Electron ionization - tandem mass spectrometry of glycosphingolipids. I.: The identification of compound-specific sequence ions in the collision-induced dissociation spectra of the immonium ions of two isomeric hexaglycosylceramides

AbstractA permethylated-reduced hexaglycosylceramide in a complex glycolipid mixture isolated from a unique human tissue has been identified by using tandem mass spectrometry (MS/MS). The mass spectrum of this glycolipid mixture, obtained by using in-beam electron ionization, is very complex, and fragment ions derived from the hexaglycosylceramide cannot be distinguished from other ions. Tandem mass spectrometry using a four-sector mass spectrometer gave the mass spectrum of the immonium ion of the permethylated-reduced hexaglycosylceramide (m/z 1645.8), which is characteristic of its structure. Comparison of this MS/MS spectrum with those of two similarly derivatized blood group hexaglycosylceramide isomers permitted identification of the unknown glycolipid structure

Double quantum dot turnstile as an electron spin entangler

We study the conditions for a double quantum dot system to work as a reliable electron spin entangler, and the efficiency of a beam splitter as a detector for the resulting entangled electron pairs. In particular, we focus on the relative strengths of the tunneling matrix elements, the applied bias and gate voltage, the necessity of time-dependent input/output barriers, and the consequence of considering wavepacket states for the electrons as they leave the double dot to enter the beam splitter. We show that a double quantum dot turnstile is, in principle, an efficient electron spin entangler or entanglement filter because of the exchange coupling between the dots and the tunable input/output potential barriers, provided certain conditions are satisfied in the experimental set-up.Comment: published version; minor error correcte

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Expression of glycolipid blood group antigens in single human kidneys: Change in antigen expression of rejected ABO incompatible kidney grafts

Expression of glycolipid blood group antigens in single human kidneys: Change in antigen expression of rejected ABO incompatible kidney grafts. Total neutral glycolipid fractions were separated into molecular species on thin-layer chromatography plates and detected by immunostaining with monoclonal anti-blood group antibodies. Blood group A antigens based on type 1, 2, 3 and 4 carbohydrate core saccharides were present in kidneys of A1 and A1B individuals. Blood group A2 individuals expressed only small amounts of A antigen compared to A1 individuals especially of the type 3 and 4 compounds. Kidneys from non-secretor individuals contained less A antigen compared to secretor individuals, and in both groups a variation in the antigen expression between single individuals was noted. Blood group A type 2 and 3 (which is an extension of A type 2) antigens were present both as basic 6 and 9 sugar structures as well as extended saccharide chains migrating in the 8 to 11 sugar interval. In contrast, the type 1 chain based A and Lewis antigens were only present as their basic 5 to 7 sugar chains, and no elongated structures were found. Four cases of A2 kidneys initially transplanted into O recipients and removed after 5, 12, 21 days and 4 years, respectively, were also analyzed. Two of these kidneys, originating from the same donor, showed a difference in A antigen expression. The kidney functioning for four years (lost due to chronic rejection) completely lacked X antigen with five sugar residues (present in all other individuals) and contained a large amount of A antigens. This shows that the expression of antigens in an incompatible transplated organ can be changed post-transplantation, and that the organ can function even if large amounts of incompatible antigens are present

Chemical and isotopic switching within the subglacial environment of a high Arctic glacier.

Natural environmental isotopes of nitrate, sulphate and inorganic carbon are discussed in conjunction with major ion chemistry of subglacial runoff from a High Arctic glacier, Midre Lovénbreen, Svalbard. The chemical composition of meltwaters is observed to switch in accordance with subglacial hydrological evolution and redox status. Changing rapidly from reducing to oxidizing conditions, subglacial waters also depict that 15N/14N values show microbial denitrification is an active component of nutrient cycling beneath the glacier. 18O/16O ratios of sulphate are used to elucidate mechanisms of biological and abiological sulphide oxidation. Concentrations of bicarbonate appear to be governed largely by the degree of rock:water contact encountered in the subglacial system, rather than the switch in redox status, although the potential for microbiological activity to influence ambient bicarbonate concentrations is recognised. Glaciers are therefore highlighted as cryospheric ecosystems supporting microbial life which directly impacts upon the release of solute through biogeochemically mediated processes