Accuracy of computed tomography angiography in the detection of pulmonary embolism in patients with high body weight

BACKGROUND The accuracy of CT pulmonary angiography (CTPA) in detecting or excluding pulmonary embolism has not yet been assessed in patients with high body weight (BW). METHODS This retrospective study involved CTPAs of 114 patients weighing 75-99 kg and those of 123 consecutive patients weighing 100-150 kg. Three independent blinded radiologists analyzed all examinations in randomized order. Readers' data on pulmonary emboli were compared with a composite reference standard, comprising clinical probability, reference CTPA result, additional imaging when performed and 90-day follow-up. Results in both BW groups and in two body mass index (BMI) groups (BMI <30 kg/m(2) and BMI ≥ 30 kg/m(2), i.e., non-obese and obese patients) were compared. RESULTS The prevalence of pulmonary embolism was not significantly different in the BW groups (P=1.0). The reference CTPA result was positive in 23 of 114 patients in the 75-99 kg group and in 25 of 123 patients in the ≥ 100 kg group, respectively (odds ratio, 0.991; 95% confidence interval, 0.501 to 1.957; P=1.0). No pulmonary embolism-related death or venous thromboembolism occurred during follow-up. The mean accuracy of three readers was 91.5% in the 75-99 kg group and 89.9% in the ≥ 100 kg group (odds ratio, 1.207; 95% confidence interval, 0.451 to 3.255; P=0.495), and 89.9% in non-obese patients and 91.2% in obese patients (odds ratio, 0.853; 95% confidence interval, 0.317 to 2.319; P=0.816). CONCLUSION The diagnostic accuracy of CTPA in patients weighing 75-99 kg or 100-150 kg proved not to be significantly different.

Search for Low-Molecular-Weight Biomarkers in Plant Tissues and Seeds Using Metabolomics: Tools, Strategies, and Applications

This chapter summarises the metabolomic strategies currently in force used in plant science and describes the methods used. The metabolite profiling and fingerprinting of plant tissues through MS- and/or NMR-based approaches and the subsequent identification of biomarkers is detailed. Strategies for the microisolation and de novo identification of unknown biomarkers are also discussed. The various approaches are illustrated by a metabolomic study of the maize response to herbivory. A review of recent metabolomic studies performed on seed and crop plant tissues involving various analytical strategies is provided.

TimX, a novel player in protein import across the inner mitochondrial membrane of T. brucei

Mitochondrial protein import is an essential function of the unique mitochondrion in T. brucei as roughly 1000 different nuclear encoded proteins need to be correctly localized to their mitochondrial subcompartment. For this reason the responsible import machinery is expected to be similarly complex as in other Eukaryotes. This was recently demonstrated for the translocation machinery in the outer mitochondrial membrane. In contrast, the composition of the inner membrane import machinery and the exact molecular pathway(s) taken by various substrates are still ill-defined. To elucidate this further, we performed a pulldown analysis of epitope tagged TbTim17 in combination with quantitative mass spectrometry. By this we identified novel components of the mitochondrial import machinery in trypanosomes. One of these, TimX, is an essential mitochondrial membrane protein of 42 kDa that is unique to kinetoplastids. This protein migrates on Blue Native PAGE in a high molecular weight complex similar to TbTim17. Ablation of either of the two proteins leads to a destabilization of the complex containing the other protein. Furthermore, its involvement in protein import could be demonstrated by in vivo and in vitro protein import assays. This corroborates that TimX together with TbTim17 forms a protein import complex in the inner mitochondrial membrane. As TbTim17 the TimX protein was subjected to pulldown analysis in combination with quantitative mass spectrometry. The overlap of candidates defined by these two sets of IPs likely defines further components of the inner membrane translocase which are presently being analyzed. In summary our study on novel components of the trypanosome mitochondrial protein import system gives us fascinating new insights into evolution of the mitochondrion.

High-Frequency in Situ Optical Measurements During a Storm Event: Assessing Relationships Between Dissolved Organic Matter, Sediment Concentrations, and Hydrologic Processes

Dissolved organic matter (DOM) dynamics during storm events has received considerable attention in forested watersheds, but the extent to which storms impart rapid changes in DOM concentration and composition in highly disturbed agricultural watersheds remains poorly understood. In this study, we used identical in situ optical sensors for DOM fluorescence (FDOM) with and without filtration to continuously evaluate surface water DOM dynamics in a 415 km(2) agricultural watershed over a 4 week period containing a short-duration rainfall event. Peak turbidity preceded peak discharge by 4 h and increased by over 2 orders of magnitude, while the peak filtered FDOM lagged behind peak turbidity by 15 h. FDOM values reported using the filtered in situ fluorometer increased nearly fourfold and were highly correlated with dissolved organic carbon (DOC) concentrations (r(2) = 0.97), providing a highly resolved proxy for DOC throughout the study period. Discrete optical properties including specific UV absorbance (SUVA(254)), spectral slope (S(290-350)), and fluorescence index (FI) were also strongly correlated with in situ FDOM and indicate a shift toward aromatic, high molecular weight DOM from terrestrially derived sources during the storm. The lag of the peak in FDOM behind peak discharge presumably reflects the draining of watershed soils from natural and agricultural landscapes. Field and experimental evidence showed that unfiltered FDOM measurements underestimated filtered FDOM concentrations by up to similar to 60% at particle concentrations typical of many riverine systems during hydrologic events. Together, laboratory and in situ data provide insights into the timing and magnitude of changes in DOM quantity and quality during storm events in an agricultural watershed, and indicate the need for sample filtration in systems with moderate to high suspended sediment loads.

CHARACTERIZATION OF HUMAN ACID ALPHA-GLUCOSIDASE

The goal of this study was to investigate the properties of human acid (alpha)-glucosidase with respect to: (i) the molecular heterogeneity of the enzyme and (ii) the synthesis, post-translational modification, and transport of acid (alpha)-glucosidase in human fibroblasts.^ The initial phase of these investigations involved the purification of acid (alpha)-glucosidase from the human liver. Human hepatic acid (alpha)-glucosidase was characterized by isoelectric focusing and native and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Four distinct charge forms of hepatic acid (alpha)-glucosidase were separated by chromatofocusing and characterized individually. Charge heterogeneity was demonstrated to result from differences in the polypeptide components of each charge form.^ The second aspect of this research focused on the biosynthesis and the intracellular processing and transport of acid (alpha)-glucosidase in human fibroblasts. These experiments were accomplished by immune precipitation of the biosynthetic intermediates of acid (alpha)-glucosidase from radioactively labeled fibroblasts with polyclonal and monoclonal antibodies raised against human hepatic acid (alpha)-glucosidase. The immune precipitated biosynthetic forms of acid (alpha)-glucosidase were analyzed by SDS-PAGE and autoradiography. The pulse-chase experiments demonstrated the existence of several transient, high molecular weight precursors of acid (alpha)-glucosidase. These precursors were demonstrated to be intermediates of acid (alpha)-glucosidase at different stages of transport and processing in the Golgi apparatus. Other experiments were performed to examine the role of co-translational glycosylation of acid (alpha)-glucosidase in the transport and processing of precursors of this enzyme.^ A specific immunological assay for detecting acid (alpha)-glucosidase was developed using the monoclonal antibodies described above. This method was modified to increase the sensitivity of the assay by utilization of the biotin-avidin amplification system. This method was demonstrated to be more sensitive for detecting human acid (alpha)-glucosidase than the currently used biochemical assay for acid (alpha)-glucosidase activity. It was also demonstrated that the biotin-avidin immunoassay could discriminate between normal and acid (alpha)-glucosidase deficient fibroblasts, thus providing an alternative approach to detecting this inborn error in metabolism. (Abstract shortened with permission of author.) ^

The low molecular weight (LMW) isoforms of cyclin E provide a novel mechanism of cell cycle deregulation

Cyclin E, in complex with cyclin dependent kinase 2 (CDK2), is a positive regulator of G1 to S phase progression of the cell cycle. Deregulation of G1/S phase transition occurs in the majority of tumors. Cyclin E is overexpressed and post-translationally generates low molecular weight (LMW) isoforms in breast cancer, but not normal cells. Such alteration of cyclin E is linked to poor prognosis. Therefore, we hypothesized that the LMW isoforms of cyclin E provide a novel mechanism of cell cycle de-regulation in cancer cells. Insect cell expression system was used to explore the biochemical properties of the cyclin E isoforms. Non-tumorigenic (76NE6) and tumorigenic (T47D) mammary epithelial cells transfected with the cyclin E isoforms and breast tumor tissue endogenously expressing the LMW isoforms were used to study the biologic consequences of the LMW isoforms of cyclin E. All model systems studied show that the LMW forms (compared to full-length cyclin E) have increased kinase activity when partnered with CDK2. Increases in the percentage of cells in S phase and colony formation were also observed after overexpression of LMW compared to full-length cyclin E. The LMW isoforms of cyclin E utilize several mechanisms to attain their hyper-activity. They bind CDK2 more efficiently, and are resistant to inhibition by cyclin dependent kinase inhibitors (CKIs) as compared to full-length cyclin E. In addition, the LMW isoforms sequester the CKIs from full-length cyclin E abrogating the overall negative regulation of cyclin E. Despite their correlation with adverse biological consequences, the direct role of the LMW isoforms of cyclin E in mediating tumorigenesis remained unanswered. Subsequent to LMW cyclin E expression in 76NE6 cells, they lose their ability to enter quiescence and exhibit genomic instability, both characteristic of a tumor cell phenotype. Furthermore, injection of 76NE6 cells overexpressing each of the cyclin E isoforms into the mammary fat pad of nude mice revealed that the LMW isoforms of cyclin E yield tumors, whereas the full-length cyclin E does not. In conclusion, the LMW isoforms of cyclin E utilize several mechanisms to acquire a hyperactive phenotype that results in deregulation of the cell cycle and initiates the tumorigenic process in otherwise non-transformed mammary epithelial cells. ^

Low-molecular-weight hydrocarbons in sediments at DSDP Sites 89-585 and 89-586

C2-C8 hydrocarbon concentrations (about 35 compounds identified, including saturated, aromatic, and olefinic compounds) from 38 shipboard sealed, deep-frozen core samples of Deep Sea Drilling Project Sites 585 (East Mariana Basin) and 586 (Ontong-Java Plateau) were determined by a gas stripping-thermovaporization method. Total concentrations, which represent the hydrocarbons dissolved in the pore water and adsorbed on the mineral surfaces of the sediment, vary from 20 to 630 ng/g of rock at Site 585 (sub-bottom depth range 332-868 m). Likewise, organic-carbon normalized yields range from 3*10**4 to 9*10**5 ng/g Corg, indicating that the organic matter is still in the initial, diagenetic evolutionary stage. The highest value (based on both rock weight and organic carbon) is measured in an extremely organic-carbon-poor sample of Lithologic Subunit VB (Core 585-30). In this unit (504-550 m) several samples with elevated organic-carbon contents and favorable kerogen quality including two thin "black-shale" layers deposited at the Cenomanian/Turonian boundary (not sampled for this study) were encountered. We conclude from a detailed comparison of light hydrocarbon compositions that the Core 585-30 sample is enriched in hydrocarbons of the C2-C8 molecular range, particularly in gas compounds, which probably migrated from nearby black-shale source layers. C2-C8 hydrocarbon yields in Site 586 samples (sub-bottom depth range 27-298 m) did not exceed 118 ng/g of dry sediment weight (average 56 ng/g), indicating the immaturity of these samples.

Low-molecular-weight hydrocarbon concentrations, organic carbon contents, and Rock-Eval pyrolysis hydrogen indices at DSDP Holes 75-530A and 75-532

A series of C2-C8 hydrocarbons (including saturated, aromatic, and olefinic compounds) from deep-frozen core samples taken during DSDP Leg 75 (Holes 530A and 532) were analyzed by a combined hydrogen-stripping/thermovaporization method. Concentrations representing both hydrocarbons dissolved in the pore water and adsorbed on the mineral surfaces vary in Hole 530A from about 10 to 15,000 ng/g of dry sediment weight depending on the lithology (organic-carbon-lean calcareous oozes versus "black shales"). Likewise, the organic-carbon-normalized C2-C8 hydrocarbon concentrations vary from 3,500 to 93,100 ng/g Corg, reflecting drastic differences in the hydrogen contents and hence the hydrocarbon potential of the kerogens. The highest concentrations measured of nearly 10**5 ng/g Corg are about two orders of magnitude below those usually encountered in Type-II kerogen-bearing source beds in the main phase of petroleum generation. Therefore, it was concluded that Hole 530A sediments, even at 1100 m depth, are in an early stage of evolution. The corresponding data from Hole 532 indicated lower amounts (3,000-9,000 ng/g Corg), which is in accordance with the shallow burial depth and immaturity of these Pliocene/late Miocene sediments. Significant changes in the light hydrocarbon composition with depth were attributed either to changes in kerogen type or to maturity related effects. Redistribution pheonomena, possibly the result of diffusion, were recognized only sporadically in Hole 530A, where several organic-carbon lean samples were enriched by migrated gaseous hydrocarbons. The core samples from Hole 530A were found to be severely contaminated by large quantities of acetone, which is routinely used as a solvent during sampling procedures on board Glomar Challenger.

Organic geochemistry of sediment samples from Prydz Bay

High molecular weight aliphatic hydrocarbons were extracted from sediments at two sites (741 and 742) drilled during Ocean Drilling Program Leg 119 in Prydz Bay, a major embayment on the continental shelf of East Antarctica. The distributions of n-alkanes and triterpenoid and steroid hydrocarbons suggest that the n-alkanes and steranes are mainly of terrestrial origin and that the hydrocarbons are immature to slightly mature in the Lower Cretaceous sediments and immature to mature in the Tertiary sediments. At Site 741, the Lower Cretaceous depositional sequence, which is generally characterized by immature hydrocarbons, is interrupted by sediment having more mature components, suggesting a change of source during part of Early Cretaceous time. At Site 742, the mature geochemical parameters of a Pliocene sample correlate with results reported elsewhere for Site 739. In all but one of the other Tertiary samples, the geochemical parameters indicate intermediate maturity. The Lower Cretaceous and Pliocene sediments average about 1.9% organic carbon, a value of interest from the point of view of potential sources of petroleum offshore from Antarctica.

Biogeochemistry of the Darwin Mounds, NE Atlantic

The Darwin Mounds are a series of small (<=5 m high, 75-100 m diameter) sandy features located in the northern Rockall Trough. They provide a habitat for communities of Lophelia pertusa and associated fauna. Suspended particulate organic matter (sPOM) reaching the deep-sea floor, which could potentially fuel this deep-water coral (DWC) ecosystem, was collected during summer 2000. This was relatively "fresh" (i.e. dominated by labile lipids such as polyunsaturated fatty acids) and was derived largely from phytoplankton remains and faecal pellets, with contributions from bacteria and microzooplankton. Labile sPOM components were enriched in the benthic boundary layer (~10 m above bottom (mab)) relative to 150 mab. The action of certain benthic fauna that are exclusively associated with the DWC ecosystem (e.g. echiuran worms) leads to the subduction of fresh organic material into the sediments. The mound surface sediments are enriched in organic carbon, relative to off-mound sites. There is no evidence for hydrocarbon venting at this location.

Proto-kerogens in Holocene sediments of ODP Hole 165-1002C

Proto-kerogens were isolated, by extraction and HF/HC1 treatment, from core samples of Holocene sediments of the Cariaco Trench, with interpolated ages of 900, 2850 and 6000 years, and examined via a combination of microscopic, spectroscopic and pyrolytic methods. It appears that these proto-kerogens were chiefly formed from phytoplanktonic components via the degradation-recondensation pathway. The natural sulfurisation pathway only afforded a minor contribution, in spite of the conditions prevailing in the water column and sediments that correspond to those generally considered as especially favourable for the formation of sulfurised organic matter. Proto-kerogen formation via sulfurisation, i.e. the endpoint of the continuum leading to insoluble high molecular weight structures cross-linked by sulfur and resistant to acid hydrolysis, is therefore a rather slow process under these conditions. However, the contribution of sulfurised moieties to the total proto-kerogen substantially increased with depth due to continuous sulfurisation in the time/depth interval, whereas formation through degradation-recondensation is almost complete for the 900 years old sample onwards. Proto-kerogen formation via carbohydrate sulfurisation is faster than lipid sulfurisation and only sulfurised carbohydrates were detected in the shallowest sample. In contrast, sulfurised lipids occur in the other two proto-kerogens. Moreover, their contribution relative to sulfurised carbohydrates increases with depth, probably due to the higher resistance of lipids to mineralisation compared to carbohydrates.

Low-molecular-weight hydrocarbons in sediments of Broken Ridge and Ninetyeast Ridge

Core samples taken during Leg 121 drilling aboard the JOIDES Resolution in the central Indian Ocean were analyzed for their low-molecular-weight hydrocarbon contents. Forty-three samples from the Broken Ridge and 39 samples from the Ninetyeast Ridge drill sites, deep-frozen on board immediately after recovery, were studied by a dynamic headspace technique (hydrogen-stripping/thermovaporization). Light hydrocarbons (saturated and olefinic) with two to four carbon atoms, and toluene as a selected aromatic compound, were identified. Total C2-C4 saturated hydrocarbon yields vary considerably from virtually zero in a Paleogene calcareous ooze from Hole 757B to nearly 600 nanogram/gram of dry-weight sediment (parts per billion) in a Cretaceous claystone from Hole 758A. An increase of light-hydrocarbon yields with depth, and hence with sediment temperature, was observed from Hole 758A samples down to a depth of about 500 meters below seafloor. Despite extreme data scatter due to lithological changes over this depth interval, this increased yield indicates the onset of temperature-controlled hydrocarbon formation reactions. Toluene contents are also extremely variable (generally between 10 and 100 ppb) and reach more than 300 ppb in two samples of tuffaceous lithology (Sections 121-755A-17R-4 and 121-758A-48R-4). As for the saturated hydrocarbons, there was also an increase of toluene yields with increasing depth in Hole 758A.