Target and suspect per- and polyfluoroalkyl substances in fish from an AFFF-impacted waterway

A major source of toxic per- and polyfluoroalkyl substances (PFAS) is aqueous film-forming foams (AFFF) used in firefighting and training at airports and military installations, however, PFAS have many additional sources in consumer products and industrial processes. A field study was conducted on fish tissues from three reaches of the Columbia Slough, located near Portland International Airport, OR, that are affected by AFFF and other PFAS sources. Fishes including largescale sucker (Catostomus macrocheilus), goldfish (Carassius auratus), and largemouth bass (Micropterus salmoides) were collected in 2019 and 2020. Fish blood, liver, and fillet (muscle) were analyzed for target and suspect PFAS by liquid chromatography high resolution mass spectrometry (LC-HRMS). Data were analyzed for patterns by fish species, tissue type, and river reach. Thirty-three out of 50 target PFAS and additional suspect compounds were detected at least once during the study, at concentrations up to 856 ng/g. Seven carboxylic acids (PFOA, PFNA, PFDA, PFUdA, PFDoA, PFTrDA, PFTeDA), three sulfonates (PFHxS, PFOS, PFDS), three electrofluorination-based compounds (FBSA, FHxSA, FOSA), and two fluorotelomer-based compounds (8:2 FTS, 10:2 FTS) were the most frequently detected compounds in all tissue types. The C6 (PFHxS) to C10 (PFDS) homologs were detected with PFOS and FHxSA at concentrations 1-3 orders of magnitude greater than the other PFAS detected. This is the first report of Cl-PFOS, FPeSA, and FHpSA detected in fish tissue. In all fish samples, fillet concentrations of PFAS were the lowest, followed by liver, and blood concentrations of PFAS were the highest. Differences in PFAS concentrations were driven primarily by tissue types and to a lesser extent fish species, but weakly by river reach. The Oregon Health Authority modified an existing fish consumption advisory on the Columbia Slough to recommend no whole-body consumption of most fish to avoid elevated levels of PFOS in fish liver. Measured PFAS concentrations in fish tissues indicate the potential for adverse ecological effects.

Nontarget Chemical Composition of Surface Waters May Reflect Ecosystem Processes More than Discrete Source Contributions

We investigated environmental, landscape, and microbial factors that could structure the spatiotemporal variability in the nontarget chemical composition of four riverine systems in the Oregon Coast Range, USA. We hypothesized that the nontarget chemical composition in river water would be structured by broad-scale landscape gradients in each watershed. Instead, only a weak relationship existed between the nontarget chemical composition and land cover gradients. Overall, the effects of microbial communities and environmental variables on chemical composition were nearly twice as large as those of the landscape, and much of the influence of environmental variables on the chemical composition was mediated through the microbial community (i.e., environment affects microbes, which affect chemicals). Therefore, we found little evidence to support our hypothesis that chemical spatiotemporal variability was related to broad-scale landscape gradients. Instead, we found qualitative and quantitative evidence to suggest that chemical spatiotemporal variability of these rivers is controlled by changes in microbial and seasonal hydrologic processes. While the contributions of discrete chemical sources are undeniable, water chemistry is undoubtedly impacted by broad-scale continuous sources. Our results suggest that diagnostic chemical signatures can be developed to monitor ecosystem processes, which are otherwise challenging or impossible to study with existing off-the-shelf sensors.

Target and Suspect Screening Integrated with Machine Learning to Discover Per- and Polyfluoroalkyl Substance Source Fingerprints

This study elucidates per- and polyfluoroalkyl substance (PFAS) fingerprints for specific PFAS source types. Ninety-two samples were collected from aqueous film-forming foam impacted groundwater (AFFF-GW), landfill leachate, biosolids leachate, municipal wastewater treatment plant effluent (WWTP), and wastewater effluent from the pulp and paper and power generation industries. High-resolution mass spectrometry operated with electrospray ionization in negative mode was used to quantify up to 50 target PFASs and screen and semi-quantify up to 2,266 suspect PFASs in each sample. Machine learning classifiers were used to identify PFASs that were diagnostic of each source type. Four C5-C7 perfluoroalkyl acids and one suspect PFAS (trihydrogen-substituted fluoroethernonanoic acid) were diagnostic of AFFF-GW. Two target PFASs (5:3 and 6:2 fluorotelomer carboxylic acids) and two suspect PFASs (4:2 fluorotelomer-thia-acetic acid and N-methylperfluoropropane sulfonamido acetic acid) were diagnostic of landfill leachate. Biosolids leachates were best classified along with landfill leachates and N-methyl and N-ethyl perfluorooctane sulfonamido acetic acid assisted in that classification. WWTP, pulp and paper, and power generation samples contained few target PFASs, but fipronil (a fluorinated insecticide) was diagnostic of WWTP samples. Our results provide PFAS fingerprints for known sources and identify target and suspect PFASs that can be used for source allocation.

Machine Learning Applications for Chemical Fingerprinting and Environmental Source Tracking Using Non-target Chemical Data

A frequent goal of chemical forensic analyses is to select a panel of diagnostic chemical features─colloquially termed a chemical fingerprint─that can predict the presence of a source in a novel sample. However, most of the developed chemical fingerprinting workflows are qualitative in nature. Herein, we report on a quantitative machine learning workflow. Grab samples (n = 51) were collected from five chemical sources, including agricultural runoff, headwaters, livestock manure, (sub)urban runoff, and municipal wastewater. Support vector classification was used to select the top 10, 25, 50, and 100 chemical features that best discriminate each source from all others. The cross-validation balanced accuracy was 92-100% for all sources (n = 1,000 iterations). When screening for diagnostic features from each source in samples collected from four local creeks, presence probabilities were low for all sources, except for wastewater at two downstream locations in a single creek. Upon closer investigation, a wastewater treatment facility was located ∼3 km upstream of the nearest sample location. In addition, using simulated in silico mixtures, the workflow can distinguish presence and absence of some sources at 10,000-fold dilutions. These results strongly suggest that this workflow can select diagnostic subsets of chemical features that can be used to quantitatively predict the presence/absence of various sources at trace levels in the environment.

500 30-DAY SURVIVAL AND RECOVERY AFTER HIP FRACTURE BY MOBILISATION TIMING AND DEMENTIA: A UK DATABASE STUDY

Introduction

To compare 30-day survival and recovery of prefracture ambulation between patients mobilised early (on the day of or day after surgery) and patients mobilised late (2 days of more after surgery) in England and Wales. To determine whether the presence of dementia influences the association between mobilisation timing and 30-day survival and recovery.

Methods

Secondary analysis of the UK National Hip Fracture Database linked to hospitalisation records for 126,897 patients 60 years or older who underwent surgery for nonpathological first hip fracture in England or Wales between 2014 and 2016. We used logistic regression to regress survival and ambulation recovery at 30-days with respect to mobilisation timing, overall and by dementia, with adjustment for confounding using a propensity score for mobilisation treatment with respect to confounders.

Results

Overall, 99,667 (79%) patients mobilised early. Among those who mobilised early compared to those who mobilised late, the weighted odds ratio of survival was 1.92 (95% CI 1.80–2.05), of recovering outdoor ambulation was 1.25 (95% CI 1.03–1.51), and of recovering indoor ambulation was 1.53 (95% CI 1.32–1.78) by 30 days. Early compared with late mobilisation led to a 3.8% increase in the weighted probability of survival, 22.8% increase in weighted probability of recovering outdoor ambulation and 10.0% increase in the weighted probability of recovering indoor ambulation, by 30-days. Patients with dementia were less likely to mobilise early but increases in survival and ambulation recovery were observed both for those with and without dementia.

Conclusion

Early mobilisation led to increase probability of survival and recovery for patients (with and without dementia) after hip fracture. Early mobilisation should be incorporated as a measured indicator of quality internationally. Reasons for failure to mobilise early should also be captured to inform quality improvement initiatives.

501 DISCHARGE AFTER HIP FRACTURE SURGERY IN RELATION TO MOBILISATION TIMING BY PATIENT CHARACTERISTICS: A NATIONAL DATABASE STUDY

Introduction

Early mobilisation leads to a two-fold increase in the odds of discharge by 30-days compared to late mobilisation. Whether this association varies by identified reasons for delayed mobilisation is unknown.

Methods

Audit data linked to hospitalisation records for patients 60 years or older surgically treated for hip fracture in England/Wales 2014–2016. Adjusted proportional odds regression models tested whether the cumulative incidences of discharge differed for early compared with late mobilisation across subgroups defined by dementia, delirium, hypotension, prefracture ambulation and residence, accounting for competing risk of death.

Results

Overall, 34,253 patients presented with dementia, 9,818 with delirium, and 10,123 with hypotension. Prefracture, 100,983 were ambulant outdoors, 30,834 were ambulant indoors only, 107,144 were admitted from home, and 23,588 from residential care. 10%, 8%, 8%, 12%, and 12% fewer patients with dementia, delirium, hypotension, ambulant indoors only prefracture, or from residential care mobilised early compared to those without dementia, delirium, hypotension, with outdoor ambulation prefracture, or from home. Adjusted odds ratios of discharge by 30-days for early compared with late mobilisation were 1.71 (95% CI 1.62–1.81) for those with dementia, 2.06 (95% CI 1.98–2.15) without dementia, 1.56 (95% CI 1.41–1.73) with delirium, 2.00 (95% CI 1.93–2.07) without delirium, 1.83 (95% CI, 1.66–2.02) with hypotension, 1.95 (95% CI, 1.89–2.02) without hypotension, 2.00 (95% CI 1.92–2.08) with outdoor ambulation prefracture, 1.80 (95% CI 1.70–1.91) with indoor ambulation only prefracture, 2.30 (95% CI 2.19–2.41) from home, and 1.64 (95% CI 1.51–1.77) from residential care.

Conclusion

Irrespective of dementia, delirium, hypotension, prefracture ambulation or residence, early compared to late mobilisation increased the likelihood of discharge by 30-days. Fewer patients with these conditions, poorer prefracture ambulation, or from residential care mobilised early. There is a need reduce this care gap by ensuring sufficient resource to enable all patients to benefit from early mobilisation.

Environmental Source Tracking of Per- and Polyfluoroalkyl Substances within a Forensic Context: Current and Future Techniques

The source tracking of per- and polyfluoroalkyl substances (PFASs) is a new and increasingly necessary subfield within environmental forensics. We define PFAS source tracking as the accurate characterization and differentiation of multiple sources contributing to PFAS contamination in the environment. PFAS source tracking should employ analytical measurements, multivariate analyses, and an understanding of PFAS fate and transport within the framework of a conceptual site model. Converging lines of evidence used to differentiate PFAS sources include: identification of PFASs strongly associated with unique sources; the ratios of PFAS homologues, classes, and isomers at a contaminated site; and a site's hydrogeochemical conditions. As the field of PFAS source tracking progresses, the development of new PFAS analytical standards and the wider availability of high-resolution mass spectral data will enhance currently available analytical capabilities. In addition, multivariate computational tools, including unsupervised (i.e., exploratory) and supervised (i.e., predictive) machine learning techniques, may lead to novel insights that define a targeted list of PFASs that will be useful for environmental PFAS source tracking. In this Perspective, we identify the current tools available and principal developments necessary to enable greater confidence in environmental source tracking to identify and apportion PFAS sources.

34 Discharge After Hip Fracture Surgery by Mobilisation Timing: Secondary Analysis of the UK National Hip Fracture Database

Background

To maximise the benefits of hip fracture surgery the National Institute for Health and Care Excellence Clinical Guideline recommends mobilisation on the day after hip fracture surgery based a low to moderate quality trial with a small sample size. There is a need to generate additional evidence to support early mobilisation as a new UK Best Practice Tariff (BPT).

Objective

To determine whether mobilisation timing was associated with the cumulative incidence of hospital discharge by 30-days after hip fracture surgery, accounting for potential confounders and the competing risk of in-hospital death.

Method

We examined data for 135,105 patients 60 years or older who underwent surgery for nonpathological first hip fracture between January 2014 and December 2016 in any hospital in England or Wales. We tested whether the cumulative incidences of discharge differed between those mobilised early (within 36 hours of surgery) and those mobilised late accounting for potential confounders and the competing risk of in-hospital death.

Results

106,722 (79%) of patients first mobilised early. The average rate of discharge was 60.1 (95% CI 59.8–60.5) per 1,000 patient days, varying from 65.2 (95% CI 64.8–65.6) among those who mobilised early to 44.5 (95% CI 43.9–45.1) among those who mobilised late, accounting for the competing risk of death. By 30-days postoperatively, the crude and adjusted odds ratios of discharge were 2.26 (95% CI 2.2–2.32) and 1.93 (95% CI 1.86–1.99) respectively among those who first mobilised early compared to those who mobilised late, accounting for the competing risk of death.

Conclusion

Early mobilisation led to a near two fold increase in the adjusted odds of discharge by 30-days postoperatively. We recommend inclusion of mobilisation within 36 hours of surgery as a new UK BPT to help reduce delays to mobilisation currently experienced by one-fifth of patients surgically treated for hip fracture.

132 Physical Function Comparison of Acutely Unwell COVID-Negative Older Adults Pre-Pandemic and Through-Pandemic; “Covid-Protected”

Introduction

The risk of severe morbidity after COVID-19 infection is high in older adults (Lithander et al, 2020). Subsequent responsive UK Government guidance for older adults included self-isolation during the pandemic. It is therefore hypothesised that during the pandemic older adults are inadvertently deconditioned due to iatrogenic factors such as inactivity, social isolation, hospital-avoidance and malnutrition, and present with reduced resilience to illness and lower levels of function. The OPU continued to admit COVID-negative, or recently termed “COVID-protected”, patients throughout the pandemic. Data captured prior to, and during the COVID-19 pandemic has been compared to explore the implications on older adults, and elicit whether they are protected from the consequences of the pandemic?

Method

Demographic and physical function data (average 6 m gait-speed, Elderly Mobility Scale) were captured pre- and through-pandemic for all patients admitted to a COVID-negative OPU ward over a one month period. Ethical review was provided through local Trust governance process.

Results

Pre-pandemic 2019 (n = 67, mean(±SD) age 82.7(±8.2) years, 61%, hospital length-of-stay (LOS) 7.9(±7.3) days, hospital mortality-rate 7.2%) and through-pandemic 2020 (n = 73, 83.1(±8.3) years, 59%♀, LOS 9.0(±9.1) days, hospital mortality-rate 7.5%) data were captured during July 2019 and May 2020 respectively. There were no between-group differences in age [t(−.313) = 138, p = 0.755], gender [X², 1 df, p = 0.782], LOS [t(0.78) = 134, p = 0.44], or hospital mortality-rate [X² 1 df, p = 0.96]. Through-pandemic patients had a significantly slower 6 m gait-speed (0.11(±0.05) m.s-1) than pre-pandemic (0.16(±0.24) m.s-1); [t(2.74) = 93, p = 0.007] and lower median (IQR) Elderly Mobility Scale (4(6 IQR) vs 9 (12 IQR) [u = 866, p = 0.015]).

Conclusion

Our data indicates this relatively short period of self-isolation might have significant implications on the physical function of older adults. The likely mechanism is iatrogenic deconditioning. Critical Public Health and policy responses are required to mitigate these unforeseen risks by deploying prehabilitative counter-measures and accurately targeted hospital and community rehabilitation.

Missed opportunities for physical activity management at key points throughout the chemotherapy pathway for colorectal survivors: an observational interview study

PURPOSE

Physical activity (PA) is central to self-management for people with colorectal cancer (CRC) to support health behaviour and function secondary to cancer treatment. However, there is limited evidence on how health professionals (HPs) promote PA during cancer treatment. This study aimed to investigate how and when PA is promoted throughout the chemotherapy pathway among colorectal cancer survivors.

METHODS

A qualitative study was conducted with adults with CRC receiving chemotherapy at a large cancer centre. Cross-sectional observation of clinical consultations was conducted at four points during the chemotherapy pathway: prior, midpoint, final cycle, and 8 weeks following chemotherapy. Following completion of treatment, audio-recorded, semi-structured interviews were conducted with patients and HPs and transcribed verbatim. Codes and themes were identified and triangulated from all the data using framework analysis. Observational themes are reported and complimented by interview data.

RESULTS

Throughout the chemotherapy pathway (pre, midpoint, end), many opportunities were missed by HPs to promote PA as a beneficial means to maintain functioning and ameliorate cancer treatment side effects. When discussed, PA levels were used only to determine fitness for future oncological treatment. No PA promotion was observed despite patients reporting low PA levels or treatment side effects. Post-treatment, PA promotion was more routinely delivered by HPs, as evidenced by problem-solving and onward referrals to relevant HPs.

CONCLUSION

PA promotion was largely absent during treatment despite it being a key component of patient self-management following treatment. This suggests considerable missed opportunities for HPs to provide cancer survivors with PA evidence-based interventions. Further research is necessary to identify how best to ensure PA is promoted throughout the cancer journey.

IMPLICATION FOR CANCER SURVIVORS

These findings suggest many may not be receiving support to be physically active during treatment.

Arsenic in Bangladeshi soils related to physiographic region, paddy management, and mirco- and macro-elemental status

While the impact of arsenic in irrigated agriculture has become a major environmental concern in Bangladesh, to date there is still a limited understanding of arsenic in Bangladeshi paddy soils at a landscape level. A soil survey was conducted across ten different physiographic regions of Bangladesh, which encompassed six types of geomorphology (Bil, Brahmaputra floodplain, Ganges floodplain, Meghna floodplain, Karatoya-Bangali floodplain and Pleistocene terrace). A total of 1209 paddy soils and 235 matched non-paddy soils were collected. The source of irrigation water (groundwater and surface water) was also recorded. The concentrations of arsenic and sixteen other elements were determined in the soil samples. The concentration of arsenic was higher in paddy soils compared to non-paddy soils, with soils irrigated with groundwater being higher in arsenic than those irrigated with surface water. There was a clear difference between the Holocene floodplains and the Pleistocene terraces, with Holocene floodplain soils being higher in arsenic and other elements. The results suggest that arsenic is most likely associated with less well weathered/leached soils, suggesting it is either due to the geological newness of Holocene sediments or differences between the sources of sediments, which gives rise to the arsenic problems in Bangladeshi soils.

Marine Primary Productivity as a Potential Indirect Source of Selenium and Other Trace Elements in Atmospheric Deposition

Atmospheric processes play an important role in the supply of the trace element selenium (Se) as well as other essential trace elements to terrestrial environments, mainly via wet deposition. Here we investigate whether the marine biosphere can be identified as a source of Se and of other trace elements in precipitation samples. We used artificial neural network (ANN) modeling and other statistical methods to analyze relationships between a high-resolution atmospheric deposition chemistry time series (March 2007-January 2009) from Plynlimon (UK) and exposure of air masses to marine chlorophyll a and to other source proxies. Using ANN sensitivity analyses, we found that higher air mass exposure to marine productivity leads to higher concentrations of dissolved organic carbon (DOC) in rainfall. Furthermore, marine productivity was found to be an important but indirect factor in controlling Se as well as vanadium (V), cobalt (Co), nickel (Ni), zinc (Zn), and aluminum (Al) concentrations in atmospheric deposition, likely via scavenging by organic compounds derived from marine organisms. Marine organisms may thus play an indirect but important role in the delivery of trace elements to terrestrial environments and food chains.

Selenium cycling across soil-plant-atmosphere interfaces: a critical review

Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels.

Trenbolone acetate metabolite transport in rangelands and irrigated pasture: observations and conceptual approaches for agro-ecosystems

To assess the relative ecological risks of trenbolone acetate (TBA) use in agro-ecosystems, we evaluated the spatiotemporal dynamics of TBA metabolite transport during irrigation and rainfall events. Within a pasture, TBA-implanted heifers (40 mg TBA, 8 mg estradiol) were briefly penned (24 h) at high stocking densities (500 animal units (AU)/ha), prior to irrigation. Irrigation runoff concentrations of 17α-trenbolone (17α-TBOH) 0.3 m downslope were 11 ng/L in the wetting front, but quickly decreased to ∼0.5 ng/L, suggesting mass transfer limitations to transport. At 3 and 30 m downslope, efficient attenuation of 17α-TBOH concentrations is best explained by infiltration and surface partitioning. At plot scales, transport through vegetated filter strips resulted in <0.5-7 ng/L 17α-TBOH concentrations in rainfall-induced runoff with partial subsequent attenuation. Thus, even under intense grazing scenarios, TBA-metabolite transport potential is expected to be low in rangelands, with ecological risks primarily arising from uncontrolled animal access to receiving waters. However, 17α-TBOH concentrations in initial runoff were predicted to exceed threshold levels (i.e., no observed adverse effect levels [NOAELs]) for manure concentrations exceeding 2.0 ng/g-dw, which occurs throughout most of the implant life. For comparison, estrone and 17β-estradiol were modeled and are likely capable of exceeding NOAELs by a factor of ∼2-5 in irrigation runoff, suggesting that both endogenous and exogenous steroids contribute to endocrine disruption potential in agro-ecosystems.

Surface and subsurface attenuation of trenbolone acetate metabolites and manure-derived constituents in irrigation runoff on agro-ecosystems

Although studies have evaluated the ecotoxicity and fate of trenbolone acetate (TBA) metabolites, namely 17α-trenbolone (17α-TBOH), 17β-trenbolone (17β-TBOH), and trendione (TBO), their environmental transport processes remain poorly characterized with little information available to guide agricultural runoff management. Therefore, we evaluated TBA metabolite transport in representative agricultural systems with concurrent assessment of other manure-derived constituents. Leachate generated using manure from TBA-implanted cattle was applied to a subsurface infiltration plot (4 m) and surface vegetative filter strips (VFSs; 3, 4, and 5 m). In the subsurface experiment, 17α-TBOH leachate concentrations were 36 ng L(-1) but decreased to 12 ng L(-1) in initial subsurface discharge. Over 75 minutes, concentrations linearly increased to 23 ng L(-1) (C/Co = 0.32-0.64). In surface experiments (n = 4), 17α-TBOH leachate concentrations ranged from 11-150 ng L(-1), remained nearly constant with time, but were attenuated by ∼70-90% after VFS treatment with no statistical dependence on the VFS length. While attenuation clearly occurred, the observations of a highly mobile fraction of all constituents in both surface runoff and subsurface discharge suggest that these treatment strategies may not always be capable of achieving threshold discharge concentrations. To attain no observed adverse effect levels (NOAELs) in receiving waters, concurrent assessment of leachate concentrations and available dilution capacities can be used to guide target treatment performance levels for runoff management. Dilution is usually necessary to achieve NOAELs, and receiving waters with less than 70-100 fold dilution capacity are at the highest risk for steroidal endocrine disruption.

Mass balance approaches to characterizing the leaching potential of trenbolone acetate metabolites in agro-ecosystems

Several studies have documented the occurrence and fate of trenbolone acetate (TBA) metabolites in soil and water. However, considerable uncertainty still exists with respect to TBA risk in agro-ecosystems because limited data are available to quantify excretion, transformation, and leaching processes. To address these uncertainties, we used experimental mesocosms and a mass balance approach to estimate the TBA metabolite leaching potential from manure excreted by implanted (40 mg TBA, 8 mg 17β-estradiol) beef cattle. Manure sample analysis indicates that over 113 days, a maximum of 9.3% (3,200 μg/animal unit [AU]) of the implant dose was excreted as 17α-trenbolone (17α-TBOH), and <1% was excreted as 17β-trenbolone (65 μg/AU) or trendione (3 μg/AU). While most (>97%) of the total excreted mass of 17α-TBOH transforms to uncharacterized products, 0.3-0.6% (100-220 μg/AU) of the implant dose accumulates on land surfaces and is available for subsequent transport. During rainfall or irrigation events, a maximum of 0.005-0.06% (1.6-22 μg/AU 17α-TBOH) or 0.005-0.012% (1.8-4 μg/AU 17α-TBOH) of the dose leached into runoff, respectively. Leaching potentials peak at 5-30 days postimplantation, suggesting that targeted timing of implantation and irrigation could minimize steroid leaching during rainfall and irrigation events.

Product-to-parent reversion of trenbolone: unrecognized risks for endocrine disruption

Trenbolone acetate (TBA) is a high-value steroidal growth promoter often administered to beef cattle, whose metabolites are potent endocrine-disrupting compounds. We performed laboratory and field phototransformation experiments to assess the fate of TBA metabolites and their photoproducts. Unexpectedly, we observed that the rapid photohydration of TBA metabolites is reversible under conditions representative of those in surface waters (pH 7, 25°C). This product-to-parent reversion mechanism results in diurnal cycling and substantial regeneration of TBA metabolites at rates that are strongly temperature- and pH-dependent. Photoproducts can also react to produce structural analogs of TBA metabolites. These reactions also occur in structurally similar steroids, including human pharmaceuticals, which suggests that predictive fate models and regulatory risk assessment paradigms must account for transformation products of high-risk environmental contaminants such as endocrine-disrupting steroids.

Identification and environmental implications of photo-transformation products of trenbolone acetate metabolites

Despite the widespread use of the anabolic androgen trenbolone acetate (TBA) in animal agriculture, evidence demonstrating the occurrence of TBA metabolites such as 17β-trenbolone (17β-TBOH), 17α-trenbolone (17α-TBOH), and trendione (TBO) is relatively scarce, potentially due to rapid transformation processes such as direct photolysis. Therefore, we investigated the phototransformation of TBA metabolites and associated ecological implications by characterizing the photoproducts arising from the direct photolysis of 17β-TBOH, 17α-TBOH, and TBO and their associated ecotoxicity. LC-HRMS/MS analysis identified a range of hydroxylated products that were no longer photoactive, with primary photoproducts consisting of monohydroxy species and presumptive diastereomers. Also observed were higher-order hydroxylated products probably formed via subsequent reaction of primary photoproducts. NMR analysis confirmed the formation of 12,17-dihydroxy-estra-5(10),9(11),dien-3-one (12-hydroxy-TBOH; 2.2 mg), 10,12,17-trihydroxy-estra-4,9(11),dien-3-one (10,12-dihydroxy-TBOH; 0.7 mg), and a ring-opened 11,12-dialdehyde oxidation product (TBOH-11,12-dialdehyde; 1.0 mg) after irradiation of ∼14 mg of 17β-trenbolone. Though unconfirmed by NMR, our data suggest that the formation of additional isomeric products may occur, likely due to the reactivity of the unique 4,9,11 conjugated triene structure of trenbolone. In vivo exposure studies employing Japanese medaka (Oryzias latipes) indicate that low concentrations of 17α-TBOH photoproduct mixtures can alter ovarian follicular development, and photoproducts alter whole-body 17β-estradiol levels. Therefore, direct photolysis yields photoproducts with strong structural similarity to parent steroids, and these photoproducts still retain enough biological activity to elicit observable changes to endocrine function at trace concentrations. These data indicate that environmental transformation processes do not necessarily reduce steroid hormone ecotoxicity.

On the fringes of conquest: maya-spanish contact in colonial belize

The defeat of the Aztecs of Mexico by Hernán Cortés in 1521 was but the beginning of a long and torturous conquest of Central America that did not always result in the mastery of people and production for which the Spanish had hoped. The Maya of the resource-poor Yucatán peninsula were spared the heavy colonial hand that held fast to central Mexico and its riches. In addition, the dense forests of the peninsula served as a haven for refugees fleeing oppressive conditions in colonial towns. Despite the paucity of documentary information on Maya communities of the frontier, knowledge of Maya-Spanish relations in the 16th and 17th centuries has advanced in recent years through archeological and ethnohistorical research. Work in one region of the Maya lowlands has brought us closer to an understanding of the early interaction of the rulers and the ruled.

Gamma-ray spectroscopy at the limits: first observation of rotational bands in 255Lr

The rotational band structure of 255Lr has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, 255Lr is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2-[521] and 7/2-[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.

Observation of a rotational band in the odd-Z transfermium nucleus 101251Md

A rotational band has been unambiguously observed in an odd-proton transfermium nucleus for the first time. An in-beam gamma-ray spectroscopic study of 101/251Md has been performed using the gamma-ray array JUROGAM combined with the gas-filled separator RITU and the focal plane device GREAT. The experimental results, compared to Hartree-Fock-Bogolyubov calculations, lead to the interpretation that the rotational band is built on the [521]1/2(-) Nilsson state.

Measurement of the sign of the spectroscopic quadrupole moment for the 2(1)+ state in 70Se: no evidence for oblate shape

Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of 70Se ions was postaccelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording deexcitation gamma rays in the highly segmented MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the first 2+ state is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect. Experimental evidence is presented here for a prolate shape for the first 2+ state in 70Se, reopening the question over whether there are, as reported earlier, deformed oblate shapes near to the ground state in the light selenium isotopes.

Nuclear isomers in superheavy elements as stepping stones towards the island of stability

A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the 'island of stability'; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons--the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.

Structure of the odd-A, shell-stabilized nucleus 253/102No

In-beam gamma-ray spectroscopic measurements have been made on 253/102No. A single rotational band was identified up to a probable spin of 39/2planck, which is assigned to the 7/2(+)[624] Nilsson configuration. The bandhead energy and the moment of inertia provide discriminating tests of contemporary models of the heaviest nuclei. Novel methods were required to interpret the sparse data set associated with cross sections of around 50 nb. These methods included comparisons of experimental and simulated spectra, as well as testing for evidence of a rotational band in the gammagamma matrix.

Conversion electron cascades in 254(102)No

The spectrum of prompt conversion electrons emitted by excited 254No nuclei has been measured, revealing discrete lines arising from transitions within the ground state band. A striking feature is a broad distribution that peaks near 100 keV and comprises high multiplicity electron cascades, probably originating from M1 transitions within rotational bands built on high K states.

Evaluation of phosphodiesterase I-based protocols for the detection of multiply damaged sites in DNA: the detection of abasic, oxidative and alkylative tandem damage in DNA oligonucleotides

It has been proposed that DNA multiply damaged sites (MDS), where more than one moiety in a local region ( approximately 1 helical turn, 10 bp) of the DNA is damaged, are lesions of enhanced biological significance. However, other than indirect measures, there are few analytical techniques that allow direct detection of MDS in DNA. In the present study we demonstrate the potential of protocols incorporating an exonucleolytic snake venom phosphodiesterase (SVPD) digestion stage to permit the direct detection of certain tandem damage, in which two lesions are immediately adjacent to each other on the same DNA strand. A series of prepared oligonucleotides containing either single or pairs of tetrahydrofuran moieties (F), thymine glycol lesions (T(g)) or methylphosphotriester adducts (Me-PTE) were digested with SVPD and the digests examined by either (32)P-end-labelling or electrospray mass spectrometry. The unambiguous observation of SVPD-resistant 'trimer' species in the digests of oligonucleotides containing adjacent F, T(g) and Me-PTE demonstrates that the SVPD digestion strategy is capable of allowing direct detection of certain tandem damage. Furthermore, in studies to determine the specificity of SVPD in dealing with pairs of lesions on the same strand, it was found mandatory to have the two lesions immediately adjacent to each other in order to generate the trimer species; pairs of lesions separated by as few as one or two normal nucleotides behave principally as single lesions towards SVPD.

Corn pollen deposition on milkweeds in and near cornfields

The density of corn pollen on leaves of milkweed plants inside and outside of cornfields was measured in several studies from different localities. The purpose was to obtain a representative picture of naturally occurring pollen densities to provide a perspective for laboratory and field studies of monarch larvae feeding on milkweed leaves with Bt corn pollen. Pollen density was highest (average 170.6 grains per cm(2)) inside the cornfield and was progressively lower from the field edge outward, falling to 14.2 grains per cm(2) at 2 m. Inside the cornfield, and for each distance from the field edge, a frequency distribution is presented showing the proportion of leaf samples with different pollen densities. Inside cornfields, 95% of leaf samples had pollen densities below 600 grains per cm(2) and the highest pollen density observed was 1400 grains per cm(2), which occurred in a study with a rainless anthesis period. All other studies had rainfall events during the anthesis period. A single rain event can remove 54-86% of the pollen on leaves. Leaves on the upper portion of milkweed plants, where young monarch larvae tend to feed, had only 30-50% of the pollen density levels of middle leaves.

Presence of benzo[a]pyrene diol epoxide adducts in target DNA leads to an increase in UV-induced DNA single strand breaks and supF gene mutations

Exposure to DNA damaging agents and mutagens often occurs as combinations of agents, or as complex mixtures of chemicals. We found that plasmid DNA adducted with benzo[a]pyrene diol epoxide (BPDE) was more susceptible to UV-induced single strand breaks than was control DNA. To determine whether the increase in DNA damage also applied to mutagenic lesions, the supF gene forward mutation assay was used to compare mutations induced by BPDE alone, UVB, UVC, BPDE followed by UVB and BPDE followed by UVC. It was found that the mutation frequency for BPDE + UVB (1167 in 10(4) transformants) was higher than BPDE alone (12 in 10(4) transformants) or UVB alone (446 in 10(4) transformants), and the mutation frequency for BPDE + UVC (197 in 10(4) transformants) was higher than BPDE alone or UVC alone (26 in 10(4) transformants). For BPDE + UVB and BPDE + UVC there was a significant increase in plasmids with multiple mutations. Whilst these indicate error prone repair due to the single strand breaks, the different mutation frequencies in plasmids treated to give similar levels of strand breaks suggest other mechanisms for the mutations in plasmids with single mutation events. The spectrum of non-multiple mutations in the two combined treatments included both UV signature mutations (GC-->AT as the most common mutation) and BPDE signature mutations (GC-->TA and GC-->CG as the most common mutations). However, the increase in absolute mutation frequency of BPDE signature mutations between BPDE treatment and BPDE + UV treatment was greater than the increase in absolute mutation frequency of UV signature mutations, even though the level of BPDE adducts was identical in each case. These results suggest two possibilities: (i) the BPDE adducts are photoactivated to a more mutagenic lesion, or (ii) the presence of UV lesions lead to the BPDE adducts becoming more mutagenic.

Characterization of DNA damage at purine residues in oligonucleotides and calf thymus DNA induced by the mutagen 1-nitrosoindole-3-acetonitrile

N-Nitrosoindoles can efficiently transfer the nitroso group to nucleophilic targets in isolated purine nucleotides, causing depurination, deamination, and the formation of a novel guanine analogue, oxanine [Lucas, L. T., Gatehouse, D., and Shuker, D. E. G. (1999) J. Biol. Chem. 274, 18319-18326]. To determine the likely biological relevance of these modification pathways, the reactivity of 1-nitrosoindole-3-acetonitrile (NIAN), a model 3-substituted N-nitrosoindole, with oligonucleotides and calf thymus DNA was examined at physiological pH and temperature. Reaction of NIAN with single-stranded oligonucleotides containing various guanine motifs resulted in the production of single-strand break products at guanine sites due to the formation of alkali-labile lesions. The number of lesions increased with NIAN concentration and incubation time. Modification of calf thymus DNA by NIAN resulted in depurination, which gave the corresponding purine bases, deamination coupled with depurination, which gave xanthine, and the formation of oxanine. The former pathway was clearly the most important, and all reaction products exhibited a dose-response relationship. Cytosine and thymine residues were inactive toward NIAN. Further studies revealed an additional product in NIAN-treated duplex DNA containing a CCGG motif that was characterized as an interstrand cross-link, the yield of which increased with increasing NIAN concentration. These results indicate that the transnitrosating ability of NIAN to modify purine residues is preserved at the macromolecular level, with guanine residues appearing to be a primary site of reaction. All of these modification processes are potentially mutagenic events if they occur in vivo.

Foraging resources of adult Mexican corn rootworm (Coleoptera: Chrysomelidae) in Bell County, Texas

Pollen analyses were used to determine pollen foraging resources of adult Mexican corn rootworms, Diabrotica virgifera zeae Krysan & Smith, captured near Temple, Bell County, TX, in 1996 and 1997. In 1996, adult Mexican corn rootworms were captured in a corn, Zea mays L., field. In 1997, nine locations outside of cornfields were added. Overall, 92% of the beetles (n = 1,323) contained pollen. More than 142,000 pollen grains were counted, representing 45 families, 63 genera, and 27 species. Overall, in 1996, noncorn grass pollen (70%) occurred in the greatest percentage of total pollen followed by corn (17%), then nongrass pollen (13%). In 1997, noncorn grass pollen (76%) had the greatest percentage, then nongrass (18%), and finally corn pollen (6%). Corn pollen was found in 34% of the beetles in 1996 and 26% in 1997. Fifteen Asteraceae taxa were encountered including sunflower, Helianthus annuus L. Thirteen Fabaceae were found including soybean, Glycine max L. Mexican corn rootworm adults foraged mainly on noncorn grass pollen, but also foraged on pollen from a large diversity of plant species, indicating that noncorn pollen may play a role in the food habits of Mexican corn rootworm adults.

Uracil-DNA glycosylase-DNA substrate and product structures: conformational strain promotes catalytic efficiency by coupled stereoelectronic effects

Enzymatic transformations of macromolecular substrates such as DNA repair enzyme/DNA transformations are commonly interpreted primarily by active-site functional-group chemistry that ignores their extensive interfaces. Yet human uracil-DNA glycosylase (UDG), an archetypical enzyme that initiates DNA base-excision repair, efficiently excises the damaged base uracil resulting from cytosine deamination even when active-site functional groups are deleted by mutagenesis. The 1.8-A resolution substrate analogue and 2.0-A resolution cleaved product cocrystal structures of UDG bound to double-stranded DNA suggest enzyme-DNA substrate-binding energy from the macromolecular interface is funneled into catalytic power at the active site. The architecturally stabilized closing of UDG enforces distortions of the uracil and deoxyribose in the flipped-out nucleotide substrate that are relieved by glycosylic bond cleavage in the product complex. This experimentally defined substrate stereochemistry implies the enzyme alters the orientation of three orthogonal electron orbitals to favor electron transpositions for glycosylic bond cleavage. By revealing the coupling of this anomeric effect to a delocalization of the glycosylic bond electrons into the uracil aromatic system, this structurally implicated mechanism resolves apparent paradoxes concerning the transpositions of electrons among orthogonal orbitals and the retention of catalytic efficiency despite mutational removal of active-site functional groups. These UDG/DNA structures and their implied dissociative excision chemistry suggest biology favors a chemistry for base-excision repair initiation that optimizes pathway coordination by product binding to avoid the release of cytotoxic and mutagenic intermediates. Similar excision chemistry may apply to other biological reaction pathways requiring the coordination of complex multistep chemical transformations.

Entry distribution, fission barrier, and formation mechanism of 254102No

The entry distribution in angular momentum and excitation energy for the formation of 254No has been measured after the 208Pb(48Ca,2n) reaction at 215 and 219 MeV. This nucleus is populated up to spin 22Planck's over 2pi and excitation energy greater, similar6 MeV above the yrast line, with the half-maximum points of the energy distributions at approximately 5 MeV for spins between 12Planck's over 2pi and 22Planck's over 2pi. This suggests that the fission barrier is greater, similar5 MeV and that the shell-correction energy persists to high spin.

Detection of DNA alkylphosphotriesters by 32P postlabeling: evidence for the nonrandom manifestation of phosphotriester lesions in vivo

Many genotoxic carcinogens react with the sugar-phosphate backbone in DNA to form phosphotriester (PTE) adducts. These lesions are relatively abundant and persistent for some alkylating carcinogens and may therefore serve as useful biomarkers with which to assess genotoxic exposure and potential mutagenic risk. In the present study, we have developed a 32p postlabeling method that permits analysis of total methyl and/or ethyl PTE in DNA at the femtomole level. The technique is based on the inability of all known nucleolytic enzymes to cleave the internucleotide PTE bond. Consequently, complete digestion of alkylated DNA with these nucleases in the presence of an alkaline phosphatase yields PTE-dinucleoside phosphates. These species are then converted to the corresponding dinucleoside phosphates (dNpdNs) by treatment with alkali to permit subsequent 32p labeling. The resulting labeled dinucleotides (32pd-NpdN) are then analyzed by PAGE. Validation of this method has been carried out using a polydeoxythymidylic acid oligonucleotide containing a site-specific methyl PTE. The method has been applied to the in vitro analysis of calf thymus (CT) DNA treated with dimethylsulfate (DMS) or diethylsulfate (DES) and to the analysis of liver DNA from mice treated in vivo with nitrosodiethylamine. In each case, autoradiograms of the polyacrylamide gels showed the anticipated five bands representing the sixteen labeled dinucleotides, with proportional increases observed as the concentrations of DMS or DES used in the in vitro treatment of CT DNA were increased. The identity and frequency of the nucleosides located 5' to the PTE lesions were obtained by nuclease P1 digestion of the gel-isolated 32pdNpdN species and by analysis of the released labeled mononucleotides, 32pdN, by high-performance liquid chromatography with radioactivity detection. Results obtained from CT DNA treated with DMS or DES showed that the frequency of the four detected nucleotides reflected the normal nucleoside content of CT DNA, indicating the random formation of methyl and ethyl PTE adducts in the in vitro modified DNA. However, studies using liver DNA from three strains of mice treated in vivo with nitrosodiethylamine indicated that the frequency of the thymidine and the 2'-deoxyguanosine 5' to the ethyl PTE was significantly different from the corresponding normal nucleoside content. These results are indicative of (a) the nonrandom formation of ethyl PTE in vivo and/or (b) base sequence-specific ethyl PTE repair.

Guillain-Barré syndrome: delayed diagnosis following anaesthesia

Guillain-Barré syndrome following anaesthesia or surgery is rare. Diagnosis is often delayed, which may lead to an increase in morbidity. There is now good evidence that early diagnosis and treatment reduces this morbidity. The two cases highlight the difficulties with diagnosis in the perioperative period and further discuss the aetiology, diagnostic features and complications of childhood Guillain-Barré syndrome.