Kinetics of phytoremediation of petroleum hydrocarbon contaminated soil.

Earthmaster and the University of Waterloo have successfully developed plant growth promoting rhizobacteria (PGPR) - Enhanced Phytoremediation Systems (PEPSystems™) which have been deployed across Canada for the treatment of soil contaminated with petroleum hydrocarbons (PHCs), including CCME fractions F2 and F3. A challenge with phytoremediation is to predict the length of time to remediate a site so that site owners will be inclined to use the technology. In previous field trials of PEPSystems, it was determined that PHC was mostly degraded by microbes in the rhizosphere, following first-order exponential decay kinetics. Using new PEPSystems data collected from multiple commercial remediation sites across Western Canada, the kinetic equations of PHC decay were tested to determine if remediation time was accurately predicted. In general, when compared to the predicted time to remediation endpoint, data from recent commercial field applications showed that 35% and 20% less time was needed to reach remediation endpoints for fractions F2 and F3, respectively. As a result, the predictive kinetic equation for fraction F2 degradation was updated to reflect current remediation outcomes. Insufficient data were available to update the F3 equation. Being able to more accurately predict remediation timelines will enhance the value and utilization of PEPSystems.

Opinion: Taking phytoremediation from proven technology to accepted practice.

Phytoremediation is the use of plants to extract, immobilize, contain and/or degrade contaminants from soil, water or air. It can be an effective strategy for on site and/or in situ removal of various contaminants from soils, including petroleum hydrocarbons (PHC), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), solvents (e.g., trichloroethylene [TCE]), munitions waste (e.g., 2,4,6-trinitrotoluene [TNT]), metal(loid)s, salt (NaCl) and radioisotopes. Commercial phytoremediation technologies appear to be underutilized globally. The primary objective of this opinion piece is to discuss how to take phytoremediation from a proven technology to an accepted practice. An overview of phytoremediation of soil is provided, with the focus on field applications, to provide a frame of reference for the subsequent discussion on better utilization of phytoremediation. We consider reasons why phytoremediation is underutilized, despite clear evidence that, under many conditions, it can be applied quite successfully in the field. We offer suggestions on how to gain greater acceptance for phytoremediation by industry and government. A new paradigm of phytomanagement, with a specific focus on using phytoremediation as a "gentle remediation option" (GRO) within a broader, long-term management strategy, is also discussed.

Newborn respiratory distress: airway abnormalities.

Respiratory distress is a common symptom in the newborn. Surfactant deficiency in the preterm infant and meconium aspiration and transient tachypnea in the term newborn are among the most common causes of respiratory distress, but primary airway abnormalities can also present with respiratory distress in the newborn. Delay in diagnosis of airway abnormality can be life threatening. Radiologists are among the first to be consulted in the evaluation of a neonate with respiratory distress, and knowledge of the spectrum of airway anomalies is essential for making the correct diagnosis. This article describes airway abnormalities that can present as respiratory distress in a neonate.

Tetralogy of Fallot with double aortic arch and discontinuous left pulmonary artery.

We report a case of Tetralogy of Fallot with double aortic arch and discontinuous left pulmonary artery, supplied by the ductus arteriosus, a rare entity.

Bilateral vocal cord paralysis requiring tracheostomy due to neuroborreliosis.

Neuroborreliosis can cause multiple cranial and peripheral neuropathies; however, involvement of both recurrent laryngeal nerves is rare. We report the case of a 90-year-old man who presented with dysphonia and right upper and lower extremity weakness. His course was complicated by bilateral vocal cord paralysis and respiratory failure requiring tracheostomy. The diagnosis of borreliosis was made by detection of IgM and IgG antibodies against Borrelia burgdorferi on enzyme immunoassay and Western blot. The patient received IV ceftriaxone for 2 weeks, followed by complete recovery of motor and vocal function over 2 months. Our case is the third report of bilateral vocal cord paralysis in the literature, and the first one, to our knowledge, presenting with respiratory failure requiring an artificial airway. Physicians should be aware of this unusual complication of neuroborreliosis.

Plant growth-promoting bacteria facilitate the growth of barley and oats in salt-impacted soil: implications for phytoremediation of saline soils.

Plant growth-promoting bacteria (PGPB) strains that contain the enzyme 1-amino-cyclopropane-1-carboxylate (ACC) deaminase can lower stress ethylene levels and improve plant growth. In this study, ACC deaminase-producing bacteria were isolated from a ) salt-impacted ( 50 dS/m) farm field, and their ability to promote plant growth of barley 1): and oats in saline soil was investigated in pouch assays (1% NaCI), greenhouse trials (9.4 dS/m), and field trials (6-24 dS/m). A mix of previously isolated PGPB strains UW3 (Pseudomonas sp.) and UW4 (P. sp.) was also tested for comparison. Rhizobacterial isolate CMH3 (P. corrugata) and UW3+UW4 partially alleviated plant salt stress in growth pouch assays. In greenhouse trials, CMH3 enhanced root biomass of barley and oats by 200% and 50%, respectively. UW3+UW4, CMH3 and isolate CMH2 also enhanced barley and oat shoot growth by 100%-150%. In field tests, shoot biomass of oats tripled when treated with UW3+UW4 and doubled with CHM3 compared with that of untreated plants. PGPB treatment did not affect salt uptake on a per mass basis; higher plant biomass led to greater salt uptake, resulting in decreased soil salinity. This study demonstrates a method for improving plant growth in marginal saline soils. Associated implications for salt

Motorized dirt bike injuries in children.

BACKGROUND: The number of dirt bike injuries in children in the United States is increasing and poses a public health problem. OBJECTIVE: The purpose of our study was to identify the imaging patterns of dirt bike injuries in children and associations with morbidity and mortality. METHODS: The study included 85 children (83 boys, 2 girls) <18 year of age (mean age 12.3 years, standard deviation 3 years) with dirt bike injury treated at a tertiary care pediatric hospital. Imaging studies and hospital medical records were reviewed. Outcomes were classified into the following categories: short-term disability, long-term disability or no follow-up available. Imaging studies were reviewed for head, torso, and extremity injuries. One-tailed z test for two proportions was used to determine significant differences between various proportions. Chi-square test with Yates correction was used to determine the significance of long-term disability with injury type. RESULTS: Long bone fractures were the most common injuries. Lower extremity fractures accounted for 79% of extremity fractures and were significantly more common than upper extremity fractures (p = 0.001). Head injuries included fractures (n = 9), brain contusion (n = 5), and meningeal hemorrhage (n = 2). Head injury was associated with long-term disability (p < 0.0001). All torso injuries were solitary. CONCLUSIONS: Long-term disability was associated with head injuries but not with torso or extremity injuries. Lower extremity injuries were significantly more common than upper extremity injuries. Torso solid organ injuries were uniformly solitary.

Breathing resistance and ultrafine particle deposition in nasal-laryngeal airways of a newborn, an infant, a child, and an adult.

As a human grows from birth to adulthood, both airway anatomy and breathing conditions vary, altering the deposition rate and pattern of inhaled aerosols. However, deposition studies have typically focused on adult subjects, results of which may not be readily extrapolated to children. This study numerically evaluated the age-related effects on the airflow and aerosol dynamics in image-based nose-throat models of a 10-day-old newborn, a 7-month-old infant, a 5-year-old child, and a 53-year-old adult. Differences in airway physiology, breathing resistance, and aerosol filtering efficiency among the four models were quantified and compared. A high-fidelity fluid-particle transport model was employed to simulate the multi-regime airflows and particle transport within the nasal-laryngeal airways. Ultrafine particles were evaluated under breathing conditions ranging from sedentary to heavy activities. Results of this study indicate that the nasal-laryngeal airways at different ages, albeit differ significantly in morphology and dimension, do not significantly affect the total deposition fractions or maximum local deposition enhancement for ultrafine aerosols. Further, the deposition partitioning in the sub-regions of interest is different among the four models. Results of this study corroborate the use of the in vivo-based diffusion parameter (D(0.5)Q(-0.28)) over the replica-based parameter in correlating nasal-laryngeal depositions of ultrafine aerosols. Improved correlations have been developed for the four age groups by implementing this in vivo-based diffusion parameter as well as the Cunningham correction factor.

Bioavailability of copper and zinc in mining soils.

The soil-contact exposure pathway can be the main driver of ecological risk assessments. There is currently no standard method to measure bioavailability of metals in soil to ecological receptors, yet the influence of metal bioavailability on toxicity has been known for decades and is a major factor influencing risk to ecological receptors. Bioavailability is to a large degree governed by varying soil characteristics within and among sites, yet ecological screening benchmarks are often derived on a total-concentration basis. We compared a calcium chloride (CaCl2) extraction, cyclodextrin extraction, simulated earthworm gut (SEG) test, earthworm kinetic bioaccumulation test, and metal residues in plant tissues with a battery of invertebrate and toxicity tests using mining soils consisting of high organic-matter content cocontaminated with copper (Cu) and zinc (Zn). Earthworm (Eisenia andrei) tissue concentrations of Cu and Zn were regulated and were not predictive of invertebrate toxicity. All chemical measures of bioavailability correlated with several biological responses; however, CaCl2-extractable Cu and SEG-extractable Cu and Zn best predicted effects to E. andrei. Total Cu concentrations in soil best correlated with effects to plants. Overall, a chemical measure was the best predictor of toxicity to each organism compared with biological measures, although the exact measure was dependent on organism and end point. Chemical-extraction techniques provide relatively quick, inexpensive indicators of essential metal bioavailability compared with biological measures; however, no single measure was indicative of all effects to all organisms.

Atypical antipsychotics for the treatment of ICU delirium.

Delirium is commonly described in critically ill patients as 1 factor contributing to increased length of intensive care unit and hospital stay, secondary complications, and increased mortality. Initial screening tools for delirium in hospitalized patients are generally easy to use; however, many centers have struggled with implementing these tools in a consistent and systematic manner. Haloperidol has traditionally been prescribed as the primary agent of choice for the treatment of delirium in critically ill patients. Clinicians have been challenged to consider alternative agents due to adverse effects such as extrapyramidal symptoms, QTc prolongation, and possible torsades de pointes with haloperidol use. The atypical antipsychotics are attractive alternatives to haloperidol with improved safety profiles but are flawed by limited data to support dosing and efficacy in this patient population. Future studies that provide large, prospective, double-blinded, placebo-controlled data to support the implementation of these agents as standard therapy over haloperidol are needed.

Comparison of biological and chemical measures of metal bioavailability in field soils: test of a novel simulated earthworm gut extraction.

Bioavailability of metals in soil is a major factor influencing estimates of risk associated with exposure of ecological receptors. Metal concentrations in soil are often compared to ecological screening benchmarks, which are based on total concentrations in soil. Often, the total concentration is not correlated with toxicity. No standardised method exists for determining the bioavailability of metals in soil to ecological receptors. Several surrogate measures of bioavailability were compared to the results of a battery of toxicity tests using copper (Cu), lead (Pb), and zinc (Zn)-contaminated soils collected from a former industrial area. A calcium chloride (CaCl(2)) extraction, cyclodextrin (HPCD) extraction, simulated earthworm gut (SEG) test, and earthworm bioaccumulation test were performed using the soils. Extractable metals using the CaCl(2) solution were not correlated with any biological responses of earthworms (Eisenia andrei), collembola (Folsomia candida), northern wheatgrass (Elymus lanceolatus), or alfalfa (Medicago sativa L.). Concentrations of metals in the HPCD extracts were highly variable and were not adequate for revealing adverse effects. E. andrei tissue concentrations were variable but were predictive of adverse effects to invertebrates. The results of the SEG test correlated with most of the biological endpoints. Bioavailable Cu was correlated with adverse effects to invertebrates and plants using the SEG test. Overall, coefficients of determination associated with the relationships between the biological responses and each measure of bioavailability indicated that those for the SEG test were greater than those for the other surrogate measures of bioavailability. Further validation is required before this test is routinely used to estimate metal bioavailability and toxicity.

Photosynthetic redox imbalance influences flavonoid biosynthesis in Lemna gibba.

Plants accumulate flavonoids in response to a myriad of environmental challenges, especially when exposed to ultraviolet (UV) radiation or situations causing oxidative stress. However, the origin and nature of the signal triggering their accumulation remain obscure. In this study, a group of flavonoids belonging to the flavone class was identified in Lemna gibba (duckweed). These flavones accumulated upon exposure to UV radiation, low temperature, copper and the photosynthetic electron transport (PET) inhibitors 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) and 1,2-dihydroxyanthraquinone (DHATQ). All of these stressors were also shown to promote PET chain (PETC) reduction; however, in the co-presence of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) or a light regime that oxidized the PETC, flavonoid accumulation ceased. Chloroplast-derived reactive oxygen species (ROS) were not associated with all of the stress conditions that promoted both PETC reduction and flavonoid synthesis, indicating that ROS were not a strict requisite for flavonoid accumulation. Transcripts for the flavonoid biosynthetic genes, chalcone synthase (CHS) and chalcone isomerase, were similarly responsive to the PETC redox state, as were a panel of transcripts revealed by differential display PCR. Collectively, these results provide evidence that PETC redox status is one of the factors affecting flavonoid biosynthesis.

Determination of microbial carbon sources and cycling during remediation of petroleum hydrocarbon impacted soil using natural abundance (14)C analysis of PLFA.

In a petroleum impacted land-farm soil in Sarnia, Ontario, compound-specific natural abundance radiocarbon analysis identified biodegradation by the soil microbial community as a major pathway for hydrocarbon removal in a novel remediation system. During remediation of contaminated soils by a plant growth promoting rhizobacteria enhanced phytoremediation system (PEPS), the measured Delta(14)C of phospholipid fatty acid (PLFA) biomarkers ranged from -793 per thousand to -897 per thousand, directly demonstrating microbial uptake and utilization of petroleum hydrocarbons (Delta(14)C(PHC) = -1000 per thousand). Isotopic mass balance indicated that more than 80% of microbial PLFA carbon was derived from petroleum hydrocarbons (PHC) and a maximum of 20% was obtained from metabolism of more modern carbon sources. These PLFA from the contaminated soils were the most (14)C-depleted biomarkers ever measured for an in situ environmental system, and this study demonstrated that the microbial community in this soil was subsisting primarily on petroleum hydrocarbons. In contrast, the microbial community in a nearby uncontaminated control soil maintained a more modern Delta(14)C signature than total organic carbon (Delta(14)C(PLFA) = +36 per thousand to -147 per thousand, Delta(14)C(TOC) = -148 per thousand), indicating preferential consumption of the most modern plant-derived fraction of soil organic carbon. Measurements of delta(13)C and Delta(14)C of soil CO(2) additionally demonstrated that mineralization of PHC contributed to soil CO(2) at the contaminated site. The CO(2) in the uncontaminated control soil exhibited substantially more modern Delta(14)C values, and lower soil CO(2) concentrations than the contaminated soils, suggesting increased rates of soil respiration in the contaminated soils. In combination, these results demonstrated that biodegradation in the soil microbial community was a primary pathway of petroleum hydrocarbon removal in the PEPS system. This study highlights the power of natural abundance radiocarbon for determining microbial carbon sources and identifying biodegradation pathways in complex remediation systems.

Three year field test of a plant growth promoting rhizobacteria enhanced phytoremediation system at a land farm for treatment of hydrocarbon waste.

Phytoremediation of total petroleum hydrocarbons (TPH) has the potential to be a sustainable waste management technology if it can be proven to be effective in the field. Over the past decade, our laboratory has developed a system which utilizes plant growth promoting rhizobacteria (PGPR) enhanced phytoremediation (PEP) that, following extensive greenhouse testing, was shown to be effective at remediating TPH from soils. This system consists of physical soil manipulation and plant growth following seed inoculation with PGPR. PGPR elicit biomass increases, particularly in roots, by minimizing plant stress in highly contaminated soils. Extensive development of the root system enhances degradation of contaminants by the plants and supports an active rhizosphere that effectively promotes TPH degradation by a broad microbial consortium. Following promising greenhouse trials, field tests of PEP were performed over a period of three years at a Southern Ontario site (approximately 130 g kg(-1) TPH) used for land farming of refinery hydrocarbon waste for many years. The low molecular weight fractions (the Canadian Council of Ministers of the Environment (CCME) fractions 1 and 2) were removed through land farming and bioremediation; the high molecular weight, recalcitrant fractions (CCME fractions 3 and 4) remained at high levels in the soil. Using PEP, we substantially remediated fractions 3 and 4, and lowered TPH from 130 g kg(-1) to approximately 50 g kg(-1) over a three year period. The amount of plant growth and extent of oil remediation were consistently enhanced by PGPR.

An evidence-based review of the cardiovascular risks of nonsteroidal anti-inflammatory drugs.

Nonsteroidal anti-inflammatory drugs (NSAIDs), both nonselective and cyclooxygenase-2-specific inhibitors, are commonly used medications for the relief of acute and chronic pain associated with a wide range of medical conditions. Because of the extensive use of these agents, adverse events that occur infrequently may still affect the overall risk/benefit ratio of this class of medications. Serious adverse cardiovascular (CV) events have been reported with NSAID use, but unfortunately, definitive evidence regarding the precise CV risk associated with these drugs, as a class and individually, is lacking. Therefore, it is an issue of public health importance that physicians be guided by careful assessment of the existing evidence to make reasonable choices in prescribing these medications. The investigators review the key clinical trials, meta-analyses of clinical trials, and epidemiologic studies on the subject of the CV safety of NSAIDs and identify key variables that define the CV risk of the NSAIDs. In conclusion, it is important that cardiologists, who are not among those physicians frequently prescribing NSAIDs, have a particular responsibility to have up-to-date, thoughtfully synthesized information about the CV risks of these drugs, especially when administered to patients receiving low-dose aspirin for cardioprotection.

The effect of plant growth-promoting rhizobacteria on asparagus seedlings and germinating seeds subjected to water stress under greenhouse conditions.

Plant growth-promoting rhizobacteria (PGPR) can have positive effects on vigour and productivity, especially under stress conditions. In asparagus (Asparagus officinalis L.) field culture, seeds are planted in high-density nurseries, and 1-year-old crowns are transplanted to production fields. Performance can be negatively affected by water stress, transplant shock, and disease pressure on wounded roots. PGPR inoculation has the potential to alleviate some of the stresses incurred in the production system. In this study, the effects of PGPR (Pseudomonas spp.) treatment were determined on 3-week-old greenhouse-grown seedlings and germinating seeds of 2 asparagus cultivars. The pots were irrigated to a predetermined level that resulted in optimum growth or the plants were subjected to drought or flooding stress for 8 weeks. The cultivars responded differently to PGPR: single inoculations of seedlings enhanced growth of 'Guelph Millennium' under optimum conditions and 'Jersey Giant' seedlings under drought stress. Seed inoculations with PGPR resulted in a positive response only for 'Guelph Millennium', for which both single or multiple inoculations enhanced plant growth under drought stress.

Examination of the mechanism of phenanthrenequinone toxicity to Vibrio fischeri: evidence for a reactive oxygen species-mediated toxicity mechanism.

Phenanthrenequinone (PHQ) is a photoproduct of phenanthrene, one of the most prevalent polycyclic aromatic hydrocarbons in the environment. Phenanthrenequinone is a compound of substantial interest, because its toxicity can be much greater than its parent chemical to aquatic organisms. The toxicity mechanisms of PHQ to the luminescent marine bacterium Vibrio fischeri were examined in the present study. Phenanthrenequinone can redox cycle in bacterial cells and transfer electrons to O2, enhancing the production of superoxide (O*2-), hydrogen peroxide (H2O2), and other reactive oxygen species (ROS). Exposure of cells to PHQ increased activity of superoxide dismutase (SOD), which detoxifies the ROS superoxide. Concentrations of PHQ that induced the production of H2O2 and other ROS, as well as the elevated levels of Fe-SOD, were correlated with its toxicity as measured by luminescence. Furthermore, toxicity of PHQ to V. fischeri was lowered under the anaerobic conditions, suggesting that the absence of oxygen, which would limit the production of ROS, alleviated toxicity of PHQ. Thus, a ROS-mediated toxicity mechanism of PHQ is highly implicated by in the present study.