Abstract
The Simons Observatory is a ground-based cosmic microwave background experiment that consists of three 0.4 m small-aperture telescopes and one 6 m Large Aperture Telescope, located at an ...elevation of 5300 m on Cerro Toco in Chile. The Simons Observatory Large Aperture Telescope Receiver (LATR) is the cryogenic camera that will be coupled to the Large Aperture Telescope. The resulting instrument will produce arcminute-resolution millimeter-wave maps of half the sky with unprecedented precision. The LATR is the largest cryogenic millimeter-wave camera built to date, with a diameter of 2.4 m and a length of 2.6 m. The coldest stage of the camera is cooled to 100 mK, the operating temperature of the bolometric detectors with bands centered around 27, 39, 93, 145, 225, and 280 GHz. Ultimately, the LATR will accommodate 13 40 cm diameter optics tubes, each with three detector wafers and a total of 62,000 detectors. The LATR design must simultaneously maintain the optical alignment of the system, control stray light, provide cryogenic isolation, limit thermal gradients, and minimize the time to cool the system from room temperature to 100 mK. The interplay between these competing factors poses unique challenges. We discuss the trade studies involved with the design, the final optimization, the construction, and ultimate performance of the system.
Cytochrome c oxidase (CcO) is a large membrane-bound hemeprotein that catalyzes the reduction of dioxygen to water. Unlike classical dioxygen binding hemeproteins with a heme b group in their active ...sites, CcO has a unique binuclear center (BNC) composed of a copper atom (CuB) and a heme a 3 iron, where O2 binds and is reduced to water. CO is a versatile O2 surrogate in ligand binding and escape reactions. Previous time-resolved spectroscopic studies of the CO complexes of bovine CcO (bCcO) revealed that photolyzing CO from the heme a 3 iron leads to a metastable intermediate (CuB-CO), where CO is bound to CuB, before it escapes out of the BNC. Here, with a pump-probe based time-resolved serial femtosecond X-ray crystallography, we detected a geminate photoproduct of the bCcO–CO complex, where CO is dissociated from the heme a 3 iron and moved to a temporary binding site midway between the CuB and the heme a 3 iron, while the locations of the two metal centers and the conformation of Helix-X, housing the proximal histidine ligand of the heme a 3 iron, remain in the CO complex state. This new structure, combined with other reported structures of bCcO, allows for a clearer definition of the ligand dissociation trajectory as well as the associated protein dynamics.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
The Behavior Rating Inventory of Executive Function–Adult Version (BRIEF-A) is a standardized rating scale of subjective executive functioning. We provide univariate and multivariate base rates (BRs) ...for scale/index scores in the clinical range (T scores ≥65), reliable change, and inter-rater information not included in the Professional Manual. Participants were adults (ages = 18–90 years) from the BRIEF-A self-report (N = 1,050) and informant report (N = 1,200) standardization samples, as well as test–retest (n = 50 for self, n = 44 for informant) and inter-rater (n = 180) samples. Univariate BRs of elevated T scores were low (self-report = 3.3%–15.4%, informant report = 4.5%–16.3%). Multivariate BRs revealed the common occurrence of obtaining at least one elevated T-score across scales (self-report = 26.5%–37.3%, informant report = 22.7%–30.3%), whereas virtually none had elevated scores on all scales. Test–retest scores were highly correlated (self = .82–.94; informant = .91–.96). Inter-rater correlations ranged from .44 to .68. Significant (p < .05) test–retest T-score differences ranged from 7 to 12 for self-report, from 6 to 8 for informant report, and from 16 to 21 points for inter-rater T-score differences. Applications of these findings are discussed.
Full text
Available for:
NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
Droplet injection strategies are a promising tool to reduce the large amount of sample consumed in serial femtosecond crystallography (SFX) measurements at X-ray free electron lasers (XFELs) with ...continuous injection approaches. Here, we demonstrate a new modular microfluidic droplet injector (MDI) design that was successfully applied to deliver microcrystals of the human NAD(P)H:quinone oxidoreductase 1 (NQO1) and phycocyanin. We investigated droplet generation conditions through electrical stimulation for both protein samples and implemented hardware and software components for optimized crystal injection at the Macromolecular Femtosecond Crystallography (MFX) instrument at the Stanford Linac Coherent Light Source (LCLS). Under optimized droplet injection conditions, we demonstrate that up to 4-fold sample consumption savings can be achieved with the droplet injector. In addition, we collected a full data set with droplet injection for NQO1 protein crystals with a resolution up to 2.7 , leading to the first room-temperature structure of NQO1 at an XFEL. NQO1 is a flavoenzyme associated with cancer, Alzheimer's and Parkinson's disease, making it an attractive target for drug discovery. Our results reveal for the first time that residues Tyr128 and Phe232, which play key roles in the function of the protein, show an unexpected conformational heterogeneity at room temperature within the crystals. These results suggest that different substates exist in the conformational ensemble of NQO1 with functional and mechanistic implications for the enzyme's negative cooperativity through a conformational selection mechanism. Our study thus demonstrates that microfluidic droplet injection constitutes a robust sample-conserving injection method for SFX studies on protein crystals that are difficult to obtain in amounts necessary for continuous injection, including the large sample quantities required for time-resolved mix-and-inject studies.
A 3D-printed modular droplet injector successfully delivered microcrystals of human NAD(P)H:quinone oxidoreductase 1 (NQO1) and phycocyanin with electrical stimulation in a serial crystallography experiment at 120 Hz repetition rate.
Cytochrome
c
oxidase (C
c
O) reduces dioxygen to water and harnesses the chemical energy to drive proton translocation across the inner mitochondrial membrane by an unresolved mechanism. By using ...time-resolved serial femtosecond crystallography, we identified a key oxygen intermediate of bovine C
c
O. It is assigned to the P
R
-intermediate, which is characterized by specific redox states of the metal centers and a distinct protein conformation. The heme
a
3
iron atom is in a ferryl (Fe
4+
= O
2−
) configuration, and heme
a
and Cu
B
are oxidized while Cu
A
is reduced. A Helix-X segment is poised in an open conformational state; the heme
a
farnesyl sidechain is H-bonded to S382, and loop-I-II adopts a distinct structure. These data offer insights into the mechanism by which the oxygen chemistry is coupled to unidirectional proton translocation.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Objectives
The Maraviroc Switch (MARCH) study week 48 data demonstrated that maraviroc, a chemokine receptor‐5 (CCR5) inhibitor, was a safe and effective switch for the ritonavir‐boosted protease ...inhibitor (PI/r) component of a two nucleos(t)ide reverse transcriptase inhibitor N(t)RTI plus PI/r‐based antiretroviral regimen in patients with R5‐tropic virus. Here we report the durability of this finding.
Methods
MARCH, an international, multicentre, randomized, 96‐week open‐label switch study, enrolled HIV‐1‐infected adults with R5‐tropic virus who were stable (> 24 weeks) and virologically suppressed plasma viral load (pVL) < 50 HIV‐1 RNA copies/mL. Participants were randomized to continue their current PI/r‐based regimen (PI/r) or to switch to MVC plus two N(t)RTIs (MVC) (1:2 randomization). The primary endpoint was the difference in the proportion with pVL < 200 copies/mL at 96 weeks. The switch arm was defined as noninferior if the lower limit of the 95% confidence interval (CI) for the difference was < −12% in the intention‐to‐treat (ITT) population. Safety endpoints (the difference in the mean change from baseline or a comparison of proportions) were analysed as key secondary endpoints.
Results
Eighty‐two (PI/r) and 156 (MVC) participants were randomized and included in the ITT analysis; 71 (87%) and 130 (83%) were in follow‐up and on therapy at week 96. At week 96, 89.0% and 90.4% in the PI/r and MVC arms, respectively, had pVL < 50 copies/mL (95% CI ‐6.6, 10.2). Moreover, in those switching away from PI/r, there were significant reductions in mean total cholesterol (differences 0.31 mmol/L; P = 0.02) and triglycerides (difference 0.44 mmol/L; P < 0.001). Changes in CD4 T‐cell count, renal function, and serious and nonserious adverse events were similar in the two arms.
Conclusions
MVC as a switch for a PI/r is safe and effective at maintaining virological suppression while having significant lipid benefits over 96 weeks.
Full text
Available for:
BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
