Bioavailability of heavy metals in soils: definitions and practical implementation--a critical review.

Worldwide regulatory frameworks for the assessment and remediation of contaminated soils have moved towards a risk-based approach, taking contaminant bioavailability into consideration. However, there is much debate on the precise definition of bioavailability and on the standardization of methods for the measurement of bioavailability so that it can be reliably applied as a tool for risk assessment. Therefore, in this paper, we reviewed the existing definitions of heavy metal bioavailability in relation to plant uptake (phytoavailability), in order to better understand both the conceptual and operational aspects of bioavailability. The related concepts of specific and non-specific adsorption, as well as complex formation and organic ligand affinity were also intensively discussed to explain the variations of heavy metal solubility and mobility in soils. Further, the most frequently used methods to measure bioavailable metal soil fractions based on both chemical extractions and mechanistic geochemical models were reviewed. For relatively highly mobile metals (Cd, Ni, and Zn), a neutral salt solution such as 0.01 M CaCl2 or 1 M NH4NO3 was recommended, whereas a strong acid or chelating solution such as 0.43 M HNO3 or 0.05 M DTPA was recommended for strongly soil-adsorbed and less mobile metals (Cu, Cr, and Pb). While methods which assessed the free metal ion activity in the pore water such as DGT and DMT or WHAM/Model VI, NICA-Donnan model, and TBLM are advantageous for providing a more direct measure of bioavailability, few of these models have to date been properly validated.

A case of atypical fibroxanthoma of subungual type: ultrasound and magnetic resonance imaging findings.

Subungual atypical fibroxanthoma is a rare mesenchymal skin tumor of intermediate malignancy. It classically presents as a relatively nondescript, erythematous nodule; it may ulcerate and bleed, but pain and pruritus are uncommon. In the differential diagnoses of subungual tumors, glomus tumor, soft tissue chondroma, keratoacanthoma, hemangioma, lobular capillary hemangioma, epidermal and mucoid cysts, squamous cell carcinoma, and malignant melanoma have been suggested. But atypical fibroxanthoma has not been included in the differential diagnoses. We report a case that occurred in a 56-year-old man with subungual atypical fibroxanthoma mimicking malignant soft tissue tumor in the right fifth toe.

Effect of essential inorganic metals on primary thermal degradation of lignocellulosic biomass.

This study employed thermogravimetric analysis (TGA) and analytical Py-GC/MS in order to examine the catalytic effect of main inorganic metals (K, Mg and Ca) on the thermal degradation and the formation of pyrolytic products in lignocellulosic biomass. In addition, potential mechanisms of the primary pyrolysis in presence of the inorganic metals were derived. TG analysis showed that when potassium content increased in the biomass, char formation increased from 10.5 wt.% to 19.6 wt.% at 550 °C, and temperatures at which the maximum degradation rate was achieved shifted from 367 °C to 333 °C. With increasing magnesium content, the maximum degradation rate increased from 1.21 wt.%/°C to 1.43 wt.%/°C. Analytical Py-GC/MS revealed that potassium had a distinguished catalytic effect promoting the formation of low molecular weight compounds and suppressing the formation of levoglucosan. An increase in the yield of C6 and C2C6 lignin derivatives with increasing potassium content was also observed.

Characterization of lignin-rich residues remaining after continuous super-critical water hydrolysis of poplar wood (Populus albaglandulosa) for conversion to fermentable sugars.

Poplar wood flour (Populous albaglandulosa) was treated with sub- and super-critical water (subcritical: 325, 350°C; super-critical: 380, 400, 425°C) for 60s at 220 ± 10 atm. Hydrochloric acid (0.05%v/v) was added to samples as acidic catalyst. The final products were separated into water soluble fraction and undegraded solids. The yields of undegraded solids were thoroughly dependent on temperature severity and mainly composed of lignin fragments. Average molecular weights of the lignins were between 1500 and 4400 Da, which was only 1/3-1/8-fold of poplar milled wood lignin (13,250 Da). DFRC (Derivatization Followed by Reductive Cleavage) analysis revealed that C6C3 phenols (coniferyl and sinapyl alcohol) were rarely detected in the lignins, indicating occurrence of two probable lignin reactions during SCW hydrolysis: lignin fragmentation via splitting of ß-O-4 linkage and loss of propane side chains. These results were also confirmed by (1)H and (13)C NMR spectroscopic analysis.

17-year-old girl with headache and complex partial seizure.

Supratentorial cortical ependymoma is a rare clinical entity where ependymoma occurring in the cortex without any connection to the ventricular system since ependymoma usually arises from the lining of the ventricular system or central canal of spinal cord. There have been 14 such cases reported in the literature.We report the first case of a supratentorial extraaxial cortical anaplastic ependymoma with minimal cortical attachment in a 17-years-old girl, presented with headache and complex partial seizure. Histological features of anaplasia including numerous mitoses, necrosis and high Ki-67 lead to postoperative adjuvant radiation therapy although gross total resection was achieved.

Comparison of temporal lobectomies of children and adults with intractable temporal lobe epilepsy.

INTRODUCTION: The aim of the study was to assess the difference in clinical characteristics and postsurgical outcomes between children and adults who have undergone temporal lobectomy (TL). MATERIALS AND METHODS: We retrospectively reviewed the medical records of 52 patients who had undergone TL between 2006 and 2008. Nineteen patients were classified as children (18 years old) according to the age when TL had been performed. RESULTS: Twelve of 19 (63.2%) children and 24 of 33 (72.7%) adults became seizure free. Rapid secondary generalization such as generalized tonic or tonic-clonic seizures showed a tendency to be more prominent in children (four of 19, 21.1%) than in adults (three of 33, 9.1%). Patients in childhood had significantly more multifocal discharges on interictal electroencephalography (EEG) (42.1%) compared to adults (15.2%, p = 0.014). The mean extent of surgical excision was 5.0 cm in children and 4.1 cm in adults (p = 0.001). The incidence of hippocampal sclerosis, the most common pathologic finding in the two groups, was 57.9% (11 of 19) in children and 78.8% (26 of 33) in adults. Malformations of cortical development were significantly more frequent in children (nine of 19, 47.4%) than in adults (seven of 33, 21.2%). Dual pathology was found in 31.6% of children and in 12.1% of adults. The intelligence quotient and memory quotient values in children with temporal lobe resection remained nearly steady during follow-up period without significant decline. CONCLUSION: Patients undergoing TL during childhood compared to during adulthood had distinctively different interictal EEG, resectional extents, and pathologic findings.

Resective pediatric epilepsy surgery in Lennox-Gastaut syndrome.

OBJECTIVE: The objective of this study was to evaluate the role of resective pediatric epilepsy surgery for Lennox-Gastaut syndrome (LGS). METHODS: We analyzed clinical data of 27 children and adolescents who had LGS and underwent resective epilepsy surgery despite abundant (>30% of preoperative interictal and/or ictal epileptiform discharges) generalized or generalized contralateral maximal and multiregional electroencephalogram abnormalities. RESULTS: On high-resolution MRI, cerebral lesions were noted in 23 (85.2%) patients but not in 4 (14.8%) patients. The age of patients at the time of surgery was between 1.7 and 17.3 years (mean: 7.8 years). Surgeries were lobar or multilobar resection in 21 (77.8%) patients and hemispherotomy in 6 (22.2%). At a mean of 33.1 months' postoperative follow-up, 16 (59.3%) patients had no seizures and 4 (14.8%) had infrequent seizures. Of 4 patients without brain abnormalities found on MRI, 2 patients became seizure-free after resective surgery was performed on the basis of electrophysiologic studies and concordant results in other multimodal neuroimages. Malformation of cortical development was the most common pathology and was seen in 20 (74.1%) patients, but 2 (7.4% patients) did not show any abnormal pathology. Sixteen (72.7%) patients, including 14 who had no seizures and 2 who had infrequent seizures after surgery, showed an increase in developmental quotient. No clinical profile was significantly associated with postoperative seizure-free rate. CONCLUSIONS: Resective epilepsy surgery should be considered for children with LGS, despite abundant generalized and multiregional electroencephalogram abnormalities.

Outcome of surgical treatment in non-lesional intractable childhood epilepsy.

PURPOSE: The aim of this study is to investigate seizure outcomes following epilepsy surgery in non-lesional neocortical pediatric epilepsy. METHODS: We performed a retrospective study on 27 patients with intractable childhood epilepsy who received epilepsy surgery between 1999 and 2006 at Sang-gye Paik Hospital and Severance Children's Hospital. None of the patients had any detectable lesions on MRI. Surgical outcome was assessed at least 2 years postoperatively; clinical characteristics, surgical outcome, pathologic findings, types of surgery, localizing features on SPECT, FDG-PET, and long-term video-EEG were reviewed. RESULTS: Eighteen patients (67%) demonstrated an Engel class I outcome postoperatively. The mean follow-up duration was 4.3 years (range, 2.2-9 years). Eighteen out of 27 cases (67%) showed focal localizing features on ictal SPECT, and 21 of 27 cases (78%) showed abnormal findings on PET. Single lobectomy was the most common procedure, and was performed in 20 patients (74%). Multilobar resection was performed in seven patients (26%). Cortical dysplasia was the most common finding during pathological examination, and was observed in 15 (56%) cases. In addition, gliosis was found in two patients (7%) and non-specific pathological findings were described in 10 patients (37%). CONCLUSIONS: In children with intractable epilepsy and a MRI demonstrating no abnormal lesions, epileptic surgery should be strongly considered when cortical pathology can be identified from other studies.

Interaction of D2 with Ti-adsorbed polyaniline and implication for hydrogen storage.

Interaction of D2 with Ti-adsorbed polyaniline (PANI) and TiO2 at low Ti coverages has been investigated by temperature programmed desorption, Auger electron spectroscopy, and H2-D2 exchange in a high pressure cell. In contrast to recent DFT calculations (Lee et al. Phys. Rev. Lett. 2006, 97, 56104-56107) that have shown a multiple number of molecular hydrogen chemisorption on Ti-decorated PANI, only 0.52 D2 molecules per Ti atomically adsorb on Ti-deposited PANI at 87 K at a nominal Ti coverage of 2 ML. Broad TPD spectra of D2, HD, and H2 were observed, which showed a common peak at 250 K and another isotope-dependent peak at higher temperature. Ti deposited on TiO2 forms clusters with a size distribution at 87 K, on which D2 atomically adsorbs. As the Ti coverage increases, the D2 desorption peak gradually shifts from 200 to 260 K and the number of D2 molecules adsorbed per Ti also increases from 0.26 at 0.1 ML to 0.87 at 2 ML. We attribute this to the fact that D2 adsorbs on larger clusters with a greater adsorption energy. TPD spectra of D2 desorbing from Ti (2 ML)/PANI and Ti (1 ML)/TiO2 look very similar to each other. This led us to conclude that Ti also adsorbs on PANI in clusters. We suggest that no molecular D2 adsorption on Ti/PANI at 87 K is due to a reduced electron backdonation ability of Ti upon clustering. The small number of adsorbed D2 per Ti on both substrates was ascribed to irreversible D2 adsorption only on relatively large Ti clusters, while D2 adsorbs reversibly on small clusters. This was indirectly confirmed by the observation that continuous H2-D2 isotope exchange occurs to produce HD on Ti/PANI as well as on Ti/TiO2 at 106 K in a high pressure cell at 5.7 mTorr. Desorption mechanisms involving H atom abstraction from PANI by Ti clusters are proposed to account for the complex isotope-dependent TPD spectra. Implication of the present results for hydrogen storage based on Ti-dispersed polymers is briefly addressed.

Levels of polychlorinated biphenyls (PCBs) in transformer oils from Korea.

Using Korean waste official method, polychlorinated biphenyls (PCBs) were analyzed from 33 transformer oils collected under National Institute of Environmental Research (NIER) in Republic of Korea (ROK) and their emission rate in Korea was estimated. Practical quantification limits analyzed by this method were in the ranges of 0.02 and 0.05 mg L(-1), and recovery of samples was in the ranges of 77-97%. The analytical results showed that PCBs in the transformer oils were identified as Aroclor 1242, 1254 or 1260. Twenty-nine samples were determined to contain PCBs of >0.05 mg L(-1) and among these samples, nine samples contained to have >2 mg kg(-1) which is limit of Waste Control Act (WCA) with regard to PCBs in transformer oil from Korea. The concentrations of PCBs in transformer oils were between N.D. (not detected) and 48.33 mg kg(-1). PCBs concentrations did not exceed 50 mg kg(-1) which is generally accepted limit for the definition of waste in POPs Guideline of Basel Convention.

Development and clinical evaluation of a highly sensitive DNA microarray for detection and genotyping of human papillomaviruses.

Human papillomavirus (HPV) has been found in cervical cancer, tonsillar cancer, and certain types of head and neck cancers. We report on a DNA microarray-based method for the simultaneous detection and typing of HPVs. The genotype spectrum discriminated by this HPV DNA microarray includes 15 high-risk HPV genotypes and 12 low-risk HPV genotypes. The HPV DNA microarray showed high degrees of specificity and reproducibility. We evaluated the performance of the HPV DNA microarray by application to three HPV-positive cell lines (HeLa, Caski, and SiHa cells) and two HPV-negative cell lines (C33A and A549 cells). The HPV DNA microarray successfully identified the known types of HPV present in the cell lines. The detection limit of the HPV DNA microarray was at least 100-fold higher than that of PCR. To assess the clinical applicability of the HPV DNA microarray, we performed the HPV genotyping assay with 73 nonmalignant and malignant samples from 39 tonsillar cancer patients. Twenty-five of the 39 (64.1%) malignant samples were positive for HPV, whereas 3 of 34 (8.8%) nonmalignant samples were positive for HPV. This result shows a preferential association of HPV with tonsillar carcinomas. The correlations of the presence of HPV with the grade of differentiation and risk factors were not significant. Our data show that the HPV DNA microarray may be useful for the diagnosis and typing of HPV in large-scale epidemiological studies.