13 research outputs found
Measuring global ocean heat content to estimate the earth energy imbalance
The energy radiated by the Earth toward space does not compensate the incoming radiation from the Sun leading to a small positive energy imbalance at the top of the atmosphere (0.4–1 Wm–2). This imbalance is coined Earth’s Energy Imbalance (EEI). It is mostly caused by anthropogenic greenhouse gas emissions and is driving the current warming of the planet. Precise monitoring of EEI is critical to assess the current status of climate change and the future evolution of climate. But the monitoring of EEI is challenging as EEI is two orders of magnitude smaller than the radiation fluxes in and out of the Earth system. Over 93% of the excess energy that is gained by the Earth in response to the positive EEI accumulates into the ocean in the form of heat. This accumulation of heat can be tracked with the ocean observing system such that today, the monitoring of Ocean Heat Content (OHC) and its long-term change provide the most efficient approach to estimate EEI. In this community paper we review the current four state-of-the-art methods to estimate global OHC changes and evaluate their relevance to derive EEI estimates on different time scales. These four methods make use of: (1) direct observations of in situ temperature; (2) satellite-based measurements of the ocean surface net heat fluxes; (3) satellite-based estimates of the thermal expansion of the ocean and (4) ocean reanalyses that assimilate observations from both satellite and in situ instruments. For each method we review the potential and the uncertainty of the method to estimate global OHC changes. We also analyze gaps in the current capability of each method and identify ways of progress for the future to fulfill the requirements of EEI monitoring. Achieving the observation of EEI with sufficient accuracy will depend on merging the remote sensing techniques with in situ measurements of key variables as an integral part of the Ocean Observing System
Mutation of Asn-475 in the Venezuelan Equine Encephalitis Virus nsP2 Cysteine Protease Leads to a Self-Inhibited State
The
alphaviral nsP2 cysteine protease of the Venezuelan equine
encephalitis virus (VEEV) is a validated antiviral drug target. Clan
CN proteases contain a cysteine protease domain that is intimately
packed with an <i>S</i>-adenosyl-l-methionine-dependent
RNA methyltransferase (SAM MTase) domain. Within a cleft formed at
the interface of these two domains, the peptide substrate is thought
to bind. The nucleophilic cysteine can be found within a conserved
motif, <sup>475</sup>NV<u>C</u>WAK<sup>480</sup>,
which differs from that of papain (<sup>22</sup>CGS<u>C</u>WAFS<sup>29</sup>). Mutation of the motif residue, N475, to alanine
unexpectedly produced a self-inhibited state in which the N-terminal
residues flipped into the substrate-binding cleft. Notably, the N-terminal
segment was not hydrolyzedî—¸consistent with a catalytically
incompetent state. The N475A mutation resulted in a 70-fold decrease
in <i>k</i><sub>cat</sub>/<i>K</i><sub>m</sub>. A side chain–substrate interaction was predicted by the
structure; the S701A mutation led to a 17-fold increase in <i>K</i><sub>m</sub>. An Asn at the n-2 position relative to the
Cys was also found in the coronaviral papain-like proteases/deubiquitinases
(PLpro) of the SARS and MERS viruses, and in several papain-like human
ubiquitin specific proteases (USP). The large conformational change
in the N475A variant suggests that Asn-475 plays an important role
in stabilizing the N-terminal residues and in orienting the carbonyl
during nucleophilic attack but does not directly hydrogen bond the
oxyanion. The state trapped <i>in crystallo</i> is an unusual
result of site-directed mutagenesis but reveals the role of this highly
conserved Asn and identifies key substrate-binding contacts that may
be exploited by peptide-like inhibitors
Engineering an Fc-Fusion of a Capsule Degrading Enzyme for the Treatment of Anthrax
Polymers of d-glutamic acid (PDGA) form the
capsule of
the highly virulent Ames strain of B. anthracis. PDGA is antiphagocytic and weakly immunogenic; it enables the bacteria
to evade the innate immune responses. CapD is an enzyme that catalyzes
the covalent anchoring of PDGA. CapD is an Ntn-amido hydrolase that
utilizes an internal Thr-352 as its nucleophile and general acid and
base. An internal cleavage produces a free N-terminal Thr-352 and
a short and long polypeptide chain. The chains were circularly permuted
(CP) to move Thr-352 to the N-terminus of the polypeptide. We previously
showed that a branched PEG-CapDS334C-CP could protect mice
(80% survival) against a 5 LD50 challenge with B. anthracis Ames without the use of antibiotics, monoclonals,
or vaccines. In attempts to improve the in vivo circulation
time of CapD and enhance its avidity to its polymeric substrate, an
Fc-domain of a mouse IgG1 was fused to CapDS334C-CP and
the linker length and sequence were optimized. The resulting construct,
Fc-CapDS334C-CP, then was pegylated with a linear 2 kDa
mPEG at S334C to produce mPEG-Fc-CapDS334C-CP. Interestingly,
the fusion of the Fc-domain and incorporation of the S334C mutation
imparted acid stability, but slightly reduced the kcat (∼ 2-fold lower). In vivo,
the measured protein concentration in sera was higher for the Fc-fusion
constructs compared to the mPEG-Fc-CapDS334C-CP. However,
the exposure calculated from measured sera enzymatic activity was
higher for the mPEG-CapDS334C-CP. The pegylated Fc-fusion
was less active than the PEG-CapDS334C-CP, but detectable
in sera at 24 h by immunoblot. Here we describe the engineering of
a soluble, active, pegylated Fc-fusion of B. anthracis CapD (mPEG-Fc-CapD-CP) with activity in vitro,
in serum, and on encapsulated bacteria
Regional organizations and the politics of sanctions against undemocratic behaviour in the Americas
The Evolution of Self-Reported Urinary and Sexual Dysfunction over the Last Two Decades: Implications for Comparative Effectiveness Research
BACKGROUND: Despite the paramount importance of patient-reported outcomes, little is known about the evolution of patient-reported urinary and sexual function over time. OBJECTIVE: To evaluate differences in pretreatment urinary and sexual function in two population-based cohorts of men with prostate cancer enrolled nearly 20 yr apart. DESIGN, SETTING, AND PARTICIPANTS: Patients were enrolled in the Prostate Cancer Outcomes Study (PCOS) or the Comparative Effectiveness Analysis of Surgery and Radiation (CEASAR) study, two population-based cohorts that enrolled patients with incident prostate cancer from 1994 to 1995 and from 2011 to 2012, respectively. Participants completed surveys at baseline and various time points thereafter. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We performed multivariable logistic and linear regression analysis to investigate differences in pretreatment function between studies. RESULTS AND LIMITATIONS: The study comprised 5469 men of whom 2334 (43%) were enrolled in PCOS and 3135 (57%) were enrolled in CEASAR. Self-reported urinary incontinence was higher in CEASAR compared with PCOS (7.7% vs 4.7%; adjusted odds ratio [OR]: 1.83; 95% confidence interval [CI], 1.39–2.43). Similarly, self-reported erectile dysfunction was more common among CEASAR participants (44.7% vs 24.0%) with an adjusted OR of 3.12 (95% CI, 2.68–3.64). Multivariable linear regression models revealed less favorable self-reported baseline function among CEASAR participants in the urinary incontinence and sexual function domains. The study is limited by its observational design and possibility of unmeasured confounding. CONCLUSIONS: Reporting of pretreatment urinary incontinence and erectile dysfunction has increased over the past two decades. These findings may reflect sociological changes including heightened media attention and direct-to-consumer marketing, among other potential explanations. PATIENT SUMMARY: Patient reporting of urinary and sexual function has evolved and is likely contingent on continually changing societal norms. Recognizing the evolving nature of patient reporting is essential in efforts to conduct high-quality, impactful comparative effectiveness research
Inflammatory cardiac valvulitis in TAX1BP1-deficient mice through selective NF-κB activation
Nuclear factor kappa B (NF-κB) is a key mediator of inflammation. Unchecked NF-κB signalling can engender autoimmune pathologies and cancers. Here, we show that Tax1-binding protein 1 (TAX1BP1) is a negative regulator of TNF-α- and IL-1β-induced NF-κB activation and that binding to mono- and polyubiquitin by a ubiquitin-binding Zn finger domain in TAX1BP1 is needed for TRAF6 association and NF-κB inhibition. Mice genetically knocked out for TAX1BP1 are born normal, but develop age-dependent inflammatory cardiac valvulitis, die prematurely, and are hypersensitive to low doses of TNF-α and IL-1β. TAX1BP1−/− cells are more highly activated for NF-κB than control cells when stimulated with TNF-α or IL-1β. Mechanistically, TAX1BP1 acts in NF-κB signalling as an essential adaptor between A20 and its targets