Latest Miocene - Pliocene Larger Foraminifera and depositional environments of the carbonate bank of La Désirade Island, Guadeloupe (French Antilles)

In this paper we present first results of the study of planktonic Foraminifera, large benthic Foraminifera and carbonate facies of La Désirade, aiming at a definition of the age and depositional environments of the Neogene carbonates of this island. The study of planktonic Foraminifera from the Detrital Offshore Limestones (DOL) of the Anciènne Carrière allows to constrain the biochronology of this formation to the lower Zone N19 and indicates a latest Miocene to early Pliocene (5.48 - 4.52 Ma) age. Large benthic Foraminifera were studied both as isolated and often naturally split specimens from the DOL, and in thin sections of limestones from the DOL and the Limestone Table (LT). The assemblages of Foraminifera include Nummulitidae, Amphisteginidae, Asterigerinidae, Peneroplidae, Soritidae, Rotalidae (Globigerinidae: Globigerinoides, Sphaeroidenellopsis, Orbulina) and incrusting Foraminifera (Homotrema and Sporadotrema). The genera Amphistegina, Archaias and Operculina are discussed. Concerning the Nummulitidae we include both "Paraspiroclypeus" chawneri and "Nummulites" cojimarensis, as well as a newly described species, Operculina desiradensis new species, in the genus Operculina, because the differences between these 3 species are rather on the specific than the generic level, while their morphology, studied by SEM, is compatible with the definition of the genus Operculina (D'Orbigny1826, emend. Hottinger 1977). The three species can be easily distinguished on the basis of their differences in spiral growth: while O. desiradensis has an overall logarithmic spiral growth, O. cojimarensis and especially O. chawneri show a tighter and more geometric spiral growth. O. cojimarensis and O. chawneri were originally described from Cuba in outcrops originally dated as Oligocene and later redated as early Pliocene. Therefore, O. chawneri was considered until now as restricted to the early Pliocene. However, in the absence of a detailed morphometric and biostratigraphic study of the Caribbean Neogene nummulitids, it is difficult to evaluate the biochronologic range of these species.The history of the carbonates begins with the initial tectonic uplift and erosion of the Jurassic igneous basement of La Désirade, that must have occurred at latest in late Miocene times, when sea-level oscillated around a long term stable mean. The rhythmic deposition of the Désirade Limestone Table (LT) can be explained by synsedimentary subsidence in a context of rapidly oscillating sea-level due to precession-driven (19-21 kyr) glacio-eustatic sea-level changes during the latest Miocene- Pliocene. Except for a thin reef cap present at the eastern edge of the LT, no other in-place reefal constructions have been observed in the LT. The DOL of western Désirade are interpreted as below wave base gravity deposits that accumulated beneath a steep fore-reef slope. They document the mobilisation of carbonate material (including Larger Foraminifera) from an adjacent carbonate platform by storms and their gravitational emplacement as debris and grain flows. The provenance of both the reefal carbonate debris and the tuffaceous components redeposited in the carbonates of La Désirade must be to the west, i. e. the carbonate platforms of Marie Galante and Grande Terre.

The gamma subunit is a specific component of the Na,K-ATPase and modulates its transport function.

The role of small, hydrophobic peptides that are associated with ion pumps or channels is still poorly understood. By using the Xenopus oocyte as an expression system, we have characterized the structural and functional properties of the gamma peptide which co-purifies with Na,K-ATPase. Immuno-radiolabeling of epitope-tagged gamma subunits in intact oocytes and protease protection assays show that the gamma peptide is a type I membrane protein lacking a signal sequence and exposing the N-terminus to the extracytoplasmic side. Co-expression of the rat or Xenopus gamma subunit with various proteins in the oocyte reveals that it specifically associates only with isozymes of Na,K-ATPase. The gamma peptide does not influence the formation and cell surface expression of functional Na,K-ATPase alpha-beta complexes. On the other hand, the gamma peptide itself needs association with Na,K-ATPase in order to be stably expressed in the oocyte and to be transported efficiently to the plasma membrane. Gamma subunits do not associate with individual alpha or beta subunits but only interact with assembled, transport-competent alpha-beta complexes. Finally, electrophysiological measurements indicate that the gamma peptide modulates the K+ activation of Na,K pumps. These data document for the first time the membrane topology, the specificity of association and a potential functional role for the gamma subunit of Na,K-ATPase.

Tibial component positioning in total knee arthroplasty: bone coverage and extensor apparatus alignment.

Correct positioning of the tibial component in total knee arthroplasty (TKA) must take into account both an optimal bone coverage (defined by a maximal cortical bearing with posteromedial and anterolateral support) and satisfactory patellofemoral tracking. Consequently, a compromise position must be found by the surgeon during the operation to simultaneously meet these two requirements. Moreover, tibial tray positioning depends upon the tibial torsion, which has been shown to act mainly in the proximal quarter of the tibia. Therefore, the correct application of the tibial tray is also theoretically related to the level of bone resection. In this study, we first quantified the torsional profile given by an optimal bone coverage for a symmetrical tibial tray design and for an asymmetrical one. Then, for the two types of tibial trays, we measured the angle difference between optimal bone coverage and an alignment on the middle of the tibial tubercule. Results showed that the values of the torsional profile given by the symmetrical tray were more scattered than those from the asymmetrical one. However, determination of the mean differential angle between the position providing optimal bone coverage and the one providing the best patellofemoral tracking indicated that the symmetrical prosthetic tray offered the best compromise between these two requirements. Although the tibiofemoral joint is known to be asymmetric in both shape and dimension, the asymmetrical tray chosen in this study was found to fulfill this compromise with more difficulty.

Development of a multistrain bacterial bioreporter platform for the monitoring of hydrocarbon contaminants in marine environments.

Petroleum hydrocarbons are common contaminants in marine and freshwater aquatic habitats, often occurring as a result of oil spillage. Rapid and reliable on-site tools for measuring the bioavailable hydrocarbon fractions, i.e., those that are most likely to cause toxic effects or are available for biodegradation, would assist in assessing potential ecological damage and following the progress of cleanup operations. Here we examined the suitability of a set of different rapid bioassays (2-3 h) using bacteria expressing the LuxAB luciferase to measure the presence of short-chain linear alkanes, monoaromatic and polyaromatic compounds, biphenyls, and DNA-damaging agents in seawater after a laboratory-scale oil spill. Five independent spills of 20 mL of NSO-1 crude oil with 2 L of seawater (North Sea or Mediterranean Sea) were carried out in 5 L glass flasks for periods of up to 10 days. Bioassays readily detected ephemeral concentrations of short-chain alkanes and BTEX (i.e., benzene, toluene, ethylbenzene, and xylenes) in the seawater within minutes to hours after the spill, increasing to a maximum of up to 80 muM within 6-24 h, after which they decreased to low or undetectable levels. The strong decrease in short-chain alkanes and BTEX may have been due to their volatilization or biodegradation, which was supported by changes in the microbial community composition. Two- and three-ring PAHs appeared in the seawater phase after 24 h with a concentration up to 1 muM naphthalene equivalents and remained above 0.5 muM for the duration of the experiment. DNA-damage-sensitive bioreporters did not produce any signal with the oil-spilled aqueous-phase samples, whereas bioassays for (hydroxy)biphenyls showed occasional responses. Chemical analysis for alkanes and PAHs in contaminated seawater samples supported the bioassay data, but did not show the typical ephemeral peaks observed with the bioassays. We conclude that bacterium-based bioassays can be a suitable alternative for rapid on-site quantitative measurement of hydrocarbons in seawater.

Inversion of crosshole seismic data in heterogenous environments : Comparison of waveform and ray-based approaches

High-resolution tomographic imaging of the shallow subsurface is becoming increasingly important for a wide range of environmental, hydrological and engineering applications. Because of their superior resolution power, their sensitivity to pertinent petrophysical parameters, and their far reaching complementarities, both seismic and georadar crosshole imaging are of particular importance. To date, corresponding approaches have largely relied on asymptotic, ray-based approaches, which only account for a very small part of the observed wavefields, inherently suffer from a limited resolution, and in complex environments may prove to be inadequate. These problems can potentially be alleviated through waveform inversion. We have developed an acoustic waveform inversion approach for crosshole seismic data whose kernel is based on a finite-difference time-domain (FDTD) solution of the 2-D acoustic wave equations. This algorithm is tested on and applied to synthetic data from seismic velocity models of increasing complexity and realism and the results are compared to those obtained using state-of-the-art ray-based traveltime tomography. Regardless of the heterogeneity of the underlying models, the waveform inversion approach has the potential of reliably resolving both the geometry and the acoustic properties of features of the size of less than half a dominant wavelength. Our results do, however, also indicate that, within their inherent resolution limits, ray-based approaches provide an effective and efficient means to obtain satisfactory tomographic reconstructions of the seismic velocity structure in the presence of mild to moderate heterogeneity and in absence of strong scattering. Conversely, the excess effort of waveform inversion provides the greatest benefits for the most heterogeneous, and arguably most realistic, environments where multiple scattering effects tend to be prevalent and ray-based methods lose most of their effectiveness.

A novel method for automated classification of epileptiform activity in the human electroencephalogram-based on independent component analysis.

Diagnosis of several neurological disorders is based on the detection of typical pathological patterns in the electroencephalogram (EEG). This is a time-consuming task requiring significant training and experience. Automatic detection of these EEG patterns would greatly assist in quantitative analysis and interpretation. We present a method, which allows automatic detection of epileptiform events and discrimination of them from eye blinks, and is based on features derived using a novel application of independent component analysis. The algorithm was trained and cross validated using seven EEGs with epileptiform activity. For epileptiform events with compensation for eyeblinks, the sensitivity was 65 +/- 22% at a specificity of 86 +/- 7% (mean +/- SD). With feature extraction by PCA or classification of raw data, specificity reduced to 76 and 74%, respectively, for the same sensitivity. On exactly the same data, the commercially available software Reveal had a maximum sensitivity of 30% and concurrent specificity of 77%. Our algorithm performed well at detecting epileptiform events in this preliminary test and offers a flexible tool that is intended to be generalized to the simultaneous classification of many waveforms in the EEG.

NrsZ: a novel, processed, nitrogen-dependent, small non-coding RNA that regulates Pseudomonas aeruginosa PAO1 virulence.

The opportunistic pathogen Pseudomonas aeruginosa PAO1 has a remarkable capacity to adapt to various environments and to survive with limited nutrients. Here, we report the discovery and characterization of a novel small non-coding RNA: NrsZ (nitrogen-regulated sRNA). We show that under nitrogen limitation, NrsZ is induced by the NtrB/C two component system, an important regulator of nitrogen assimilation and P. aeruginosa's swarming motility, in concert with the alternative sigma factor RpoN. Furthermore, we demonstrate that NrsZ modulates P. aeruginosa motility by controlling the production of rhamnolipid surfactants, virulence factors notably needed for swarming motility. This regulation takes place through the post-transcriptional control of rhlA, a gene essential for rhamnolipids synthesis. Interestingly, we also observed that NrsZ is processed in three similar short modules, and that the first short module encompassing the first 60 nucleotides is sufficient for NrsZ regulatory functions.

Production of human secretory component with dimeric IgA binding capacity using viral expression systems.

The cDNA encoding the NH2-terminal 589 amino acids of the extracellular domain of the human polymeric immunoglobulin receptor was inserted into transfer vectors to generate recombinant baculo- and vaccinia viruses. Following infection of insect and mammalian cells, respectively, the resulting truncated protein corresponding to human secretory component (hSC) was secreted with high efficiency into serum-free culture medium. The Sf9 insect cell/baculovirus system yielded as much as 50 mg of hSC/liter of culture, while the mammalian cells/vaccinia virus system produced up to 10 mg of protein/liter. The M(r) of recombinant hSC varied depending on the cell line in which it was expressed (70,000 in Sf9 cells and 85-95,000 in CV-1, TK- 143B and HeLa). These variations in M(r) resulted from different glycosylation patterns, as evidenced by endoglycosidase digestion. Efficient single-step purification of the recombinant protein was achieved either by concanavalin A affinity chromatography or by Ni(2+)-chelate affinity chromatography, when a 6xHis tag was engineered to the carboxyl terminus of hSC. Recombinant hSC retained the capacity to specifically reassociate with dimeric IgA purified from hybridoma cells.

Estimation of inelastic seismic material properties of a surgical sea-bed from multi-component marine seismic data

To date, state-of-the-art seismic material parameter estimates from multi-component sea-bed seismic data are based on the assumption that the sea-bed consists of a fully elastic half-space. In reality, however, the shallow sea-bed generally consists of soft, unconsolidated sediments that are characterized by strong to very strong seismic attenuation. To explore the potential implications, we apply a state-of-the-art elastic decomposition algorithm to synthetic data for a range of canonical sea-bed models consisting of a viscoelastic half-space of varying attenuation. We find that in the presence of strong seismic attenuation, as quantified by Q-values of 10 or less, significant errors arise in the conventional elastic estimation of seismic properties. Tests on synthetic data indicate that these errors can be largely avoided by accounting for the inherent attenuation of the seafloor when estimating the seismic parameters. This can be achieved by replacing the real-valued expressions for the elastic moduli in the governing equations in the parameter estimation by their complex-valued viscoelastic equivalents. The practical application of our parameter procedure yields realistic estimates of the elastic seismic material properties of the shallow sea-bed, while the corresponding Q-estimates seem to be biased towards too low values, particularly for S-waves. Given that the estimation of inelastic material parameters is notoriously difficult, particularly in the immediate vicinity of the sea-bed, this is expected to be of interest and importance for civil and ocean engineering purposes.

The effect of femoral component rotation on the five-year outcome of cemented mobile bearing total knee arthroplasty.

PURPOSE: Performing total knee replacement, accurate alignment and neutral rotation of the femoral component are widely believed to be crucial for the ultimate success. Contrary to absolute bone referenced alignment, using a ligament balancing technique does not automatically rotate the femoral component parallel to the transepicondylar axis. In this context we established the hypothesis that rotational alignment of the femoral component parallel to the transepicondylar axis (0° ± 3°) results in better outcome than alignment outside of this range. METHODS: We analysed 204 primary cemented mobile bearing total knee replacements five years postoperatively. Femoral component rotation was measured on axial radiographs using the condylar twist angle (CTA). Knee society score, range of motion as well as subjective rating documented outcome. RESULTS: In 96 knees the femoral component rotation was within the range 0 ± 3° (neutral rotation group), and in 108 knees the five-year postoperative rotational alignment of the femoral component was outside of this range (outlier group). Postoperative CTA showed a mean of 2.8° (±3.4°) internal rotation (IR) with a range between 6° external rotation (ER) and 15° IR (CI 95). No difference with regard to subjective and objective outcome could be detected. CONCLUSION: The present work shows that there is a large given natural variability in optimal rotational orientation, in this study between 6° ER and 15° IR, with numerous co-factors determining correct positioning of the femoral component. Further studies substantiating pre- and postoperative determinants are required to complete the understanding of resulting biomechanics in primary TKA.

Presence of an oligodendroglioma-like component in newly diagnosed glioblastoma identifies a pathogenetically heterogeneous subgroup and lacks prognostic value: central pathology review of the EORTC_26981/NCIC_CE.3 trial.

Glioblastoma (GBM) is a morphologically heterogeneous tumor type with a median survival of only 15 months in clinical trial populations. However, survival varies greatly among patients. As part of a central pathology review, we addressed the question if patients with GBM displaying distinct morphologic features respond differently to combined chemo-radiotherapy with temozolomide. Morphologic features were systematically recorded for 360 cases with particular focus on the presence of an oligodendroglioma-like component and respective correlations with outcome and relevant molecular markers. GBM with an oligodendroglioma-like component (GBM-O) represented 15% of all confirmed GBM (52/339) and was not associated with a more favorable outcome. GBM-O encompassed a pathogenetically heterogeneous group, significantly enriched for IDH1 mutations (19 vs. 3%, p = 0.003) and EGFR amplifications (71 vs. 48%, p = 0.04) compared with other GBM, while co-deletion of 1p/19q was found in only one case and the MGMT methylation frequency was alike (47 vs. 46%). Expression profiles classified most of the GBM-O into two subtypes, 36% (5/14 evaluable) as proneural and 43% as classical GBM. The detection of pseudo-palisading necrosis (PPN) was associated with benefit from chemotherapy (p = 0.0002), while no such effect was present in the absence of PPN (p = 0.86). In the adjusted interaction model including clinical prognostic factors and MGMT status, PPN was borderline nonsignificant (p = 0.063). Taken together, recognition of an oligodendroglioma-like component in an otherwise classic GBM identifies a pathogenetically mixed group without prognostic significance. However, the presence of PPN may indicate biological features of clinical relevance for further improvement of therapy.