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Monitoring of CO2 degassing in seismoactive areas allows the study of correlations of gas release and seismic activity. Reliable continuous monitoring of the gas flow rate in rough field conditions requires robust methods capable of measuring gas flow at different types of gas outlets such as wet mofettes, mineral springs, and boreholes. In this paper we focus on the methods and results of the long-term monitoring of CO2 degassing in the West Bohemia/Vogtland region in central Europe, which is typified by the occurrence of earthquake swarms and discharge of carbon dioxide of magmatic origin. Besides direct flow measurement using flowmeters, we introduce a novel indirect technique based on quantifying the gas bubble contents in a water column, which is capable of functioning in severe environmental conditions. The method calculates the mean bubble fraction in a water–gas mixture from the pressure difference along a fixed depth interval in a water column. Laboratory tests indicate the nonlinear dependence of the bubble fraction on the flow rate, which is confirmed by empirical models found in the chemical and nuclear engineering literature. Application of the method in a pilot borehole shows a high correlation between the bubble fraction and measured gas flow rate. This was specifically the case for two coseismic anomalies in 2008 and 2014, when the flow rate rose during a seismic swarm to a multitude of the preseismic level for several months and was followed by a long-term flow rate decline. However, three more seismic swarms occurring in the same fault zone were not associated with any significant CO2 flow anomaly. We surmise that this could be related to the slightly farther distance of the hypocenters of these swarms compared to the two ones which caused the coseismic CO2 flow rise. Further long-term CO2-flow monitoring is required to verify the mutual influence of CO2 degassing and seismic activity in the area.

After discovering a jet activity near the south pole of Saturn's moon Enceladus, the Cassini mission demonstrated the existence of a subsurface water ocean with a unique sampling opportunity through flybys. Diurnal variations in the observed brightness of the plume suggest a tidal control, although the existence and timing of two activity maxima seem to contradict stress analysis predictions. Here, we re-interpret the observed plume variability by combining a 3D global model of tidal deformation of the fractured ice shell with a 1D local model of transport processes within south-polar faults. Our model successfully predicts the observed plume's temporal variability by combining two independent vapour transport mechanisms: slip-controlled jet flow and normal-stress-controlled ambient flow. Moreover, it provides a possible explanation for the differences between the vapour and solid emission rates during the diurnal cycle and the observed fractionation of the various icy particle families. Our model prediction could be tested by future JWST observations targeted when Enceladus is at different positions on its orbit and could be used to determine the optimal strategy for plume material sampling by future space missions., (© 2024. The Author(s).)

The pregnane X receptor (PXR) is a drug/xenobiotic-activated transcription factor of crucial importance for major cytochrome P450 xenobiotic-metabolizing enzymes (CYP) expression and regulation in the liver and the intestine. One of the major target genes regulated by PXR is the cytochrome P450 enzyme (CYP3A4), which is the most important human drug-metabolizing enzyme. In addition, PXR is supposed to be involved both in basal and/or inducible expression of many other CYPs, such as CYP2B6, CYP2C8, 2C9 and 2C19, CYP3A5, CYP3A7, and CYP2A6. Interestingly, the dynamics of PXR-mediated target genes regulation has not been systematically studied and we have only a few mechanistic mathematical and biologically based models describing gene expression dynamics after PXR activation in cellular models. Furthermore, few indirect mathematical PKPD models for prediction of CYP3A metabolic activity in vivo have been built based on compartmental models with respect to drug⁻drug interactions or hormonal crosstalk. Importantly, several negative feedback loops have been described in PXR regulation. Although current mathematical models propose these adaptive mechanisms, a comprehensive mathematical model based on sufficient experimental data is still missing. In the current review, we summarize and compare these models and address some issues that should be considered for the improvement of PXR-mediated gene regulation modelling as well as for our better understanding of the quantitative and spatial dynamics of CYPs expression., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

Hepsin is a type II transmembrane serine protease that is expressed in several human tissues. Overexpression of hepsin has been found to correlate with tumour progression and metastasis, which is so far best studied for prostate cancer, where more than 90% of such tumours show this characteristic. To enable improved future patient treatment, we have developed a monoclonal humanized antibody that selectively inhibits human hepsin and does not inhibit other related proteases. We found that our antibody, hH35, potently inhibits hepsin enzymatic activity at nanomolar concentrations. Kinetic characterization revealed non-linear, slow, tight-binding inhibition. This correlates with the crystal structure we obtained for the human hepsin-hH35 antibody Fab fragment complex, which showed that the antibody binds hepsin around α3-helix, located far from the active centre. The unique allosteric mode of inhibition of hH35 is distinct from the recently described HGFA (hepatocyte growth factor activator) allosteric antibody inhibition. We further explain how a small change in the antibody design induces dramatic structural rearrangements in the hepsin antigen upon binding, leading to complete enzyme inactivation.

C.E.R.A., a continuous erythropoietin (EPO) receptor activator, has been developed to provide stable maintenance of hemoglobin levels at once-monthly dosing intervals and smooth and steady anemia correction. The comparative EPO receptor binding properties of C.E.R.A. and epoetin-beta were assessed by surface plasmon resonance using soluble recombinant EPO receptors and by competition binding on cultured UT-7 cells. Calculated equilibrium dissociation constants (surface plasmon resonance assay) for C.E.R.A. and epoetin-beta were 140 and 2.9 nmol/l, respectively. Respective IC(50) values (competition binding assay) were 200 and 1.5 nmol/l. Compared with epoetin-beta, C.E.R.A. has approximately 50- to 100-fold lower affinity for EPO receptor binding sites. Analysis of the equilibrium binding curves indicates that the difference in affinity is mainly due to slower association. The different receptor binding properties of C.E.R.A. may enable continuous stimulation of erythropoiesis and, combined with a long half-life and slow systemic clearance, permit administration at extended intervals., ((c) 2008 S. Karger AG, Basel.)

Matrix metalloproteinase (MMPs) are critical for the degradation of extracellular matrix components and, therefore, need to be regulated tightly. Almost all MMPs share a homologous C-terminal haemopexin-like domain (PEX). Besides its role in macromolecular substrate processing, the PEX domains appear to play a major role in regulating MMP activation, localisation and inhibition. One intriguing property of MMP9 is its competence to bind different proteins, involved in these regulatory processes, with high affinity at an overlapping recognition site on its PEX domain. With the crystal structure of the PEX9 dimer, we present the first example of how PEX domains accomplish these diverse roles. Blade IV of PEX9 mediates the non-covalent and predominantly hydrophobic dimerisation contact. Large shifts of blade III and, in particular, blade IV, accompany the dimerisation, resulting in a remarkably asymmetric homodimeric structure. The asymmetry provides a novel mechanism of adaptive protein recognition, where different proteins (PEX9, PEX1, and TIMP1) can bind with high affinity to PEX9 at an overlapping site. Finally, the structure illustrates how the dimerisation generates new properties on both a physico-chemical and functional level.

Interleukin-16 (IL-16) acts as a chemoattractant for CD4+ cells, as a modulator of T-cell activation, and plays a key role in asthma. This report describes the cytokine-inducing effects of IL-16 on total peripheral blood mononuclear cells (PBMC) and PBMC subpopulations. While CD4+ T lymphocytes did not secrete cytokines in response to rhIL-16, CD14+ CD4+ monocytes and maturing macrophages secrete IL-1beta, IL-6, IL-15 and tumour necrosis factor-alpha (TNF-alpha) upon rhIL-16 stimulation. The mRNA species for these four cytokines were detected as early as 4 hr post-stimulation, with protein being secreted by 24 hr. Secretion of IL-1beta and IL-6 by total PBMC was dose dependent, with maximal secretion being observed using 50 ng/ml rhIL-16. However, for IL-15 or TNF-alpha maximal secretion by total PBMC occurred with all concentrations between 5 ng/ml to 500 ng/ml rhIL-16. Purified monocytes/macrophages secreted maximal concentrations of all four cytokines in the presence of 500 ng/ml rhIL-16, except for monocytes where maximal secretion of IL-15 was, interestingly, observed with only 50 ng/ml rhIL-16. The use of higher concentrations of rhIL-16 (1000 ng/ml) inhibited secretion of all four cytokines. While these IL-16-induced cytokines are likely to be involved in the immune system's response to antigen, the data suggest that IL-16 may play a key role in initiating and/or sustaining an inflammatory response.

The structure of a folded core of IL-16 is similar to that of intracellular protein modules called PDZ domains. IL-16 is thus the first extracellular protein found to have a PDZ-like fold. However, it does not exhibit normal peptide binding properties of PDZ domains. This is due to alterations of the structure at the 'PDZ-like binding site' of IL-16 (the GLGF cleft): the GLGF cleft of IL-16 is much smaller than those of PDZ-domains and is additionally blocked with a tryptophan side chain at its center. Our experiments indicate also that IL-16 nonspecifically aggregates in solution; but formation of a homo-tetrameric protein is not required, in contrast to previous suggestions, for its chemo-attractant activity.

The yeast RNA polymerase I is a multimeric complex composed of 14 distinct subunits, 5 of which are shared by the three forms of nuclear RNA polymerase. The reasons for this structural complexity are still largely unknown. Isolation of an inactive form of RNA Pol I lacking the A43, ABC23, and A14 subunits (RNA Pol I delta) allowed us to investigate the function of the shared subunit ABC23 by in vitro reconstitution experiments. Addition of recombinant ABC23 alone to the RNA Pol I delta reactivated the enzyme to up to 50% of the wild-type enzyme activity. The recombinant subunit was stably and stoichiometrically reassociated within the enzymatic complex. ABC23 was found to be required for the formation of the first phosphodiester bond, but it was not involved in DNA binding by RNA Pol I, as shown by gel retardation and surface plasmon resonance experiments, and did not recycle during transcription. Electron microscopic visualization and electrophoretic analysis of the subunit depleted and reactivated forms of the enzyme indicate that binding of ABC23 caused a major conformational change leading to a transcriptionally competent enzyme. Altogether, our results demonstrate that the ABC23 subunit is required for the structural and functional integrity of RNA Pol I and thus should be considered as part of the core enzyme.