The potential for carbon dioxide removal by enhanced rock weathering in the tropics: An evaluation of Costa Rica.

Tropical environments show great potential to sequester CO2 by enhanced rock weathering (ERW) of powdered mafic rocks applied to agricultural fields. This study seeks to assess carbon dioxide reduction (CDR) potential in the humid tropics (1) by experimental weathering of mafic rock powders in conditions simulating humid tropical soils, and (2) from weathering rates determined from a Holocene tropical soil chronosequence where parent material is andesitic sediments. Experimentally determined weathering rates by leaching of basaltic andesites from Costa Rica (Arenal and Barva) for 50 t ha-1 applications indicate potential sequestration of 2.4 to 4.5 t CO2 ha-1 yr-1, whereas the USGS basalt standard BHVO-1 yields a rate of 11.9 t ha-1 yr-1 (influenced by more mafic composition and finer particle size). The chronosequence indicates a rate of 1.7 t CO2 ha-1 yr-1. The weathering experiment consisted of 0.6 mm of powdered rock applied atop 12 mm of Ultisol at 35 °C. To simulate a tropical soil solution, 100-mL aliquots of a dilute solution of oxalic acid in carbonated DI water were rained onto soils over a 14-day period to simulate soil moisture in the humid tropics. Solutions were collected and analyzed by ICPMS for concentrations of leached cations. A potential ERW scenario for Costa Rica was assessed assuming that one-half of lowland agricultural kaolinitic soils (mainly Ultisols, common crop and pasture soils, excluding protected areas) were to receive 50 t ha-1 of annual or biennial applications of powdered mafic rock. With an experimentally determined humid tropical CDR rate for basaltic andesite (3.5 t ha-1 yr-1) and allowances for carbon costs (e.g. emissions from processing and delivery) that reduce CDR to a net 3.2 t ha-1 yr-1, potential annual CDR of this tropical nation is ∼2-4 million tons, amounting to ∼25-50 % of annual CO2 emissions (mainly from transportation in Costa Rica).

Stochastic modelling of pesticide transport to drinking water sources via runoff and resulting human health risk assessment.

A modelling framework was developed to facilitate a probabilistic assessment of health risks posed by pesticide exposure via drinking water due to runoff, with the inclusion of influential site conditions and in-stream processes. A Monte-Carlo based approach was utilised to account for the inherent variability in pesticide and population properties, as well as site and climatic conditions. The framework presented in this study was developed with an ability to integrate different data sources and adapt the model for various scenarios and locations to meet the users' needs. The results from this model can be used by farm advisors and catchment managers to identify lower risk pesticides for use for given soil and site conditions and implement risk mitigation measures to protect water resources. Pesticide concentrations in surface water, and their risk of regulatory threshold exceedances, were simulated for fifteen pesticides in an Irish case study. The predicted concentrations in surface water were then used to quantify the level of health risk posed to Irish adults and children. The analysis indicated that herbicides triclopyr and MCPA occur in the greatest concentrations in surface water, while mecoprop was associated with the highest potential for health risks. The study found that the modelled pesticides posed little risk to human health under current application patterns and climatic conditions in Ireland using international acceptable intake values. A sensitivity study conducted examined the impact seasonal conditions, timing of application, and instream processes, have on the transport of pesticides to drinking water.

Impact of historical legacy pesticides on achieving legislative goals in Europe.

Pesticides are widely used in agriculture to optimise food production. However, the movement of pesticides into water bodies negatively impacts aquatic environments. The European Union (EU) aims to make food systems fair, healthy and environmentally friendly through its current Farm to Fork strategy. As part of this strategy, the EU plans to reduce the overall use and risk of chemical pesticides by 50 % by 2030. The attainment of this target may be compromised by the prevalence of legacy pesticides arising from historical applications to land, which can persist in the environment for several decades. The current EU Farm to Fork policy overlooks the potential challenges of legacy pesticides and requirements for their remediation. In this review, the current knowledge regarding pesticide use in Europe, as well as pathways of pesticide movement to waterways, are investigated. The issues of legacy pesticides, including exceedances, are examined, and existing and emerging methods of pesticide remediation, particularly of legacy pesticides, are discussed. The fact that some legacy pesticides can be detected in water samples, more than twenty-five years after they were prohibited, highlights the need for improved EU strategies and policies aimed at targeting legacy pesticides in order to meet future targets.

Batch adsorption of herbicides from aqueous solution onto diverse reusable materials and granulated activated carbon.

This study reports the kinetics and isotherms of the adsorption of five herbicides, MCPA, mecoprop-P, 2,4-D, fluroxypyr and triclopyr, from aqueous solutions onto a range of raw and pyrolysed waste materials originating from an industrial setting. The raw waste materials investigated demonstrated little capability for any herbicide adsorption. Granulated activated carbon (GAC) was capable of the best removal of the herbicides, with >95% removal observed. A first order kinetic model fitted the data best for GAC adsorption of 2,4-D, while a pseudo-first order model fitted the data best for GAC adsorption of fluroxypyr and triclopyr, indicating that adsorption was via physisorption. A pseudo-second order kinetic model fitted the GAC adsorption of MCPA and mecoprop-P, which is indicative of chemisorption. The adsorption of the herbicides in all cases was best described by the Freundlich model, indicating that adsorption occurred onto heterogeneous surfaces.

A risk ranking of pesticides in Irish drinking water considering chronic health effects.

This paper presents a novel scoring system which facilitates a relative ranking of pesticide risk to human health arising from contaminated drinking water. This method was developed to identify risky pesticides to better inform monitoring programmes and risk assessments. Potential risk was assessed considering pesticide use, chronic human health effects and environmental fate. Site-specific soil conditions, such as soil erodibility, hydrologic group, soil depth, clay, sand, silt, and organic carbon content of soil, were incorporated to demonstrate how pesticide fate can be influenced by the areas in which they are used. The indices of quantity of use, consequence and likelihood of exposure, hazard score and quantity-weighted hazard score were used to describe the level of concern that should be attributed to a pesticide. Metabolite toxicity and persistence were also considered in a separate scoring to highlight the contribution metabolites make to overall pesticide risk. This study presents two sets of results for 63 pesticides in an Irish case study, (1) risk scores calculated for the parent compounds only and (2) a combined pesticide-metabolite risk score. In both cases the results are assessed for two locations with differing soil and hydrological properties. The method developed in this paper can be adapted by pesticide users to assess and compare pesticide risk at site level using pesticide hazard scores. Farm advisors, water quality monitors, and catchment managers can apply this method to screen pesticides for human health risk at a regional or national level.

Midcarpal Instability: The Role of Wrist Arthroscopy.

The evidence behind management options for midcarpal instability (MCI) is scarce, relying solely on case series. Established treatments cause significant loss of wrist motion. As understanding of the condition has progressed, surgeons have been trying soft tissue techniques. The treatment option should be chosen for the appropriate type and grade of MCI. The Hargreaves grading system for palmar MCI aids treatment decision-making. A possible role for arthroscopy in treatment of MCI has been developed using arthroscopic thermal capsular shrinkage, appropriate for cases with dynamic instabilities. Static deformities require a soft tissue reconstruction or a partial wrist fusion.

Bioaccumulation of metals in ryegrass (Lolium perenne L.) following the application of lime stabilised, thermally dried and anaerobically digested sewage sludge.

The uptake and accumulation of metals in plants is a potential pathway for the transfer of environmental contaminants in the food chain, and poses potential health and environmental risks. In light of increased population growth and urbanisation, the safe disposal of sewage sludge, which can contain significant levels of toxic contaminants, remains an environmental challenge globally. The aims of this experiment were to apply municipal sludge, having undergone treatment by thermal drying, anaerobic digestion, and lime stabilisation, to permanent grassland in order to assess the bioaccumulation of metals (B, Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Nb, Mo, Sb, Ba, W, Pb, Fe, Cd) by perennial ryegrass over a period of up to 18 weeks after application. The legislation currently prohibits use of grassland for fodder or grazing for at least three weeks after application of treated sewage sludge (biosolids). Five treatments were used: thermally dried (TD), anaerobically digested (AD) and lime stabilised (LS) sludge all from one wastewater treatment plant (WWTP), AD sludge from another WWTP, and a study control (grassland only, without application of biosolids). In general, there was no significant difference in metal content of the ryegrass between micro-plots that received treated municipal sludge and the control over the study duration. The metal content of the ryegrass was below the levels at which phytotoxicity occurs and below the maximum levels specified for animal feeds.

The accuracy of magnetic resonance imaging in prostate cancer staging: a single-institution experience.

BACKGROUND: Magnetic resonance imaging (MRI) has a wide reported variation in sensitivity and specificity for staging prostate cancer (PCA). AIMS: We examined the accuracy of MRI in detecting PCA, and in identifying extracapsular extension (ECE) and seminal vesicle invasion (SVI) in PCA patients at our institution. METHODS: We retrospectively reviewed pre-biopsy MRI findings and correlated the same with subsequent radical prostatectomy pathology reports in all patients undergoing radical prostatectomy between 2010 and 2012. Specifically, comparison was made between MRI and pathologic stage. Age, serum prostate-specific antigen level and Gleason score were recorded. RESULTS: MRI detected signal abnormalities in 50 out of 88 PCA patients undergoing radical prostatectomy. Of these, 12 had ECE and 7 had SVI on final histology. The sensitivity and specificity of MRI for detecting ECE were 75 and 100%, respectively. The sensitivity and specificity of MRI for detecting SVI were 16.7 and 100%, respectively. The positive predictive values for determining ECE and SVI were 100% and negative predictive values were 96.2 and 90.6%, respectively. CONCLUSIONS: MRI may be reliable for excluding ECE and SVI in PCA patients where the lesion is visible on MRI. It has a good diagnostic ability for ECE, but is less accurate for identifying SVI. This article supports the use of MRI in the preoperative evaluation of PCA.

Complexities of abdominoperineal surgery: synchronous resection of an ano-rectal adenocarcinoma and pelvic schwannoma.

Abdominoperineal resection (APR) is indicated for low rectal/ano-rectal cancers. It necessitates fastidious pelvic dissection posing certain operative difficulties. We present the surgical challenges in a unique case of a patient presenting with a low rectal adenocarcinoma and a synchronous pelvic schwannomas, both requiring resection. A 71-year-old gentleman presented for surveillance colonoscopy following previous excision of colonic polyps. This investigation revealed a polypoid mass at the ano-rectal junction which was histologically proven as an adenocarcinoma with high-grade dysplasia. A staging computed tomography scan revealed an incidental 10 × 15 cm homogeneous, pre-sacral mass. After meticulous operative planning, the patient underwent successful open resection of this mass and concurrent APR for his low rectal lesion. This case demonstrates a rare presentation of a low rectal adenocarcinoma and concurrent pelvic schwannoma. We discuss the technical difficulties encountered in the management of such complex pelvic tumours and highlight the successful outcomes of the synchronous resection.

Stepwise effects of the BCR sequential chemical extraction procedure on dissolution and metal release from common ferromagnesian clay minerals: a combined solution chemistry and X-ray powder diffraction study.

Sequential extraction procedures (SEPs) are commonly used to determine speciation of trace metals in soils and sediments. However, the non-selectivity of reagents for targeted phases has remained a lingering concern. Furthermore, potentially reactive phases such as phyllosilicate clay minerals often contain trace metals in structural sites, and their reactivity has not been quantified. Accordingly, the objective of this study is to analyze the behavior of trace metal-bearing clay minerals exposed to the revised BCR 3-step plus aqua regia SEP. Mineral quantification based on stoichiometric analysis and quantitative powder X-ray diffraction (XRD) documents progressive dissolution of chlorite (CCa-2 ripidolite) and two varieties of smectite (SapCa-2 saponite and SWa-1 nontronite) during steps 1-3 of the BCR procedure. In total, 8 (+/-1) % of ripidolite, 19 (+/-1) % of saponite, and 19 (+/-3) % of nontronite (% mineral mass) dissolved during extractions assumed by many researchers to release trace metals from exchange sites, carbonates, hydroxides, sulfides and organic matter. For all three reference clays, release of Ni into solution is correlated with clay dissolution. Hydrolysis of relatively weak Mg-O bonds (362 kJ/mol) during all stages, reduction of Fe(III) during hydroxylamine hydrochloride extraction and oxidation of Fe(II) during hydrogen peroxide extraction are the main reasons for clay mineral dissolution. These findings underscore the need for precise mineral quantification when using SEPs to understand the origin/partitioning of trace metals with solid phases.

The effects of acute and chronic JJ stent placement on upper urinary tract motility and calculus transit.

OBJECTIVE: To determine the pathophysiological changes in upper urinary tract motility and calculus transit which may occur following JJ stent insertion. MATERIALS AND METHODS: The acute and chronic effects of JJ stent placement were studied in 24 canine renal units. Intrarenal and intraureteric pressures and motility were measured, in addition to transit times for complete passage of synthetic calculi from the upper ureter into the bladder. RESULTS: Acute effects included raised renal intrapelvic pressure, reduced pelvic and ureteric motility and delayed calculus transit time. Prolonged JJ stent placement was associated with return of intrapelvic pressure to normal but persistent changes in both renal and ureteric motility and also calculus transit time. CONCLUSION: In situ JJ stents impair upper urinary tract motility and experimental calculus transit time and may delay passage of ureteric calculi or calculus fragments following extracorporeal shock wave lithotripsy.

Recovery of ureteric motility following complete and partial ureteric obstruction.

Complete and partial ureteric obstruction was created in 2 groups of 10 mongrel dogs by placing a ligature around, or inserting a fine bore plastic stent into, the lower end of the left ureter (Groups 1 and 2). After 4 weeks the ligature or stent was removed, a 2.5-cm segment of ureter was harvested for in vitro analysis and the ureter reimplanted into the bladder. Pelvic and ureteric pressures and motility were recorded before, during and after the period of obstruction via a subcutaneously placed nephrostomy tube. Pre-obstruction resting intra-ureteric pressure was 2.1 +/- 0.3 mm Hg (mean +/- SEM), with regular contractions 8.9 +/- 0.7/min of 36.2 +/- 1.2 mm Hg amplitude. After 4 weeks of obstruction, contractility was abolished in Group 1 but increased in Group 2, 71.5 +/- 3.3 mm Hg, with irregular multiphasic contractions seen following diuresis. Intra-ureteric pressure was 16.3 + 1.2 mm Hg in Group 1 and 9.3 + 1.2 mm Hg in Group 2. In vitro experiments confirmed the patterns of contractility seen in vivo. Eight weeks after reimplantation the ureter returned to normal rhythm and rate in Group 1, but increased contractility persisted both in vivo and in vitro in Group 2.

The ureter in vitro: normal motility and response to urinary pathogens.

The effects of bacteria on in vitro ureteric contractility were studied, using a model which allowed selective exposure of organisms to the ureteric mucosa and smooth muscle, respectively. A cannula attached to a pressure transducer was ligated into the proximal lumen of 2.5-cm segments of canine ureter. The distal ureter was ligated to form a closed pressure monitored system, and the segment suspended in a 20-ml organ bath containing Krebs Henseleit buffer at physiological pH and temperature. Following onset of spontaneous activity, broths of Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus were added to either the buffer solution or ureteric lumen in doses of > 10(6) organisms/ml. Experiments were repeated using heat-killed organisms, bacterial filtrates and E. coli endotoxin. Ureteric contractility was stimulated by organisms added to the buffer medium, but reversibly inhibited by bacteria placed in the ureteric lumen. Heat-killed organisms, endotoxin and live filtrates had no effect on normal motility when exposed to either the ureteric mucosa or muscularis respectively. These findings reflect the conflicting changes in ureteric motility seen in vivo when bacteria are administered systemically or directly into the ureteric lumen.

Pharmacological options for the treatment of acute ureteric colic. An in vitro experimental study.

The effects of opiate and non-steroidal anti-inflammatory agents on the in vitro canine ureter were compared using a new model for the assessment of ureteric pharmacology. A pressure measuring catheter attached to a pressure transducer and pre-calibrated pen recorder was ligated into the lumen of 2.5 cm segments of normal canine ureter. The segments were immersed in an organ bath at physiological pH and temperature and spontaneous contractility was observed in 90% of them. Morphine had a spasmogenic effect on ureteric activity which was unaffected by naloxone. This effect was similar to that of histamine and prostaglandin F2 alpha and was abolished by chlorpheniramine but not by cimetidine. Pethidine produced a transient stimulation followed by inhibition of ureteric activity which was unaffected by naloxone. Both indomethacin and diclofenac produced an abrupt inhibition which was reversible with prostaglandin F2 alpha. These data suggest that pethidine or a non-steroidal anti-inflammatory agent may by virtue of their spasmolytic effects be a superior choice of therapy for the acutely obstructed ureter.

Ischaemia-reperfusion injury in the rat kidney: effect of a single dose of sodium bicarbonate.

The protective effect of intravenous 8.4 per cent sodium bicarbonate on renal function after ischaemia was evaluated in rats subjected to 45 or 90 min warm unilateral renal ischaemia. Two groups of control animals received normal or 3 per cent saline. All solutions were given by bolus injection 3 h before ischaemia. Renal function was significantly protected in animals receiving bicarbonate. Vascular congestion of the inner stripe of the renal medulla was prevented. The survival rate in the group undergoing 90-min ischaemia was 70 per cent for animals receiving bicarbonate and nil in those given saline. Preoperative alkalinization confers significant functional and morphological protection in the ischaemic kidney.

Recognition of the highly conserved GTPase center of 23 S ribosomal RNA by ribosomal protein L11 and the antibiotic thiostrepton.

The antibiotic thiostrepton, a thiazole-containing peptide, inhibits translation and ribosomal GTPase activity by binding directly to a limited and highly conserved region of the large subunit ribosomal RNA termed the GTPase center. We have previously used a filter binding assay to examine the binding of ribosomal protein L11 to a set of ribosomal RNA fragments encompassing the Escherichia coli GTPase center sequence. We show here that thiostrepton binding to the same RNA fragments can also be detected in a filter binding assay. Binding is relatively independent of monovalent salt concentration and temperature but requires a minimum Mg2+ concentration of about 0.5 mM. To help determine the RNA features recognized by L11 and thiostrepton, a set of over 40 RNA sequence variants was prepared which, taken together, change every nucleotide within the 1051 to 1108 recognition domain while preserving the known secondary structure of the RNA. Binding constants for L11 and thiostrepton interaction with these RNAs were measured. Only a small number of sequence variants had more than fivefold effects on L11 binding affinities, and most of these were clustered around a junction of helical segments. These same mutants had similar effects on thiostrepton binding, but more than half of the other sequence changes substantially reduced thiostrepton binding. On the basis of these data and chemical modification studies of this RNA domain in the literature, we propose that L11 makes few, if any, contacts with RNA bases, but recognizes the three-dimensional conformation of the RNA backbone. We also argue from the data that thiostrepton is probably sensitive to small changes in RNA conformation. The results are discussed in terms of a model in which conformational flexibility of the GTPase center RNA is functionally important during the ribosome elongation cycle.

Detection of a key tertiary interaction in the highly conserved GTPase center of large subunit ribosomal RNA.

Searches of ribosomal RNA sequences for compensatory base changes preserving Watson-Crick base pairing have led to detailed models of the conserved secondary structures of these RNAs. In principle, tertiary interactions can also be detected by searches for phylogenetically covariant bases. Within a highly conserved region of the large subunit ribosomal RNA termed the "GTPase center," the bases G-1056-U-1082.A-1086 are found in all eubacteria (Escherichia coli numbering), while A-1056.C-1082.G-1086 are found at the homologous positions in eukaryotes; archaebacteria fall into either category with some exceptions. Either sequence can potentially form a similar set of hydrogen bonds connecting the 3 bases. To determine the contribution of these 3 bases to RNA tertiary structure, sequence variants were made in RNA fragments covering the GTPase center. Correct folding of the RNA fragments was assayed by measuring the binding affinities of two different ligands that recognize the RNA tertiary structure: the highly conserved ribosomal protein L11, which is normally associated with the GTPase center RNA, and the peptide antibiotic thiostrepton, which inhibits the GTPase activity of eubacterial and some archaebacterial ribosomes. The results strongly support the existence of a base pair between positions 1082 and 1086: single mutations at either position weaken both L11 and thiostrepton binding by approximately 10-fold or more, while compensatory double mutations bind the ligands nearly as well as the wild-type E. coli sequence. Variants at position 1056 have little effect on either L11 or thiostrepton binding; a 3-base interaction is therefore not supported by these experiments. A base pair between positions 1082 and 1086 strongly constrains the geometry with which three helical segments join in the middle of the GTPase center.

Acute and chronic bioeffects of single and multiple doses of piezoelectric shockwaves (EDAP LT.01).

Piezoelectric second generation lithotriptors are an established means of administering extracorporeal shockwave lithotripsy (ESWL) enabling treatment to be performed without anaesthesia or analgesia, but higher shockwave doses and multiple or staged treatment are frequently required. The bioeffects of this modality of ESWL, therefore, require further assessment. Seven experimental groups of adult male rabbits were treated using the EDAP LT.01 in order to determine the acute and chronic bioeffects of clinical dose, excess dose, divided excess dose, high frequency and multiple treatment (X10) piezoelectric shockwaves (PSW). Renal function was measured before and after treatment using mercaptoacetyltriglycine (MAG 3) scans. Gross and histological morphological changes were assessed at one and 30 days following application of PSW. Application of single clinical dose PSW was not associated with any significant functional or morphological renal injury. Excess dose PSW caused transient gross renal contusion, which resolved in the majority of animals with no persistent microscopic abnormality. Divided excess dose PSW resulted in no gross or microscopic damage. High frequency PSW was associated with mild histological abnormality. Multiple PSW treatments caused small discrete fibrotic lesions in all cases, without any change in renal function.

Changes in regional renal perfusion following ischemia/reperfusion injury to the rat kidney.

Post-ischemic renal failure is associated with a zone of vascular hyperaemia in the outer medulla of the kidney. The effect of this lesion on regional renal perfusion is, however, unclear. Acute unilateral renal ischemia was applied to four groups of ten adult male Wistar rats for a period of 60 min, followed by revascularisation for 0, 15, 30 or 60 min. The aorta was then clamped and Microfil was injected at a standard pressure to fill the renal vasculature. Gross and histological examinations of the renal parenchyma and vasculature were then performed. Regional renal Microfil perfusion was quantified by examination of unstained histological sections, giving rise to a vascular perfusion index (VPI) for each vascular region of the kidney. The VPIs were similar in control and ischemic kidneys that were not subjected to reflow (group 1). In contrast, the VPI was markedly decreased in the inner stripe and inner medulla in animals in which revascularisation had occurred (groups 2-4), and the vasculature in these regions was histologically shown to be packed with red blood cells. Post-ischemic renal failure is associated with hyperperfusion of the medulla resulting from blockage of the vasculature that occurs during revascularisation.