Simplifying and improving the extraction of nitrate from freshwater for stable isotope analyses

Determining the isotopic composition of nitrate (NO3_) in water can prove useful to identify NO3_ sources and to understand its dynamics in aquatic systems. Among the procedures available, the ‘ionexchange resin method’ involves extracting NO3_ from freshwater and converting it into solid silver nitrate (AgNO3), which is then analysed for 15N/14N and 18O/16O ratios. This study describes a simplified methodology where water was not pre-treated to remove dissolved organic carbon (DOC) or barium cations (added to precipitate O-bearing contaminants), which suited samples with high NO3_ ($400 mM or 25 mg L_1 NO3_) and low DOC (typically <417 mM of C or 5 mg L_1 C) levels. % N analysis revealed that a few AgNO3 samples were of low purity (compared with expected % N of 8.2), highlighting the necessity to introduce quality control/quality assurance procedures for silver nitrate prepared from field water samples. Recommendations are then made to monitor % N together with % O (expected at 28.6, i.e. 3.5 fold % N) in AgNO3 in order to better assess the type and gravity of the contamination as well as to identify potentially unreliable data

Pancreaticoduodenectomy for the treatment of pancreatic neoplasms in children: A Pediatric Surgical Oncology Research Collaborative study

BackgroundTo better characterize short- term and long- term outcomes in children with pancreatic tumors treated with pancreaticoduodenectomy (PD).MethodsPatients 21 years of age or younger who underwent PD at Pediatric Surgical Oncology Collaborative (PSORC) hospitals between 1990 and 2017 were identified. Demographic, clinical information, and outcomes (operative complications, long- term pancreatic function, recurrence, and survival) were collected.ResultsSixty- five patients from 18 institutions with a median age of 13 years (4 months- 22 years) and a median (IQR) follow- up of 2.8 (4.3) years were analyzed. Solid pseudopapillary tumor of the pancreas (SPN) was the most common histology. Postoperative complications included pancreatic leak in 14% (n = 9), delayed gastric emptying in 9% (n = 6), marginal ulcer in one patient, and perioperative (30- day) death due to hepatic failure in one patient. Pancreatic insufficiency was observed in 32% (n = 21) of patients, with 23%, 3%, and 6% with exocrine, or endocrine insufficiencies, or both, respectively. Children with SPN and benign neoplasms all survived. Overall, there were 14 (22%) recurrences and 11 deaths (17%). Univariate analysis revealed non- SPN malignant tumor diagnosis, preoperative vascular involvement, intraoperative transfusion requirement, pathologic vascular invasion, positive margins, and need for neoadjuvant chemotherapy as risk factors for recurrence and poor survival. Multivariate analysis only revealed pathologic vascular invasion as a risk factor for recurrence and poor survival.ConclusionThis is the largest series of pediatric PD patients. PD is curative for SPN and benign neoplasms. Pancreatic insufficiency is the most common postoperative complication. Outcome is primarily associated with histology.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156233/2/pbc28425.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156233/1/pbc28425_am.pd

Pancreaticoduodenectomy for the treatment of pancreatic neoplasms in children: A Pediatric Surgical Oncology Research Collaborative study

Background: To better characterize short-term and long-term outcomes in children with pancreatic tumors treated with pancreaticoduodenectomy (PD). Methods: Patients 21 years of age or younger who underwent PD at Pediatric Surgical Oncology Collaborative (PSORC) hospitals between 1990 and 2017 were identified. Demographic, clinical information, and outcomes (operative complications, long-term pancreatic function, recurrence, and survival) were collected. Results: Sixty-five patients from 18 institutions with a median age of 13 years (4 months-22 years) and a median (IQR) follow-up of 2.8 (4.3) years were analyzed. Solid pseudopapillary tumor of the pancreas (SPN) was the most common histology. Postoperative complications included pancreatic leak in 14% (n = 9), delayed gastric emptying in 9% (n = 6), marginal ulcer in one patient, and perioperative (30-day) death due to hepatic failure in one patient. Pancreatic insufficiency was observed in 32% (n = 21) of patients, with 23%, 3%, and 6% with exocrine, or endocrine insufficiencies, or both, respectively. Children with SPN and benign neoplasms all survived. Overall, there were 14 (22%) recurrences and 11 deaths (17%). Univariate analysis revealed non-SPN malignant tumor diagnosis, preoperative vascular involvement, intraoperative transfusion requirement, pathologic vascular invasion, positive margins, and need for neoadjuvant chemotherapy as risk factors for recurrence and poor survival. Multivariate analysis only revealed pathologic vascular invasion as a risk factor for recurrence and poor survival. Conclusion: This is the largest series of pediatric PD patients. PD is curative for SPN and benign neoplasms. Pancreatic insufficiency is the most common postoperative complication. Outcome is primarily associated with histology

Evaluating the utility of 15N and 18O isotope abundance analyses to identify nitrate sources: A soil zone study

15N and 18O isotope abundance analyses in nitrate (NO3?) (expressed as ?15N-NO3? and ?18O-NO3? values respectively) have often been used in research to help identify NO3? sources in rural groundwater. However, questions have been raised over the limitations as overlaps in ? values may occur between N source types early in the leaching process. The aim of this study was to evaluate the utility of using stable isotopes for nitrate source tracking through the determination of ?15N-NO3? and ?18O-NO3? in the unsaturated zone from varying N source types (artificial fertiliser, dairy wastewater and cow slurry) and rates with contrasting isotopic compositions. Despite NO3? concentrations being often elevated, soil-water nitrate poorly mirrored the 15N content of applied N and therefore, ?15N-NO3? values were of limited assistance in clearly associating nitrate leaching with N inputs. Results suggest that the mineralisation and the nitrification of soil organic N, stimulated by previous and current intensive management, masked the cause of leaching from the isotopic prospective. ?18O-NO3? was of little use, as most values were close to or within the range expected for nitrification regardless of the treatment, which was attributed to the remineralisation of nitrate assimilated by bacteria (mineralisation-immobilisation turnover or MIT) or plants. Only in limited circumstances (low fertiliser application rate in tillage) could direct leaching of synthetic nitrate fertiliser be identified (?15N-NO3? 15 ?). Nevertheless, some useful differences emerged between treatments. ?15N-NO3? values were lower where artificial fertiliser was applied compared with the unfertilised controls and organic waste treatments. Importantly, ?15N-NO3? and ?18O-NO3? variables were negatively correlated in the artificial fertiliser treatment (0.001 ? p ? 0.05, attributed to the varying proportion of fertiliser-derived and synthetic nitrate being leached) while positively correlated in the dairy wastewater plots (p ? 0.01, attributed to limited denitrification). These results suggest that it may be possible to distinguish some nitrate sources if analysing correlations between ? variables from the unsaturated zone. In grassland, the above correlations were related to N input rates, which partly controlled nitrate concentrations in the artificial fertiliser plots (high inputs translated into higher NO3? concentrations with an increasing proportion of fertiliser-derived and synthetic nitrate) and denitrification in the dairy wastewater plots (high inputs corresponded to more denitrification). As a consequence, nitrate source identification in grassland was more efficient at higher input rates due to differences in ? values widening between treatments

Simplifying and improving the extraction of nitrate from freshwater for stable isotope analyses

Determining the isotopic composition of nitrate (NO3 ) in water can prove useful to identify NO3 sources and to understand its dynamics in aquatic systems. Among the procedures available, the `ion-exchange resin method? involves extracting NO3 from freshwater and converting it into solid silver nitrate (AgNO3), which is then analysed for 15N/14N and 18O/16O ratios. This study describes a simplified methodology where water was not pre-treated to remove dissolved organic carbon (DOC) or barium cations (added to precipitate O-bearing contaminants), which suited samples with high NO3 (<400 uM or 25 mgL-1 NO3) and low DOC (typically <417 uM of C or 5 mgL-1 C) levels. % N analysis revealed that a few AgNO3 samples were of low purity (compared with expected % N of 8.2), highlighting the necessity to introduce quality control / quality assurance procedures for silver nitrate prepared from field water samples. Recommendations are then made to monitor % N together with % O (expected at 28.6, i.e. 3.5 fold % N) in AgNO3 in order to better assess the type and gravity of the contamination as well as to identify potentially unreliable data

Can a pediatric trauma center improve the response to a mass casualty incident?

Recent events including the 2001 terrorist attacks on New York; Hurricane Katrina; the 2010 Haitian and Chilean earthquakes; and the 2011 earthquake, tsunami, and nuclear disaster in Japan have reminded disaster planners and responders of the tremendous scale of mass casualty disasters and their resulting human devastation. Although adult disaster medicine is a well-developed field with roots in wartime medicine, we are increasingly recognizing that children may comprise up to 50% of disaster victims, and response mechanisms are often designed without adequate preparation for the number of pediatric victims that can result. In this short educational review, we explore the differences between the pediatric and adult disaster and trauma populations, the requirements for designation of a site as a pediatric trauma center (PTC), and the magnitude of the problem of pediatric disaster patients as described in the literature, specifically as it pertains to the availability and use of designated PTCs as opposed to trauma centers in general. We also review our own experience in planning and simulating pediatric mass casualty events and suggest strategies for preparedness when there is no PTC available. We aim to demonstrate from this brief survey that the availability of a designated PTC in the setting of a mass casualty disaster event is likely to significantly improve the outcome for the pediatric demographic of the affected population. We conclude that the relative scarcity of disaster data specific to children limits epidemiologic study of the pediatric disaster population and offer suggestions for strategies for future study of our hypothesis. Systematic review, level III

Availability of a pediatric trauma center in a disaster surge decreases triage time of the pediatric surge population: a population kinetics model

BACKGROUND: The concept of disaster surge has arisen in recent years to describe the phenomenon of severely increased demands on healthcare systems resulting from catastrophic mass casualty events (MCEs) such as natural disasters and terrorist attacks. The major challenge in dealing with a disaster surge is the efficient triage and utilization of the healthcare resources appropriate to the magnitude and character of the affected population in terms of its demographics and the types of injuries that have been sustained. RESULTS: In this paper a deterministic population kinetics model is used to predict the effect of the availability of a pediatric trauma center (PTC) upon the response to an arbitrary disaster surge as a function of the rates of pediatric patients' admission to adult and pediatric centers and the corresponding discharge rates of these centers. We find that adding a hypothetical pediatric trauma center to the response documented in an historical example (the Israeli Defense Forces field hospital that responded to the Haiti earthquake of 2010) would have allowed for a significant increase in the overall rate of admission of the pediatric surge cohort. This would have reduced the time to treatment in this example by approximately half. The time needed to completely treat all children affected by the disaster would have decreased by slightly more than a third, with the caveat that the PTC would have to have been approximately as fast as the adult center in discharging its patients. Lastly, if disaster death rates from other events reported in the literature are included in the model, availability of a PTC would result in a relative mortality risk reduction of 37%. CONCLUSIONS: Our model provides a mathematical justification for aggressive inclusion of PTCs in planning for disasters by public health agencies

Delayed family reunification of pediatric disaster survivors increases mortality and inpatient hospital costs: a simulation study

Disasters occur randomly and can severely tax the health care delivery system of affected and surrounding regions. A significant proportion of disaster survivors are children, who have unique medical, psychosocial, and logistical needs after a mass casualty event. Children are often transported to specialty centers after disasters for a higher level of pediatric care, but this can also lead to separation of these survivors from their families. In a recent theoretical article, we showed that the availability of a pediatric trauma center after a mass casualty event would decrease the time needed to definitively treat the pediatric survivor cohort and decrease pediatric mortality. However, we also found that if the pediatric center was too slow in admitting and discharging patients, these benefits were at risk of being lost as children became "trapped" in the slow center. We hypothesized that this effect could result in further increased mortality and greater costs. Here, we expand on these ideas to test this hypothesis via mathematical simulation. We examine how a delay in discharge of part of the pediatric cohort is predicted to affect mortality and the cost of inpatient care in the setting of our model. We find that mortality would increase slightly (from 14.2%-16.1%), and the cost of inpatient care increases dramatically (by a factor of 21) if children are discharged at rates consistent with reported delays to reunification after a disaster from the literature. Our results argue for the ongoing improvement of identification technology and logistics for rapid reunification of pediatric survivors with their families after mass casualty events