Ecotoxicity evaluation using the avoidance response of the oribatid mite Oppia nitens (Acari: Oribatida) in bioplastics, microplastics, and contaminated Superfund field sites.

Bioplastics are considered sustainable alternatives to conventional microplastics which are recognized as a threat to terrestrial ecosystems. However, little is known about the potential ecotoxicological effects of bioplastics on soil fauna and ecosystems. The present study assessed the toxicity of microplastics [Polystyrene (PS), Polyethylene (PE)] and bioplastics [Polyvinyl alcohol (PVA), Sodium polyacrylate (NaPa) on a key soil fauna Oppia nitens, a soil oribatid mite, and investigated the ecological relevance of O. nitens avoidance response as a valuable tool for the risk assessment of contaminated soils such as the Superfund sites. Findings showed that the mites' net response indicated avoidance behavior such that in most cases as concentrations of micro- and bioplastics increased, so did the avoidance responses. The avoidance EC50 endpoints showed PS < PE < PVA < NaPa, indicating higher deleterious effects of microplastics. High toxicity of PS in soils to O. nitens at EC50 of 165 (±25) mg/kg compared to bioplastics and other known contaminants poses an enormous threat to soil. For bioplastics in this study, there were no significant avoidances at concentrations up to 16,200 mg/kg compared to PS and PE which showed avoidance responses at 300 and 9000 mg/kg respectively, implying that bioplastics might be relatively safer to soil mites compared to conventional microplastics. Also, results indicated that long-term heavy metal pollution such as in contaminated Superfund sites decreased microbial biomass; a useful bioindicator of soil pollution. Furthermore, O. nitens avoidance of heavy metals contaminated sites demonstrated the ecological relevance of avoidance response test when assessing the habitat integrity of contaminated soil. The present study further supports the inclusion of the oribatid mite, O. nitens in the ecological risk assessment of contaminants in soil.

Prognostic Factors for Outcome in Localized Extremity Rhabdomyosarcoma. Pooled Analysis from Four International Cooperative Groups.

BACKGROUND: Extremity rhabdomyosarcomas do not always show satisfactory outcomes. We analyzed data from 643 patients treated in 14 studies conducted by European and North American groups between 1983 and 2004 to identify factors predictive of outcome. PROCEDURE: Clinical factors, including age; histology; site of primary (hand and foot vs. other); size; invasiveness (T stage); nodal involvement (N stage); and treatment factors, including post-surgical group; chemotherapy type and duration; radiotherapy; and treatment (before or after 1995); were evaluated for impact on overall survival (OS). RESULTS: 5-year OS were 67% (se 1.8). Multivariate analysis showed that lower OS correlated with age >3 years, T2 and N1 stage, incomplete initial surgery, treatment before 1995, and European cooperative group treatment. Patients with gross residual disease after initial incomplete resection/biopsy had similar outcomes in both continental groups. The better global survival of patients treated in American studies was accounted for by differences in outcome in the subset of those with grossly resected tumors (OS 86% [se 3] for COG patients vs. 68% [se 4] for European patients (P = 0.004)). When excluding chemotherapy duration from the model, analysis in this subset of patients showed that cooperative group (P = 0.001), site (P = 0.001), and T stage (P = 0.05) were all significant. However, after adding duration of chemotherapy (≥27 weeks) to the model, only primary site remained significant (P = 0.006). CONCLUSION: This meta-analysis confirms the role of many established prognostic factors but identifies for the first time that chemotherapy duration may have an impact on outcome in patients with grossly resected tumors.

Spectroscopic and computational studies of cobalamin species with variable lower axial ligation: implications for the mechanism of Co-C bond activation by class I cobalamin-dependent isomerases.

5'-deoxyadenosylcobalamin (coenzyme B12, AdoCbl) serves as the cofactor for several enzymes that play important roles in fermentation and catabolism. All of these enzymes initiate catalysis by promoting homolytic cleavage of the cofactor's Co-C bond in response to substrate binding to their active sites. Despite considerable research efforts, the role of the lower axial ligand in facilitating Co-C bond homolysis remains incompletely understood. In the present study, we characterized several derivatives of AdoCbl and its one-electron reduced form, Co(II)Cbl, by using electronic absorption and magnetic circular dichroism spectroscopies. To complement our experimental data, we performed computations on these species, as well as additional Co(II)Cbl analogues. The geometries of all species investigated were optimized using a quantum mechanics/molecular mechanics method, and the optimized geometries were used to compute absorption spectra with time-dependent density functional theory. Collectively, our results indicate that a reduction in the basicity of the lower axial ligand causes changes to the cofactor's electronic structure in the Co(II) state that replicate the effects seen upon binding of Co(II)Cbl to Class I isomerases, which replace the lower axial dimethylbenzimidazole ligand of AdoCbl with a protein-derived histidine (His) residue. Such a reduction of the basicity of the His ligand in the enzyme active site may be achieved through proton uptake by the catalytic triad of conserved residues, DXHXGXK, during Co-C bond homolysis.

Probing the nature of the Co(III) ion in corrins: the structural and electronic properties of dicyano- and aquacyanocobyrinic acid heptamethyl ester and a stable yellow dicyano- and aquacyanocobyrinic acid heptamethyl ester.

A stable yellow derivative of cobyrinic acid heptamethyl ester, (5R,6R)-Coα,Coß-dicyano-5,6-dihydro-5-hydroxy-heptamethylcob(III)yrinate-c,6-lactone (DCSYCbs), was prepared from dicyanocobyrinic acid heptamethyl ester (DCCbs). The C5 carbon is oxidized and the c side chain cyclized to form a lactone at C6; the 13 atom, 14 π-e(-) delocalized system of corrins is interrupted, giving a triazamethine system with four conjugated double bonds between N22 and N24 and an isolated double bond between N21 and C4. Stable yellow aquacyanocobyrinic acid heptamethyl ester (ACSYCbs) was prepared by driving off HCN with N(2) in a methanol/acetic acid solution. The electronic spectra of DCCbs and DCSYCbs appear similar except that the bands in DCSYCbs are shifted to shorter wavelengths and the γ-band is much less intense. The experimental spectra were adequately modeled using TD-DFT at the PBE1PBE/6-311G(d,p) level of theory. DCSYCbs crystallizes in the space group P2(1)2(1)2(1) (R(1) = 6.08%) with Z = 4, including one methanol solvent molecule and one water molecule per cobester. The addition of a hydroxyl group at C5 causes loss of the double bond between C5 and C6 and elongation of the C5-C6 bond. From a combination of two-dimensional (1)H TOCSY and ROESY NMR spectra and (1)H/(13)C HSQC and HMBC data, the complete (1)H and (13)C NMR assignments of DCSYCbs were possible, except for two of the ester methyl groups and the (13)C resonances of the two axial cyanide ligands. The latter were assigned using relative chemical shifts calculated by GIAO-DFT methods. The (59)Co resonance of DCCbs was observed at 4074 ppm while that of DCSYCbs is shifted downfield to 4298 ppm. Comparison with available (59)Co data of analogous systems suggests that the more π-conjugated corrin of DCCbs interacts more strongly with the metal than the less extensively conjugated macrocycle of DCSYCbs. As the strength of the interaction between Co(III) and an equatorial macrocycle increases, ν(CN) of axially coordinated CN(-) shifts to lower frequency; in DCSYCbs and DCCbs ν(CN) occurs at 2138 and 2123 cm(-1), respectively. Hence the corrin ligand in DCCbs interacts more strongly with the metal than the stable yellow corrin ligand, with its diminished conjugation. The UV-vis spectral data and DFT-calculated MOs are consistent with greater overlap between the corrin and the metal orbitals in DCCbs relative to DCSYCbs, which gives the metal in the former a softer, more covalent character.

Prognostic significance and tumor biology of regional lymph node disease in patients with rhabdomyosarcoma: a report from the Children's Oncology Group.

PURPOSE: Regional lymph node disease (RLND) is a component of the risk-based treatment stratification in rhabdomyosarcoma (RMS). The purpose of this study was to determine the contribution of RLND to prognosis for patients with RMS. PATIENTS AND METHODS: Patient characteristics and survival outcomes for patients enrolled onto Intergroup Rhabdomyosarcoma Study IV (N = 898, 1991 to 1997) were evaluated among the following three patient groups: nonmetastatic patients with clinical or pathologic negative nodes (N0, 696 patients); patients with clinical or pathologic positive nodes (N1, 125 patients); and patients with a single site of metastatic disease (77 patients). RESULTS: Outcomes for patients with nonmetastatic alveolar N0 RMS were significantly better than for patients with N1 RMS (5-year failure-free survival [FFS], 73% v 43%, respectively; 5-year overall survival [OS], 80% v 46%, respectively; P < .001). Patients with a single site of alveolar metastasis had even worse FFS and OS (23% FFS and OS, P = .01) when compared with patients with N1 RMS; however, the differences was not as large as the differences between patients with N0 RMS and N1 RMS. For embryonal RMS, there was no statistically significant difference in FFS or OS (P = .41 and P = .77, respectively) for patients with N1 versus N0 RMS. Gene array analysis of primary tumor specimens identified that genes associated with the immune system and antigen presentation were significantly increased in N1 versus N0 alveolar RMS. CONCLUSION: RLND alters prognosis for alveolar but not embryonal RMS. For patients with N1 disease and alveolar histology, outcomes were more similar to distant metastatic disease rather than local disease. Current data suggest that more aggressive therapy for patients with alveolar N1 RMS may be warranted.

Regional nodal involvement and patterns of spread along in-transit pathways in children with rhabdomyosarcoma of the extremity: a report from the Children's Oncology Group.

PURPOSE: To evaluate the incidence and prognostic factors for regional failure, with attention to the in-transit pathways of spread, in children with nonmetastatic rhabdomyosarcoma of the extremity. METHODS AND MATERIALS: The Intergroup rhabdomyosarcoma studies III, IV-Pilot, and IV enrolled 226 children with rhabdomyosarcoma of the extremity. Failure at the in-transit (epitrochlear/brachial and popliteal) and proximal (axillary/infraclavicular and inguinal/femoral) lymph nodes was evaluated. The median follow-up for the surviving patients was 10.4 years. RESULTS: Of the 226 children, 55 (24%) had clinical or pathologic evidence of either in-transit and/or proximal lymph node involvement at diagnosis. The actuarial 5-year risk of regional failure was 12%. The prognostic factors for poor regional control were female gender and lymph node involvement at diagnosis. In the 116 patients with a distal extremity primary tumor, 5% had in-transit lymph node involvement at diagnosis. The estimated 5-year incidences of in-transit and proximal nodal failure was 12% and 8%, respectively. The in-transit failure rate was 0% for patients who underwent radiotherapy and/or underwent lymph node sampling of the in-transit nodal site but was 15% for those who did not (p = .07). However, the 5-year event-free survival rate did not differ between these two groups (64% vs. 55%, respectively, p = .47). CONCLUSION: The high incidence of regional involvement necessitates aggressive identification and treatment of regional lymph nodes in patients with rhabdomyosarcoma of the extremity. In patients with distal extremity tumors, in-transit failures were as common as failures in more proximal regional sites. Patients who underwent complete lymph node staging with appropriate radiotherapy to the in-transit nodal site, if indicated, were at a slightly lower risk of in-transit failure.

Treatment results for patients with localized, completely resected (Group I) alveolar rhabdomyosarcoma on Intergroup Rhabdomyosarcoma Study Group (IRSG) protocols III and IV, 1984-1997: a report from the Children's Oncology Group.

PURPOSE: To assess local control, event-free survival (EFS), and overall survival (OS) rates in 71 patients with localized, completely resected (Group I) alveolar rhabdomyosarcoma (ALV RMS) and their relation to radiation therapy (RT) on IRSG Protocols III and IV, 1984-1997. METHODS: Chart review and standard statistical procedures. PATIENTS AND TUMORS: Patients were 1-18 years at diagnosis (median, 6 years). Primary tumor sites were extremity/trunk (N = 54), head/neck (N = 9), genitourinary tract (N = 7), and perineum (N = 1). Thirty patients received VA +/- C with RT; 41 received VA +/- C alone. RT was assigned, not randomized. RESULTS: Fifty-four patients had Stage 1 (favorable site, any size) or Stage 2 (unfavorable site, < or = 5 cm) tumors. Eight-year EFS was 90%, with 100% local control for 17 patients given RT. Eight-year EFS was 88%, with 92% local control for 37 patients without RT; P = 0.52 for EFS comparisons, 0.3 for local control comparisons. In 17 Stage 3 patients (unfavorable site, tumors >5 cm, N0), 8-year EFS was 84% with 100% local control in 13 patients given RT; 8-year EFS was only 25% and local control 50% in 4 patients without RT. Local recurrence was the most common site of first failure in non-irradiated patients. CONCLUSION: Patients with Stage 1-2 ALV RMS had slightly but statistically insignificantly improved local control, EFS, and OS rates when local RT was given. The need for local RT in Stage 1-2 patients deserves evaluation in a randomized study. Local control, EFS, and OS rates were significantly improved in Stage 3 patients receiving local RT.

NMR spectroscopy and molecular modelling studies of nitrosylcobalamin: further evidence that the deprotonated, base-off form is important for nitrosylcobalamin in solution.

The structure of nitrosylcobalamin (NOCbl) in solution has been studied by NMR spectroscopy and the 1H and 13C NMR spectra have been assigned. 13C and 31P NMR chemical shifts, the UV-vis spectrum of NOCbl and the observed pKbase-off value of approximately 5.1 for NOCbl provide evidence that a significant fraction of NOCbl is present in the base-off, 5,6-dimethylbenzimidazole (DMB) deprotonated, form in solution. NOE-restrained molecular mechanics modelling of base-on NOCbl gave annealed structures with minor conformational differences in the flexible side chains and the nucleotide loop position compared with the X-ray structure. A molecular dynamics simulation at 300 K showed that DMB remains in close proximity to the alpha face of the corrin in the base-off form of NOCbl. Simulated annealing calculations produced two major conformations of base-off NOCbl. In the first, the DMB is perpendicular to the corrin and its B3 nitrogen is about 3.1 A away from and pointing directly at the metal ion; in the second the DMB is parallel to and tucked beneath the D ring of the corrin.

Imaging guidelines for children with Ewing sarcoma and osteosarcoma: a report from the Children's Oncology Group Bone Tumor Committee.

The Children's Oncology Group (COG) is a multi-institutional cooperative group dedicated to childhood cancer research that has helped to increase the survival of children with cancer through clinical trials. These clinical trials include a standardized regimen of imaging examinations performed prior to, during, and following therapy. This article presents imaging guidelines developed by a multidisciplinary group from the COG Bone Tumor Committee. These guidelines provide both required and recommended studies. Recommended examinations may become required in the future. These guidelines should be considered a work in progress that will evolve with advances in imaging and childhood cancer research.

Determination of the anomeric configuration in carbohydrates by longitudinal cross-correlated relaxation studies: application to mono- and disaccharides.

The role of cross-correlated relaxation between the anomeric proton chemical shift anisotropy (CSA) and its dipolar relaxation with nearby proton on the longitudinal relaxation in mono- and disaccharides at two magnetic field strengths has been investigated and shown to directly report the identity of their anomeric configuration.

Chemoselective deprotection of alpha-indole and imidazole ribonucleosides.

A series of 2 ',3 '-isopropylidene and 5 '-trityl-protected alpha-indole and alpha/beta-benzimidazole and imidazole ribonucleosides were deprotected with different acids. Selectivity was achieved for 5 '-versus 2 ',3 '- deprotection by using formic acid in the alpha-indole ribonucleoside series. Treatment of alpha-indole ribonucleosides with a mixture of formic acid and ether at room temperature afforded 2 ',3 '-deprotected alpha-ribonucleosides, whereas treatment of the alpha-benzimidazole ribonucleosides with the same acid afforded the 5 '-deprotected ribonucleoside without any 2 ', 3 '-deprotected products. The structures of these ribonucleosides were elucidated with 2D (NOESY, COSY, and HMQC) NMR spectroscopy.

Amperometric detection of hydrazine by cyclic voltammetry and flow injection analysis using ruthenium modified glassy carbon electrodes.

Glassy carbon electrodes modified with (5-amino-1,10-phenanthroline)bis(bipyridine)ruthium(II) chloride hydrate, [(bpy)(2)Ru(5-phenNH(2))]Cl(2).H(2)O, are shown to oxidize hydrazine with excellent sensitivity. The presence of an amine group on the ruthenium complex facilitates electropolymerization onto the electrode surface. Using cyclic voltammetry, a large catalytic current is observed upon oxidation of hydrazine in phosphate buffer (pH 5.0), compared to the current obtained from the ruthenium-modified electrode with no hydrazine present. The sensitivity of cyclic voltammetry is sufficient for obtaining a linear calibration curve for hydrazine over the range of 10(-5) to 10(-2)M. Hydrodynamic amperometry was used to determine the working potential for flow injection analysis. The limit of detection for hydrazine was determined to be 8.5muM using FIA. The thickness of these films was shown to increase linearly with the number of electropolymerization cycles, in the range of 1000-2500nm for 5-20 cycles, respectively, using Rutherford backscattering spectrometry (RBS). RBS analysis also suggests that the film is multilayered with the outermost layers containing a high ruthenium concentration, followed by layers where the concentration of ruthenium decreases linearly and approaches zero at the electrode surface.

NMR observations of 13C-enriched coenzyme B12 bound to the ribonucleotide reductase from Lactobacillus leichmannii.

The 13C NMR resonance and one-bond 1H-13C coupling constants of coenzyme B12 enriched in 13C in the cobalt-bound carbon have been observed in the complex of the coenzyme with the B12-dependent ribonucleotide reductase from Lactobacillus leichmannii. Neither the 13C NMR chemical shift nor the 1H-13C coupling constants are significantly altered by binding of the coenzyme to the enzyme. The results suggest that ground-state Co-C bond distortion is not utilized by this enzyme to activate coenzyme B12 for C-Co bond homolysis.

Regio- and stereoselective glycosylation: synthesis of 5-haloimidazole alpha-ribonucleosides.

We describe the synthesis of novel 5-haloimidazole ribonucleosides as precursors of modified cobalamins. A regio- and stereoselective glycosylation of protected ribose with silylated 4(5)-haloimidazoles produces 5-haloimidazole ribonucleosides predominantly in the alpha-configuration (60-75%) without any 4-substituted imidazole ribonucleoside. The structure of the 5-fluoroimidazole ribonucleoside was confirmed by X-ray crystallography and 2D NMR spectroscopy.

The enzymatic activation of coenzyme B12.

The enzymatic "activation" of coenzyme B12 (5'-deoxyadenosylcobalamin, AdoCbl), in which homolysis of the carbon-cobalt bond of the coenzyme is catalyzed by some 10(9)- to 10(14)-fold, remains one of the outstanding problems in bioinorganic chemistry. Mechanisms which feature the enzymatic manipulation of the axial Co-N bond length have been investigated by theoretical and experimental methods. Classical mechanochemical triggering, in which steric compression of the long axial Co-N bond leads to increased upward folding of the corrin ring and stretching of the Co-C bond is found to be feasible by molecular modeling, but the strain induced in the Co-C bond seems to be too small to account for the observed catalytic power. The modeling study shows that the effect is a steric one which depends on the size of the axial nucleotide base, as substitution of imidazole (Im) for the normal 5,6-dimethylbenzimidazole (Bzm) axial base decreases the Co-C bond labilization considerably. An experimental test was thus devised using the coenzyme analog with Im in place of Bzm (Ado(Im)Cbl). Studies of the enzymatic activation of this analog by the B12-dependent ribonucleoside triphosphate reductase from Lactobacillus leichmannii coupled with studies of the non-enzymatic homolytic lability of the Co-C bond of Ado(Im)Cbl show that the enzyme is only slightly less efficient (3.8-fold, 0.8 kcal mol(-1)) at activating Ado(Im)Cbl than at activating AdoCbl itself. This suggests, in agreement with the modeling study, that mechanochemical triggering can make only a small contribution to the enzymatic activation of AdoCbl. Another possibility, electronic stabilization of the Co(II) homolysis product by compression of the axial Co-N bond, requires that enzymatic activation be sensitive to the basicity of the axial nucleotide. Preliminary studies of the enzymatic activation of a coenzyme analog with a 5-fluoroimidazole axial nucleotide suggest that the catalysis of Co-C bond homolysis may indeed be significantly slowed by the decrease in basicity.

Cross-correlated relaxation between H1' chemical shift anisotropy and H1'-H2' dipolar relaxation mechanisms in ribonucleosides: application to the characterization of their anomeric configuration.

Cross-correlated nuclear spin relaxation between 1H chemical shift anisotropy (CSA) and 1H-1H dipolar relaxation mechanisms in ribonucleosides in solution phase are observed and used to identify their anomeric configuration. Only alpha-ribonucleosides showed the presence of cross-correlated spin relaxation through differential spin-lattice relaxation (T1) of the H1' doublet. Dependence of the magnitude and the orientation of the H1' CSA tensor values on the glycosidic torsion angle and the fast time-scale internal motions present in the ribose moiety play a significant role in the characterization of the anomeric configuration of the nucleosides via cross-correlated relaxation.

Regioselective glycosylation: synthesis of alpha-indoline nucleosides.

Novel indoline ribonucleosides with the alpha-N-glycoside configuration are synthesized with very high regioselectivity in 90-96%yield, using TMS protected indolines and 2,3-O-(1-methylethylidene)-5-O-(triphenylmethyl)-alpha/beta-D-ribofuranose. The structures of these ribonucleosides were elucidated with X-ray crystallography as well as 2D (NOESY, COSY, and HMQC) NMR spectroscopy.

Kinetic and thermodynamic studies on ligand substitution reactions and base-on/base-off equilibria of cyanoimidazolylcobamide, a vitamin B12 analog with an imidazole axial nucleoside.

Ligand substitution reactions of the vitamin B12 analog cyanoimidazolylcobamide, CN(Im)Cbl, with cyanide were studied. Cyanide substitutes imidazole (Im) in the alpha-position more slowly than it substitutes dimethylbenzimidazole in cyanocobalamin (vitamin B12). The kinetics of the displacement of Im by CN- showed saturation behaviour at high cyanide concentration; the limiting rate constant was found to be 0.0264 s(-1) at 25 degrees C and is characterized by the activation parameters: DeltaH(not =) = 111 +/- 2 kJ mol(-1), DeltaS(not =) = +97 +/- 6 J K(-1) mol(-1), and DeltaV(not =) = +9.3 +/- 0.3 cm3 mol(-1). These parameters are interpreted in terms of an I(d) mechanism. The equilibrium constant for the reaction of CN(Im)Cbl with CN- was found to be 861 +/- 75 M(-1), which is significantly less than that obtained for the reaction of cyanocobalamin with CN- (viz. 10(4) M(-1)). pKbase-off for the base-on/base-off equilibrium was determined spectrophotometrically and found to be 0.99 +/- 0.05, which is about 0.9 pH units higher than that obtained previously in the case of cyanocobalamin. In addition, the kinetics of the base-on/base-off reaction was studied using a pH-jump technique and the data obtained revealed evidence for an acid catalyzed reaction path. The results obtained in this study are discussed in reference to those reported previously for cyanocobalamin.