U mobilization and associated U isotope fractionation by sulfur-oxidizing bacteria

Uranium (U) contamination of the environment causes high risk to health, demanding for effective and sustainable remediation. Bioremediation via microbial reduction of soluble U(VI) is generating high fractions (>50%) of insoluble non-crystalline U(IV) which, however, might be remobilized by sulfur-oxidizing bacteria. In this study, the efficacy of Acidithiobacillus (At.) ferrooxidans and Thiobacillus (T.) denitrificans to mobilize non-crystalline U(IV) and associated U isotope fractionation were investigated. At. ferrooxidans mobilized between 74 and 91% U after 1 week, and U mobilization was observed for both, living and inactive cells. Contrary to previous observations, no mobilization by T. denitrificans could be observed. Uranium mobilization by At. ferrooxidans did not cause U isotope fractionation suggesting that U isotope ratio determination is unsuitable as a direct proxy for bacterial U remobilization. The similar mobilization capability of active and inactive At. ferrooxidans cells suggests that the mobilization is based on the reaction with the cell biomass. This study raises doubts about the long-term sustainability of in-situ bioremediation measures at U-contaminated sites, especially with regard to non-crystalline U(IV) being the main component of U bioremediation.

Carbamazepine derivatives with P2X4 receptor-blocking activity

Antagonists for the P2 receptor subtype P2X4, an ATP-activated cation channel receptor, have potential as novel drugs for the treatment of neuropathic pain and other inflammatory diseases. In the present study, a series of 47 carbamazepine derivatives including 32 novel compounds were designed, synthesized, and evaluated as P2X4 receptor antagonists. Their potency to inhibit ATP-induced calcium influx in 1321N1 astrocytoma cells stably transfected with the human P2X4 receptor was determined. Additionally, species selectivity (human, rat, mouse) and receptor subtype selectivity (P2X4 vs P2X1, 2, 3, 7) were investigated for selected derivatives. The most potent compound of the present series, which exhibited an allosteric mechanism of P2X4 inhibition, was N,N-diisopropyl-5H-dibenz[b,f]azepine-5-carboxamide (34, IC50 of 3.44μM). The present study extends the so far very limited knowledge on structure-activity relationships of P2X4 receptor antagonists.

A differential capacitive electrical field sensor array for contactless measurement of respiratory rate

Although respiratory rate is an important vital sign for early detection of deterioration, on general wards it is not routinely monitored. Since patients may not tolerate cables attached to their chest, we developed an unobtrusive and contactless measurement method which can be placed under a mattress. The sensor array uses the Maxwell-Wagner relaxation effect by capacitive injection of a high-frequency voltage into the torso and subsequent measurement of respiratory-induced phase shift. Simulations of the entire measurement scenario indicate an improved signal-to-noise ratio if a differential method is applied with specific positioning of the electrodes. A prototype was designed and the simulations were confirmed with measurements on a phantom and in a human self-experiment by the authors using self-constructed hardware. Movement artifacts were detected using an artifact detection algorithm which allows reliable estimation of the respiratory rate.

Fe Isotope Variations in Natural Materials Measured Using High Mass Resolution Multiple Collector ICPMS

We present the first measurements of Fe isotope variations in chemically purified natural samples using high mass resolution multiple-collector inductively coupled plasma source mass spectrometry (MC-ICPMS). High mass resolution allows polyatomic interferences at Fe masses to be resolved (especially, (40)Ar(14)N(+), (40)Ar(16)O(+), and (40)Ar(16)OH(+)). Simultaneous detection of Fe isotope ion beams using multiple Faraday collectors facilitates high-precision isotope ratio measurements. Fe in basalt and paleosol samples was extracted and purified using a simple, single-stage anion chemistry procedure. A Cu "element spike" was used as an internal standard to correct for variations in mass bias. Using this procedure, we obtained data with an external precision of 0.03-0.11 per thousand and 0.04-0.15 per thousand for delta(56/54)Fe and delta(57/54)Fe, respectively (2sigma). Use of Cu was necessary for such reproducibility, presumably because of subtle effects of residual sample matrix on mass bias. These findings demonstrate the utility of high-resolution MC-ICPMS for high-precision Fe isotope analysis in geologic and other natural materials. They also highlight the importance of internal monitoring of mass bias, particularly when using routine methods for Fe extraction and purification.

Individual and common antigen-recognition sites of liver-derived T cells in patients with autoimmune hepatitis

Autoimmune hepatitis (AIH) is characterized by dense T-cell infiltrations in the liver tissue, but little is known how T cells influence the pathogenesis. To address this question, the distribution of T-cell receptor variable beta-chain (TCR Vbeta) transcripts of peripheral blood and liver-infiltrating T cells from previously untreated patients with newly diagnosed acute exacerbated AIH was investigated. Furthermore, the lengths and sequences of complementary-determining region 3 (CDR3) were studied. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and CDR3 spectratyping revealed multiple clonal expansions of liver-infiltrating T cells but not peripheral T cells within various TCR Vbeta families. Further analysis of overexpressed TCR Vbeta transcripts using TCR beta-chain-joining element (TCR Jbeta)-specific primers in a nested PCR showed characteristic Vbeta/Jbeta combinations. Subsequent sequencing of CDR3 regions from PCR products confirmed the clonality of T-cell expansions and the usage of common and individual CDR3 motifs. In conclusion, the clonality of expanded T cells within the liver tissue during early clinical manifestation of untreated AIH indicated that autoantigen-specific T cells accumulate at the inflammation site. Individual and common CDR3 motifs argued for predominant epitopes that were recognized by liver-infiltrating T cells in AIH patients.

Divergent effects of tumor necrosis factor alpha on apoptosis of human neutrophils

Apoptosis of neutrophils is a key mechanism to control the intensity of the acute inflammatory response. Previously, the cytokine tumor necrosis factor alpha (TNF-alpha) was reported by some to have pro-apoptotic and by others to have antiapoptotic effects on neutrophils. The aim of this study was to explain these contradictory results. We found that TNF-alpha at low concentrations strongly decreased apoptosis of neutrophils. However, at higher concentrations, TNF-alpha lost its protective effects, and also reversed the protective effects of interferon-gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF). This pro-apoptotic effect of TNF-alpha was blocked by anti-CD11b and was absent in neutrophils from patients with chronic granulomatous disease, which cannot produce toxic oxygen metabolites. Under these circumstances, we found that TNF-alpha retained its anti-apoptotic effects even at high concentrations. In conclusion, the protective effects against apoptosis of IFN-gamma, GM-CSF, and TNF-alpha itself are overruled when the concentration of TNF-alpha is high enough to produce a respiratory burst. These dual, concentration-dependent effects of TNF-alpha provide an explanation for previous controversial reports and support a dominant role for TNF-alpha in neutrophil apoptosis.

92Nb-(92)Zr and the Early Differentiation History of Planetary Bodies

The niobium-92-zirconium-92 ((92)Nb-(92)Zr) extinct radioactive decay system (half-life of about 36 million years) can place new time constraints on early differentiation processes in the silicate portion of planets and meteorites. Zirconium isotope data show that Earth and the oldest lunar crust have the same relative abundances of (92)Zr as chondrites. (92)Zr deficits in calcium-aluminum-rich inclusions from the Allende meteorite constrain the minimum value for the initial (92)Nb/(93)Nb ratio of the solar system to 0.001. The absence of (92)Zr anomalies in terrestrial and lunar samples indicates that large silicate reservoirs on Earth and the moon (such as a magma ocean residue, a depleted mantle, or a crust) formed more than 50 million years after the oldest meteorites formed.

The viral clearance in interferon-treated chronic hepatitis C is associated with increased cytotoxic T cell frequencies

BACKGROUND/AIMS

Cytotoxic T lymphocytes have been demonstrated in peripheral blood and liver tissue of patients with chronic hepatitis C virus infection, but their significance for viral clearance is unknown. Therefore, we analyzed hepatitis C virus-specific cytotoxic T lymphocyte precursor frequencies in chronic hepatitis C virus carriers during interferon-alpha treatment.

METHODS

Blood mononuclear cells or CD8+ T cells from HLA-A2 positive and negative patients and controls were analyzed in chromium-release assays using a panel of 18 synthetic peptides from the HCV core, E1 and NS4 antigens bearing HLA-A2 binding motifs. Specific cytotoxic T lymphocyte precursor frequencies were studied within CD8+ T cells derived from interferon-alpha-treated patients using a TNF-alpha-based ELISPOT assay and compared to viremia levels.

RESULTS

T cells from 16 of 24 HLA-A2+ but none of the six HLA-A2- patients with chronic hepatitis C and six HLA-A2+ healthy controls lysed targets pulsed with peptide cocktails. Fine specificity revealed four very immunogenic epitopes in the core (C36-44, C132-140) and the envelope regions (E332-340, E363-372). Cytotoxic T lymphocyte precursor frequencies were prospectively analyzed in 11 interferon-alpha-treated HLA-A2+ hepatitis C virus patients. Four sustained and two transient therapy responders showed lower pretreatment viremia levels and significantly higher specific cytotoxic T lymphocyte precursor frequencies during viral clearance compared to five therapy non-responders and untreated controls.

CONCLUSIONS

The quantitative induction of HLA-class I restricted responses by interferon-alpha could contribute to a beneficial outcome of hepatitis C virus infections. Furthermore, it appears that the balance between viral load and specific cellular immune responses is critical for successful viral clearance.

Quantitative and functional analysis of core-specific T-helper cell and CTL activities in acute and chronic hepatitis B

AIMS/BACKGROUND

CD4+ T-helper cell (Th) responses to hepatitis B virus (HBV) core antigen (HBc) are increased during exacerbations in acute and chronic hepatitis B (AHB, CHB) and might influence the induction of CD8+ cytotoxic T lymphocytes (CTL) that are important for viral clearance.

METHODS

HBc-specific proliferative responses and cytokine release of blood mononuclear cells (PBMC) were studied in patients with AHB or CHB, as well as responders and non-responders to interferon-alpha treatment (IFN-R, IFN-NR), by [3H]-thymidine-uptake, enzyme-linked immunosorbent assay (ELISA) and Elispot assay and were compared to peptide HBc18 27-specific CTL precursor frequencies among CD8+ T cells derived from HLA-A2+ patients.

RESULTS

HBc-specific proliferative PBMC responses and Th frequencies were significantly increased in AHB patients compared with untreated CHB patients. PBMC derived from IFN-R showed stronger cellular responses than IFN-NR. Stimulated PBMC from all patient groups secreted significantly more IFN-gamma than IL-4 indicating Th1/Th0 cell responses. Furthermore, in AHB and IFN-R patients, high peptide HBc18-27-specific CTL precursor frequencies closely correlated with strong HBc-specific Th responses, whereas in untreated CHB and IFN-NR patients lower CTL frequencies were observed without correlation to Th activities.

CONCLUSIONS

HBV core-specific Th-cell responses appeared to support efficient CTL induction in patients with viral clearance, whereas in chronic HBV carriers quantitatively insufficient Th and CTL responses were observed. This observation could be important for future therapeutic strategies.

The cellular immune responses induced in the follow-up of interferon-alpha treated patients with chronic hepatitis C may determine the therapy outcome

BACKGROUND/AIMS

To study whether the host's immune response determines viral clearance in chronic hepatitis C, virological markers and antigen-specific T cell reactions were analysed in 30 chronic HCV carriers followed up during interferon-alpha therapy, 11 untreated anti-HCV positive individuals and 10 healthy controls.

METHODS

Proliferative T helper cell responses to recombinant HCV core and non-structural antigens were monitored by 3H-thymidine uptake assay and compared to quantitative viraemia levels and HCV genotypes.

RESULTS

Of the 30 treated patients, six had sustained complete responses (20%), another six were transient therapy responders (20%) and 18 were non-responders (60%). Viral clearance was associated with the HCV genotype 3 and low pretreatment viral load. In a substantial proportion of complete and transient therapy responders, increased NS3-, helicase- and NS4-antigen-specific T cell responses were observed during interferon-alpha therapy. In non-responders and in the later clinical courses of transient therapy responders, core and NS5-specific T cell responses dominated. In addition, 11 untreated anti-HCV antibody positive individuals were studied. Two HCV-RNA negative patients who might have recovered from HCV infection showed strong persistent lymphoproliferative responses to NS3, helicase and NS4 antigens, whereas seven of the nine viraemic patients reacted with HCV core or NS5 antigens.

CONCLUSIONS

Interferon-alpha treatment enhances NS3-, helicase- and NS4-antigen-specific T helper cell responses in patients with viral clearance, whereas viral persistence was associated with increased T cell reactivities against core and NS5 antigens. Immunogenetical, immunological and virological factors that may influence differential T cell induction in chronic hepatitis C are discussed.