Characterization of peptide O⋯HN hydrogen bonds via1H-detected 15N/17O solid-state NMR spectroscopy.

High sensitivity and resolution solid-state NMR methods are reported, that straightforwardly select hydrogen-bonded 15N-17O pairs from amongst all other nitrogen and oxygen sites in peptides, to aid protein secondary and tertiary structure determination. Significantly improved sensitivity is obtained with indirect 1H detection under fast MAS and stronger relayed dipole couplings.

An Atomistic Picture of Boron Oxide Catalysts for Oxidative Dehydrogenation Revealed by Ultrahigh Field 11B-17O Solid-State NMR Spectroscopy.

Boron oxide/hydroxide supported on oxidized activated carbon (B/OAC) was shown to be an inexpensive catalyst for the oxidative dehydrogenation (ODH) of propane that offers activity and selectivity comparable to boron nitride. Here, we obtain an atomistic picture of the boron oxide/hydroxide layer in B/OAC by using 35.2 T 11B and 17O solid-state NMR experiments. NMR spectra measured at 35.2 T resolve the boron and oxygen sites due to narrowing of the central-transition powder patterns. A 35.2 T 2D 11B{17O} dipolar heteronuclear correlation NMR spectrum revealed the structural connectivity between boron and oxygen atoms. The approach outlined here should be generally applicable to determine atomistic structures of heterogeneous catalysts containing quadrupolar nuclei.

Residue-Specific High-Resolution 17O Solid-State Nuclear Magnetic Resonance of Peptides: Multidimensional Indirect 1H Detection and Magic-Angle Spinning.

Oxygen is an integral component of proteins but remains sparsely studied because its only NMR active isotope, 17O, has low sensitivity, low resolution, and large quadrupolar couplings. These issues are addressed here with efficient isotopic labeling, high magnetic fields, fast sample spinning, and 1H detection in conjunction with multidimensional experiments to observe oxygen sites specific to each amino acid residue. Notably, cross-polarization at high sample spinning frequencies provides efficient 13C ↔ 17O polarization transfer. The use of 17O for initial polarization is found to provide better sensitivity per unit time compared to 1H. Sharp isotropic 17O peaks are obtained by using a low-power multiple-quantum sequence, which in turn allows extraction of quadrupolar parameters for each oxygen site. Finally, the potential to determine sequential assignments and long-range distance restraints is demonstrated by using 3D 1H/13C/17O experiments, suggesting that such methods can become an essential tool for biomolecular structure determination.

Deep vein thrombosis in acute respiratory distress syndrome caused by bacterial pneumonia.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a clinical syndrome characterized by acute hypoxaemia, and few studies have reported the incidence of deep vein thrombosis (DVT) in direct ARDS caused by bacterial pneumonia. We performed a study to evaluate the prevalence, risk factors, prognosis and potential thromboprophylaxis strategies of DVT in these patients. METHODS: Ninety patients were included. Demographic, and clinical data, laboratory data and outcome variables were obtained, and comparisons were made between the DVT and non-DVT groups. RESULTS: Of the 90 patients, 40 (44.4%) developed lower extremity DVT. Compared with non-DVT patients, DVT patients had higher systemic inflammatory response syndrome (SIRS) scores, lower serum creatinine levels, higher D-dimer levels, and higher rates of sedative therapy and invasive mechanical ventilation (IMV). Multivariate analysis showed an association between the SIRS score (OR 3.803, P = 0.027), level of serum creatinine (OR 0.988, P = 0.001), IMV (OR 5.822, P = 0.002) and DVT. The combination of SIRS score, serum creatinine level and IMV has a sensitivity of 80.0% and a specificity of 74.0% for screening for DVT. The survival rate within 28 days after ARDS in the DVT group was significantly lower than that in the non-DVT group (P = 0.003). There was no difference in the prevalence of DVT between the 41 patients who received thromboprophylaxis and the 49 patients who did not receive thromboprophylaxis (41.5% vs 46.9%; P = 0.603). CONCLUSIONS: The prevalence of DVT is high in hospitalized patients with direct ARDS caused by bacterial pneumonia and may be associated with adverse outcomes. The current thromboprophylaxis strategies may need to be further optimized.

High-Flow Nasal Cannula for Chronic Obstructive Pulmonary Disease with Acute Compensated Hypercapnic Respiratory Failure: A Randomized, Controlled Trial.

Introduction: Currently, there is a lack of evidence on the utilization of high-flow nasal cannula (HFNC) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) accompanied by hypercapnic respiratory failure. We aimed to explore the efficacy and safety of HFNC compared with conventional oxygen therapy (COT) in such patients. Methods: This was a prospective, randomized, controlled trial. Patients with AECOPD with a baseline arterial blood gas pH ≥7.35, PaO2 <60 mmHg, and PaCO2 >45 mmHg were enrolled. The primary endpoint was treatment failure, which needs mechanical ventilation. Results: A total of 320 patients were randomized to either the HFNC group (n = 160) or the COT group (n = 160). Sixteen (10.0%) patients in the HFNC group had treatment failure during hospitalization, which was significantly lower than the COT group figure of 31 (19.4%) patients (p = 0.026). Twenty-four hours after recruitment, the PaCO2 of the HFNC group was lower than that of the COT group (54.1 ± 9.79 mmHg vs 56.9 ± 10.1 mmHg, p = 0.030). PaCO2 higher than 59 mmHg after HFNC for 24 h was identified as an independent risk factor for treatment failure [OR 1.078, 95% CI 1.006-1.154, p = 0.032]. Conclusion: In AECOPD patients with acute compensated hypercapnic respiratory failure, HFNC improved the prognosis compared with COT. Therefore, HFNC might be considered for first-line oxygen therapy in select patients. Trial Registration Number: ClinicalTrials.Gov: NCT02439333.

Serum ß2-Microglobulin is Associated with Mortality in Hospitalized Patients with Exacerbated Chronic Obstructive Pulmonary Disease.

Purpose: We hypothesized that increased level of serum ß2-microglobulin (ß2M) is an independent factor associated with higher mortality in hospitalized patients with exacerbated chronic obstructive pulmonary disease (COPD). Patients and Methods: We retrospectively analyzed 488 hospitalized patients with exacerbated COPD as the first diagnosis at Beijing Chao-Yang hospital, P. R. China between December 31st, 2012 and December 28th, 2017. Concentrations of serum ß2M and other clinical indexes were measured or collected on admission, and all patients were followed up to 90 days. The relationship between ß2M and 30- and 90-day all-cause mortality was explored by Cox regression analysis adjusted for age, C-reactive protein values, N-terminal pro-brain natriuretic peptide/100, respiratory failure [RF, defined as partial arterial oxygen pressure (PaO2) <60 mmHg on room air or PaO2 over the fraction of inspired oxygen (PaO2/FiO2) < 300], eosinopenia, consolidation, and acidaemia. Results: Median concentrations of ß2M were significantly higher in non-survivals compared to survivals within 30 days (4.11 mg/L (IQR 3.10-6.60) vs 2.79mg/L (IQR 2.13-3.76), P < 0.001) and 90 days (3.79 mg/L (IQR 2.61-6.69) vs 2.79 mg/L (IQR 2.13-3.73), P < 0.001). Serum levels of ß2M were correlated with 30-day and 90-day mortality in overall exacerbated COPD patients, with hazard ratios (HRs) of 1.09 (95% CI 1.04-1.14, P = 0.001) and 1.09 (95% CI 1.05-1.14, P < 0.001). In exacerbated COPD patients without RF and with RF, the HRs were 1.06 (95% CI 0.995-1.137, P = 0.069) and 1.14 (95% CI 1.02-1.27, P = 0.021) for 30-day mortality, 1.09 (95% CI 1.02-1.15, P = 0.010) and 1.14 (95% CI 1.03-1.26, P = 0.014) for 90-day mortality, respectively. Conclusion: Our data showed that concentrations of serum ß2M were associated with an increased risk of mortality, suggesting that ß2M might be a valuable predictor of poor prognosis for hospitalized patients with exacerbated COPD.

Achieving 1 ppm field homogeneity above 24 T: Application of differential mapping for shimming Keck and the Series Connected Hybrid magnets at the NHMFL.

Powered resistive and resistive-superconductive hybrid magnets can reach fields higher than superconducting NMR magnets but lack the field homogeneity and temporal stability needed for high resolution NMR. Due to field fluctuations in powered magnets, commercially available mapping systems fail to produce maps of these magnets with sufficient reproducibility, thus hampering attempts to improve homogeneity of the field they generate. Starting with a commercial mapper, we built a mapping system which uses a two-channel (measurement + reference) mapper probe. We used this system to map and then to shim two magnets of Florida Bitter type at the National High Magnetic Field Laboratory in Tallahassee, FL. With a combination of passive (ferromagnetic) and active shims we achieved 2.3 ppm homogeneity in 1 cm diameter spherical volume (dsv) at 25.0 T in the Keck resistive magnet, and 0.9 ppm homogeneity in 1 cm dsv at 23.5, 28.2, and 35.2 T in the series-connected resistive-superconductive hybrid (SCH) magnet.

Ni(OH)2/CNTs hierarchical spheres for a foldable all-solid-state supercapacitor with high specific energy.

Energy density and mechanical strength are crucial for practical usage of flexible supercapacitors. Herein, we demonstrate a flexible supercapacitor using Ni(OH)2/CNTs hierarchical spheres with high specific capacity (854 C g-1) and tough PBI-KOH solid polymer electrolyte. The integrated device shows high specific energy (50.6 W h kg-1) and good flexibility under folding tests.

Enhanced High-Temperature Cyclic Stability of Al-Doped Manganese Dioxide and Morphology Evolution Study Through in situ NMR under High Magnetic Field.

In this work, Al-doped MnO2 (Al-MO) nanoparticles have been synthesized by a simple chemical method with the aim to enhance cycling stability. At room temperature and 50 °C, the specific capacitances of Al-MO are well-maintained after 10 000 cycles. Compared with pure MnO2 nanospheres (180.6 F g-1 at 1 A g-1), Al-MO also delivers an enhanced specific capacitance of 264.6 F g-1 at 1 A g-1. During the cycling test, Al-MO exhibited relatively stable structure initially and transformed to needlelike structures finally both at room temperature and high temperature. In order to reveal the morphology evolution process, in situ NMR under high magnetic field has been carried out to probe the dynamics of structural properties. The 23Na spectra and the SEM observation suggest that the morphology evolution may follow pulverization/reassembling process. The Na+ intercalation/deintercalation induced pulverization, leading to the formation of tiny MnO2 nanoparticles. After that, the pulverized tiny nanoparticles reassembled into new structures. In Al-MO electrodes, doping of Al3+ could slow down this structure evolution process, resulting in a better electrochemical stability. This work deepens the understanding on the structural changes in faradic reaction of pseudocapacitive materials. It is also important for the practical applications of MnO2-based supercapacitors.

[Clinical analyses of fungal pleurisy: a report of 4 cases].

OBJECTIVE: To explore the clinical features of fungal pleurisy. METHODS: Four cases of fungal pleurisy diagnosed by medical thoracoscopy at Beijing Chaoyang Hospital from April 2005 to December 2012 were retrospectively studied. RESULTS: There were 3 males and 1 female with an age range of 43-73 years. The time from initial onset to definite diagnosis was 17 days to 4 months. Among them, two were previously healthy while another two had underlying diseases. The diagnoses were mucor pleuritis (n = 1) and aspergillus (n = 3). There was one case of empyema. One case was diagnosed as non-Hodgkin lymphoma two years ago and had pleural metastasis during hospitalization. And another one suffered concurrently from diabetes mellitus and hypoproteinemia. The primary clinical manifestations included fever (n = 2), cough and sputum (n = 3), breathlessness (n = 4) and weight loss (n = 2). The major chest computed tomography (CT) scan revealed pleural effusion with thickening. All cases had an elevated plasma level of C-reactive protein (CRP). The characteristics of pleural effusion were empyema (n = 1) and exudates (n = 3). Pleural fluid smear and culture tests for bacteria and fungi were negative, so were pleural fluid smear tests for mycobacteria. All cases were confirmed through histopathological examination of pleural biopsies and cured after systemic antifungal therapy and pleural irrigation. CONCLUSIONS: Fungal pleurisy is infrequent. Early thoracoscopy is vital because of a low positive yield of microbiologic testing of pleural fluid specimens. Systemic antifungal therapy and pleural irrigation improve the prognosis.

A new automatic baseline correction method based on iterative method.

A new automatic baseline correction method for Nuclear Magnetic Resonance (NMR) spectra is presented. It is based on an improved baseline recognition method and a new iterative baseline modeling method. The presented baseline recognition method takes advantages of three baseline recognition algorithms in order to recognize all signals in spectra. While in the iterative baseline modeling method, besides the well-recognized baseline points in signal-free regions, the 'quasi-baseline points' in the signal-crowded regions are also identified and then utilized to improve robustness by preventing the negative regions. The experimental results on both simulated data and real metabolomics spectra with over-crowded peaks show the efficiency of this automatic method.

[The evaluation of combined CT pulmonary and bronchial arteriography for the diagnosis of hemoptysis].

OBJECTIVE: To establish the method of multi-slice spiral CT pulmonary angiography (CTPA)combined with bronchial angiography (CTBA) and to evaluate its value for diagnosis and treatment in hemoptysis. METHODS: After contrast material was administered intravenously, a 16-detector row helical CT scanner (Light Speed Ultra 16; GE Medical Systems) was used to complete CTPA first with a scan delay time of 12 - 16 s. Then CTBA was carried out, with a scan delay time of 26 - 28 s. The images were reformatted to evaluate the pulmonary artery and bronchial artery (BA). RESULTS: In 36 cases of hemoptysis, CTPA showed 7 pulmonary arterial abnormalities (3 cases with pulmonary embolism, 4 cases with one of pulmonary artery abnormity, primary pulmonary artery leiomyosarcoma, loss of sharpness of pulmonary artery or occlusion of right-inferior lung artery). In the 36 cases, CTBA showed 37 right BAs (11 tortuosity and thickening), 40 left right BAs (10 tortuosity and thickening) and 3 non-bronchial systemic arteries (1 from abdominal aorta tortuosity and thickening). Abnormal vessels had a close relation with pulmonary diseases. CONCLUSIONS: With this method CTPA and CTBA can be completed in a single procedure and abnormal pulmonary arteries and bronchial arteries can be shown clearly. This procedure maybe of important value for the diagnosis and treatment of hemoptysis.