39 research outputs found
Advancing Stream-Tracer Techniques and their Mathematical Analysis
Stream-tracer tests are often conducted to evaluate transport and reaction processes in streams and their adjacent hyporheic zones. But in spite of broad application, serious caveats remain, even with regards to supposedly well established approaches of stream-tracer techniques. In this thesis, I address several of these problems with regard to experiments and their mathematical analysis.
One of these common techniques are gas-tracer tests, which are used for estimating rate coefficients for reaeration across the air-water-interface. In this thesis, I illustrate how large errors are made by erroneously assuming a constant tracer input source over time, which can usually not be guaranteed in the field. I also suggest an easy-to-implement method that accounts for this temporal variability in the analysis process. Additionally, I show that neglecting dispersion in transport leads to an underestimation of reaeration rate coefficients, and that these effects carry over to the calculation of metabolic rates, such as aerobic respiration and photosynthesis from measured concentrations of dissolved oxygen.
Furthermore, conceptual models linking in-stream transport to hyporheic exchange are often stark simplifications of the processes occurring in nature. To what extent these models can nonetheless be useful in the estimation of hyporheic exchange processes I investigated by comparing in-stream and subsurface measurements of stream-tracer tests. I show that the two different observation approaches provide snapshots of very different parts of the stream-hyporheic zone system, that cannot easily be reconciled. Whereas the in-stream observations provide information on shallow hyporheic processes with effect on whole-stream chemistry, the subsurface results reveal the spatial distribution of reactivity in the stream bed that is not captured by the in-stream analysis, thereby identifying the location of a highly reactive benthic biolayer.
The shortcomings of stream-tracer techniques are also particularly evident in the context of reactive tracers, which have become a popular tool for the estimation of aerobic respiration rates and hyporheic exchange in streams. The application of the reactive tracer resazurin requires extensions of general models linking in-stream transport and hyporheic exchange with compound-specific properties. This way, models have become increasingly complex, making the reliable estimation of their associated parameters difficult. I present a nested local-in-global parameter estimation approach, that allows determining a set of transport and reaction parameters coupled with the inference of a continuous function describing the hyporheic travel-time distribution of the tracer compound in an efficient way.
This thesis thus aims at advancing stream-tracer techniques with respect to their experimental methods, the conceptual assumptions regarding transport and reaction processes as well as the estimation of parameters associated with these models.Markierversuchen werden hĂ€ufig durchgefĂŒhrt um Transport- und Reaktionsprozessen in FlĂŒssen und ihren angrenzenden hyporheischen Zonen zu bestimmen. Obwohl es sich hierbei um eine weit verbreitete Methode handelt, die hĂ€ufig Anwendung findet, weisen verschiedenste Aspekte dieses Ansatzes grobe Defizite auf. In dieser Arbeit thematisiere ich einige dieser Defizite in Bezug auf experimentelle Methoden und ihre mathematische Auswertung.
Markierversuche mit Gasen stellen eine Gruppe dieser fehlerbehafteten Methoden dar. Diese werden hĂ€ufig durchgefĂŒhrt um WiederbelĂŒftungsraten von FlĂŒssen zu ermitteln. In meiner Dissertation stelle ich dar, welche Fehler durch die fĂ€lschliche Annahme einer konstanten Tracergaseingabe ĂŒber die Zeit gemacht werden, da dieses kontinuierliche Signal unter Feldbedingungen gewöhnlicherweise nicht gewĂ€hrleistet werden kann. Ich zeige eine einfache Möglichkeit auf, den zeitlichen Trend der Gaszugabe im Auswertungsschritt zu berĂŒcksichtigen. Zudem weise ich nach, dass das VernachlĂ€ssigen von dispersivem Transport in der Auswertung zu einer UnterschĂ€tzung des Ratenkoeffizienten der WiederbelĂŒftung fĂŒhrt, die sich in der Berechnung von metabolischen Raten (aerobe Respiration und Fotosynthese) aus Konzentrationszeitreihen des gelösten Sauerstoffs fortpflanzen.
Des weiteren betrachte ich die ValiditĂ€t konzeptioneller Modelle, die Transport im Fluss mit hyporheischem Austausch in Verbindung setzen. Diese Modelle stellen zumeist grobe Vereinfachungen der RealitĂ€t dar. In welchem MaĂe diese Modelle dennoch zulĂ€ssige AbschĂ€tzungen hyporheischer Austauschprozesse liefern untersuche ich in dieser Arbeit anhand eines Vergleichs von Markierstoffkonzentrationen, die im Fluss selbst bzw. in der hyporheischen Zone erfasst werden. Ich zeige auf, dass diese beiden verschiedenen Betrachtungspunkte inkongruente Anteile des Gesamtsystems darstellen, die kaum in Einklang gebracht werden können. WĂ€hrend die Aufzeichnung im Fluss Informationen liefert ĂŒber flache hyporheische Prozesse, welche die im Fluss vorherrschenden Bedingungen beeinflussen, zeigen die Beobachtungen in der hyporheischen Zone die Zonierung der ReaktivitĂ€t im Flussbett auf, und ermöglichen es somit, die Lage einer reaktiven benthischen Bioschicht zu identifizieren.
Die UnzulĂ€nglichkeiten der Markierversuche in FlĂŒssen sind besonders offensichtlich im Zusammenhang mit reaktiven Markierversuchen, die seit einigen Jahren vermehrt Einsatz finden um aerobe Respirationsraten und hyporheischen Austausch in FlĂŒssen abzuschĂ€tzen. FĂŒr die Verwendung des reaktiven Markierstoffs Resazurin ist es notwendig, bestehende Modelle um substanzspezifische Eigenschaften des Markierstoffs zu erweitern. Dadurch nehmen die Modelle zunehmend an KomplexitĂ€t zu, was die zuverlĂ€ssige AbschĂ€tzung der Modellparameter erschwert. In meiner Arbeit stelle ich einen geschachtelten Algorithmus vor, der die globale AbschĂ€tzung von Transport- und Reaktionsparametern mit der lokalen Inferenz einer kontinuierlichen Funktion, welche die hyporheische FlieĂzeitverteilung des Markierstoffs beschreibt, auf effiziente Weise verbindet.
Ziel dieser Dissertation ist es somit, bestehende Markierversuchs-Verfahren zu ver-bessern in Hinblick auf experimentelle Methoden, konzeptionelle Annahmen des Transport- und Reaktionsverhaltens, sowie der AbschÀtzung der Modellparameter
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
Large-Scale Recombinant Production of the SARS-CoV-2 Proteome for High-Throughput and Structural Biology Applications
The highly infectious disease COVID-19 caused by the Betacoronavirus SARS-CoV-2 poses a severe threat to humanity and demands the redirection of scientific efforts and criteria to organized research projects. The international COVID19-NMR consortium seeks to provide such new approaches by gathering scientific expertise worldwide. In particular, making available viral proteins and RNAs will pave the way to understanding the SARS-CoV-2 molecular components in detail. The research in COVID19-NMR and the resources provided through the consortium are fully disclosed to accelerate access and exploitation. NMR investigations of the viral molecular components are designated to provide the essential basis for further work, including macromolecular interaction studies and high-throughput drug screening. Here, we present the extensive catalog of a holistic SARS-CoV-2 protein preparation approach based on the consortiumâs collective efforts. We provide protocols for the large-scale production of more than 80% of all SARS-CoV-2 proteins or essential parts of them. Several of the proteins were produced in more than one laboratory, demonstrating the high interoperability between NMR groups worldwide. For the majority of proteins, we can produce isotope-labeled samples of HSQC-grade. Together with several NMR chemical shift assignments made publicly available on covid19-nmr.com, we here provide highly valuable resources for the production of SARS-CoV-2 proteins in isotope-labeled form
31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two
Background
The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd.
Methods
We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background.
Results
First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001).
Conclusions
In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival
Adding 6 months of androgen deprivation therapy to postoperative radiotherapy for prostate cancer: a comparison of short-course versus no androgen deprivation therapy in the RADICALS-HD randomised controlled trial
Background
Previous evidence indicates that adjuvant, short-course androgen deprivation therapy (ADT) improves metastasis-free survival when given with primary radiotherapy for intermediate-risk and high-risk localised prostate cancer. However, the value of ADT with postoperative radiotherapy after radical prostatectomy is unclear.
Methods
RADICALS-HD was an international randomised controlled trial to test the efficacy of ADT used in combination with postoperative radiotherapy for prostate cancer. Key eligibility criteria were indication for radiotherapy after radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to radiotherapy alone (no ADT) or radiotherapy with 6 months of ADT (short-course ADT), using monthly subcutaneous gonadotropin-releasing hormone analogue injections, daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as distant metastasis arising from prostate cancer or death from any cause. Standard survival analysis methods were used, accounting for randomisation stratification factors. The trial had 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 80% to 86% (hazard ratio [HR] 0·67). Analyses followed the intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov, NCT00541047.
Findings
Between Nov 22, 2007, and June 29, 2015, 1480 patients (median age 66 years [IQR 61â69]) were randomly assigned to receive no ADT (n=737) or short-course ADT (n=743) in addition to postoperative radiotherapy at 121 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 9·0 years (IQR 7·1â10·1), metastasis-free survival events were reported for 268 participants (142 in the no ADT group and 126 in the short-course ADT group; HR 0·886 [95% CI 0·688â1·140], p=0·35). 10-year metastasis-free survival was 79·2% (95% CI 75·4â82·5) in the no ADT group and 80·4% (76·6â83·6) in the short-course ADT group. Toxicity of grade 3 or higher was reported for 121 (17%) of 737 participants in the no ADT group and 100 (14%) of 743 in the short-course ADT group (p=0·15), with no treatment-related deaths.
Interpretation
Metastatic disease is uncommon following postoperative bed radiotherapy after radical prostatectomy. Adding 6 months of ADT to this radiotherapy did not improve metastasis-free survival compared with no ADT. These findings do not support the use of short-course ADT with postoperative radiotherapy in this patient population
Duration of androgen deprivation therapy with postoperative radiotherapy for prostate cancer: a comparison of long-course versus short-course androgen deprivation therapy in the RADICALS-HD randomised trial
Background
Previous evidence supports androgen deprivation therapy (ADT) with primary radiotherapy as initial treatment for intermediate-risk and high-risk localised prostate cancer. However, the use and optimal duration of ADT with postoperative radiotherapy after radical prostatectomy remains uncertain.
Methods
RADICALS-HD was a randomised controlled trial of ADT duration within the RADICALS protocol. Here, we report on the comparison of short-course versus long-course ADT. Key eligibility criteria were indication for radiotherapy after previous radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to add 6 months of ADT (short-course ADT) or 24 months of ADT (long-course ADT) to radiotherapy, using subcutaneous gonadotrophin-releasing hormone analogue (monthly in the short-course ADT group and 3-monthly in the long-course ADT group), daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as metastasis arising from prostate cancer or death from any cause. The comparison had more than 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 75% to 81% (hazard ratio [HR] 0·72). Standard time-to-event analyses were used. Analyses followed intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and
ClinicalTrials.gov
,
NCT00541047
.
Findings
Between Jan 30, 2008, and July 7, 2015, 1523 patients (median age 65 years, IQR 60â69) were randomly assigned to receive short-course ADT (n=761) or long-course ADT (n=762) in addition to postoperative radiotherapy at 138 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 8·9 years (7·0â10·0), 313 metastasis-free survival events were reported overall (174 in the short-course ADT group and 139 in the long-course ADT group; HR 0·773 [95% CI 0·612â0·975]; p=0·029). 10-year metastasis-free survival was 71·9% (95% CI 67·6â75·7) in the short-course ADT group and 78·1% (74·2â81·5) in the long-course ADT group. Toxicity of grade 3 or higher was reported for 105 (14%) of 753 participants in the short-course ADT group and 142 (19%) of 757 participants in the long-course ADT group (p=0·025), with no treatment-related deaths.
Interpretation
Compared with adding 6 months of ADT, adding 24 months of ADT improved metastasis-free survival in people receiving postoperative radiotherapy. For individuals who can accept the additional duration of adverse effects, long-course ADT should be offered with postoperative radiotherapy.
Funding
Cancer Research UK, UK Research and Innovation (formerly Medical Research Council), and Canadian Cancer Society
Large-Scale Recombinant Production of the SARS-CoV-2 Proteome for High-Throughput and Structural Biology Applications
The highly infectious disease COVID-19 caused by the Betacoronavirus SARS-CoV-2 poses a severe threat to humanity and demands the redirection of scientific efforts and criteria to organized research projects. The international COVID19-NMR consortium seeks to provide such new approaches by gathering scientific expertise worldwide. In particular, making available viral proteins and RNAs will pave the way to understanding the SARS-CoV-2 molecular components in detail. The research in COVID19-NMR and the resources provided through the consortium are fully disclosed to accelerate access and exploitation. NMR investigations of the viral molecular components are designated to provide the essential basis for further work, including macromolecular interaction studies and high-throughput drug screening. Here, we present the extensive catalog of a holistic SARS-CoV-2 protein preparation approach based on the consortiumâs collective efforts. We provide protocols for the large-scale production of more than 80% of all SARS-CoV-2 proteins or essential parts of them. Several of the proteins were produced in more than one laboratory, demonstrating the high interoperability between NMR groups worldwide. For the majority of proteins, we can produce isotope-labeled samples of HSQC-grade. Together with several NMR chemical shift assignments made publicly available on covid19-nmr.com, we here provide highly valuable resources for the production of SARS-CoV-2 proteins in isotope-labeled form.This work was supported by Goethe University (Corona funds),
the DFG-funded CRC: âMolecular Principles of RNA-Based
Regulation,â DFG infrastructure funds (project numbers:
277478796, 277479031, 392682309, 452632086, 70653611), the
state of Hesse (BMRZ), the Fondazione CR Firenze (CERM),
and the IWB-EFRE-program 20007375. This project has
received funding from the European Unionâs Horizon 2020
research and innovation program under Grant Agreement No.
871037. AS is supported by DFG Grant SCHL 2062/2-1 and by the
JQYA at Goethe through project number 2019/AS01. Work in the
lab of KV was supported by a CoRE grant from the University of
New Hampshire. The FLI is a member of the Leibniz Association
(WGL) and financially supported by the Federal Government of
Germany and the State of Thuringia. Work in the lab of RM was
supported by NIH (2R01EY021514) and NSF (DMR-2002837).
BN-B was supported by theNSF GRFP.MCwas supported byNIH
(R25 GM055246 MBRS IMSD), and MS-P was supported by the
HHMI Gilliam Fellowship. Work in the labs of KJ and KT was
supported by Latvian Council of Science Grant No. VPP-COVID
2020/1-0014. Work in the UPATâs lab was supported by the
INSPIRED (MIS 5002550) project, which is implemented under
the Action âReinforcement of the Research and Innovation
Infrastructure,â funded by the Operational Program
âCompetitiveness, Entrepreneurship and Innovationâ (NSRF
2014â2020) and cofinanced by Greece and the EU (European
Regional Development Fund) and the FP7 REGPOT CT-2011-
285950ââSEE-DRUGâ project (purchase of UPATâs 700MHz
NMR equipment). Work in the CM-G lab was supported by
the Helmholtz society. Work in the lab of ABö was supported
by the CNRS, the French National Research Agency (ANR, NMRSCoV2-
ORF8), the Fondation de la Recherche MĂ©dicale (FRM,
NMR-SCoV2-ORF8), and the IR-RMN-THC Fr3050 CNRS.
Work in the lab of BM was supported by the Swiss National
Science Foundation (Grant number 200020_188711), the
GĂŒnthard Stiftung fĂŒr Physikalische Chemie, and the ETH
Zurich. Work in the labs of ABö and BM was supported by a
common grant from SNF (grant 31CA30_196256). This work was
supported by the ETHZurich, the grant ETH40 18 1, and the grant
Krebsliga KFS 4903 08 2019. Work in the lab of the IBS Grenoble
was supported by the Agence Nationale de Recherche (France)
RA-COVID SARS2NUCLEOPROTEIN and European Research
Council Advanced Grant DynamicAssemblies. Work in the
CA lab was supported by Patto per il Sud della Regione
SicilianaâCheMISt grant (CUP G77B17000110001). Part of
this work used the platforms of the Grenoble Instruct-ERIC
center (ISBG; UMS 3518 CNRS-CEA-UGA-EMBL) within the
Grenoble Partnership for Structural Biology (PSB), supported
by FRISBI (ANR-10-INBS-05-02) and GRAL, financed within
the University Grenoble Alpes graduate school (Ecoles
Universitaires de Recherche) CBH-EUR-GS (ANR-17-EURE-
0003). Work at the UW-Madison was supported by grant
numbers NSF MCB2031269 and NIH/NIAID AI123498. MM
is a RamĂłn y Cajal Fellow of the Spanish AEI-Ministry of
Science and Innovation (RYC2019-026574-I), and a âLa
Caixaâ Foundation (ID 100010434) Junior Leader Fellow
(LCR/BQ/PR19/11700003). Funded by project COV20/00764
fromthe Carlos III Institute of Health and the SpanishMinistry
of Science and Innovation to MMand DVL. VDJ was supported
by the Boehringer Ingelheim Fonds. Part of this work used the
resources of the Italian Center of Instruct-ERIC at the CERM/
CIRMMP infrastructure, supported by the Italian Ministry for
University and Research (FOE funding). CF was supported by
the Stiftung Polytechnische Gesellschaft. Work in the lab of
JH was supported by NSF (RAPID 2030601) and NIH
(R01GM123249).Peer reviewe
Large-Scale Recombinant Production of the SARS-CoV-2 Proteome for High-Throughput and Structural Biology Applications
The highly infectious disease COVID-19 caused by the Betacoronavirus SARS-CoV-2 poses a severe threat to humanity and demands the redirection of scientific efforts and criteria to organized research projects. The international COVID19-NMR consortium seeks to provide such new approaches by gathering scientific expertise worldwide. In particular, making available viral proteins and RNAs will pave the way to understanding the SARS-CoV-2 molecular components in detail. The research in COVID19-NMR and the resources provided through the consortium are fully disclosed to accelerate access and exploitation. NMR investigations of the viral molecular components are designated to provide the essential basis for further work, including macromolecular interaction studies and high-throughput drug screening. Here, we present the extensive catalog of a holistic SARS-CoV-2 protein preparation approach based on the consortiumâs collective efforts. We provide protocols for the large-scale production of more than 80% of all SARS-CoV-2 proteins or essential parts of them. Several of the proteins were produced in more than one laboratory, demonstrating the high interoperability between NMR groups worldwide. For the majority of proteins, we can produce isotope-labeled samples of HSQC-grade. Together with several NMR chemical shift assignments made publicly available on covid19-nmr.com, we here provide highly valuable resources for the production of SARS-CoV-2 proteins in isotope-labeled form