Development of multidisciplinary, evidenced-based protocol recommendations and implementation strategies for anterior lumbar interbody fusion surgery following a literature review.

The anterior lumbar interbody fusion (ALIF) procedure involves several surgical specialties, including general, vascular, and spinal surgery due to its unique approach and anatomy involved. It also carries its own set of complications that differentiate it from posterior lumbar fusion surgeries. The demonstrated benefits of treatment guidelines, such as Enhanced Recovery after Surgery in other surgical procedures, and the lack of current recommendations regarding the anterior approach, underscores the need to develop protocols that specifically address the complexities of ALIF. We aimed to create an evidence-based protocol for pre-, intra-, and postoperative care of ALIF patients and implementation strategies for our health system. A 12-member multidisciplinary workgroup convened to develop an evidence-based treatment protocol for ALIF using a Delphi consensus methodology and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system for rating the quality of evidence and strength of protocol recommendations. The quality of evidence, strength of the recommendation and specific implementation strategies for Methodist Health System for each recommendation were described. The literature search resulted in 295 articles that were included in the development of protocol recommendations. No disagreements remained once the authors reviewed the final GRADE assessment of the quality of evidence and strength of the recommendations. Ultimately, there were 39 protocol recommendations, with 16 appropriate preoperative protocol recommendations (out of 17 proposed), 9 appropriate intraoperative recommendations, and 14 appropriate postoperative recommendations. This novel set of evidence-based recommendations is designed to optimize the patient's ALIF experience from the preoperative to the postoperative period.

Novel use of riboflavin as a fluorescent tracer in the dissemination of aerosol and splatter in an open operatory dental clinic.

OBJECTIVES: The rapid spread of severe acute respiratory syndrome coronavirus 2 and the ensuing rise of the COVID-19 pandemic have impacted healthcare unprecedentedly. With the scarcity of available resources, including healthcare providers themselves, novel methods for tracking aerosol and splatter in real time are required to alleviate demand and increase safety. This study evaluates the utility of riboflavin (vitamin B2 ) as a tracer for splatter/aerosol distribution from ultrasonic scaling in an open operatory clinic. MATERIAL AND METHODS: In two experimental designs, ultrasonic scaling was performed on 18 volunteers or simulated on a manikin. Riboflavin was introduced into the irrigation system, and aerosol and splatter dissemination were evaluated for both experimental designs. RESULTS: Ultrasonic scaling utilizing riboflavin solution, in volunteers and manikins, leads to observable particle fluorescence under UV light. Contamination distribution varied across the different suction methods and between the volunteer and manikin trials. Nearly all observed incidences of contamination occurred within the operatory in use. CONCLUSIONS: Riboflavin can be used with minimal risk during dental procedures and allows for the detection of droplet spread in clinical settings in real time.

The Role of the US Trauma Centers in Older Adult Fall Prevention: A National Survey.

INTRODUCTION: Approximately 27.5% of adults 65 and older fall each year, over 3 million are treated in an emergency department, and 32 000 die. The American College of Surgeons and its Committee on Trauma (ACSCOT) have urged trauma centers (TCs) to screen for fall risk, but information on the role of TC in this opportunity for prevention is largely unknown. METHODS: A 29-item survey was developed by an ACSCOT Injury Prevention and Control Committee, Older Adult Falls workgroup, and emailed to 1000 trauma directors of the National Trauma Data Bank using Qualtrics. US TCs were surveyed regarding fall prevention, screening, intervention, and hospital discharge practices. Data collected and analyzed included respondent's role, location, population density, state designation or American College of Surgeons (ACS) level, if teaching facility, and patient population. RESULTS: Of the 266 (27%) respondents, 71% of TCs include fall prevention as part of their mission, but only 16% of TCs use fall risk screening tools. There was no significant difference between geographic location or ACS level. The number of prevention resources (F = 31.58, P < .0001) followed by the presence of a formal screening tool (F = 21.47, P < .0001) best predicted the presence of a fall prevention program. CONCLUSION: Older adult falls remain a major injury risk and injury prevention opportunity. The majority of TCs surveyed include prevention of older adult falls as part of their mission, but few incorporate the components of a fall prevention program. Development of best practices and requiring TCs to screen and offer interventions may prevent falls.

Smokeless Tobacco Cessation in an Emergency Room in Rural West Virginia.

Background: Emergency room nurses have a strong influence on the population of smokeless tobacco users. If healthcare providers address patient's tobacco use by using a brief intervention strategy (one minute or less), it increases the quit attempt rate threefold. The object of this study is to assess the effectiveness of asynchronous internet based brief tobacco intervention training with rural emergency room nurses. Methods: A 1-h asynchronous training session on smokeless tobacco use and the 2-A and 1-R (Ask, Advise, and Refer) brief tobacco intervention strategy were given to 13 emergency room nurses at a rural acute care hospital in West Virginia. Paired sample t-tests were used to compare the pre-and post-test results. Results: The 1-h training session produced significant and positive increases in all items measured: increased motivation to assist patients in quitting; increased knowledge of smokeless tobacco use, its dangers, and cessation processes; increased self-efficacy in implementing brief interventions; increased perception of tobacco cessation as important; increased perception of the effectiveness of tobacco cessation interventions; and increased acknowledgment of barriers and an awareness of how to deal with them. Conclusions: The results suggest that there is a significant potential benefit from training emergency room nurses. Brief tobacco interventions should be conducted by clinical staff during the medical history check, physical examination, or discharge phases of the emergency room visit.

Pu(iii) and Cm(iii) in the presence of EDTA: aqueous speciation, redox behavior, and the impact of Ca(ii).

The impact of calcium on the solubility, redox behavior, and speciation of the An(iii)-EDTA (An = Pu or Cm) system under reducing, anoxic conditions was investigated through batch solubility experiments, X-ray absorption spectroscopy (XAS), density functional theory (DFT), and time-resolved laser fluorescence spectroscopy (TRLFS). Batch solubility experiments were conducted from undersaturation using Pu(OH)3(am) as the solid phase in contact with 0.1 M NaCl-NaOH-HCl-EDTA-CaCl2 solutions at [EDTA] = 1 mM, pHm = 7.5-9.5, and [CaCl2] ≤20 mM. Additional samples targeted brine systems represented by 3.5 M CaCl2 and WIPP simulated brine. Solubility data in the absence of calcium were well-described by Pu(iii)-EDTA thermodynamic models, thus supporting the stabilization of Pu(iii)-EDTA complexes in solution. Cm(iii)-EDTA TRLFS data suggested the stepwise hydrolysis of An(iii)-EDTA complexes with increasing pH, and current Pu(iii)-EDTA solubility models were reassessed to evaluate the possibility of including Pu(iii)-OH-EDTA complexes and to calculate preliminary formation constants. Solubility data in the presence of calcium exhibited nearly constant log m(Pu)tot, as limited by total ligand concentration, with increasing [CaCl2]tot, which supports the formation of calcium-stabilized Pu(iii)-EDTA complexes in solution. XAS spectra without calcium showed partial oxidation of Pu(iii) to Pu(iv) in the aqueous phase, while calcium-containing experiments exhibited only Pu(iii), suggesting that Ca-Pu(iii)-EDTA complexes may stabilize Pu(iii) over short timeframes (t ≤45 days). DFT calculations on the Ca-Pu(iii)-EDTA system and TRLFS studies on the analogous Ca-Cm(iii)-EDTA system show that calcium likely stabilizes An(iii)-EDTA complexes but can also potentially stabilize An(iii)-OH-EDTA species in solution. This hints towards the possible existence of four major complex types within Ca-An(iii)-EDTA systems: An(iii)-EDTA, An(iii)-OH-EDTA, Ca-An(iii)-EDTA, and Ca-An(iii)-OH-EDTA. While the exact stoichiometry and degree of ligand protonation within these complexes remain undefined, their formation must be accounted for to properly assess the fate and transport of plutonium under conditions relevant to nuclear waste disposal.

Stopping Smokeless Tobacco Use: A Call to Action.

In the United States, single smokeless tobacco use continues to increase in conjunction with the dual use of smokeless tobacco and other nicotine products. Problematically, much of the tobacco prevention literature and funding inundates tobacco users with smoking tobacco information while neglecting to provide them any information about smokeless tobacco. Meanwhile, American tobacco companies continually market new and dissolvable tobacco products targeted at non-smokers. New data suggests that smokeless tobacco use is, also, increasing in West Virginia and, in order to address this increased use, the West Virginia Extension Service recently partnered with the Division of Tobacco Prevention in the West Virginia Department of Health and Human Resources to develop a comprehensive spit tobacco curriculum for West Virginia students between third and sixth grade. This article details the development and assessment of the spit tobacco prevention curriculum and the resulting report from the initial pilot of the program. The curriculum was piloted across six counties with the participation of schools, after-school programs and 4-H clubs. After implementation, survey results demonstrate that youth have increased awareness of the health effects of smokeless tobacco. Throughout the article, we explore West Virginia's Cooperative Extension Service's response to this emerging public health issue and release a call to action for the National Cooperative Extension Services to join us in spit tobacco prevention.

Artificial intelligence in nursing: Priorities and opportunities from an international invitational think-tank of the Nursing and Artificial Intelligence Leadership Collaborative.

AIM: To develop a consensus paper on the central points of an international invitational think-tank on nursing and artificial intelligence (AI). METHODS: We established the Nursing and Artificial Intelligence Leadership (NAIL) Collaborative, comprising interdisciplinary experts in AI development, biomedical ethics, AI in primary care, AI legal aspects, philosophy of AI in health, nursing practice, implementation science, leaders in health informatics practice and international health informatics groups, a representative of patients and the public, and the Chair of the ITU/WHO Focus Group on Artificial Intelligence for Health. The NAIL Collaborative convened at a 3-day invitational think tank in autumn 2019. Activities included a pre-event survey, expert presentations and working sessions to identify priority areas for action, opportunities and recommendations to address these. In this paper, we summarize the key discussion points and notes from the aforementioned activities. IMPLICATIONS FOR NURSING: Nursing's limited current engagement with discourses on AI and health posts a risk that the profession is not part of the conversations that have potentially significant impacts on nursing practice. CONCLUSION: There are numerous gaps and a timely need for the nursing profession to be among the leaders and drivers of conversations around AI in health systems. IMPACT: We outline crucial gaps where focused effort is required for nursing to take a leadership role in shaping AI use in health systems. Three priorities were identified that need to be addressed in the near future: (a) Nurses must understand the relationship between the data they collect and AI technologies they use; (b) Nurses need to be meaningfully involved in all stages of AI: from development to implementation; and (c) There is a substantial untapped and an unexplored potential for nursing to contribute to the development of AI technologies for global health and humanitarian efforts.

Impact of Ca(II) on the aqueous speciation, redox behavior, and environmental mobility of Pu(IV) in the presence of EDTA.

The impact of calcium on the solubility and redox behavior of the Pu(IV)-EDTA system was investigated using a combination of undersaturation solubility studies and advanced spectroscopic techniques. Batch solubility experiments were conducted in 0.1 M NaCl-NaOH-HCl-EDTA-CaCl2 solutions at constant [EDTA] = 1∙10-3 M, 1 ≤ pHm ≤ 11, and 1∙10-3 M ≤ [CaCl2] ≤ 2∙10-2 M. Additional samples targeted brine systems represented by 3.5 M CaCl2 and WIPP simulated brine. Redox conditions were buffered with hydroquinone (pe + pH ≈ 9.5) with selected samples prepared in the absence of any redox buffer. All experiments were performed at T = 22 °C under Ar atmosphere. In-situ X-ray absorption spectroscopy indicated that PuO2(ncr,hyd) was the solubility-controlling phase during the lifetime of all experiments and that aqueous plutonium was present in the +IV oxidation state across all experimental conditions except at pHm ≈ 1, where a small fraction of Pu(III) was also identified. Current thermodynamic models overestimate Pu(IV)-EDTA solubility in the absence of calcium by approximately 1-1.5 log10-units and do not describe the nearly pH-independent, increased solubility observed with increased calcium concentrations. The ternary Pu(IV)-OH-EDTA system without calcium was reevaluated using solubility data obtained in this work and reported in the literature. An updated thermodynamic model including the complexes Pu(OH)(EDTA)-, Pu(OH)2(EDTA)2-, and Pu(OH)3(EDTA)3- was derived. Solubility data collected in the presence of calcium follows a pH-independent trend (log m(Pu)tot vs. pHm), which can only be explained by assuming the formation of a quaternary complex, tentatively defined as CaPu(OH)4(EDTA)2-, in solution. The significant enhancement of plutonium solubility observed in the investigated brine systems supports the formation of a quaternary complex that is not outcompeted by Ca(EDTA)2-, even in concentrated CaCl2 solutions. Although the exact stoichiometry of the complex may need to be revisited, this new quaternary complex has a pronounced impact on plutonium predominance diagrams over a broad range of pH, pe, and calcium concentrations that are relevant to nuclear waste disposal.

Influence of ethylenediaminetetraacetic acid on the long-term oxidation state distribution of plutonium.

Spectrophotometry was used to study the effect of EDTA on plutonium oxidation state distribution as a function of time, pH, and ligand-to-metal ratio (L/M) under anoxic conditions. Novel Pu(V)-EDTA absorption bands were identified at 571, 993, 1105, and 1150 nm with molar absorption coefficients of 15 ± 1, 6 ± 1, 10 ± 1, and 10 ± 1 cm-1M-1, respectively. Pu(V)-EDTA spectral changes occurred at L/M < 1, indicating only PuVO2(EDTA)3- formed with logK = 3.6 ± 0.3. Time-resolved experiments showed EDTA drastically increased the Pu(V/VI) reduction rate, which we propose is driven by amine lone-pair electron donation and the oxidative decarboxylation of EDTA. Oxidation of Pu(III)-EDTA to Pu(IV)-EDTA occurred on a slower time scale (110-237 days) than previously reported (<15 min) and is hypothesized to be radiolysis driven. Pu(V/VI)-EDTA and Pu(III)-EDTA both approached Pu(IV)-EDTA stabilization over time, yet Pu(V/VI)-EDTA solubility data was ≥ 1.0 log10 units higher than predicted by Pu(IV)-EDTA solubility models, indicating that current thermodynamic models are incomplete. Ultimately, the data show EDTA preferentially stabilizes Pu(IV) over time regardless of initial oxidation state, but Pu(V)-EDTA can persist under environmentally-relevant conditions, emphasizing the need to continue investigating redox reactions, speciation, and behavior of these complexes to support the transuranic waste disposal and surface remediation/containment efforts.

Extending surgeon response times in tier 2 traumas does not adversely affect patient outcomes.

BACKGROUND: The presence of a trauma surgeon during patient resuscitations is required at most American College of Surgeons-verified trauma centers despite little evidence showing improved patient outcomes in the less-than-critically injured (Tier 2) trauma patients. This study was designed to identify the impact of extending required surgeon response times on outcomes in tier 2 trauma patients. METHODS: An American College of Surgeons-verified level 2 trauma center extended the maximum allowed surgeon response time for tier 2 activations from 60 min to 120 min on November 1, 2011. Surgeon response time and patient outcomes of the retrospective control group (January 1, 2008-October 31, 2011) were then compared with the prospective test group (November 1, 2011-December 31, 2014). Primary outcomes included mortality and hospital length of stay (HLOS). Secondary outcomes were emergency department length of stay, and time from ED arrival to CT scan. A subset analysis of all patients evaluated by a surgeon within 60 min of arrival versus those evaluated by a surgeon after 60 min was also performed. RESULTS: The control and test groups were composed of 757 and 792 patients, and their mean injury severity score was 9.0 and 6.0, respectively. Emergency department length of stay showed a statistically significant increase of 12 min, whereas HLOS was unchanged throughout the study. Mortality was not significantly different between the groups. Subset analysis revealed a median surgeon arrival time of 15 min in the <60-min group and 85 min in the >60-min group, whereas the injury severity score, HLOS, and mortality were not significantly different between these subsets. No correlation existed between these outcomes and surgeon arrival time. CONCLUSIONS: Doubling required surgeon response time in tier 2 trauma patients does not produce negative outcomes in this patient group. Mandatory surgeon response times in similar patient groups can be re-evaluated to allow for greater flexibility of a limited surgeon workforce while still providing safe care.

Comparative analysis of uranium bioassociation with halophilic bacteria and archaea.

Rock salt represents a potential host rock formation for the final disposal of radioactive waste. The interactions between indigenous microorganisms and radionuclides, e.g. uranium, need to be investigated to better predict the influence of microorganisms on the safety assessment of the repository. Hence, the association process of uranium with two microorganisms isolated from rock salt was comparatively studied. Brachybacterium sp. G1, which was isolated from the German salt dome Gorleben, and Halobacterium noricense DSM15987T, were selected as examples of a moderately halophilic bacterium and an extremely halophilic archaeon, respectively. The microorganisms exhibited completely different association behaviors with uranium. While a pure biosorption process took place with Brachybacterium sp. G1 cells, a multistage association process occurred with the archaeon. In addition to batch experiments, in situ attenuated total reflection Fourier-transform infrared spectroscopy was applied to characterize the U(VI) interaction process. Biosorption was identified as the dominating process for Brachybacterium sp. G1 with this method. Carboxylic functionalities are the dominant interacting groups for the bacterium, whereas phosphoryl groups are also involved in U(VI) association by the archaeon H. noricense.

Survey of American College of Surgeons Committee on trauma members on firearm injury: Consensus and opportunities.

BACKGROUND: In the United States, there is a perceived divide regarding the benefits and risks of firearm ownership. The American College of Surgeons Committee on Trauma Injury Prevention and Control Committee designed a survey to evaluate Committee on Trauma (COT) member attitudes about firearm ownership, freedom, responsibility, physician-patient freedom and policy, with the objective of using survey results to inform firearm injury prevention policy development. METHODS: A 32-question survey was sent to 254 current U.S. COT members by email using Qualtrics. SPSS was used for χ exact tests and nonparametric tests, with statistical significance being less than 0.05. RESULTS: Our response rate was 93%, 43% of COT members have firearm(s) in their home, 88% believe that the American College of Surgeons should give the highest or a high priority to reducing firearm-related injuries, 86% believe health care professionals should be allowed to counsel patients on firearms safety, 94% support federal funding for firearms injury prevention research. The COT participants were asked to provide their opinion on the American College of Surgeons initiating advocacy efforts and there was 90% or greater agreement on 7 of 15 and 80% or greater on 10 of 15 initiatives. CONCLUSION: The COT surgeons agree on: (1) the importance of formally addressing firearm injury prevention, (2) allowing federal funds to support research on firearms injury prevention, (3) retaining the ability of health care professionals to counsel patients on firearms-related injury prevention, and (4) the majority of policy initiatives targeted to reduce interpersonal violence and firearm injury. It is incumbent on trauma and injury prevention organizations to leverage these consensus-based results to initiate prevention, advocacy, and other efforts to decrease firearms injury and death. LEVEL OF EVIDENCE: Prognostic/epidemiologic study, level I; therapeutic care, level II.

Multistage bioassociation of uranium onto an extremely halophilic archaeon revealed by a unique combination of spectroscopic and microscopic techniques.

The interactions of two extremely halophilic archaea with uranium were investigated at high ionic strength as a function of time, pH and uranium concentration. Halobacterium noricense DSM-15987 and Halobacterium sp. putatively noricense, isolated from the Waste Isolation Pilot Plant repository, were used for these investigations. The kinetics of U(VI) bioassociation with both strains showed an atypical multistage behavior, meaning that after an initial phase of U(VI) sorption, an unexpected interim period of U(VI) release was observed, followed by a slow reassociation of uranium with the cells. By applying in situ attenuated total reflection Fourier-transform infrared spectroscopy, the involvement of phosphoryl and carboxylate groups in U(VI) complexation during the first biosorption phase was shown. Differences in cell morphology and uranium localization become visible at different stages of the bioassociation process, as shown with scanning electron microscopy in combination with energy dispersive X-ray spectroscopy. Our results demonstrate for the first time that association of uranium with the extremely halophilic archaeon is a multistage process, beginning with sorption and followed by another process, probably biomineralization.

Perceptions of the Role of West Virginia's Cooperative Extension Service in Tobacco Control Coalitions.

Despite the fact that the consequences of tobacco use are well identified and known, it remains the single most preventable cause of disease and death in the United States. In West Virginia alone, the adult prevalence of cigarette smoking is 26.8%. This study researches the perceptions of the Cooperative Extension Service's involvement and role in county-level coalitions that address tobacco use in West Virginia. The research findings provide practical areas to increase the role of the Extension Service in these vital efforts to save lives, reduce economic hardships on families, and reduce the health-care burden on the state government.

Understanding Genomic Knowledge in Rural Appalachia: The West Virginia Genome Community Project.

PURPOSE: Rural communities have limited knowledge about genetics and genomics and are also underrepresented in genomic education initiatives. The purpose of this project was to assess genomic and epigenetic knowledge and beliefs in rural West Virginia. SAMPLE: A total of 93 participants from three communities participated in focus groups and 68 participants completed a demographic survey. The age of the respondents ranged from 21 to 81 years. Most respondents had a household income of less than $40,000, were female and most were married, completed at least a HS/GED or some college education working either part-time or full-time. METHOD: A Community Based Participatory Research process with focus groups and demographic questionnaires was used. FINDINGS: Most participants had a basic understanding of genetics and epigenetics, but not genomics. Participants reported not knowing much of their family history and that their elders did not discuss such information. If the conversations occurred, it was only during times of crisis or an illness event. Mental health and substance abuse are topics that are not discussed with family in this rural population. CONCLUSIONS: Most of the efforts surrounding genetic/genomic understanding have focused on urban populations. This project is the first of its kind in West Virginia and has begun to lay the much needed infrastructure for developing educational initiatives and extending genomic research projects into our rural Appalachian communities. By empowering the public with education, regarding the influential role genetics, genomics, and epigenetics have on their health, we can begin to tackle the complex task of initiating behavior changes that will promote the health and well-being of individuals, families and communities.

Multiscale Speciation of U and Pu at Chernobyl, Hanford, Los Alamos, McGuire AFB, Mayak, and Rocky Flats.

The speciation of U and Pu in soil and concrete from Rocky Flats and in particles from soils from Chernobyl, Hanford, Los Alamos, and McGuire Air Force Base and bottom sediments from Mayak was determined by a combination of X-ray absorption fine structure (XAFS) spectroscopy and X-ray fluorescence (XRF) element maps. These experiments identify four types of speciation that sometimes may and other times do not exhibit an association with the source terms and histories of these samples: relatively well ordered PuO2+x and UO2+x that had equilibrated with O2 and H2O under both ambient conditions and in fires or explosions; instances of small, isolated particles of U as UO2+x, U3O8, and U(VI) species coexisting in close proximity after decades in the environment; alteration phases of uranyl with other elements including ones that would not have come from soils; and mononuclear Pu-O species and novel PuO2+x-type compounds incorporating additional elements that may have occurred because the Pu was exposed to extreme chemical conditions such as acidic solutions released directly into soil or concrete. Our results therefore directly demonstrate instances of novel complexity in the Å and µm-scale chemical speciation and reactivity of U and Pu in their initial formation and after environmental exposure as well as occasions of unexpected behavior in the reaction pathways over short geological but significant sociological times. They also show that incorporating the actual disposal and site conditions and resultant novel materials such as those reported here may be necessary to develop the most accurate predictive models for Pu and U in the environment.

Bacterial Pu(V) reduction in the absence and presence of Fe(III)-NTA: modeling and experimental approach.

Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes, can be precipitated to "immobilized" plutonium phases in systems that promote bioreduction. Ferric iron (Fe(3+)) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe(2+)) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria. Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe(3+)) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY (S. alga) reduced Pu(V)(PuO(2) (+)) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO(4(am).) In the absence of Fe(3+) and NTA, reduction of PuO(2) (+) was directly biotic, but modeling simulations support that PuO(2) (+) reduction in the presence of Fe(3+) and NTA was due to an abiotic stepwise reduction of PuO(2) (+) to Pu(4+), followed by reduction of Pu(4+) to Pu(3+), both through biogenically produced Fe(2+). This means that PuO(2) (+) reduction was slowed by first having Fe(3+) reduced to Fe(2+). Modeling results also show that the degree of PuPO(4(am)) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO(4(am)).

Surface complexation of Neptunium(V) onto whole cells and cell components of Shewanella alga: modeling and experimental study.

We systematically quantified surface complexation of Np(V) onto whole cells, cell wall, and extracellular polymeric substances (EPS) of Shewanella alga strain BrY. We first performed acid and base titrations and used the mathematical model FITEQL to estimate the concentrations and deprotonation constants of specific surface functional groups. Deprotonation constants most likely corresponded to a carboxyl group not associated with amino acids (pK(a) approximately 5), a phosphoryl site (pK(a) approximately 7.2), and an amine site (pK(a) > 10). We then carried out batch sorption experiments with Np(V) and each of the S. alga components as a function of pH. Since significant Np(V) sorption was observed on S. alga whole cells and its components in the pH range 2-5, we assumed the existence of a fourth site: a low-pK(a) carboxyl site (pK(a) approximately 2.4) that is associated with amino acids. We used the SPECIATE submodel of the biogeochemical model CCBATCH to compute the stability constants for Np(V) complexation to each surface functional group. The stability constants were similar for each functional group on S. alga bacterial whole cells, cell walls, and EPS, and they explain the complicated sorption patterns when they are combined with the aqueous-phase speciation of Np(V). For pH < 8, the aquo NpO(2)(+) species was the dominant form of Np(V), and its log K values for the low-pK(a) carboxyl, mid-pK(a) carboxyl, and phosphoryl groups were 1.8, 1.8, and 2.5-3.1, respectively. For pH greater than 8, the key surface ligand was amine >XNH(3)(+), which complexed with NpO(2)(CO(3))(3)(5-). The log K for NpO(2)(CO(3))(3)(5-) complexed onto the amine groups was 3.1-3.9. All of the log K values are similar to those of Np(V) complexes with aqueous carboxyl and N-containing carboxyl ligands. These results help quantify the role of surface complexation in defining actinide-microbiological interactions in the subsurface.

Gamma-glutamyl transpeptidase null mice fail to develop tolerance to coumarin-induced Clara cell toxicity.

Coumarin was used as a model Clara cell toxicant to test the hypothesis that tolerance to injury requires increased gamma-glutamyl transpeptidase (GGT) activity. Wildtype (GGT(+/+)) and GGT-deficient (GGT(-/-)) mice on a C57BL/6/129SvEv hybrid background were dosed orally with corn oil (vehicle) or coumarin (200 mg/kg). In vehicle-treated mice, Clara cell secretory protein (CC10) expression was distributed throughout the bronchiolar epithelium. After one dose of coumarin, CC10 expression was dramatically reduced and the bronchiolar epithelium was devoid of Clara cells in GGT(+/+) and GGT(-/-) mice. In wildtype mice, 9 doses of coumarin produced tolerance, characterized as a renewed bronchiolar epithelium with Clara cells expressing CC10 along with a 40% increase in total glutathione (GSH) and a 7-fold increase in GGT activity in the lung. In contrast, tolerance was not observed in GGT(-/-) mice. To assess whether changes in whole lung levels of GSH and GGT activity reflect Clara cell specific changes an enriched population of cells was isolated from female wildtype B6C3F1 mice made tolerant to coumarin. Compared to Clara cells from control mice, GSH and GGT activity increased 3- and 13-fold, respectively. Collectively, these data suggest Clara cell tolerance to coumarin toxicity requires increased GGT activity favoring enhanced GSH synthesis.