Towards 2D Borane Chemistry in Hexagonal Cyclic Compounds.

A comprehensive comparison between known benzene mono-substituted compounds R-Ph and the corresponding isoelectronic unknown R-cyclohexaborane(12) molecules is carried out from a geometric and electronic structure point of view, with R={H, BH2, CH3, NH2, OH, F ; AlH2, SiH3, PH2, SH, Cl ; NO2, OCH3}. We suggest new chemical names for the 2D borane compounds and analyze the geometric and electronic structure carbon vs. boron comparatives by means of HOMO-LUMO gaps, bonding schemes, electron density topological properties and predicted NMR chemical shifts. The predictions on the properties in planar hexagonal cyclic boranes may help in the design of synthesis procedures for these yet-unkown compounds.

Depression and anxiety in systemic lupus erythematosus: A case-control study on prevalence and associated factors in a single-center cohort.

OBJECTIVES: To evaluate the prevalence of self-perceived depression and anxiety in patients with systemic lupus erythematosus (SLE) and to explore associated factors. METHODS: Cross-sectional study of unselected patients with SLE (ACR-97 criteria) and controls with chronic inflammatory rheumatic diseases. Both completed the Hospital Anxiety and Depression Scale (HADS). Demographic and clinical characteristics, comorbidity, and treatments were collected, and a multivariate analysis was performed to explore factors associated with depression and anxiety in SLE. RESULTS: The study population comprised 172 patients and 215 controls. Women accounted for 93% of the patients with SLE. Fibromyalgia was recorded in 12.8% and a history of depression in 17%. According to HADS, 37.2% fulfilled the diagnostic criteria for depression and 58.7% those for anxiety; prevalence was similar in the controls (32.6% and 55.1%, respectively). Up to a third of patients with self-perceived depression were not receiving antidepressants. There was no concordance between a previous history of depression and current depression. In the multivariate model, current depression was associated with single marital status (OR 2.69; 95% CI: 1.17-6.42; p = .022), fibromyalgia (7.69; 2.35-30.72; p = .001), smoking (3.12; 1.24-8.07; p = .016), severity of SLE (0.76; 0.6-0.94; p = .016), and organ damage (1.27; 1.01-1.61; p = .042). Current anxiety was only associated with fibromyalgia (3.97; 1.21-17.98; p = .036). CONCLUSIONS: Depression and anxiety are most likely underdiagnosed in SLE. Prevalence appears to be similar to that of other chronic inflammatory rheumatic diseases. Anxiety is associated with fibromyalgia, while depression is also associated with single marital status, smoking, organ damage, and severity of SLE.

Insight into polyproline II helical bundle stability in an antifreeze protein denatured state.

The use of polyproline II (PPII) helices in protein design is currently hindered by limitations in our understanding of their conformational stability and folding. Recent studies of the snow flea antifreeze protein (sfAFP), a useful model system composed of six PPII helices, suggested that a low denatured state entropy contributes to folding thermodynamics. Here, circular dichroism spectroscopy revealed minor populations of PPII like conformers at low temperature. To get atomic level information on the conformational ensemble and entropy of the reduced, denatured state of sfAFP, we have analyzed its chemical shifts and {1H}-15N relaxation parameters by NMR spectroscopy at four experimental conditions. No significant populations of stable secondary structure were detected. The stiffening of certain N-terminal residues at neutral versus acidic pH and shifted pKa values leads us to suggest that favorable charge-charge interactions could bias the conformational ensemble to favor the formation the C1-C28 disulfide bond during nascent folding, although no evidence for preferred contacts between these positions was detected by paramagnetic relaxation enhancement under denaturing conditions. Despite a high content of flexible glycine residues, the mobility of the sfAFP denatured ensemble is similar for denatured α/ß proteins both on fast ps/ns as well as slower µs/ms timescales. These results are in line with a conformational entropy in the denatured ensemble resembling that of typical proteins and suggest that new structures based on PPII helical bundles should be amenable to protein design.

Hydrogen bonding patterns and cooperativity in polyproline II helical bundles.

Hydrogen bond cooperativity (HBC) plays an important role in stabilizing protein assemblies built by α-helices and ß-sheets, the most common secondary structures. However, whether HBC exists in other types of protein secondary structures such as polyproline II (PPII) helices remains unexplored. This is intriguing, since PPII systems as assembling blocks are continuously emerging across multiple fields. Here, using a combination of computational chemistry tools and molecular modeling corroborated by experimental observables, we characterize the distinct H-bonding patterns present in PPII helical bundles and establish that HBC stabilizes intermolecular PPII helices as seen in other protein assemblies such as amyloid fibrils. In addition to cooperative interactions in canonical CO···HN H-bonds, we show that analogous interactions in non-canonical CO···HαCα H-bonds are relevant in Gly-rich PPII bundles, thus compensating for the inability of glycine residues to create hydrophobic cores. Our results provide a mechanistic explanation for the assembly of these bundles.

Subcutaneous vs intravenous abatacept in rheumatoid arthritis-interstitial lung disease. National multicentre study of 397 patients.

BACKGROUND: Evidence on abatacept (ABA) utility for rheumatoid arthritis (RA) - associated interstitial lung disease (ILD) is growing. Clinical trials have shown equivalence in subcutaneous (SC) and intravenous (IV) administration of ABA for articular manifestations. However, this has not been studied in respiratory outcomes. OBJECTIVE: To compare the effectiveness of ABA in RA-ILD patients according to the route of administration. METHODS: National retrospective multicentre study of RA-ILD patients on treatment with ABA. They were divided into 2 groups: a) IV, and b) SC. The following outcomes were analysed from baseline to final follow-up using linear mixed models: a) forced vital capacity (FVC), b) diffusing capacity of the lungs for carbon monoxide (DLCO), c) chest high resolution computed tomography (HRCT), d) dyspnoea, e) RA activity, and f) sparing corticosteroids effect. RESULTS: A total of 397 patients were included (94 IV-ABA and 303 SC-ABA), median follow-up of 24 [10-48] months. After adjustment for possible confounders, FVC and DLCO remained stable during the first 24 months without differences between IV-ABA and SC-ABA (p = 0.6304 and 0.5337). Improvement/ stability of lung lesions in HRCT was observed in 67 % of patients (75 % IV-ABA, 64 % SC-ABA; p = 0.07). Dyspnoea stabilized/ improved in 84 % of patients (90 % IV-ABA, 82 % SC-ABA; p = 0.09). RA - disease activity improved in both groups. No statistically significant differences regarding any of the variables studied between the two groups were found. ABA was withdrawn in 87 patients (21.9 %), 45 % IV-ABA and 37 % SC-ABA (p = 0.29). ILD worsening and articular inefficacy were the most common reasons for ABA discontinuation. CONCLUSION: In patients with RA-ILD, ABA seems to be equally effective regardless of the route of administration.