Field applications of zein as a precise nanoscale delivery system for methoxyfenozide

When insecticides are applied in the environment, much of the product does not reach the target pest. Biopolymeric nanoparticles as nanocarriers have the potential to improve insecticide efficacy by improving absorption, coverage, and permeability while protecting the insecticide active ingredient from abiotic conditions and extending efficacy through controlled release. We conducted a series of experiments using a biopolymeric nanoparticle synthesized from zein, a biodegradable maize protein, to compare efficacy of a nanodelivered hydrophobic insect growth regulator (methoxyfenozide) against a commercial formulation. Positively charged zein nanoparticles (empty and loaded with methoxyfenozide) were compared to the formulated product, Intrepid 2F, as a foliar spray in-field on soybean. Chrysodeixis includens (Walker) was used as a model and was fed sprayed soybean leaves to evaluate efficacy of the tested foliar products over time. A separate set of leaves was sampled to measure residue levels of methoxyfenozide (MFZ) over time following foliar application using QuEChERS extraction and high-resolution liquid chromatography-mass spectrometry. Regression analysis found no differences in mortality slopes between positively charged zein nanoparticles loaded with methoxyfenozide [(+)ZNP(MFZ)] and Intrepid 2F, suggesting comparable efficacy of the synthesized nanoparticles to a commercial product. Higher concentrations of MFZ were present in (+)ZNP(MFZ)-treated in leaf tissue at 3 d following spray when compared to Intrepid 2F. The multiyear study results demonstrate that nanoparticles loaded with MFZ are comparable to Intrepid 2F under field conditions, with potential short-term benefits.

Supporting proactive planning for climate change adaptation and conservation using an attributed road-river structure dataset

Freshwater species and their habitats, and transportation networks are at heightened risk from changing climate and are priorities for adaptation, with the sheer abundance and individuality of road-river structures complicating mitigation efforts. We present a new spatial dataset of road-river structures attributed as culverts, bridges, or fords, and use this along with data on gradient and stream order to estimate structure sensitivity and exposure in and out of special areas of conservation (SAC) and built-up areas to determine vulnerability to damage across river catchments in Wales, UK. We then assess hazard of flooding likelihood at the most vulnerable structures to determine those posing high risk of impact on roads and river-obligate species (fishes and mussels) whose persistence depends on aquatic habitat connectivity. Over 5% (624/11,680) of structures are high vulnerability and located where flooding hazard is highest, posing high risk of impact to roads and river-obligate species. We assess reliability of our approach through an on-ground survey in a river catchment supporting an SAC and more than 40% (n = 255) of high-risk structures, and show that of the subset surveyed >50% had obvious physical degradation, streambank erosion, and scouring. Our findings help us to better understand which structures pose high-risk of impact to river-obligate species and humans with increased flooding likelihood.

Long-term river invertebrate community responses to groundwater and surface water management operations

River flow regimes have been transformed by groundwater and surface water management operations globally, prompting widespread ecological responses. Yet, empirical evidence quantifying the simultaneous effects of groundwater and surface water management operations on freshwater ecosystems remains limited. This study combines a multi-decadal freshwater invertebrate dataset (1995-2016) with groundwater model outputs simulating the effects of different anthropogenic flow alterations (e.g. groundwater abstraction, effluent water returns) and river discharges. A suite of flow alteration- and flow-ecology relationships were modelled that tested different invertebrate community responses (taxonomic, functional, flow response guilds, individual taxa). Most flow alteration-ecology relationships were not statistically significant, highlighting the absence of consistent, detectable ecological responses to long-term water management operations. A small number of significant statistical models provided insights into how flow alterations transformed specific ecological assets; including Ephemeroptera, Plecoptera and Trichoptera taxa which are rheophilic in nature being positively associated with groundwater abstraction effects reducing river discharges by 0-15%. This represents a key finding from a water resource management operation perspective given that such flow alteration conditions were observed on average in over two-thirds of the study sites examined. In a small number of instances, specific invertebrate responses displayed relative declines associated with the most severe groundwater abstraction effects and artificial hydrological inputs (predominantly effluent water returns). The strongest flow-ecology relationships were recorded during spring months, when invertebrate communities were most responsive to antecedent minimum and maximum discharges, and average flow conditions in the preceding summer months. Results from this study provide new evidence indicating how groundwater and surface water resources can be managed to conserve riverine ecological assets. Moreover, the ensemble of flow alteration- and flow-ecology relationships established in this study could be used to guide environmental flow strategies. Such findings are of global importance given that future climatic change and rising societal water demands are likely to further transform river flow regimes and threaten freshwater ecosystems.

Endophyte-enhanced phytoremediation of DDE-contaminated using Cucurbita pepo: A field trial

Although the use of the pesticide 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) was banned from the mid-1970s, its most abundant and recalcitrant degradation product, 2,2-bis(p-chlorophenyl)-1,1-dichloro-ethylene (DDE), is still present in terrestrial and aquatic ecosystems worldwide. Zucchini (Cucurbita pepo ssp. pepo) has been shown to accumulate high concentrations of DDE and was proposed for phytoremediation of contaminated soils. We performed a field trial covering a full plant life cycle. C. pepo plants inoculated with the plant growth-promoting endophytic strains Sphingomonas taxi UH1, Methylobacterium radiotolerans UH1, Enterobacter aerogenes UH1, or a consortium combining these 3 strains were grown on a DDE-contaminated field for 100 days. The effects of these inoculations were examined at both the plant level, by evaluating plant weight and plant DDE-content, and at the level of the cultivable and total endophytic communities. Inoculating plants with S. taxi UH1, M. radiotolerans UH1, and the consortium increased plant weight. No significant effects of the inoculations were observed on DDE-concentrations in plant tissues. However, the amount of DDE accumulated by C. pepo plants per growing season was significantly higher for plants that were inoculated with the consortium of the 3 strains. Therefore, inoculation of C. pepo with DDE-degrading endophytes might be promising for phytoremediation applications.

Macroinvertebrate community responses to hydrological controls and groundwater abstraction effects across intermittent and perennial headwater streams

Intermittent rivers comprise a significant proportion of river networks globally and their spatial extent is predicted to increase with rising water abstraction pressures. Despite this, the ecological implications of hydrological modifications within intermittent rivers have received limited research attention. This paper examines macroinvertebrate assemblages across intermittent and perennial sections of headwater streams within the Hampshire Avon catchment (United Kingdom) over a five-year period. The composition of faunal assemblages was quantified in relation to four hydrological metrics: the duration of flowing conditions, the geographical proximity to the nearest perennial source along each watercourse (two observed flow parameters) and two modelled groundwater abstraction influences. The results highlight that macroinvertebrate communities inhabiting sites which dry periodically and are positioned at greater distances (>c. 2.5km) above the perennial source (the most upstream point of permanent flow within a given year) possessed the highest conservation values. These sites supported species that are rare in many areas of Europe (e.g. Ephemeroptera: Paraletophlebia werneri) or with limited geographical distribution across the United Kingdom (e.g. Trichoptera: Limnephilus bipunctatus). A range of faunal community diversity indices were found to be more sensitive to the antecedent flow duration and distance from the perennial source, rather than any effects of groundwater abstraction. Taxonomic richness responded most strongly to these observed flow parameters and varied more markedly with the distance from the perennial source compared to the antecedent flow duration. Several taxa were significantly associated with the observed flow parameters, particularly those predominantly inhabiting perennially flowing systems. However, the distance that such fauna could migrate into intermittent reaches varied between taxa. This research demonstrates the overriding importance of antecedent flow durations and the geographical proximity to perennial sources on macroinvertebrate communities within intermittent and perennial headwater streams.

Macroinvertebrate Taxonomic and Functional Trait Compositions within Lotic Habitats Affected By River Restoration Practices

The widespread degradation of lotic ecosystems has prompted extensive river restoration efforts globally, but many studies have reported modest ecological responses to rehabilitation practices. The functional properties of biotic communities are rarely examined within post-project appraisals, which would provide more ecological information underpinning ecosystem responses to restoration practices and potentially pinpoint project limitations. This study examines macroinvertebrate community responses to three projects which aimed to physically restore channel morphologies. Taxonomic and functional trait compositions supported by widely occurring lotic habitats (biotopes) were examined across paired restored and non-restored (control) reaches. The multivariate location (average community composition) of taxonomic and functional trait compositions differed marginally between control and restored reaches. However, changes in the amount of multivariate dispersion were more robust and indicated greater ecological heterogeneity within restored reaches, particularly when considering functional trait compositions. Organic biotopes (macrophyte stands and macroalgae) occurred widely across all study sites and supported a high alpha (within-habitat) taxonomic diversity compared to mineralogical biotopes (sand and gravel patches), which were characteristic of restored reaches. However, mineralogical biotopes possessed a higher beta (between-habitat) functional diversity, although this was less pronounced for taxonomic compositions. This study demonstrates that examining the functional and structural properties of taxa across distinct biotopes can provide a greater understanding of biotic responses to river restoration works. Such information could be used to better understand the ecological implications of rehabilitation practices and guide more effective management strategies.

Urban ponds as an aquatic biodiversity resource in modified landscapes

Urbanization is a global process contributing to the loss and fragmentation of natural habitats. Many studies have focused on the biological response of terrestrial taxa and habitats to urbanization. However, little is known regarding the consequences of urbanization on freshwater habitats, especially small lentic systems. In this study, we examined aquatic macro-invertebrate diversity (family and species level) and variation in community composition between 240 urban and 782 nonurban ponds distributed across the United Kingdom. Contrary to predictions, urban ponds supported similar numbers of invertebrate species and families compared to nonurban ponds. Similar gamma diversity was found between the two groups at both family and species taxonomic levels. The biological communities of urban ponds were markedly different to those of nonurban ponds, and the variability in urban pond community composition was greater than that in nonurban ponds, contrary to previous work showing homogenization of communities in urban areas. Positive spatial autocorrelation was recorded for urban and nonurban ponds at 0-50 km (distance between pond study sites) and negative spatial autocorrelation was observed at 100-150 km and was stronger in urban ponds in both cases. Ponds do not follow the same ecological patterns as terrestrial and lotic habitats (reduced taxonomic richness) in urban environments; in contrast, they support high taxonomic richness and contribute significantly to regional faunal diversity. Individual cities are complex structural mosaics which evolve over long periods of time and are managed in diverse ways. This facilitates the development of a wide range of environmental conditions and habitat niches in urban ponds which can promote greater heterogeneity between pond communities at larger scales. Ponds provide an opportunity for managers and environmental regulators to conserve and enhance freshwater biodiversity in urbanized landscapes whilst also facilitating key ecosystem services including storm water storage and water treatment.

Exposure of Cucurbita pepo to DDE-contamination alters the endophytic community: A cultivation dependent vs a cultivation independent approach

2,2-bis(p-chlorophenyl)-1,1-dichloro-ethylene (DDE) is the most abundant and persistent degradation product of the pesticide 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) and is encountered in contaminated soils worldwide. Both DDE and DDT are classified as Persistent Organic Pollutants (POPs) due to their high hydrophobicity and potential for bioaccumulation and biomagnification in the food chain. Zucchini (Cucurbita pepo ssp. pepo) has been shown to accumulate high concentrations of DDE and other POPs and has been proposed as a phytoremediation tool for contaminated soils. The endophytic bacteria associated with this plant may play an important role in the remedial process. Therefore, this research focuses on changes in endophytic bacterial communities caused by the exposure of C. pepo to DDE. The total bacterial community was investigated using cultivation-independent 454 pyrosequencing, while the cultivable community was identified using cultivation-dependent isolation procedures. For both procedures, increasing numbers of endophytic bacteria, as well as higher diversities of genera were observed when plants were exposed to DDE. Several bacterial genera such as Stenotrophomonas sp. and Sphingomonas sp. showed higher abundance when DDE was present, while, for example Pseudomonas sp. showed a significantly lower abundance in the presence of DDE. These findings suggest tolerance of different bacterial strains to DDE, which might be incorporated in further investigations to optimize phytoremediation with the possible use of DDE-degrading endophytes.

Optimization of isolation and cultivation of bacterial endophytes through addition of plant extract to nutrient media

Many endophytes have beneficial effects on plants and can be exploited in biotechnological applications. Studies hypothesize that only 0.001-1% of all plant-associated bacteria are cultivable. Moreover, even after successful isolations, many endophytic bacteria often show reduced regrowth capacity. This research aimed to optimize isolation processes and culturing these bacteria afterwards. We compared several minimal and complex media in a screening. Beside the media themselves, two gelling agents and adding plant extract to media were investigated to enhance the number and diversity of endophytes as well as the growth capacity when regrown after isolation. In this work, 869 medium delivered the highest numbers of cultivable bacteria, as well as the highest diversity. When comparing gelling agents, no differences were observed in the numbers of bacteria. Adding plant extract to the media lead to a slight increase in diversity. However, when adding plant extract to improve the regrowth capacity, sharp increases of viable bacteria occurred in both rich and minimal media.

LYMPH PRESSURES IN STERILE INFLAMMATION

1. The normal lymph pressure in the legs of anesthetized dogs is not measurable. 2. The maximum pressure of lymph in the quiescent leg under conditions of sterile inflammation is around 120 cm. of lymph. 3. Venous pressure rises immediately in a region subjected to sterile inflammation and then slowly returns to normal. The rise in lymph pressure follows the rise in venous pressure. 4. Changes in lymph flow, lymph pressure, and protein concentration of the lymph occur when the part producing lymph is subjected to external temperatures between 50° and 60°C.

Interrelationships among growth, endocrine, immune, and temperament variables in neonatal Brahman calves

Interrelationships among growth, endocrine, immune, and temperament variables were assessed in neonatal Brahman calves. The velocity upon exiting a working chute (exit velocity) of an animal was measured and used as an objective indicator of temperament to classify calves as calm, intermediate, or temperamental. Calves (n = 116) were weighed weekly between d 0 and 21 to 24, and blood samples were collected for plasma and serum on d 0, 1, 2, 7, 14, and 21 to 24 after birth to measure concentrations of immunoglobulins, cortisol, and epinephrine (EPI). Body weight increased from d 0 through d 21 to 24 (P < 0.001) with bulls (n = 60) having greater BW than heifers (n = 56; P = 0.02). Serum concentrations of cortisol were greatest on d 0 before declining (P < 0.001) over the ensuing 21 to 24 d and were not related to temperament (P = 0.89) or sex (P = 0.97). Concentrations of EPI were affected by time, with an increase in EPI concentrations in temperamental bulls between 2 and 14 d of age (P < 0.008). Concentrations of EPI were not affected by temperament (P = 0.44) or sex (P = 0.68). Serum immunoglobulin concentrations peaked on d 1 before declining (P < 0.01) but were not related to temperament (P = 0.40 to 0.68). Of the stress hormones measured (cortisol and EPI), only cortisol was associated with the early performance of the calf. Calf BW at d 21 to 24 and BW gain were positively associated with serum immunoglobulin concentrations, yet negatively associated with concentrations of cortisol. Serum immunoglobulin concentrations were negatively correlated with cortisol concentrations (r = -0.28; P = 0.003), yet positively associated with EPI concentrations (r = 0.51; P = 0.003). During the neonatal period in this study, there was no relationship of temperament with passive immunity or stress hormone concentrations; however, growth was positively associated with passive immunity and negatively associated with stress hormones. Measuring exit velocity as early in life as d 21 to 24 fails to accurately predict temperament at weaning in over 40% of Brahman calves. Our conclusion is that measurement of exit velocity should be done nearer to the time of weaning than to birth. These data can be beneficial in developing best management practices for young calves.

Immunoneutralization of procalcitonin as therapy of sepsis

Prior studies have demonstrated that the prohormone, procalcitonin (ProCT), and its component calcitonin precursors (CTpr) are increased in the serum of septic patients, correlate with the severity of the illness, and persist for relatively long periods of time. Animal studies in septic hamsters have revealed that the administration of ProCT is toxic and that immunoneutralization with IgG that is reactive to this molecule significantly improves survival. A large animal model of a very rapidly lethal polymicrobial sepsis has been developed in the pig in order to measure continuous physiological and metabolic parameters and also to compare the effects in this animal of an immunoneutralization, which is performed late in the course of the disease, to an identical, but early, therapy. Based upon the physiological and metabolic parameters, the late therapy, which was initiated during the fourth hour at a time when pigs were nearly moribund, was found to be as beneficial as early therapy. In both late and early therapy, the only animals to survive at the predetermined time of euthanasia were those which had received immunoneutralization therapy.

Calcitonin precursors: early markers of gut barrier dysfunction in patients with acute pancreatitis

BACKGROUND

Severe acute pancreatitis is associated with an early increase in intestinal permeability and endotoxemia. Endotoxin is a potent stimulator for the production and release of procalcitonin and its components (calcitonin precursors; [CTpr]). The aim of this study is to evaluate the role of plasma CTpr as an early marker for gut barrier dysfunction in patients with acute pancreatitis.

METHODS

Intestinal permeability to macromolecules (polyethylene glycol 3350), serum endotoxin and antiendotoxin core antibodies, plasma CTpr, and serum C-reactive protein (CRP) were measured on admission in 60 patients with acute pancreatitis. Attacks were classified as mild (n = 48) or severe (n = 12) according to the Atlanta criteria.

RESULTS

Compared with mild attacks of acute pancreatitis, severe attacks were significantly associated with an increase in intestinal permeability index (median: 0.02 vs. 0.006, P < 0.001), the frequency of endotoxemia (73% vs. 41%, P = 0.04), and the extent of depletion of serum IgM antiendotoxin antibodies (median: 43 MMU vs. 100 MMU, P = 0.004). Plasma CTpr levels were significantly elevated in patients with severe attacks compared with mild attacks on both the day of admission and on day 3 (median: 64 vs. 22 fmol/mL, P = 0.03; and 90 vs. 29 fmol/mL, P = 0.003 respectively). A positive and significant correlation was observed between the admission serum endotoxin and plasma CTpr levels on admission (r = 0.7, P < 0.0001) and on day 3 (r = 0.96, P < 0.0001), and between plasma CTpr on day 7 and the intestinal permeability index (r = 0.85, P = 0.0001). In contrast, only a weak positive correlation was observed between peak serum levels of CRP and plasma CTpr on admission (r = 0.3, P = 0.017) and on day 7 (r = 0.471, P = 0.049), as well as between CRP and each of the admission serum endotoxin (r = 0.3, P = 0.03) and the intestinal permeability index (r = 0.375, P = 0.007).

CONCLUSIONS

In patients with acute pancreatitis, plasma concentrations of CTpr appear to reflect more closely the derangement in gut barrier function rather than the extent of systemic inflammation.

Late immunoneutralization of procalcitonin arrests the progression of lethal porcine sepsis

BACKGROUND

Procalcitonin (ProCT) is becoming increasingly recognized as a mediator as well as a marker of sepsis. Serum ProCT concentrations rise soon after induction of sepsis and remain elevated over a prolonged period of time. In contrast, many pro-inflammatory cytokines, e.g., tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1beta), rise and decline early in the course of sepsis. Researchers have improved survival in animal models of sepsis by prophylactically blocking IL-1beta and TNF-alpha with immunotherapy, but therapeutic treatment has been less successful in clinical trials. We hypothesized that the sustained elevation of ProCT in the serum would allow for effective therapeutic immunoneutralization of this peptide late in the course of sepsis.

METHODS

Lethal polymicrobial sepsis was induced in 10 castrated, male Yorkshire pigs by intraabdominal spillage of cecal contents (1 gm/kg) and intraabdominal instillation of 2 x 10(11) cfu of a toxigenic strain of E. coli (O18:K1:H7). The treated group (n = 5) received an intravenous infusion of purified rabbit antiserum to the aminoterminus of porcine ProCT. The control group (n = 5) received nonreactive, purified rabbit IgG. The purified antiserum was infused to all animals 3 h after the induction of sepsis, at which time very severe physiologic dysfunction was manifest, and many of the animals appeared to be preterminal. Physiologic and metabolic parameters were measured until death or for 15 h after induction of sepsis, at which time all surviving animals were euthanized.

RESULTS

Therapeutic immunoneutralization of serum ProCT improved most measured physiologic and metabolic parameters in septic pigs. Specifically, there was a significant increase in mean arterial pressure, urine output and cardiac index in all animals treated with ProCT antibody. Serum creatinine was significantly lower in treated animals. Although acidosis was not as severe in treated animals, as indicated by higher pH values and lower lactate concentrations, these results did not achieve statistical significance. Significantly, 11 h after the induction of sepsis there was 100% mortality in the control group while only one animal in the treated group expired.

CONCLUSION

The prolonged elevation of ProCT concentrations in sepsis allows neutralization of this peptide to be effective during the course of this disorder. These findings suggest that immunoneutralization of ProCT may be a useful treatment in clinical situations where sepsis is already fully established.

Calcitonin precursors in the prediction of severity of acute pancreatitis on the day of admission

BACKGROUND

Calcitonin precursors are sensitive markers of inflammation and infection. The aim of this study was to evaluate the role of plasma calcitonin precursor levels on the day of admission in the prediction of severity of acute pancreatitis, and to compare this with the Acute Physiology And Chronic Health Evaluation (APACHE) II scoring system.

METHODS

Plasma concentrations of calcitonin precursors were determined on admission in 69 patients with acute pancreatitis. APACHE II scores were calculated on admission. Attacks were classified as mild (n = 55) or severe (n = 14) according to the Atlanta criteria. Plasma calcitonin precursor levels were determined with a sensitive radioimmunoassay.

RESULTS

On the day of hospital admission, plasma levels of calcitonin precursors were significantly greater in patients with a severe attack compared with levels in those with a mild attack of pancreatitis (median 64 versus 25 fmol/ml; P = 0.014), but the APACHE II scores were no different (median 9 versus 8; P = 0.2). The sensitivity, specificity, positive predictive and negative predictive values, and accuracy for the prediction of severe acute pancreatitis were 67, 89, 57, 93 and 85 per cent respectively for plasma calcitonin precursor levels higher than 48 fmol/ml, and 69, 45, 23, 86 and 50 per cent respectively for an APACHE II score greater than 7. Differences in the specificity and accuracy of the two prognostic indicators were significant (P < 0.001 and P = 0.001 respectively). A plasma calcitonin precursor concentration of more than 160 fmol/ml on admission was highly accurate (94 per cent) in predicting the development of septic complications and death.

CONCLUSION

The assay of plasma calcitonin precursors on the day of admission to hospital has the potential to provide a more accurate prediction of the severity of acute pancreatitis than the APACHE II scoring system.

Calcitonin gene-related peptide expression in sepsis: postulation of microbial infection-specific response elements within the calcitonin I gene promoter

BACKGROUND

Recently, we reported an unexpected ubiquitous expression of calcitonin (CT)-mRNA in a hamster peritonitis model of sepsis. Using this animal model,we undertook a study to further investigate the pattern of expression of the calcitonin I (CALC-I) gene and CT gene-related peptide (CGRP)-mRNA in sepsis.

METHODS

Live Escherichia coli impregnated in agar pellets were implanted in the peritoneal cavities of hamsters. Twelve hours after sepsis induction, the septic and healthy control animals were sacrificed and tissues and peritoneal macrophages were collected. CGRP-mRNA content was evaluated by reverse transcription polymerase chain reaction (RT-PCR), quantitated by the Taq-Man technique, and compared with the mRNA expression of CT, tumor necrosis factor alpha (TNF-alpha), and interleukin-6 (IL-6). The 5' untranslated regions of the mRNA and potential alternative splicing sites were identified by 5' rapid amplification of cDNA ends.

RESULTS

We found a tissue-wide, ubiquitous and uniform expression of CGRP-mRNA in all septic tissues examined. CGRP-mRNA was detectable by RT-PCR in various extraneuronal and extrathyroidal septic tissues, but not in healthy control tissues. As found for CT-mRNA in our earlier studies, CGRP-mRNA seemed to be more specifically up-regulated as compared with other classical cytokines (ie, II-6 and TNF-alpha). Importantly, the 5' untranslated sequence in control and septic thyroid was similar to the sequence obtained from septic spleen.

CONCLUSIONS

We postulate the presence of microbial infection-specific response elements in the CALC-I gene promotor, which, upon a specific stimulus, override the tissue-selective expression pattern. This new form of endocrine plasticity may be of importance in the response to systemic inflammation.

Plant-facilitated mobilization and translocation of weathered 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) from an agricultural soil

Field experiments were conducted to determine the uptake and translocation of highly weathered 2,2-bis(p-chlorophenyl)1,1-dichloroethylene (p,p'-DDE) from an agricultural soil. In soil containing known amounts of p,p'-DDE, experimental plots containing zucchini, pumpkin, or spinach were constructed. At destructive harvest, three soil fractions were collected that differed in the degree of influence exerted by the plant roots. The bulk soil was vegetation-free, the near-root zone was within the area encompassed by the roots, and the rhizosphere remained physically attached to the roots at harvest. For each crop, statistically significant decreases were found in the concentration of p,p'-DDE in either the near-root zone or the rhizosphere relative to the bulk soil, suggesting plant-facilitated mobilization and/or degradation of the residue. Plant tissues were analyzed to determine the extent of contaminant removal from the soil and the magnitude of translocation through the shoot system. The concentration of p,p'-DDE in the roots of both zucchini and pumpkin was more than an order of magnitude larger than the bulk soil concentration, followed by significant translocation through the plant tissues to the fruit. The data indicate that certain plants may effectively accumulate residues of persistent organic pollutants in their tissues, suggesting phytoremediation as a possible treatment strategy.

Plant-facilitated mobilization and translocation of weathered 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) from an agricultural soil

Field experiments were conducted to determine the uptake and translocation of highly weathered 2,2-bis(p-chlorophenyl)1,1-dichloroethylene (p,p'-DDE) from an agricultural soil. In soil containing known amounts of p,p'-DDE, experimental plots containing zucchini, pumpkin, or spinach were constructed. At destructive harvest, three soil fractions were collected that differed in the degree of influence exerted by the plant roots. The bulk soil was vegetation-free, the near-root zone was within the area encompassed by the roots, and the rhizosphere remained physically attached to the roots at harvest. For each crop, statistically significant decreases were found in the concentration of p,p'-DDE in either the near-root zone or the rhizosphere relative to the bulk soil, suggesting plant-facilitated mobilization and/or degradation of the residue. Plant tissues were analyzed to determine the extent of contaminant removal from the soil and the magnitude of translocation through the shoot system. The concentration of p,p'-DDE in the roots of both zucchini and pumpkin was more than an order of magnitude larger than the bulk soil concentration, followed by significant translocation through the plant tissues to the fruit. The data indicate that certain plants may effectively accumulate residues of persistent organic pollutants in their tissues, suggesting phytoremediation as a possible treatment strategy.

Effects of anti-inflammatory agents on serum levels of calcitonin precursors during human experimental endotoxemia

Calcitonin precursor (CTpr) levels are both markers and mediators of inflammation. The duration of their elevation after intravenous endotoxin challenge and the effects of anti-inflammatory therapies were studied in 52 subjects. CTpr levels maximized at 24 h in all subjects. At 7 days (n=4), after levels of acute-phase cytokines and C-reactive protein had normalized, CTpr levels remained 2-4-fold above baseline levels. The elimination half-life of CTpr levels ranged from 26.9 to 45.7 h. At 24 h, endotoxin and ibuprofen (compared with endotoxin alone) increased CTpr levels approximately 2-fold (P=.03), whereas soluble tumor necrosis factor receptor blunted the increase in CTpr levels by 2-3-fold (P=.0015). However, soluble interleukin-1 receptor failed to alter the increase in CTpr levels. Thus, the fact that anti-inflammatory agents may alter CTpr levels resulting from a single stimulus must be considered when CTpr is used as a clinical marker. Of importance, this study reveals that anti-inflammatory agents may modulate the CTpr level, which is a potential toxic mediator of inflammation.

Effect of solute concentration on sorption of polyaromatic hydrocarbons in soil: uptake rates

The effect of solute concentration on sorption kinetics may be a factor in determining bioavailability and transport of organic pollutants in soils and sediments, but there is conflict in the literature over whether sorption is concentration-dependent. Sorption of phenanthrene and pyrene to seven soils ranging in organic carbon (OC) content from 0.18 to 43.9% was studied. Careful analysis revealed that experimentally the normalized rate of approach to equilibrium for compounds exhibiting a concave-down (with respect to the solute concentration axis) nonlinear isotherm increases with concentration. However, the effect is rather small and is most apparent when the fraction of total solute finally taken up by the solid (F) is low. The explanation is rooted in the nonlinearity of the isotherm and the finite-bath condition of the experiment and can be expressed in terms of two opposing effects. On the one hand, the apparent diffusivity of a (concave-down) nonlinearly sorbing compound within particles increases with concentration because its affinity for the solid phase decreases with increasing concentration. On the other hand, rates in finite-bath reactors carried out at the same liquid/solid ratio will suffer from a batch process temporal bias called the "shrinking gradient" effect. It is an artifact of the methodology and is due to gradient driving forces that slow the sorption rate as F declines. In nonlinear cases F declines as concentration increases. The shrinking gradient effect vanishes as the liquid/solid ratio approaches infinity. Although this effect is self-correcting when an appropriate nonlinear diffusion model is applied, consensus about such models has not yet been achieved. To provide bounds for the shrinking gradient effect in finite-bath systems semiempirically, two models that give lower and upper bounds of the characteristic sorption time tau in the limit of infinite bath have been employed: (a) a wetting front model, which assumes sorption is rate-limited by molecular migration, and (b) a fast diffusion model, which assumes a mass-transfer resistance at the sorption site. The results are consistent with an intrinsic positive concentration dependence of sorption kinetics.

Influence of soil moisture on the sequestration of organic compounds in soil

A study was conducted as a part of continuing investigation of the effect of soil moisture on the sequestration of organic compounds aged in the soil. Here, experiments focused on the effects of moisture changes within the soil before, during, and after contaminant addition. The extractability of aged (68 d) phenanthrene was greater from soil that had been subjected to wetting and drying cycles prior to solute addition as compared to soil initially maintained at constant moisture. The recovery of phenanthrene added to moist soil was increased relative to extractability from soil that was air-dried at the time of the contaminant addition. Repeated wetting and drying of soil after the addition of atrazine or phenanthrene resulted in decreased extractability of the compounds as compared to samples maintained at constant moisture. A method for rapidly sequestering contaminants is proposed and may be useful in limiting the time required for laboratory studies involving "aged" contaminants. These data build upon the findings of earlier work from our laboratory and indicate that changes in the moisture conditions of soil can affect the availability of sequestered contaminants possibly through alterations in the structure of the natural solid.