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PubMed2004

A lattice model for the simulation of one and two dimensional 129Xe exchange spectra produced by translational diffusion.

Xenon-129 spectra in some heterogeneous polymer systems consist of two resonances which collapse to a single resonance as a function of temperature. Two different resonances arise from spatially separated, distinct sorption environments and spectral collapse occurs when xenon atoms diffuse from one environment to the other at a sufficiently fast rate. This exchange mechanism involves a distribution of time constants and a two domain lattice model is used to generate a realistic distribution of correlation times resulting from diffusion in a heterogeneous matrix. The distribution of correlation times is inhomogeneous in the sense that different xenon atoms would exchange between the two domains or environments with a variety of time constants and the resulting spectrum is a superposition of spectra associated with each of the time constants. To demonstrate the nature of exchange according to this model, diffusion out of a sphere is simulated which corresponds to a progressive saturation experiment used to determine the diffusion constant of xenon in polystyrene. Then the model is used to demonstrate the difference between homogeneous and heterogeneous spectral collapse in one- and two-dimensional examples. Lastly, the simulation model is used to interpret one- and two- dimensional xenon-129 line shape changes for xenon sorbed into poly(2,6-dimethyl-1,4-phenylene oxide) as a function of temperature. Two broad resonances are observed at low temperatures in this polymer corresponding to xenon-129 sorbed in high free volume and low free volume domains. Exchange between the two main resonances collapses the spectrum to a single peak at higher temperatures. Both the collapse in one dimension and exchange in two dimensions as a function of mixing time can be simulated using the distribution from the lattice model. An average domain size of 70 nm is estimated by combining the simulation of the exchange experiment with the results of a one-dimensional progressive saturation experiment. The size of the sites sorbing individual xenon atoms has been reported from positron annihilation lifetime spectroscopy as 1.4 nm for the high free volume sites and 0.3 nm for the low free volume sites. The domain size is more than an order of magnitude larger than the individual sorption site indicating that domains consist of many sites as assumed in the lattice model description.

Absorption↗

PubMed2003

Functional analysis of an arthritogenic synovial fibroblast.

Increasing attention has been directed towards identifying non-T-cell mechanisms as potential therapeutic targets in rheumatoid arthritis. Synovial fibroblast (SF) activation, a hallmark of rheumatoid arthritis, results in inappropriate production of chemokines and matrix components, which in turn lead to bone and cartilage destruction. We have demonstrated that SFs have an autonomous pathogenic role in the development of the disease, by showing that they have the capacity to migrate throughout the body and cause pathology specifically to the joints. In order to decipher the pathogenic mechanisms that govern SF activation and pathogenic potential, we used the two most prominent methods of differential gene expression analysis, differential display and DNA microarrays, in a search for deregulated cellular pathways in the arthritogenic SF. Functional clustering of differentially expressed genes, validated by dedicated in vitro functional assays, implicated a number of cellular pathways in SF activation. Among them, diminished adhesion to the extracellular matrix was shown to correlate with increased proliferation and migration to this matrix. Our findings support an aggressive role for the SF in the development of the disease and reinforce the perspective of a transformed-like character of the SF.

Adjuvants, Immunologic↗

PubMed2006

Matrix metalloproteinase-9 in laminae of black walnut extract treated horses correlates with neutrophil abundance.

We sought to determine whether a correlation exists between neutrophil infiltration and tissue matrix metalloproteinase-9 (MMP-9) content in digital laminae collected during the prodromal and acute phases of laminitis in horses treated with an aqueous black walnut heartwood extract (BWE). Hoof laminar tissue was obtained at the onset of leukopenia and at the onset of clinical signs of lameness from BWE-treated horses and at equivalent times from control horses. Thin sections of laminae were screened for neutrophils by immunohistochemistry with an anti-CD13 monoclonal antibody and extracts of the same tissues were screened for SDS-renaturable and native MMP-9 activities by denaturing and non-denaturing gelatin zymography. Samples were also screened for MMP-2 and MMP-9 gene expression by RT-qPCR. Control laminae were devoid of both MMP-9 and neutrophils, whereas neutrophils and SDS-renaturable MMP-9 activity were detected in laminae from BWE-treated horses and were strongly correlated at the acute stage of the disease at which time laminar MMP-9 gene expression was significantly (15-fold) elevated. In contrast, BWE-treatment did not significantly elevate MMP-2 gene or protein expression in the laminae. Interestingly, MMP-9 that was present in extracts of laminae from BWE-treated horses at both the prodromal and acute stages of the disease was mainly in the zymogen form, suggesting that the accumulation of the MMP did not contribute to pathology during these stages. However, elevated presence of the MMP-9 zymogen in the tissue would predispose it to catastrophic damage should conditions arise that cleave the regulatory propeptide domain.

Animals↗

PubMed2006

Morphological integration in the carnivoran skull.

The correlated evolution of traits may be a principal factor in morphological evolution, but it is typically studied in genetic or developmental systems. Most studies examining phenotypic trait correlations, through analysis of morphological integration, consider only few taxa, with limited ability to test hypotheses of the influence of trait integration on morphological variation and diversity. The few comparative studies in less inclusive groups have yielded varying relationships of integration to the key factors of phylogeny and diet. In this paper, I present analyses of cranial morphological integration in 30 species from the mammalian order Carnivora, spanning eight extant families and a wide range of ecological and morphological diversity. Fifty-five cranial landmarks were captured through three-dimensional digitization of 15-22 specimens for each species. Using a node-based phylogenetic distance matrix, a significant correlation was found between similarity in patterns of integration and phylogenetic relatedness within Felidae (cats) and Canidae (dogs), but not within more inclusive clades, when size-related variation was removed. When size was included, significant correlations were found across all Caniformia, Musteloidea, Mustelidae, and Felidae. There was a significant correlation between phylogeny and morphological integration only within the higher-level clade Feliformia (cats, civets, mongooses, and hyaenas) when a branch-length-based phylogenetic distance matrix was analyzed, with and without size. In contrast, diet was significantly correlated with similarity in morphological integration in arctoid carnivorans (bears, raccoons, and weasels), but had no significant relationship with integration in feliforms or canids. These results support the proposition that evolutionary history is correlated with cranial integration across large clades, although in some smaller clades diet also exerts significant influence on the correlated evolution of traits.

Animals↗

PubMedDate not supplied

Matrix metalloproteinase-8 in sera and from polymorphonuclear leucocytes in rheumatoid arthritis: in vitro characterization and correlation with disease activity.

OBJECTIVES: To determine matrix metalloproteinase-8 (MMP-8) secretion from rheumatoid arthritis (RA) peripheral blood polymorphonuclear leucocytes (PMNs), in response to immune complexes (IC), cytokines and their combinations, and to study correlation of serum MMP-8 with disease activity. METHODS: PMNs from RA patients and controls were stimulated in vitro with interleukin-15 (IL-15), IL-18, adherent immune complexes, rabbit anti-human immunoglobulin G (anti-HIgG), human immunoglobulin G (HIgG), and their F (ab') 2 prongs, phorbol myristate acetate (PMA) or combinations of above. Supernatants from these experiments and sera from both groups were assayed for MMP-8 using ELISA and correlated with disease activity measures in patients. RESULTS: MMP-8 secretion from stimulated PMNs was compared to unstimulated PMNs. Immune complexes elicited significant MMP-8 secretion (p = 0.006 and 0.001, control and RA respectively). Unlike HIgG and its F (ab')2 fragment, very high secretion was elicited by anti-HIgG (242.37 +/- 10.85 ng/ml) and its F (ab')2 prong (195.85 +/- 28.67 ng/ml). IL-15 did not elicit any secretion. IL-18 with PMA increased secretion significantly only from RA PMNs (p = 0.003). Serum MMP-8 correlated positively with serum CRP (p = 0.017) and not with disease activity score (p = 0.199). CONCLUSIONS: We for the first time demonstrate that immune complexes elicit MMP-8 secretion from PMNs. Except for higher secretion from RA PMNs in response to combination of IL-18 and PMA, both control and RA PMNs respond similarly to various stimuli. Secretion by anti-HIgG occurs by a mechanism independent of Fc receptor. Correlation with CRP suggest that serum MMP-8 may be an indicator of acute inflammatory activity.

Adult↗

PubMed2006

Correlations of oral tongue cancer invasion with matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) expression.

BACKGROUND AND OBJECTIVES: In oral tongue cancer, the degree of tumor invasion has a significant effect on the prognosis. We hypothesized that the destruction of extracellular matrix and neovascularization are related to tumor infiltration mechanism. By studying the tissues of early stage oral tongue cancer patients, we are intending to clarify the invasion-related factors. MATERIALS AND METHODS: To demonstrate the invasion process in early T-stage oral tongue cancer, the expressions of extracellular matrix destruction-related molecules (MMP-2, MMP-9) and neovascularization-related molecule (VEGF) were observed by immunohistochemical study. Also, staining of CD31 was done for quantification of neovascularization. We analyzed relationship between expression of each substances and tumor invasion depth, tumor free survival rates, and cervical lymph node metastasis rate. RESULTS: The expression rates of MMP-2, MMP-9, VEGF in 38 early oral cancer patients were 52.6%, 78.9%, and 52.6%, respectively. Significant correlation was found between the VEGF expression and microvessel density showed by CD31 immunohistochemical staining (P < 0.001). VEGF expressions were significantly related with tumor invasion depth (P = 0.002). The tumor-free survival rate of those patients with VEGF-positive tumors was significantly poorer than in those with VEGF-negative tumors (P = 0.019). CONCLUSIONS: These results indicate that VEGF is a useful marker for predicting the tumor invasion in patients with early tongue cancer.

Adult↗

PubMed1998

Incorporating correlations between measurements into the estimation of age-related reference ranges.

An LMS-based maximum likelihood method of fitting age-related reference ranges is extended to incorporate non-independent measurements by including the matrix of the correlations between standard normalized repeat measurements into the likelihood. The likelihood is maximized via iterative re-estimation of the correlation structure and the reference range parameters until convergence is achieved. The correlation structure is explicitly modelled and the extent to which the estimated centiles depend on the adequacy with which the correlation structure is modelled is investigated. The method is illustrated using CD4 counts of uninfected children born to HIV-1 infected women. This data set consists of 5063 CD4 counts taken from 745 children at irregular ages between birth and 10 years of age. The data exhibited a strong correlation structure with correlations decreasing with increasing time between measurements and being lower for younger measurement ages. However, incorporation of the correlation had little effect on the choice of model for the median or on the fitted centiles or their precision.

Adolescent↗

PubMed1997

Association between facial height development and mandibular growth rotation in low and high MP-SN angle faces: a longitudinal study.

Two groups of children with low (n = 29) and high (n = 29) MP-SN angles were followed longitudinally from 6 to 15 years of age. The purpose was to thoroughly examine associations between vertical craniofacial growth and mandibular growth rotation. Correlations between dimensional and rotational variables occurred in different variable pairs in the two groups and changed with age. Increase in posterior lower facial height distinguished itself by being consistently positively correlated with forward matrix rotation irrespective of mandibular plane angle or age. The same applied to increase in ramus height. Increase in lower anterior facial height was, surprisingly, weakly correlated with mandibular rotation, but strongly and positively correlated with increase in corpus length. Overdevelopment of lower anterior facial height in high angle cases occurred because the steep mandibular plane directed corpus growth more downward than normal, not because the mandible rotated backward.

Adolescent↗

PubMed2005

Role of integrin-linked kinase in regulating phosphorylation of Akt and fibroblast survival in type I collagen matrices through a beta1 integrin viability signaling pathway.

A beta1 integrin phosphatidylinositol 3-kinase/Akt pathway regulates fibroblast survival in collagen matrices. When fibroblasts attach to collagen, Akt becomes phosphorylated, providing a survival signal. In contrast, in response to mechanical forces generated during collagen contraction, Akt is dephosphorylated and fibroblasts undergo apoptosis. The kinase(s) responsible for regulating Akt phosphorylation in response to matrix-derived mechanical signals are unclear. Integrin-linked kinase (ILK) is associated with the beta1 integrin in the focal adhesion complex and as such is a candidate kinase that may regulate Akt phosphorylation and fibroblast viability. Nevertheless, there is no direct evidence that matrix-derived mechanical forces regulate cell viability by modulating ILK activity. Here, we show that ILK activity decreased in response to collagen matrix contraction, which correlated with Akt dephosphorylation and induction of fibroblast apoptosis. In contrast, enforced activation of beta1 integrin by activating antibody preserved ILK and Akt activity during collagen matrix contraction, and this is associated with protection from collagen contraction-induced apoptosis. Knock-down of ILK by small, interfering RNA (siRNA) attenuated Akt phosphorylation in response to ligation of beta1 integrin by collagen or activating antibody and enhanced fibroblast apoptosis in response to collagen contraction. Kinase dead ILK attenuated Akt phosphorylation and enhanced fibroblast apoptosis, whereas hyperactive and wild type ILK augmented Akt phosphorylation and protected fibroblasts from apoptosis. Constitutively active Akt preserved Akt activity and rescued ILK siRNA-treated fibroblasts from collagen contraction-induced apoptosis. These data establish that matrix-derived mechanical forces sensed by beta1 integrin are capable of modulating ILK activity which regulates fibroblast viability via an Akt-dependent mechanism.

Apoptosis↗

PubMed2005

Relationship between matrix metalloproteinase-2 activity and cystatin C levels in patients with hepatic disease.

OBJECTIVES: A direct relationship between cystatin C levels and the severity of hepatic disease has been revealed in our previous study. This study was aimed to consider whether a correlation exists between matrix metalloproteinases (MMPs), which have been proven to be involved in liver cirrhosis, and cystatin C to reflect the severity of hepatic disease. DESIGN AND METHODS: A total of 154 consecutive patients with various liver diseases were recruited to determine their serum levels of cystatin C, MMP-2 and-9, together with other hepatic parameters. These were compared with 40 normal controls. RESULTS: Average levels of MMP-2 and cystatin C were significantly higher in patients while MMP-9 was significantly lower, as compared to controls. A linear regression analysis has revealed a direct relationship between cystatin C and MMP-2 (Y=83.39 + 270.56 X, R=0.38, P< 0.001), as well as between MMP-2 and the severity of liver diseases. CONCLUSION: This is the first study to demonstrate a correlation between cystatin C and MMP-2, suggesting that there may be certain interactions between cystatin C and MMP-2 in patients with hepatic diseases.

Alanine Transaminase↗

PubMed2005

Expression of nm23-H1 gene product in sarcomatous cancer cells of renal cell carcinoma: correlation with tumor stage and expression of matrix metalloproteinase-2, matrix metalloproteinase-9, sialyl Lewis X, and c-erbB-2.

OBJECTIVES: To investigate the clinical significance of nm23-H1 gene product in sarcomatous cancer cells, because this is known as a tumor-metastasis suppressor. Renal cell carcinoma with sarcomatoid cancer cells is characterized by high malignant potential and a poor prognosis. METHODS: We investigated the expression of nm23-H1 gene product in the carcinomatous and sarcomatous component (CC and SC) of renal cell carcinoma using immunohistochemical techniques and the relationships between the expression and clinicopathologic features. We also examined the expression of matrix metalloproteinase (MMP)-2, MMP-9, sialyl Lewis X, and c-erbB-2 in the SC because these proteins are regulated by the nm23-H1 gene or its products. RESULTS: We examined 20 renal cell carcinoma specimens that contained an SC and CC. The CC of 12 of the 20 tumors stained positively for nm23-H1 gene product. In contrast, the SC of only 3 of the 20 stained positive. The reduced expression of nm23-H1 gene product in the SC correlated significantly with tumor invasion (P <0.01), but not with tumor size or metastasis. In contrast, the expression of the nm23-H1 gene product in the CC was not associated with these pathologic features. Expression of the nm23-H1 gene product correlated negatively with MMP-2 expression (r = -0.48, P = 0.03). Other factors did not show such significant correlations with nm23-H1 gene product expression. CONCLUSIONS: Our results suggest that low expression of nm23-H1 gene products may play important roles in tumor invasion, and that this process is mediated in part by overexpression of MMP-2.

Aged↗

PubMed1998

Psychopathological dimensions in schizophrenia: a correlational approach to items of the SANS and SAPS.

Seventy DSM-III schizophrenic patients were assessed for positive and negative symptoms using Andreasen's scales for the assessment of positive and negative symptoms (SANS and SAPS) on admission. The correlation structure of the items in the SANS and SAPS was explored in dimension and item levels by use of correlation plots through a distinct analytical method displaying the proximity matrix. The results revealed at least three major dimensions of symptoms delineated as Negative Symptoms, Disorganized Thoughts and Delusions and Hallucinations. The latter two dimensions were derived from the SAPS, while Negative Symptoms comprised most of the items in the SANS. Items in Disorganized Thoughts were more correlated to Negative Symptoms than to the other items in the SAPS. 'Loss of ego boundary' delusions and experience of auditory hallucinations appeared as two sub-clusters in the group of Delusions and Hallucinations. The relative independence of persecutory, grandiose, religious, somatic and reference delusions gives support to the concept that paranoid schizophrenia stands as a distinct clinical subtype of schizophrenia. The graphical method introduced here well expresses the information of correlation matrix and is useful for exploring inter-item or inter-cluster associations.

Adolescent↗

PubMed2006

Nectar sugar composition and volumes of 47 species of Gentianales from a southern Ecuadorian montane forest.

BACKGROUND AND AIMS: This study investigates 47 taxonomically related species (Gentianales), all native to a tropical montane forest in southern Ecuador, in terms of nectar chemistry and nectar volumes in relation to pollination biology. METHODS: Nectar volumes of covered (24-h production) and uncovered (standing crop) flowers were measured in the natural habitat. Sucrose, fructose and glucose were quantified in the nectar using high performance liquid chromatography. Flower visitors were observed. KEY RESULTS: Nectar sugar concentration did not differ significantly among the pollination syndromes. Regarding sugar composition, the only significant differences were found in chiropterophilous and myiophilous flowers, which had a significantly lower sugar ratio than sphingophilous flowers. A separation of chiropterophilous and myiophilous flowers from the other pollination syndromes is further substantiated by non-linear multidimensional scaling using the chord-normalized expected species shared index of dissimilarity based on nectar sugar compositions. The matrix test revealed no correlation of observed floral visitors to nectar concentrations; however, a weak significant correlation was found between floral visitors and nectar sugar compositions. The nectar volumes of covered and uncovered flowers are related to, and differ significantly among, pollination syndromes. Matrix tests revealed correlation between floral visitors and nectar volume of covered flowers and, to a lesser extent, of uncovered flowers. CONCLUSIONS: Sucrose is the predominant floral nectar sugar in the order Gentianales, suggesting that nectar sugar composition is a conservative characteristic. However, some degree of an adaptive convergence of floral nectar compositions to principal pollinator type within the constraints set by phylogenetic history is likely. The driving force to visitation appears to be the volume of nectar the visitor can expect to consume.

Animals↗

PubMed2000

Collagen-to-smooth muscle ratio helps prediction of prognosis after pyeloplasty.

PURPOSE: We quantitatively evaluated the collagen-to-smooth muscle tissue matrix ratio in ureteropelvic junction obstruction, and compared the ratio with the degree of obstruction, patient age and postoperative renal recovery. MATERIALS AND METHODS: We analyzed histological sections from 65 patients with ureteropelvic junction obstruction and 6 normal controls. Morphological and functional grading systems were adapted to determine the degree of renal obstruction. To examine smooth muscle and collagen tissue, sections were stained using Masson's trichrome. Two distinct populations of collagen versus smooth muscle were identified and the tissue matrix ratio was calculated by color image analysis. RESULTS: The mean tissue matrix ratio plus or minus standard deviation was 1.32+/-0.79 in all patients with ureteropelvic junction obstruction but only 0.30+/-0.10 in normal controls (p <0.0001). It appeared that the lower the tissue matrix ratio, the better the improvement in postoperative hydronephrosis (r = -0.50, p = 0.0001). Better recovery of renal function after pyeloplasty was observed with a decrease in the tissue matrix ratio (r = -0.43, p = 0.0004). We divided patients according to the tissue matrix ratio into groups 1--ratio 1 or less, 2--greater than 1 to 1.5 and 3--greater than 1.5 to determine a more detailed and clinically applicable correlation of tissue matrix ratio with postoperative renal functional changes. Better improvement in postoperative renal function was observed in group 1 than in group 3 (p = 0.002). Also, the tissue matrix ratio increased with patient age (r = 0.33, p = 0.007). CONCLUSIONS: Since our data represent an objective and quantitative parameter associated with ureteropelvic junction obstruction, we believe that our findings may help to predict the prognosis after pyeloplasty.

Child↗

PubMed2003

Correlation of oxidative stress with activity of matrix metalloproteinase in patients with coronary artery disease. Possible role for left ventricular remodelling.

AIMS: Oxidative stress is implicated in the progression of heart failure, and matrix metalloproteinase (MMP) activity is increased in patients with congestive heart failure. We examined the role of oxidative stress on MMP activity in humans. METHODS AND RESULTS: We measured the MMP activity and the level of 8-iso-prostagandin F2alpha (8-iso-PGF2alpha), a specific and quantitative maker of oxidant stress, in the pericardial fluid (PF) in 47 consecutive patients with coronary artery disease who underwent coronary artery bypass surgery. Zymography of PF showed bands at 92-85kDa (MMP-9) and 72-65kDa (MMP-2). The MMP activity was expressed as the ratio to MMP-2 standard. MMP-2, MMP-9 and total gelatinolysis activities were positively correlated with left ventricular end-diastolic volume index (LVEDVI), and MMP-2 and total gelatinolysis activities were also positively correlated with LV end-systolic volume index. Moreover, MMP-2, MMP-9 and total gelatinolysis activities were all positively correlated with pericardial level of 8-iso-PGF2alpha. Also, LVDEVI was positively correlated with pericardial level of 8-iso-PGF2alpha. CONCLUSIONS: Oxidative stress may play an important role in the regulation of MMP activity. Augmented MMP activity may be involved in the development of ventricular remodelling in patients with coronary artery disease.

Aged↗

PubMed1997

Secretion of slime, the extracellular matrix of the plasmodium, as visualized with a fluorescent probe and its correlation with locomotion on the substratum.

Slime, the extracellular matrix of Physarum plasmodium, is secreted by the exocytosis of a vesicles that contain a slime precursor. Using an antibody raised against biochemically purified slime, we detected the intracellular localization of the slime vesicle. Slime vesicles are abundant in the advancing front of the plasmodium, as confirmed by electron microscopic observation in two different cross-sectional angles. Screening various reagents, we found that rhodamine-phosphatidylethanolamine (Rh-PE) binds specifically to slime in both its intravesicular and extracellular forms, as confirmed by immunoelectron microscopy using an antibody against fluorochrome rhodamine. The plasmodia vitally stained with Rh-PE exhibited dynamic fluorescent patterns during the course of locomotion. The fluorescence was conspicuous at the periphery of the leading pseudopods and oscillated according to the shuttle streaming that accompanied the relaxation and contraction of the periphery; it was intense in the relaxation phase when pseudopods extended, and became weak in the contraction phase when pseudopods contracted. The results collectively mean that the slime vesicles carried by the cytoplasmic streaming accumulated prior to secretion at the advancing margin of the plasmodium.

Animals↗

PubMed2006

Spectral function of ferromagnetic 3d metals: a self-consistent LSDA+DMFT approach combined with the one-step model of photoemission.

The electronic structure of ferromagnetic 3d-transition metals in the vicinity of the Fermi level is dominated by the spin-polarized d bands. Experimentally, this energy region can be probed in detail by means of angle-resolved ultraviolet photoemission and inverse photoemission. In several earlier studies the measured spectra were described either within a single-particle approach based on the local spin-density approximation including matrix-element effects within the so-called one-step model or by sophisticated many-body approaches neglecting these effects. In our analysis we combine for the first time correlation with matrix-element effects to achieve an improved interpretation of photoemission data from ferromagnetic nickel.

Journal Article↗

PubMed2002

Comparing PAH availability from manufactured gas plant soils and sediments with chemical and biological tests. 1. PAH release during water desorption and supercritical carbon dioxide extraction.

Soil and sediment samples from oil gas (OG) and coal gas (CG) manufactured gas plant (MGP) sites were selected to represent a range of PAH concentrations (150-40,000 mg/kg) and sample matrix compositions. Samples varied from vegetated soils to lampblack soot and had carbon contents from 3 to 87 wt %. SFE desorption (120 min) and water/XAD2 desorption (120 days) curves were determined and fit with a simple two-site model to determine the rapid-released fraction (F) for PAHs ranging from naphthalene to benzo[ghi]perylene. F values varied greatly among the samples, from ca. 10% to >90% for the two- and three-ring PAHs and from <1% to ca. 50% for the five- and six-ring PAHs. Release rates did not correlate with sample matrix characteristics including PAH concentrations, elemental composition (C, H, N, S), or "hard" and "softs" organic carbon, indicating that PAH release cannot easily be estimated on the basis of sample matrix composition. Fvalues for CG site samples obtained with SFE and water desorption agreed well (linear correlation coefficient, r2 = 0.87, slope = 0.93), but SFE yielded higher F values for the OG samples. These behaviors were attributed to the stronger ability of carbon dioxide than water to desorb PAHs from the highly aromatic (hard) carbon of the OG matrixes, while carbon dioxide and water showed similar abilities to desorb PAHs from the more polar (soft) carbon of the CG samples. The combined SFE and water desorption approaches should improve the understanding of PAH sequestration and release from contaminated soils and sediments and provide the basis for subsequent studies using the same samples to compare PAH release with PAH availability to earthworms.

Adsorption↗