Terminal Products Research Articles

Evidence for the activation of 1α-hydroxyvitamin D 2 by 25-hydroxyvitamin D-24-hydroxylase: Delineation of pathways involving 1α,24-dihydroxyvitamin D 2 and 1α,25-dihydroxyvitamin D 2

While current dogma argues that vitamin D prodrugs require side-chain activation by liver enzymes, recent data suggest that hydroxylation may also occur extrahepatically. We used keratinocytes and recombinant human enzyme to test if the 25-hydroxyvitamin D-24-hydroxylase (CYP24A1) is capable of target cell activation and inactivation of a model prodrug, 1α-hydroxyvitamin D 2 (1α(OH)D 2) in vitro. Mammalian cells stably transfected with CYP24A1 (V79-CYP24A1) converted 1α(OH)D 2 to a series of metabolites similar to those observed in murine keratinocytes and the human cell line HPK1A- ras, confirming the central role of CYP24A1 in metabolism. Products of 1α(OH)D 2 included the active metabolites 1α,24-dihydroxyvitamin D 2 (1α,24(OH) 2D 2) and 1α,25-dihydroxyvitamin D 2 (1α,25(OH) 2D 2); the formation of both indicating the existence of distinct activation pathways. A novel water-soluble metabolite, identified as 26-carboxy-1α,24(OH) 2D 2, was the presumed terminal degradation product of 1α(OH)D 2 synthesized by CYP24A1 via successive 24-hydroxylation, 26-hydroxylation and further oxidation at C-26. This acid was absent in keratinocytes from Cyp24a1 null mice. Slower clearance rates of 1α(OH)D 2 and 1α,24(OH) 2D 2 relative to 1α,25(OH) 2D 2 and 1α,25(OH) 2D 3 were noted, arguing for a role of 24-hydroxylated metabolites in the altered biological activity profile of 1α(OH)D 2. Our findings suggest that CYP24A1 can activate and inactivate vitamin D prodrugs in skin and other target cells in vitro, offering the potential for treatment of hyperproliferative disorders such as psoriasis by topical administration of these prodrugs.

Remanufacturing system based on totally automatic MIG surfacing via robot

Remanufacturing system is a term of green system project which conforms to the national sustainable development strategy. With the demand of the high adaptability of the varieties of waste machining parts, the short product cycle, the low machining cost and the high product quality are offered. Each step of the remanufacturing system from the beginning of the scanning to the accomplishment of the welding was investigted. Aiming at building a remanufacturing system based on totally automatic MIG surfacing via robot, advanced information technology, remanufacturing technology and management, through the control of the pretreatment and the optimization to minimize the time of remanufacturing and realize the remanufacturing on the terminal products of varieties, were applied. The steps mainly incude: 1) using the visual sensor which is installed at the end of the Robot to rapidly get the outline data of the machining part and the pretreatment of the data; 2) rebuilding the curved surface based on the outline data and the integrated CAD material object model; 3) building the remanufacturing model based on the CAD material object model and projecting the remanufacturing process; and 4) accomplishing the remanufacture of the machining part by the technology of MIG surfacing.

Characterization of the PCB Substrate Range of Microbial Dechlorination Process LP

We have characterized the substrate range of Process LP, a PCB dechlorination activity mediated by anaerobic bacteria, in Housatonic River sediment (Lenox, MA). Process LP has the rare ability to remove unflanked para chlorines from polychlorinated biphenyls (PCBs). We used 2,6-difluoro-4-chlorobiphenyl (DFCB) to activate Process LP in anoxic sediment microcosms and tested its ability to dechlorinate 34 potential PCB substrates, all of which are significant components of PCB mixtures found in contaminated sediments. We used gas chromatography-mass spectrometry to monitor the dechlorination of DFCB and PCBs and the appearance of products. The preferred substrates for Process LP were PCB congeners in which the target para chlorines were flanked by meta chlorines, such as those having 3,4- and 2,4,5-chlorophenyl rings. The unflanked para chlorines on PCBs with 2,4-, 2,4,6-, and sometimes 4-chlorophenyl rings, were also substrates. Furthermore, the data revealed that Process LP can also meta-dechlorinate 2,3-, 2,3,4-, and 2,3,5-chlorophenyl groups on some congeners. A single ortho chlorine on the unattacked ring generally enhanced dechlorination activity, but the presence of 3 or 4 ortho chlorines or a 4-chlorophenyl group decreased the dechlorination efficiency. PCBs with 2,4-, 2,4,6-, 2,3-, and 2,3,5-chlorophenyl rings are often terminal dechlorination products of other microbial dechlorination activities. Since these PCBs are substrates for Process LP, this dechlorination activity works especially well in tandem with other dechlorination activities and further reduces the toxicity and persistence of PCBs. The data presented here will facilitate the construction of accurate models to interpret in situ PCB dechlorination and predict PCB fate.

Experimental and theoretical study on gas-phase ion/molecule reactions of silver trimer cation, Ag3+, with 12-crown-4

The reaction mechanisms of silver trimer cation, Ag3+, with 12-crown-4 (12C4) were studied experimentally and theoretically. Using a cylindrical ion trap time-of-flight mass spectrometer, gas-phase ion/molecule reactions of Ag3+ with 12C4 were observed. Metal-ligand complexes of [Ag(12C4)]+, [Ag3(12C4)]+ and [Ag3(12C4)2]+, and of [Ag(12C4)2]+ and [Ag3(12C4)3]+, were observed as the reaction intermediates and terminal products, respectively. The formations of the [Ag12C4]+ and [Ag(12C4)2]+ complexes indicated that the neutral dimer (Ag2) had been eliminated from the trimer cation. From the results of ab initio calculations at the HF/LanL2DZ level of theory and the experiments, it is suggested that three 12C4 molecules can attach to Ag3+ through consecutive reactions and that neutral Ag2 can be easily eliminated from [Ag3(12C4)]+.

Reaction of β‐cyano esters with hydrazine hydrate. Unexpected formation of dipyrrolo[1,2‐b:1′,2′‐e][1,2,4,5]tetrazine, a novel ring system

AbstractSome intermediates and by‐products of the title reaction, known to yield 6‐hydrazinopyridazine‐3‐one derivatives, were isolated or detected when the amount of hydrazine hydrate used to react with two model β‐cyano esters was reduced to less than two equivalents. N'‐(1‐amino‐4‐hydrazino‐4‐oxo‐2‐phenylbutyli‐dene)‐4‐hydrazino‐4‐oxo‐2‐phenylbutanehydrazonamide and 3,3,8,8‐tetramethyl‐2,3,7,8‐tetrahydro‐1H,6H‐dipyrrolo[1,2‐b:1′,2′‐e][1,2,4,5]tetrazine‐1,6‐dione were isolated as the terminal products of side‐reactions; they were unreactive to hydrazine. The latter compound is a derivative of a novel ring system. Mechanism of the reaction was proposed.

Mechanisms of N 2O production following chloropicrin fumigation

Soil fumigation has recently been shown to affect the greenhouse gas balance by increasing emissions of nitrous oxide (N 2O) following chloropicrin (CP) application. However, the exact mechanisms of this increase were not investigated. The purpose of this study was to elucidate potential mechanisms of CP-induced N 2O production through laboratory incubations using chemical inhibitors (acetylene, antibacterial, antifungal, and oxygen), isotopically labeled 15N-CP, and pH modifications of a forest nursery soil. Results showed that N 2O production increased by 12.6 times following CP fumigation. Microbial activity contributed 82% to the CP-induced N 2O production, with the remaining 18% from abiotic processes as determined by incubation with sterilized soil. Inhibitor studies suggested that 20% of the N 2O production was from bacteria and 70% from fungi. There were no significant differences in N 2O production following CP fumigation under various levels of acetylene (0, 10, and 10 kPa), suggesting that traditional nitrification and denitification reactions did not significantly contribute to N 2O production following CP fumigation. 15N labeled studies indicated that 12% of fumigant source N was incorporated into the produced N 2O. No enrichment in N 2 was observed, indicating that N 2O was one of the terminal biotic mineralization products of CP. Production of N 2O is aerobic and production rates increased with increasing oxygen concentrations. Our data strongly suggested that fungal mediated denitrification reactions under aerobic conditions were the primary mechanism for CP-induced N 2O production.

Microstructural modification in full penetration and partial penetration electron beam welds in INCONEL-718 (IN-718) and its effect on fatigue crack initiation

Detailed microstructural analysis, as well as fatigue crack initiation evaluation, was carried out for electron beam (EB) welded IN-718. Fatigue test specimens were EB welded (full penetration) along their length, and a second weld pass, incorporating a slope-out from full to zero penetration along the gage length, was also applied. The specimens were fatigue tested at 523 °C and maximum stress (R=0) in the range 579 to 820 MPa. Early fatigue failure (<100,000 cycles at 0.25 Hz) was directly associated with the initiation at solidification porosity formed during “spiking” in the partial penetration weld metal at the start of the slope-out. The base metal, full penetration weld metal, and slope-out region were characterized using optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), which indicated that the microstructures of the base metal and full penetration weld metal should give good fatigue resistance. The rapid solidification of the full penetration weld metal gave an interdendritic terminal solidification product consisting of γ+NbC+Laves phase instead of the usually reported eutectic γ+Laves phase. Microstructural and chemical heterogeneities in the full penetration weld metal, combined with the sharp perturbations in penetration and solidification conditions (spiking) in the partial penetration weld metal, resulted in locally embrittled regions and interdendritic regions containing large numbers of fine pores as well as a higher volume fraction of mixed, hard interdendritic phases. These features would be consistent with a lower resistance to fatigue crack propagation in the partial penetration weld metal.

Leaf responses of micropropagated apple plants to water stress: nonstructural carbohydrate composition and regulatory role of metabolic enzymes

We examined changes in nonstructural carbohydrate biosynthesis and activities of related enzymes in leaves of micropropagated apple plants (Malus domestica Borkh. cv. 'NaganoFuji') in response to water stress, with particular emphasis on the enzymes associated with sorbitol, sucrose and starch metabolism. Water stress resulted in the accumulation of photosynthates in leaves, mainly sorbitol, sucrose, glucose and fructose, accompanied by a reduction in starch concentration. Correlation and path analysis indicated that water stress affected the partitioning of newly fixed carbon among terminal products. In response to water stress, ADP-glucose-pyrophosphorylase (ADPGPPase) activity decreased, becoming a critical and limiting step in shifting partitioning of photosynthetically fixed carbon. Amylase and ADPGPPase affected sucrose and sorbitol metabolism, mainly by regulating substrate supply; however, competition for limited substrate had a greater effect on the biosynthesis of sorbitol than of sucrose. Starch metabolism was also strictly regulated by ADPGPPase and amylase, whereas other related enzymes were downstream of the pathway for synthesis and degradation of carbohydrates and thus had relatively little effect on starch metabolism. Sorbitol dehydrogenase and sucrose phosphate synthase were critical regulators of sorbitol and sucrose metabolism, respectively.

Reflection Into Models of Finite Decidable FP-sketches in an Arithmetic Universe

We consider finite decidable FP-sketches within an arithmetic universe. By an FP-sketch we mean a sketch with terminal and binary product cones. By an arithmetic universe we mean a list-arithmetic pretopos, which is the general categorical definition we give to the concept of arithmetic universe introduced by Andrè Joyal to prove Gödel incompleteness theorems.Then, for finite decidable FP-sketches we prove a constructive version of Ehresmann-Kennison's theorem stating that the category of models of finite decidable FP-sketches in an arithmetic universe is reflective in the corresponding category of graph morphisms.The proof is done by employing the internal dependent type theory of an arithmetic universe.

Acetylenes as probes in the Fischer–Tropsch Reaction

Long-chain acetylenic molecules (from C6 to C10) have been added as probe molecules to the synthesis gas feed in Fischer–Tropsch(FT) reactions on Co/Al2O3 at 0.7 Mpa and 150–220 °C. The acetylenic molecules initiated the reaction at temperatures as low as 150 °C. Use of a phenyl-substituted acetylene allowed the FT products initiated by the alkyne to be distinguished from base case FT synthesis. Terminal alkynes produced straight chain products while internal alkynes produced both terminal and internal products. Aldehydes and alcohols with one carbon more than the added acetylenic probe molecule were the only oxygenates formed, perhaps by a hydroformylation type of reaction.

Intermittent anoxia induces oxidative stress in wheat seminal roots: assessment of the antioxidant defence system, lipid peroxidation and tissue solutes.

The effects of continuous and intermittent anoxia on components of the antioxidant defence system were evaluated in the expanded zones of wheat seedling roots. Intermittent anoxia caused oxidative stress (measured by the proportion of reduced glutathione) after three cycles of anoxia-aeration. The concentration of glutathione and activities of glutathione reductase (GR) and catalase (CAT) were decreased by 50% under both continuous and intermittent anoxia. Ascorbate peroxidase (APX) activity was unaffected by anoxia but stimulated almost 2-fold during the aerated periods of intermittent anoxia. Superoxide dismutase activity was decreased by 20% under continuous anoxia but ultimately returned to aerated activities under intermittent anoxia. Membrane damage appeared to be negligible or reversible, as K+ concentrations recovered to original levels under intermittent anoxia and there was no increase in terminal lipid peroxidation products. Addition of 5 mm exogenous ascorbate to intermittently anoxic roots prevented oxidative stress and avoided the decreases in glutathione, GR and CAT. Therefore, it is likely that the oxidative stress resulted from inadequate levels of, or damage to, these two enzymes.

Lipid peroxidation and antioxidant status in colorectal cancer

Reactive oxygen species (ROS) can induce carcinogenesis via DNA injury. Both enzymatic and non-enzymatic parameters participate in cell protection against harmful influence of oxidative stress. The aim of the present study was to assess the levels of final lipid peroxidation products like malondialdehyde (MDA) and 4-hydroxy-2-nonenal (4-HNE) in primary colorectal cancer. Moreover, we analysed the activity of main antioxidative enzymes, superoxide dismutase (Cu, Zn-SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GSSRG-R) and the level of non-enzymatic antioxidants (glutathione, vitamins C and E). Investigations were conducted in 81 primary colorectal cancers. As a control, the same amount of sample was collected from macroscopically unchanged colon regions of the most distant location to the cancer. Homogenisation of specimens provided 10% homogenates for our evaluations. Activity of antioxidant enzymes and level of glutathione were determined by spectrophotometry. HPLC revealed levels of vitamins C and E and served as a method to detect terminal products of lipid peroxidation in colorectal cancer. Our studies demonstrated a statistically significant increase in the level of lipid peroxidation products (MDA-Adc.muc.-2.65+/-0.48 nmol/g, Adc.G3-2.15+/-0.44 nmol/g, clinical IV stage 4.04+/-0.47 nmol/g, P<0.001 and 4-HNE-Adc.muc. -0.44+/-0.07 nmol/g, Adc.G3-0.44+/-0.10 nmol/g, clinical IV stage 0.52+/-0.11 nmol/g, P<0.001) as well as increase of Cu,Zn-SOD (Adc.muc.-363+/-72 U/g, Adc.G3-318+/-48 U/g, clinical IV stage 421+/-58 U/g, P<0.001), GSH-Px (Adc.muc. -2143+/-623 U/g, Adc.G3-2005+/-591 U/g, clinical IV stage 2467+/-368 U/g, P<0.001) and GSSG-R (Adc.muc.-880+/-194 U/g, Adc.G3-795+/-228 U/g, clinical IV stage 951+/-243 U/g, P<0.001) in primary tumour comparison with normal colon (MDA-1.39+/-0.15 nmol/g, HNE-0.29+/-0.03 nmol/g, Cu, Zn-SOD-117+/-25 U/g, GSH-Px-1723+/-189 U/g, GSSG-R-625+/-112 U/g) especially in mucinous and G3-grade adenocarcinomas as well as clinical IV stage of colorectal cancer. We also observed a decrease of CAT activity (Adc.muc. -40+/-14 U/g, clinical IV stage 33+/-18 U/g vs 84+/-17 U/g, P<0.001) as well as a decreased level of reduced glutathione (clinical IV stage 150+/-48 nmol/g vs 167+/-15 nmol/g, P<0.05) and vitamins C and E (vit. C-clinical IV stage 325+/-92 nmol/g vs 513+/-64 nmol/g, P<0.001; vit. E-clinical IV stage 13.3+/-10.3 nmol/g vs 37.5+/-5.2 nmol/g). Colorectal carcinogenesis is associated with serious oxidative stress and confirms that gradual advancement of oxidative-antioxidative disorders is followed by progression of colorectal cancer.

Determinação da força de arrasto e da velocidade terminal de frutos de café pela técnica de elementos finitos

Este trabalho apresenta um método alternativo para a determinação de velocidades terminais e de forças de arrasto em frutos de café, ao se variar o teor de umidade do produto e sua configuração geométrica (esférica e elíptica). Especificamente, investigou-se a aplicabilidade da técnica de elementos finitos para a obtenção de: (a) forças de arrasto no produto, usando-se valores experimentais das dimensões do fruto e de sua velocidade terminal e (b) velocidades terminais do produto, empregando-se valores experimentais das dimensões do fruto e de seu peso. A técnica dos elementos finitos mostrou-se ferramenta eficiente para simular velocidades terminais e forças de arrasto em frutos de café submetidos a um fluxo de ar. Independente do teor de umidade dos frutos, os valores simulados para a velocidade terminal e para força de arrasto no produto considerado elíptico são, estatisticamente, iguais àqueles determinados experimentalmente. Os erros relativos médios, envolvidos no valores simulados para a velocidade terminal do produto, em cada um dos teores de umidade, não foram superiores a 7,5 e 13,6% para o produto considerado elíptico e esférico, respectivamente.

BNP—Considering a Heartfelt Message

The natriuretic hormones have been discovered as mediators of the cardiac response to volume overload and mechanical dysfunction. Although there are some physiological differences between atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), it is BNP that has been found to be most useful as a clinical test. BNP is secreted along with an N terminal proBNP cleavage product (NT-proBNP). The similarities between these two tests are far greater than the differences. They are both probably useful in the diagnosis of high-risk patients (e.g. dyspnoeic) and may be useful in monitoring cardiac failure treatment. Although BNP levels in the normal range predict the risk of cardiac events and mortality, there is little evidence to promote their use as a screening test. In such an important condition as cardiac failure we should consider any messages that are likely to be of value, particularly those that are heartfelt.

Diverse Functional Implications of ADAMTS13 Gene Mutations in Patients with TTP and Congenital Deficiency.

Thrombotic thrombocytopenic purpura (TTP) is a rare disorder of small vessels that is associated with deficiency of the VWF cleaving protease ADAMTS13, causing life-threatening disseminated microvascular thrombosis. Here we report four missense mutations (V88M, G1239V, R1219W, R1123C) in three patients with congenital ADAMTS13 deficiency. The three subjects carrying the mutations had less than 10% normal ADAMTS13 plasma antigen levels (measured by ELISA), which is consistent with previously reported data showing that most ADAMTS13 mutations in TTP patients result in impaired secretion of the protein. To evaluate whether the small amount of the mutant protease present in patients' plasma had proteolytic activity, we cloned the ADAMTS13 cDNA in the pMT/Bip/His Drosophila expression vector and introduced the respective mutations by directed mutagenesis technique using wild-type cDNA as a template. These wild-type and mutant constructs were stably transfected into S2 Drosophila cells under the influence of the Drosophila BiP protein signal sequence, which allows the protein to be secreted into the medium and overcomes impaired secretion caused by the mutations. The induction of the histidine-tagged ADAMTS13 recombinants following the addition of copper was analyzed by Western blotting using an anti-hexahistidine monoclonal antibody. Equal amounts of recombinant ADAMTS13 proteins were used to evaluate proteolytic activity of recombinant proteins by cleavage of the rVWF A1-A2-A3 substrate. The proteolytic carboxyl terminal product of about 30 kDa was visualized by Western blot with a mouse monoclonal antibody directed against an epitope contained within the A3 domain of VWF. All the four missense mutations exhibited reduced activity: V88M:40%, G1239V: 66%, R1219W: 62% and R1123C: 64% of wild type activity . The results were also confirmed by collagen binding assay. For the the V88M mutation (located in the metalloprotease domain), decreased activity was confirmed by kinetic studies. In conclusion, mutant ADAMTS13 proteins found in patients with TTP, besides defective secretion, also have reduced protease activity. The mechanisms of the deficiency will be the matter of further studies.

Microstructural study of weld fusion zone of TIG welded IN 738LC nickel-based superalloy

The weld fusion zone microstructure of a commercial aerospace superalloy IN 738 was examined. Elemental segregation induced interdendritic microconstituents were identified to include terminal solidification product M 3B 2 and Ni 7Zr 2 in association with γ–γ′ eutectic constituent, which require proper consideration during the development of optimum post weld heat treatment.

Testosterone promotes apoptotic damage in human renal tubular cells

Apoptosis is a mode of cell death that participates in the kidney physiologic remodeling processes and is thought to contribute to cell loss and kidney structural damage in chronic renal diseases. Gender is one factor which contributes to accelerated nephron loss, with progression more rapid in men than in women in diabetic and nondiabetic chronic renal diseases. Mechanisms by which androgens may cause higher rate of progression of chronic renal diseases in men are poorly explored. In this study, to investigate the role of androgens on apoptotic damage and its associated mechanisms, we examined the effects of testosterone (T) (0.1 nmol/L to 1 micromol/L) on apoptosis, and apoptosis-related proteins in a proximal human tubule cell line (HK-2 cells). Additional experiments were performed in primary cultures of proximal tubular epithelial cells (PTECs). Cells were grown to subconfluence in normal growth medium, and apoptotic damage was induced by serum deprivation for 24 to 48 hours. Cycloheximide, flutamide (a T-receptor antagonist), 17-beta estradiol, or caspase inhibitors were added to cultures that were successively processed for terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end-labeling (TUNEL) analysis, annexin V/propidium iodide staining, immunofluorescence, or immunoblots to identify effects and apoptotic pathways that could be modulating cell survival. Both morphologic analysis by annexin V/propidium iodide staining and TUNEL showed that physiologic T levels (1 to 10 nmol/L) induced a significant increase in apoptosis both in HK-2 cells and PTECs. In both types of cell lines pretreatment with the androgen receptor antagonist flutamide prevented the T-induced apoptosis. T-induced apoptosis was enhanced by treatment with cycloheximide and prevented by 17beta-estradiol. Fas, Fas ligand (FasL), and Fas-associating death domain containing protein (FADD) were clearly up-regulated within 48 hours of T treatment in HK-2 cells. Also, T significantly increased the expression of Bax protein (P < 0.01 vs. control) (an effect which was blocked by flutamide), and decreased the expression of Bcl-2. Western blot analysis showed that caspase-3 was activated. Moreover, cleavage into an 85-kD poly(ADP-ribose) polymerase-1 (PARP-1) terminal breakdown product was detectable. The changes in cellular morphology induced by T at 48 hours were no longer observed after the addition of caspase-8, caspase-9, and caspase-3 inhibitors to the culture medium. These results indicate that T increases the permissiveness of proximal tubule kidney cells to apoptotic effects by triggering an apoptotic pathway involving caspase activation, Fas up-regulation, and FasL expression, thus potentially interacting with mechanisms of cell loss which have been already shown to be activated in chronic renal diseases. This is consistent with a role for T in promoting renal injury in men.

Hydrogen thresholds as indicators of dehalorespiration in constructed treatment wetlands.

Anaerobic degradation of cis-1,2-dichloroethene (cis-1,2-DCE) and 1,2-dichloroethane (1,2-DCA) was studied in microcosms derived from a laboratory-scale upflow treatment wetland system used to biodegrade chlorinated compounds present in groundwater from a Superfund site. Dechlorination kinetics of cis-1,2-DCE (0.94-1.57 d(-1)) and 1,2-DCA (0.15-0.71 d(-1)) were rapid, and degradation proceeded to completion with ethene or ethane as terminal dechlorination products. Hydrogen concentrations, measured simultaneously during dechlorination, were significantly different for the two compounds, approximately 2.5 nM for cis-1,2-DCE and 38 nM for 1,2-DCA. Methanogenesis proceeded during the degradation of 1,2-DCA when H2 concentrations were high but not during the dechlorination of cis-1,2-DCE when H2 concentrations were below published thresholds for methanogenesis. A 16S rRNA gene-based approach indicates that microorganisms closely related to Dehalococcoides ethenogenes were present and that they were distributed throughout the bottom, middle, and top of the upflow treatment wetland system. These results coupled with consideration of hydrogen thresholds, degradation kinetics, daughter products, and measurements of methanogenesis strongly suggest that halorespirers were responsible for dechlorination of cis-1,2-DCE and that 1,2-DCA dechlorination was co-metabolic, likely mediated by acetogens or methanogens. Rapid dechlorination potential was distributed throughout the wetland bed, both within and below the rhizosphere, indicating that reductive dechlorination pathways can be active in anaerobic environments located in close spatial proximity to aerobic environments and plants in treatment wetland systems.

Measurement of the malondialdehyde-2'-deoxyguanosine adduct in human urine by immuno-extraction and liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry.

The major adduct of malondialdehyde with guanine, M(1)G, was measured in human urine from non-smoking healthy individuals. M1G is a mutagenic DNA lesion and a terminal product of lipid peroxidation in vivo that may be implicated in cancer related to lifestyle and diet. On the basis of a recently developed method for the quantification of M1G as an excreted deoxynucleoside using immuno-extraction purification, chemical NaBH4 reduction and liquid chromatography combined with atmospheric pressure chemical ionization tandem mass spectrometry, we demonstrate that the average 24 h excretion rate of M1G-dR is about 12 +/- 3.8 fmol kg(-1) (n = 5).

The classical and alternative pathways of complement activation play distinct roles in spontaneous C3 fragment deposition and membrane attack complex (MAC) formation on human B lymphocytes.

The contributions of the classical (CP) and alternative (AP) pathways of complement activation to the spontaneous deposition of C3 fragments and the formation of membrane attack complexes (MAC) on human B lymphocytes, were assessed by incubating peripheral blood mononuclear cells with autologous serum in the absence and presence of selective inhibitors of the AP and CP, respectively. While the total amount of C3 fragments deposited was relatively unaffected by blocking either pathway individually, deposition was virtually abrogated by their combined blockade. A marked difference was observed, however, in the nature of the fragments deposited as a result of CP and AP activation: C3b fragments deposited via the CP were extensively ( approximately 90%) converted to the terminal degradation product, C3dg, whereas about 50% of those deposited by the AP persisted as C3b/iC3b fragments. The extent of MAC formation was also found to be highly pathway dependent, with the AP being about 15-fold more efficient at initiating this process than the CP. A model accounting for the effectiveness of the AP in both preserving C3 fragment integrity and initiating MAC is presented.