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Roles of active-site residues in catalysis, substrate binding, cooperativity, and the reaction mechanism of the quinoprotein glycine oxidase [Enzymology]

The quinoprotein glycine oxidase from the marine bacterium Pseudoalteromonas luteoviolacea (PlGoxA) uses a protein-derived cysteine tryptophylquinone (CTQ) cofactor to catalyze conversion of glycine to glyoxylate and ammonia. This homotetrameric enzyme exhibits strong cooperativity toward glycine binding. It is a good model for studying enzyme kinetics and cooperativity, specifically for being able to separate those aspects of protein function through directed mutagenesis. Variant proteins were generated with mutations in four active-site residues, Phe-316, His-583, Tyr-766, and His-767. Structures for glycine-soaked crystals were obtained for each. Different mutations had differential effects on kcat and K0.5 for catalysis, K0.5 for substrate binding, and the Hill coefficients describing the steady-state kinetics or substrate binding. Phe-316 and Tyr-766 variants retained catalytic activity, albeit with altered kinetics and cooperativity. Substitutions of His-583 revealed that it is essential for glycine binding, and the structure of H583C PlGoxA had no active-site glycine present in glycine-soaked crystals. The structure of H767A PlGoxA revealed a previously undetected reaction intermediate, a carbinolamine product-reduced CTQ adduct, and exhibited only negligible activity. The results of these experiments, as well as those with the native enzyme and previous variants, enabled construction of a detailed mechanism for the reductive half-reaction of glycine oxidation. This proposed mechanism includes three discrete reaction intermediates that are covalently bound to CTQ during the reaction, two of which have now been structurally characterized by X-ray crystallography.




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Reactive dicarbonyl compounds cause Calcitonin Gene-Related Peptide release and synergize with inflammatory conditions in mouse skin and peritoneum [Molecular Bases of Disease]

The plasmas of diabetic or uremic patients and of those receiving peritoneal dialysis treatment have increased levels of the glucose-derived dicarbonyl metabolites like methylglyoxal (MGO), glyoxal (GO), and 3-deoxyglucosone (3-DG). The elevated dicarbonyl levels can contribute to the development of painful neuropathies. Here, we used stimulated immunoreactive Calcitonin Gene–Related Peptide (iCGRP) release as a measure of nociceptor activation, and we found that each dicarbonyl metabolite induces a concentration-, TRPA1-, and Ca2+-dependent iCGRP release. MGO, GO, and 3-DG were about equally potent in the millimolar range. We hypothesized that another dicarbonyl, 3,4-dideoxyglucosone-3-ene (3,4-DGE), which is present in peritoneal dialysis (PD) solutions after heat sterilization, activates nociceptors. We also showed that at body temperatures 3,4-DGE is formed from 3-DG and that concentrations of 3,4-DGE in the micromolar range effectively induced iCGRP release from isolated murine skin. In a novel preparation of the isolated parietal peritoneum PD fluid or 3,4-DGE alone, at concentrations found in PD solutions, stimulated iCGRP release. We also tested whether inflammatory tissue conditions synergize with dicarbonyls to induce iCGRP release from isolated skin. Application of MGO together with bradykinin or prostaglandin E2 resulted in an overadditive effect on iCGRP release, whereas MGO applied at a pH of 5.2 resulted in reduced release, probably due to an MGO-mediated inhibition of transient receptor potential (TRP) V1 receptors. These results indicate that several reactive dicarbonyls activate nociceptors and potentiate inflammatory mediators. Our findings underline the roles of dicarbonyls and TRPA1 receptors in causing pain during diabetes or renal disease.




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Randomized, Placebo-Controlled, Double-Blind Phase 2 Trial Comparing the Reactogenicity and Immunogenicity of a Single Standard Dose to Those of a High Dose of CVD 103-HgR Live Attenuated Oral Cholera Vaccine, with Shanchol Inactivated Oral Vaccine as an

Reactive immunization with a single-dose cholera vaccine that could rapidly (within days) protect immunologically naive individuals during virgin soil epidemics, when cholera reaches immunologically naive populations that have not experienced cholera for decades, would facilitate cholera control. One dose of attenuated Vibrio cholerae O1 classical Inaba vaccine CVD 103-HgR (Vaxchora) containing ≥2 x 108 CFU induces vibriocidal antibody seroconversion (a correlate of protection) in >90% of U.S. adults. A previous CVD 103-HgR commercial formulation required ≥2 x 109 CFU to elicit high levels of seroconversion in populations in developing countries. We compared the vibriocidal responses of Malians (individuals 18 to 45 years old) randomized to ingest a single ≥2 x 108-CFU standard dose (n = 50) or a ≥2 x 109-CFU high dose (n = 50) of PaxVax CVD 103-HgR with buffer or two doses (n = 50) of Shanchol inactivated cholera vaccine (the immunologic comparator). To maintain blinding, participants were dosed twice 2 weeks apart; CVD 103-HgR recipients ingested placebo 2 weeks before or after ingesting vaccine. Seroconversion (a ≥4-fold vibriocidal titer rise) between the baseline and 14 days after CVD 103-HgR ingestion and following the first and second doses of Shanchol were the main outcomes measured. By day 14 postvaccination, the rates of seroconversion after ingestion of a single standard dose and a high dose of CVD 103-HgR were 71.7% (33/46 participants) and 83.3% (40/48 participants), respectively. The rate of seroconversion following the first dose of Shanchol, 56.0% (28/50 participants), was significantly lower than that following the high dose of CVD 103-HgR (P = 0.003). The vibriocidal geometric mean titer (GMT) of the high dose of CVD 103-HgR exceeded the GMT of the standard dose at day 14 (214 versus 95, P = 0.045) and was ~2-fold higher than the GMT on day 7 and day 14 following the first Shanchol dose (P > 0.05). High-dose CVD 103-HgR is recommended for accelerated evaluation in developing countries to assess its efficacy and practicality in field situations. (This study has been registered at ClinicalTrials.gov under registration no. NCT02145377.)




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Kinetics, Longevity, and Cross-Reactivity of Antineuraminidase Antibody after Natural Infection with Influenza A Viruses [Clinical Immunology]

The kinetics, longevity, and breadth of antibodies to influenza virus neuraminidase (NA) in archival, sequential serum/plasma samples from influenza A virus (IAV) H5N1 infection survivors and from patients infected with the 2009 pandemic IAV (H1N1) virus were determined using an enzyme-linked lectin-based assay. The reverse-genetics-derived H4N1 viruses harboring a hemagglutinin (HA) segment from A/duck/Shan Tou/461/2000 (H4N9) and an NA segment derived from either IAV H5N1 clade 1, IAV H5N1 clade 2.3.4, the 2009 pandemic IAV (H1N1) (H1N1pdm), or A/Puerto Rico/8/1934 (H1N1) virus were used as the test antigens. These serum/plasma samples were also investigated by microneutralization (MN) and/or hemagglutination inhibition (HI) assays. Neuraminidase-inhibiting (NI) antibodies against N1 NA of both homologous and heterologous viruses were observed in H5N1 survivors and H1N1pdm patients. H5N1 survivors who were never exposed to H1N1pdm virus developed NI antibodies to H1N1pdm NA. Seroconversion of NI antibodies was observed in 65% of the H1N1pdm patients at day 7 after disease onset, but an increase in titer was not observed in serum samples obtained late in infection. On the other hand, an increase in seroconversion rate with the HI assay was observed in the follow-up series of sera obtained on days 7, 14, 28, and 90 after infection. The study also showed that NI antibodies are broadly reactive, while MN and HI antibodies are more strain specific.




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A large palaeo-landslide reactivated by high-speed railway construction works (northern Spain)

The presence of large palaeo-landslides can hinder the construction of railway lines if they cause an alteration of the natural balance of the slope, significantly increasing the cost of the project. During the construction works in a section of the Madrid–Asturias high-speed railway line (Spain), a large-scale hillside instability affected 460 m of the section. The ground movement began 10 months after the start of the excavations and remained active throughout the observation period (2008–2010). Data provided by fieldwork, boreholes and instrumental monitoring have allowed the investigation of the geological units involved, together with the geometry and the kinematics of the mass movement. This landslide involves a Paleozoic basement with an estimated volume of 4 400 000 m3. It shows low displacement rates (<45 mm a–1) and was accommodated on a single surface of rupture, which reaches more than 60 m depth. The kinematics is favoured by structural and lithological conditions, there being a strong rheological contrast in the lower part of the mobilized ground. This movement is linked to a large palaeo-landslide that was partially reactivated when excavations undermined the lower slopes of the hillside. Technical solutions for the stabilization have already caused an additional cost of 17% over the initial budget.




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Thiostrepton Reactivates Latent HIV-1 through the p-TEFb and NF-{kappa}B Pathways Mediated by Heat Shock Response [Antiviral Agents]

Antiretroviral therapy (ART) suppresses HIV-1 replication but fails to cure the infection. The presence of an extremely stable viral latent reservoir, primarily in resting memory CD4+ T cells, remains a major obstacle to viral eradication. The "shock and kill" strategy targets these latently infected cells and boosts immune recognition and clearance, and thus, it is a promising approach for an HIV-1 functional cure. Although some latency-reversing agents (LRAs) have been reported, no apparent clinical progress has been made, so it is still vital to seek novel and effective LRAs. Here, we report that thiostrepton (TSR), a proteasome inhibitor, reactivates latent HIV-1 effectively in cellular models and in primary CD4+ T cells from ART-suppressed individuals ex vivo. TSR does not induce global T cell activation, severe cytotoxicity, or CD8+ T cell dysfunction, making it a prospective LRA candidate. We also observed a significant synergistic effect of reactivation when TSR was combined with JQ1, prostratin, or bryostatin-1. Interestingly, six TSR analogues also show reactivation abilities that are similar to or more effective than that of TSR. We further verified that TSR upregulated expression of heat shock proteins (HSPs) in CD4+ T cells, which subsequently activated positive transcriptional elongation factor b (p-TEFb) and NF-B signals, leading to viral reactivation. In summary, we identify TSR as a novel LRA which could have important significance for applications to an HIV-1 functional cure in the future.




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Sensitive Determination of Infectious Titer of Recombinant Adeno-Associated Viruses (rAAVs) Using TCID50 End-Point Dilution and Quantitative Polymerase Chain Reaction (qPCR)

Adeno-associated virus (AAV) recombinants are currently the vector of choice for many gene therapy applications. As experimental therapies progress to clinical trials, the need to characterize recombinant adeno-associated viruses (rAAVs) accurately and reproducibly increases. Accurate determination of rAAV infectious titer is important for determining the activity of each vector lot and for ensuring lot-to-lot consistency. The following protocol developed in our laboratory uses a 96-well TCID50 format and quantitative polymerase chain reaction (qPCR) detection for the determination of rAAV infectious titer.




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Titration of Recombinant Adeno-Associated Virus (rAAV) Genome Copy Number Using Real-Time Quantitative Polymerase Chain Reaction (qPCR)

This protocol is used to determine the concentration of DNase-resistant vector genomes (i.e., packaged in the capsid) in purified recombinant adeno-associated virus (rAAV) preparations. The protocol begins with treatment of the vector stock with DNase I to eliminate unencapsidated AAV DNA or contaminating plasmid DNA. This is followed by a heat treatment to heat-inactivate DNase I, to disrupt the viral capsid, and to release the packaged vector genomes for quantification by real-time polymerase chain reaction (PCR) using a set of standards (linearized plasmid used for vector production) containing known copy numbers. To accomplish high-throughput titration, the primer and probe sets used in real-time PCR are usually designed to target common elements present in most rAAV genomes, such as promoters and poly(A) signals. This strategy significantly reduces the number of PCRs, controls, and turnaround time. Several important controls should be included in the assay as follows: The first two controls should have a known copy number of the rAAV genome plasmid treated or not treated with DNase I. This control tests the effectiveness of DNase treatment. To control for potential cross-contamination between samples during the preparation process, a blank control containing nuclease-free water only should be processed and tested in parallel. A validation vector sample with a known titer should be included in every assay to monitor interassay variability. Finally, for the PCR run, a no-template control (NTC) is included to indicate cross-contamination during PCR setup.




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UK nuclear fusion reactor will fire up for the first time in 23 years

Within months researchers will attempt to create a ball of plasma hotter than the sun inside the Joint European Torus, a doughnut-shaped machine in south-east England




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The Internet Reacts To The Original Star Wars

Imagine an alternate universe where the Star Wars movies were released in chronological order - where Episodes I to III were the original, beloved trilogy. How would the internet have reacted to the film that followed? More »
    




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'Bring on Lampard and Morris!' - Chelsea fans react to reports of Gianfranco Zola exit

The Italian is reportedly set to leave Stamford Bridge at the end of his contract..




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Never-Trump group's 'mourning' ad gets presidential reaction

President Donald Trump took to Twitter overnight to attack the Lincoln Project for their latest ad criticizing the president’s coronavirus response.




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&apos;Acting like vultures&apos;: Ross Kemp&apos;s coronavirus documentary sparks furious reactions from viewers

Ross Kemp: On the NHS Frontline saw the hardened documentarian witness the struggles of an ICU first-hand




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Laurence Fox reveals brother-in-law Richard Ayoade&apos;s furious reaction to Question Time race row

The 'IT Crowd' star did not agree with Fox's comments on 'Question Time' and ignored Fox's pleas to support him on social media




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Manchester United fans react to podcast &apos;gold&apos; as Paul Scholes is ruthlessly trolled by hosts

Paul Scholes has been labelled "dumb and dumber" on the official Manchester United podcast after a comical misunderstanding.




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Jadon Sancho reacts to Liverpool transfer talk after Trent Alexander-Arnold comments

Jadon Sancho has stirred the transfer pot, teasing Liverpool fans tuning in to Trent Alexander-Arnold's Instagram Live on Thursday.




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Tina Lawson’s Reaction To ‘Savage’ Remix Is Priceless



Miss Tina runs the Beyhive.




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Kid Cudi Reacts To Landing His First No. 1 Hit



“This means so much to me!!!”




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President Donald Trump Reacts To Ahmaud Arbery Death



He addressed it during an Oval Office press gaggle.




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Twitter tells employees to work from home as tech firms react to coronavirus

As fears of a coronavirus outbreak in the U.S. grow, Twitter became the first major company to urge its stateside employees to work from home




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'The Last Dance' Episodes 5 and 6: NBA players share their reactions

NBA players react to Episodes 5 and 6 of 'The Last Dance,' which features the relationship between NBA superstars Michael Jordan and Kobe Bryant.




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Don Shula: The sports world reacts to the death of a legendary coach

Here's what figures from around the NFL and beyond are saying about legendary Miami Dolphins coach Don Shula, who has died at age 90.




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Bride's mum has brutal reaction to daughter's wedding dress picked to please her

Jenny and her mum Jacky have very different ideas about what she should wear on her big day - so they turn to Gok Wan for help




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From flying planes to stacking shelves — Virgin Australia staff react to airline's insolvency

Virgin Australia's potential collapse has left staff scrambling for jobs, as tourism and aviation industries prepare for the threat of major player leaving the market.




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Could smaller nuclear reactors be a possible energy source for Queensland?

The debate over nuclear technology is a controversial one, yet many leaders in the field believe it's time for an open and calm discussion about the energy alternative.




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The Last Dance: 'I did not anticipate this reaction'

Jason Hehir speaks to the BBC about interviewing Michael Jordan and why the documentary series has had such an impact.




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General Electric Hitachi Nuclear Energy Americas Agrees to Pay $2.7 Million for Alleged False Claims Related to Design of Advanced Nuclear Reactor

The Justice Department announced today that General Electric Hitachi Nuclear Energy Americas LLC (GE Hitachi) has agreed to pay $2.7 million to resolve allegations under the False Claims Act that it made false statements and claims to the Department of Energy and the Nuclear Regulatory Commission (NRC) concerning an advanced nuclear reactor design.



  • OPA Press Releases

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New Study Highlights OptiMSM's Influence on Key Metabolic Reactions

Bergstrom Nutrition, manufacturer of OptiMSM®, a branded form of methylsulfonylmethane (MSM), recently published an article detailing how the small intestine absorbs MSM, particularly in relation to sulfur.




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Homeostasis and regulation of autoreactive B cells




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Effects of chronic type 5 phosphodiesterase inhibition on penile microvascular reactivity in hypertensive patients with erectile dysfunction: a randomized crossover placebo-controlled trial




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Growth of microorganisms in an interfacially driven space bioreactor analog

npj Microgravity, Published online: 08 April 2020; doi:10.1038/s41526-020-0101-4

Growth of microorganisms in an interfacially driven space bioreactor analog




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Post-race driver and team reaction

Read what each driver had to say after the Abu Dhabi Grand Prix




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Driver reaction after qualifying

Driver and team reaction after Saturday's qualifying session for the Hungarian Grand Prix




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Driver reaction after the Hungarian Grand Prix

Driver and team reaction after the eventful Hungarian Grand Prix




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Driver reaction after Saturday qualifying

Read what the drivers had to say after a rain-affected qualifying at Spa Francorchamps




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Driver reaction

Driver and team reaction after the eventful Belgian Grand Prix




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Driver reaction after the race

Team and driver reaction after the European Grand Prix




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Driver and team reaction

Read what the drivers had to say after the Korean Grand Prix




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FIA bans reactive ride height for 2012

The reactive suspension system pioneered by Lotus for the 2012 system has been banned for the new season, according to reports




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Driver reaction after the German Grand Prix

Driver and team reaction after the controversial German Grand Prix




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Driver reaction after Turkish Grand Prix

All the driver's reaction after the Turkish Grand Prix




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Driver and team reaction

Driver and team reaction after the Spanish Grand Prix




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Post-race driver reaction

Reaction from drivers and teams after the Chinese Grand Prix




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Driver reaction after the Singapore Grand Prix

Read what the drivers and key team members had to say after the Singapore Grand Prix




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Post-race driver reaction

Team and driver reaction after the British Grand Prix at Silverstone




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Schumacher website to be reactivated

Michael Schumacher's personal website wil be re-launched on Thursday to mark the 20-year anniversary of his maiden F1 world championship




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Around the halls: Experts react to the killing of Iranian commander Qassem Soleimani

In a drone strike authorized by President Trump early Friday, Iranian commander Maj. Gen. Qassem Soleimani, who led the Quds Force of the Islamic Revolutionary Guards Corps, was killed at Baghdad International Airport. Below, Brookings experts provide their brief analyses on this watershed moment for the Middle East — including what it means for U.S.-Iran…

       




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Polling shows Americans see COVID-19 as a crisis, don’t think US is overreacting

As soon as the novel coronavirus began spreading across the country, some pundits—and on occasion President Trump—alleged that health experts and the media were exaggerating the problem and that policy makers were responding with measures that the American people would not tolerate. The high-quality survey research published in recent days makes it clear that the…

       




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Around the halls: Brookings experts on the Middle East react to the White House’s peace plan

On January 28 at the White House, President Trump unveiled his plan for Middle East peace alongside Israeli Prime Minister Benjanim Netanyahu. Below, Brookings experts on the peace process and the region more broadly offer their initial takes on the announcement. Natan Sachs (@natansachs), Director of the Center for Middle East Policy: This is a…

       




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Around the halls: Experts react to the killing of Iranian commander Qassem Soleimani

In a drone strike authorized by President Trump early Friday, Iranian commander Maj. Gen. Qassem Soleimani, who led the Quds Force of the Islamic Revolutionary Guards Corps, was killed at Baghdad International Airport. Below, Brookings experts provide their brief analyses on this watershed moment for the Middle East — including what it means for U.S.-Iran…