Clinical onset and course, response to treatment and outcome in 24 patients with the cblE or cblG remethylation defect complemented by genetic and in vitro enzyme study data.

BACKGROUND: The cobalamin E (cblE) (MTRR, methionine synthase reductase) and cobalamin G (cblG) (MTR, methionine synthase) defects are rare inborn errors of cobalamin metabolism leading to impairment of the remethylation of homocysteine to methionine. METHODS: Information on clinical and laboratory data at initial full assessment and during the course of the disease, treatment, outcome and quality of life was obtained in a survey-based, retrospective study from physicians caring for patients with the CblE or CblG defect. In addition, data on enzyme studies in cultured skin fibroblasts and mutations in the MTRR and MTR gene were analysed. RESULTS: In 11 cblE and 13 cblG patients, failure to thrive, feeding problems, delayed milestones, muscular hypotonia, cognitive impairment and macrocytic anaemia were the most frequent symptoms. Delay in diagnosis depended on age at first symptom and clinical pattern at presentation and correlated significantly with impaired communication abilities at follow-up. Eighteen/22 patients presented with brain atrophy or white matter disease. Biochemical response to treatment with variable combinations of betaine, cobalamin, folate was significant. The overall course was considered improving (n = 8) or stable (n = 15) in 96% of patients, however the average number of CNS symptoms per patient increased significantly over time and 16 of 23 patients were classified as developmentally delayed or severely handicapped. In vitro enzyme analysis data showed no correlation with outcome. Predominantly private mutations were detected and no genotype- phenotype correlations evident. CONCLUSIONS: The majority of patients with the cblE and cblG defect show limited clinical response to treatment and have neurocognitive impairment.

Influence of soil geochemical and physical properties on chromium(VI) sorption and bioaccessibility.

The Department of Defense (DoD) is faced with the daunting task of possible remediation of numerous soil-Cr(VI) contaminated sites throughout the continental U.S. The primary risk driver at these sites is hand-to-mouth ingestion of contaminated soil by children. In the following study we investigate the impact of soil geochemical and physical properties on the sorption and bioaccessibility of Cr(VI) in a vast array of soils relevant to neighboring DoD sites. For the 35 soils used in this study, A-horizon soils typically sorbed significantly more Cr(VI) relative to B-horizon soils. Multiple linear regression analysis suggested that Cr(VI) sorption increased with increasing soil total organic C (TOC) and decreasing soil pH. The bioaccessibility of total Cr (CrT) and Cr(VI) on the soils decreased with increasing soil TOC content. As the soil TOC content approached 0.4%, the bioaccessibility of soil bound Cr systematically decreased from approximately 65 to 10%. As the soil TOC content increased from 0.4 to 4%, the bioaccessibility of Cr(VI) and CrT remained relatively constant at approximately 4% and 10%, respectively. X-ray absorption near edge structure (XANES) spectroscopy suggested that Cr(VI) reduction to Cr(III) was prevalent and that the redox transformation of Cr(VI) increased with increasing soil TOC. XANES confirmed that nearly all bioaccessible soil Cr was the Cr(VI) moiety. Multiple linear regression analysis suggested that the bioaccessibility of Cr(VI) and its reduced counterpart Cr(III), decreased with increasing soil TOC and increasing soil pH. This is consistent with the observation that the reduction reaction and formation of Cr(III) increased with increasing soil TOC and that Cr(III) was significantly less bioaccessible relative to Cr(VI). The model was found to adequately describe CrT bioaccessibility in soils from DoD facilities where Cr(VI) contaminated sites were present. The results of this study illustrate the importance of soil properties on Cr(VI) sorption and bioassessability and help define what soil types have the greatest risk associated with Cr(VI) exposure.

Estimating reaction rate coefficients within a travel-time modeling framework.

A generalized, efficient, and practical approach based on the travel-time modeling framework is developed to estimate in situ reaction rate coefficients for groundwater remediation in heterogeneous aquifers. The required information for this approach can be obtained by conducting tracer tests with injection of a mixture of conservative and reactive tracers and measurements of both breakthrough curves (BTCs). The conservative BTC is used to infer the travel-time distribution from the injection point to the observation point. For advection-dominant reactive transport with well-mixed reactive species and a constant travel-time distribution, the reactive BTC is obtained by integrating the solutions to advective-reactive transport over the entire travel-time distribution, and then is used in optimization to determine the in situ reaction rate coefficients. By directly working on the conservative and reactive BTCs, this approach avoids costly aquifer characterization and improves the estimation for transport in heterogeneous aquifers which may not be sufficiently described by traditional mechanistic transport models with constant transport parameters. Simplified schemes are proposed for reactive transport with zero-, first-, nth-order, and Michaelis-Menten reactions. The proposed approach is validated by a reactive transport case in a two-dimensional synthetic heterogeneous aquifer and a field-scale bioremediation experiment conducted at Oak Ridge, Tennessee. The field application indicates that ethanol degradation for U(VI)-bioremediation is better approximated by zero-order reaction kinetics than first-order reaction kinetics.

Estimating kinetic mass transfer by resting-period measurements in flow-interruption tracer tests.

Flow-interruption tracer test is an effective approach to identify kinetic mass transfer processes for solute transport in subsurface media. By switching well pumping and resting, one may alter the dominant transport mechanism and generate special concentration patterns for identifying kinetic mass transfer processes. In the present research, we conducted three-phase (i.e., pumping, resting, and pumping) field-scale flow-interruption tracer tests using a conservative tracer bromide in a multiple-well system installed at the US Department of Energy Site, Oak Ridge, TN. A novel modeling approach based on the resting-period measurements was developed to estimate the mass transfer parameters. This approach completely relied on the measured breakthrough curves without requiring detailed aquifer characterization and solving transport equations in nonuniform, transient flow fields. Additional measurements, including hydraulic heads and tracer concentrations in large pumping wells, were taken to justify the assumption that mass transfer processes dominated concentration change during resting periods. The developed approach can be conveniently applied to any linear mass transfer model. Both first-order and multirate mass transfer models were applied to analyze the breakthrough curves at various monitoring wells. The multirate mass transfer model was capable of jointly fitting breakthrough curve behavior, showing the effectiveness and flexibility for incorporating aquifer heterogeneity and scale effects in upscaling effective mass transfer models.

Cerebral venous sinus thrombosis: a case series including thrombolysis.

BACKGROUND: Cerebral venous sinus thrombosis (CVST) in children is associated with a high incidence of serious morbidity and mortality. The presenting features are variable. It can be diagnostically challenging and the optimal treatment is uncertain. AIM: To describe the features of a series of children with CVST treated in a single paediatric neurology centre and to discuss the role of local thrombolysis. METHODS: Electronic databases were searched using diagnostic labels and International Classification of Diseases (ICD) codes to identify children aged 1 month to under 17 years with CVST. Their records were reviewed. RESULTS: 21 children were identified over a period of 8.25 years with a median age of 7.1 years. The presenting symptoms included headache (15 children), vomiting (14 children) and visual disturbance (eight children). Signs found included papilloedema (16 children), fever (six children) and sixth nerve palsy (six children). The most common underlying condition was middle ear infection (13 children). All cases received unfractionated heparin and four severe cases received local pharmacological thrombolysis. 48% of cases had an adverse outcome (death, chronic intracranial hypertension, residual hemiparesis or sixth nerve palsy). DISCUSSION: CVST has non-specific presenting features and a high risk of significant morbidity. CVST is typically found in association with a predisposing condition. Although heparin is the mainstay of treatment, thrombolysis may reverse deterioration as seen in three cases in this series. However, there is insufficient evidence to recommend the routine use of thrombolysis at present.

Estimating first-order reaction rate coefficient for transport with nonequilibrium linear mass transfer in heterogeneous media.

A travel-time based approach is developed for estimating first-order reaction rate coefficients for transport with nonequilibrium linear mass transfer in heterogeneous media. Tracer transport in the mobile domain is characterized by a travel-time distribution, and mass transfer rates are described by a convolution product of concentrations in the mobile domain and a memory function rather than predefining the mass transfer model. A constant first-order reaction is assumed to occur only in the mobile domain. Analytical solutions in Laplace domain can be derived for both conservative and reactive breakthrough curves (BTCs). Temporal-moment analyses are presented by using the first and second moments of conservative and reactive BTCs and the mass consumption of the reactant for an inverse Gaussian travel-time distribution. In terms of moment matching, there is no need for one to specify the mass transfer model. With the same capacity ratio and the mean retention time, all mass transfer models will lead to the same moment-derived reaction rate coefficients. In addition, the consideration of mass transfer generally yields larger estimations of the reaction rate coefficient than models ignoring mass transfer. Furthermore, the capacity ratio and the mean retention time have opposite influences on the estimation of the reaction rate coefficient: the first-order reaction rate coefficient is positively linearly proportional to the capacity ratio, but negatively linearly proportional to the mean retention time.

Myoglobinuria in boys with Duchenne muscular dystrophy on corticosteroid therapy.

Myoglobinuria is a recognised complication of Duchenne muscular dystrophy (DMD), but has only once been reported in ambulant boys on corticosteroid therapy [Dubowitz V, Kinali M, Main M, Mercuri E, Muntoni F. Remission of clinical signs in early Duchenne muscular dystrophy on intermittent low-dosage prednisolone therapy. Eur J Paediatr Neurol 2002;6(3):153-9.]. We present three prednisolone-treated boys with myoglobinuria and in two cases this was recurrent. All three showed improved motor performance in response to the introduction of corticosteroids. The greater activity of steroid-treated individuals may place their dystrophin-deficient muscles under greater mechanical stress, predisposing to further muscle fibre damage and consequent myoglobinuria. Families and physicians need to have an increased awareness of this possibility and of the appropriate management of myoglobinuria.

Transport of Sr2+ and SrEDTA2- in partially-saturated and heterogeneous sediments.

Strontium-90 has migrated deep into the unsaturated subsurface beneath leaking storage tanks in the Waste Management Areas (WMA) at the U.S. Department of Energy's (DOE) Hanford Reservation. Faster than expected transport of contaminants in the vadose zone is typically attributed to either physical hydrologic processes such as development of preferential flow pathways, or to geochemical processes such as the formation of stable, anionic complexes with organic chelates, e.g., ethylenediaminetetraacetic acid (EDTA). The goal of this paper is to determine whether hydrological processes in the Hanford sediments can influence the geochemistry of the system and hence control transport of Sr(2+) and SrEDTA(2-). The study used batch isotherms, saturated packed column experiments, and an unsaturated transport experiment in an undisturbed core. Isotherms and repacked column experiments suggested that the SrEDTA(2-) complex was unstable in the presence of Hanford sediments, resulting in dissociation and transport of Sr(2+) as a divalent cation. A decrease in sorption with increasing solid:solution ratio for Sr(2+) and SrEDTA(2-) suggested mineral dissolution resulted in competition for sorption sites and the formation of stable aqueous complexes. This was confirmed by detection of MgEDTA(2-), MnEDTA(2-), PbEDTA(2-), and unidentified Sr and Ca complexes. Displacement of Sr(2+) through a partially-saturated undisturbed core resulted in less retardation and more irreversible sorption than was observed in the saturated repacked columns, and model results suggested a significant reservoir (49%) of immobile water was present during transport through the heterogeneous layered sediments. The undisturbed core was subsequently disassembled along distinct bedding planes and subjected to sequential extractions. Strontium was unequally distributed between carbonates (49%), ion exchange sites (37%), and the oxide (14%) fraction. An inverse relationship between mass wetness and Sr suggested that sandy sediments of low water content constituted the immobile flow regime. Our results suggested that the sequestration of Sr(2+) in partially-saturated, heterogeneous sediments was most likely due to the formation of immobile water in drier regions having low hydraulic conductivities.

Distribution of uranium contamination in weathered fractured saprolite/shale and ground water.

The objective of this study was to determine how structure, stratigraphy, and weathering influence fate and transport of contaminants (particularly U) in the ground water and geologic material at the Department of Energy (DOE) Environmental Remediation Sciences Department (ERSD) Field Research Center (FRC). Several cores were collected near four former unlined adjoining waste disposal ponds. The cores were collected, described, analyzed for U, and compared with ground water geochemistry from surrounding multilevel wells. At some locations, acidic U-contaminated ground water was found to preferentially flow in small remnant fractures weathering the surrounding shale (nitric acid extractable U [U(NA)] usually < 50 mg kg(-1)) into thin (<25 cm) Fe oxide-rich clayey seams that retain U (U(NA) 239 to 375 mg kg(-1)). However, greatest contaminant transport occurs in a 2 to 3 m thick more permeable stratigraphic transition zone located between two less permeable, and generally less contaminated zones consisting of (i) overlying unconsolidated saprolite (U(NA) < 0.01 to 200 mg kg(-1)) and (ii) underlying less-weathered bedrock (U(NA) generally < 0.01 to 7 mg kg(-1)). In this transition zone, acidic (pH < 4) U-enriched ground water (U of 38 mg L(-1)) has weathered away calcite veins resulting in greater porosity, higher hydraulic conductivity, and higher U contamination (U(NA) 106 to 745 mg kg(-1)) of the weathered interbedded shale and sandstone. These characteristics of the transition zone produce an interval with a high flux of contaminants that could be targeted for remediation.

Phylogenetic and functional biomakers as indicators of bacterial community responses to mixed-waste contamination.

Few studies have demonstrated changes in community structure along a contaminant plume in terms of phylogenetic, functional, and geochemical changes, and such studies are essential to understand how a microbial ecosystem responds to perturbations. Clonal libraries of multiple genes (SSU rDNA, nirK, nirS, amoA, pmoA, and dsrAB) were analyzed from groundwater samples (n = 6) that varied in contaminant levels, and 107 geochemical parameters were measured. Principal components analyses (PCA) were used to compare the relationships among the sites with respect to the biomarker (n = 785 for all sequences) distributions and the geochemical variables. A major portion of the geochemical variance measured among the samples could be accounted for by tetrachloroethene, 99Tc, No3, SO4, Al, and Th. The PCA based on the distribution of unique biomarkers resulted in different groupings compared to the geochemical analysis, but when the SSU rRNA gene libraries were directly compared (deltaC(xy) values) the sites were clustered in a similar fashion compared to geochemical measures. The PCA based upon functional gene distributions each predicted different relationships among the sites, and comparisons of Euclidean distances based upon diversity indices for all functional genes (n = 432) grouped the sites by extreme or intermediate contaminant levels. The data suggested that the sites with low and high perturbations were functionally more similar than sites with intermediate conditions, and perhaps captured the overall community structure better than a single phylogenetic biomarker. Moreover, even though the background site was phylogenetically and geochemically distinct from the acidic sites, the extreme conditions of the acidic samples might be more analogous to the limiting nutrient conditions of the background site. An understanding of microbial community-level responses within an ecological framework would provide better insight for restoration strategies at contaminated field sites.

Changes in bacterial community structure correlate with initial operating conditions of a field-scale denitrifying fluidized bed reactor.

High levels of nitrate are present in groundwater migrating from the former waste disposal ponds at the Y-12 National Security Complex in Oak Ridge, TN. A field-scale denitrifying fluidized bed reactor (FBR) was designed, constructed, and operated with ethanol as an electron donor for the removal of nitrate. After inoculation, biofilms developed on the granular activated carbon particles. Changes in the bacterial community of the FBR were evaluated with clone libraries (n = 500 partial sequences) of the small-subunit rRNA gene for samples taken over a 4-month start-up period. Early phases of start-up operation were characterized by a period of selection, followed by low diversity and predominance by Azoarcus-like sequences. Possible explanations were high pH and nutrient limitations. After amelioration of these conditions, diversification increased rapidly, with the appearance of Dechloromonas, Pseudomonas, and Hydrogenophaga sequences. Changes in NO3, SO4, and pH also likely contributed to shifts in community composition. The detection of sulfate-reducing-bacteria-like sequences closely related to Desulfovibrio and Desulfuromonas in the FBR have important implications for downstream applications at the field site.

Natural attenuation of trichloroethylene in fractured shale bedrock.

This paper describes one of the first well-documented field examples of natural attenuation of trichloroethylene (TCE) in groundwater in a fractured shale bedrock. The study was carried out adjacent to a former waste burial site in Waste Area Grouping 5 (WAG5) on the Oak Ridge Reservation, Oak Ridge, TN. A contaminant plume containing TCE and its daughter products were detected downgradient from the buried waste pits, with most of the contamination occurring in the upper 6 m of the bedrock. The monitoring well array consists of a 35-m-long transect of multilevel sampling wells, situated along a line between the waste pits and a seep which discharges into a small stream. Concentrations of volatile organic carbons (VOCs) were highest in the waste trenches and decreased with distance downgradient towards the seep. Sampling wells indicated the presence of overlapping plumes of TCE, cis-dichloroethylene (cDCE), vinyl chloride (VC), ethylene, ethane, and methane, with the daughter products extending further downgradient than the parent (TCE). This type of distribution suggests anaerobic biodegradation. Measurements of redox potential at the site indicated that iron-reduction, sulfate reduction, and potentially methanogensis were occurring and are conducive to dechlorination of TCE. Bacteria enrichment of groundwater samples revealed the presence of methanotrophs, methanogens, iron-reducing bacteria and sulfate-reducing bacteria, all of which have previously been implicated in anaerobic biodegradation of TCE. 16S rDNA sequence from DNA extracted from two wells were similar to sequences of organisms previously implicated in the anaerobic biodegradation of chlorinated solvents. The combined data strongly suggest that anaerobic biodegradation of the highly chlorinated compounds is occurring. Aerobic biodegradation may also be occurring in oxygenated zones, including near a seep where groundwater exits the site, or in the upper bedrock during seasonal fluctuations in water table elevation and oxygen levels.

An EP2 receptor-selective prostaglandin E2 agonist induces bone healing.

The morbidity and mortality associated with impaired/delayed fracture healing remain high. Our objective was to identify a small nonpeptidyl molecule with the ability to promote fracture healing and prevent malunions. Prostaglandin E2 (PGE2) causes significant increases in bone mass and bone strength when administered systemically or locally to the skeleton. However, due to side effects, PGE2 is an unacceptable therapeutic option for fracture healing. PGE2 mediates its tissue-specific pharmacological activity via four different G protein-coupled receptor subtypes, EP1, -2, -3, and -4. The anabolic action of PGE2 in bone has been linked to an elevated level of cAMP, thereby implicating the EP2 and/or EP4 receptor subtypes in bone formation. We identified an EP2 selective agonist, CP-533,536, which has the ability to heal canine long bone segmental and fracture model defects without the objectionable side effects of PGE2, suggesting that the EP2 receptor subtype is a major contributor to PGE2's local bone anabolic activity. The potent bone anabolic activity of CP-533,536 offers a therapeutic alternative for the treatment of fractures and bone defects in patients.

Influence of soil geochemical and physical properties on the sorption and bioaccessibility of chromium(III).

There are numerous Cr(III)-contaminated sites on Department of Defense (DoD) and Department of Energy (DOE) lands that are awaiting possible clean up and closure. Ingestion of contaminated soil by children is the risk driver that generally motivates the likelihood of site remediation. The purpose of this study was to develop a simple statistical model based on common soil properties to estimate the hioaccessibility of Cr(III)-contaminated soil upon ingestion. Thirty-five uncontaminated soils from seven major soil orders, whose properties were similar to numerous U.S. DoD contaminated sites, were treated with Cr(III) and aged. Statistical analysis revealed that Cr(III) sorption (e.g., adsorption and surface precipitation) by the soils was strongly correlated with the clay content, total inorganic C, pH, and the cation exchange capacity of the soils. Soils with higher quantities of clay, inorganic C (i.e., carbonates), higher pH, and higher cation exchange capacity generally sequestered more Cr(III). The amount of Cr(III) bioaccessible from the treated soils was determined with a physiologically based extraction test (PBET) that was designed to simulate the digestive process of the stomach. The bioaccessibility of Cr(III) varied widely as a function of soil type with most soils limiting bioaccessibility to <45 and <30% after I and 100 d soil-Cr aging, respectively. Statistical analysis showed the bioaccessibility of Cr(III) on soil was again related to the clay and total inorganic carbon (TIC) content of the soil. Bioaccessibility decreased as the soil TIC content increased and as the clay content decreased. The model yielded an equation based on common soil properties that could be used to predict the Cr(III) bioaccessibility in soils with a reasonable level of confidence.

Influence of hydrological and geochemical processes on the transport of chelated metals and chromate in fractured shale bedrock.

Field-scale processes governing the transport of chelated radionuclides in groundwater remain conceptually unclear for highly structured, heterogeneous environments. The objectives of this research were to provide an improved understanding and predictive capability of the hydrological and geochemical mechanisms that control the transport behavior of chelated radionuclides and metals in anoxic subsurface environments that are complicated by fracture flow and matrix diffusion. Our approach involved a long-term, steady-state natural gradient field experiment where nonreactive Br- and reactive 57Co(II)EDTA2- 109CdEDTA2-, and 51Cr(VI) were injected into a fracture zone of a contaminated fractured shale bedrock. The spatial and temporal distribution of the tracer and solutes was monitored for 500 days using an array of groundwater sampling wells instrumented within the fast-flowing fracture regime and a slower flowing matrix regime. The tracers were preferentially transported along strike-parallel fractures coupled with the slow diffusion of significant tracer mass into the bedrock matrix. The chelated radionuclides and metals were significantly retarded by the solid phase with the mechanisms of retardation largely due to redox reactions and sorption coupled with mineral-induced chelate-radionuclide dissociation. The formation of significant Fe(III)EDTA byproduct that accompanied the dissociation of the radionuclide-chelate complexes was believed to be the result of surface interactions with biotite which was the only Fe(III)-bearing mineral phase present in these Fe-reducing environments. These results counter current conceptual models that suggest chelated contaminants move conservatively through Fe-reducing environments since they are devoid of Fe-oxyhydroxides that are known to aggressively compete for chelates in oxic regimes. Modeling results further demonstrated that chelate-radionuclide dissociation reactions were most prevalent along fractures where accelerated weathering processes are expected to expose more primary minerals than the surrounding rock matrix. The findings of this study suggest that physical retardation mechanisms (i.e. diffusion) are dominant within the matrix regime, whereas geochemical retardation mechanisms are dominant within the fracture regime.

The importance of testing for adrenoleucodystrophy in males with idiopathic Addison's disease.

X linked adrenoleucodystrophy (X-ALD) is considered to be a rare cause of Addison's disease, although several small series suggest a high incidence in young Addisonian males. A survey in the south west of England identified 12 male patients diagnosed with Addison's disease in the period 1987-99. In 10 of these (83%) X-ALD was the underlying cause; the other two were of autoimmune aetiology. Five boys had developed Addison's disease subsequent to the diagnosis of X-ALD. Of the remaining five, in three boys the diagnosis of X-ALD was considerably delayed (by six months to two years from that of Addison's disease) and in two it was only made as a result of this survey. We also identified a patient who presented with Addison's disease at the age of 5 years but was only diagnosed as having X-ALD at the age of 34 years; in the interim his diagnosis of adrenomyeloneuropathy had been missed. Our experience highlights the absolute necessity of measuring very long chain fatty acids in all males with idiopathic Addison's disease.

Cryoelectron-microscopy image reconstruction of symmetry mismatches in bacteriophage phi29.

A method has been developed for three-dimensional image reconstruction of symmetry-mismatched components in tailed phages. Although the method described here addresses the specific case where differing symmetry axes are coincident, the method is more generally applicable, for instance, to the reconstruction of images of viral particles that deviate from icosahedral symmetry. Particles are initially oriented according to their dominant symmetry, thus reducing the search space for determining the orientation of the less dominant, symmetry-mismatched component. This procedure produced an improved reconstruction of the sixfold-symmetric tail assembly that is attached to the fivefold-symmetric prolate head of phi29, demonstrating that this method is capable of detecting and reconstructing an object that included a symmetry mismatch. A reconstruction of phi29 prohead particles using the methods described here establishes that the pRNA molecule has fivefold symmetry when attached to the prohead, consistent with its proposed role as a component of the stator in the phi29 DNA packaging motor.