrent UTIs and urosepsis, and the split GFR was bilaterally reduced at diagnosis with a further reduction at the last 99mTc-DTPA. The remaining seven units with sterile urine, showed a preserved split GFR during follow up. Conclusions All strictures, regardless of their severity, should be immediately corrected. Reflux per se does not provoke renal impairment unless recurrent UTIs and urosepsis are present.

Characterization of plasma protein activity in riboflavin and UV light-treated fresh frozen plasma during 2 years of storage at −30°C

The Mirasol Pathogen Reduction Technology System (PRT) for Plasma (CaridianBCT) is based on a riboflavin and UV light treatment process resulting in pathogen inactivation due to irreversible, photochemically induced damage of nucleic acids. This study evaluated the in vitro protein quality of plasma products treated with riboflavin and UV light following treatment and subsequent storage for up to 104 weeks at -30 degrees C. Apheresis and whole blood-derived plasma products were combined with riboflavin solution and exposed to ultraviolet light. Treated plasma was then flash frozen, within 8 h of collection, stored at -30 degrees C for up to 104 weeks and analysed at different stages of storage using standard coagulation assays. Results were compared with paired, untreated units stored for the same intervals. The average percent protein retention for all time-points in PRT-treated plasma samples after 36, 69, 87 and 104 weeks of storage at -30 degrees C in comparison with controls held under similar conditions were: Total Protein, 101%, Factor VIII, 79%, Fibrinogen, 78%, Factor II, 87%, Factor XII, 86%, Factor X, 84% and Factor IX, 81%. Anticoagulant and inhibitor proteins showed between 90% and 100% retention after 1 year (52 weeks) and 69 weeks of storage. No clinically relevant complement activation was observed in treated and stored samples. Riboflavin and UV light-treated plasma demonstrates reductions in several plasma coagulation factors following treatment. This reduction in activity levels is noted immediately after treatment and remains relatively constant during 2 years of storage at -30 degrees C.

Functional characteristics of apheresis‐derived platelets treated with ultraviolet light combined with either amotosalen‐HCl (S‐59) or riboflavin (vitamin B2) for pathogen‐reduction

To examine if different pathogen-reduction technologies (PRTs) induce different degrees of platelet (PLT) storage lesion. Twenty-seven split triple-dose apheresis PLTs were PRT treated using ultraviolet light with either riboflavin (M) or psoralen (I) or remained untreated (C). Samples taken on days (d) 0 to 8 were analysed for PLT count, blood gas (pH, pO(2) and pCO(2)), metabolism (lactate, glucose, ATP content), in vitro function [swirling, hypotonic shock response (HSR) and aggregation], activation (p-selectin expression) and cellular integrity (JC-1 signal, annexin A5 release). Platelet counts of all study groups remained unchanged during storage indicating that PRT treatment did not induce relevant cell lysis. Although M units demonstrated the highest values for HSR until d5, PRT treatment lowered all parameters examined with significant differences to untreated controls by d7 of storage. During final storage, M was significantly superior over I for HSR, aggregation with TRAP-6 as agonist (collagen was similar), annexin A5 release and JC-1 signal. Regarding blood gas and metabolic analysis, the most evident effect of PRT was an elevated glycolytic flux combined with higher acidity due to increased lactate accumulation. Most likely due to impaired O(2) consumption, pH and ATP decreased more rapidly in I relative to C and M. Pathogen reduction technology-treated PLTs remained comparable to untreated units throughout 7 days of storage. Mitochondria-based oxidative respiration appeared up-regulated after the riboflavin-based PRT. Compared to the psoralen-based PRT, this resulted in significantly better ATP maintenance and in vitro function during the last storage period (d7, d8).