Polyphenol identification based on systematic and robust high-resolution accurate mass spectrometry fragmentation

High-mass resolution multi-stage mass spectrometry (MS(n)) fragmentation was tested for differentiation and identification of metabolites, using a series of 121 polyphenolic molecules. The MS(n) fragmentation approach is based on the systematic breakdown of compounds, forming a so-called spectral tree. A chip-based nanoelectrospray ionization source was used combined with an ion-trap, providing reproducible fragmentation, and accurate mass read-out in an Orbitrap Fourier transform (FT) MS enabling rapid assignment of elemental formulas to the molecular ions and all fragment ions derived thereof. The used protocol resulted in reproducible MS(n) fragmentation trees up to MS(5). Obtained results were stable over a 5 month time period, a concentration change of 100-fold, and small changes in normalized collision energy, which is key to metabolite annotation and helpful in structure and substructure elucidation. Differences in the hydroxylation and methoxylation patterns of polyphenolic core structures were found to be reflected by the differential fragmentation of the entire molecule, while variation in a glycosylation site displayed reproducible differences in the relative intensities of fragments originating from the same aglycone fragment ion. Accurate MS(n)-based spectral tree data are therefore a powerful tool to distinguish metabolites with similar elemental formula, thereby assisting compound identification in complex biological samples such as crude plant extracts.     

Does hospital-at-home make economic sense? Early discharge versus standard care for orthopaedic patients

Hospital-at-home has been promoted as a potentially effective means of replacing costly inpatient care with cheaper domiciliary care. We studied three hospital-at-home schemes in West London providing intensive home care for early discharge orthopaedic patients, comparing their costs with those of standard inpatient care. Although costs per day of hospital-at-home care were lower than those of inpatient care, the schemes appeared to increase the total duration of orthopaedic episodes, so that the costs of standard care, per episode, were lower than those of hospital-at-home. While hospital-at-home may offer considerable future potential, substitution of home care for inpatient care will not necessarily save resources.     

Determination of Clozapine and its Metabolite,Norclozapine in Various Biological Matrices Using High-Performance Liquid Chromatography

Purpose. To develop and validate an HPLC method for the quantitation of clozapine and its metabolite, norclozapine in human plasma, rat plasma, and the various human plasma lipoprotein fractions. Methods. Using liquid-liquid extraction, clozapine, and norclozapine are extracted from the biological matrix with MTBE. After concentration, the residue was reconstituted in 1mM HCl and injected on to a C6 Phenyl column (3μm, 2.0×150 mm). Mobile phase was 10mM Ammonium Acetate, pH 5—Acetonitrile—Methanol (5:3:2, v/v/v). Loxapine served as the internal standard. Absorbance was measured at 254 nm. Results. Quantitation limits for clozapine and norclozapine was 100 ng/mL and 50 ng/mL, respectively. Recovery for both clozapine and norclozapine was near 100%. Percent accuracy for intraday variability in human plasma, rat plasma, and human TRL, HDL, LDL, and LPDP lipoprotein fraction was between 92 to 113% for both analytes. Intraday precision for the same matrices was less than 9% CV for both analytes. Percent accuracy and precision for interday variability in human plasma was 97 to 103% and less than 10% CV, respectively. Samples were stabile in the autosampler for 80 h at 10°C and on the benchtop for 2 h. It should be noted, Clozapine-N-oxide, which is a known metabolite of Clozapine, was not determined since it is not clinically active. Conclusions. This method is a simple, fast and robust HPLC assay for the determination of clozapine and norclozapine in various matrices and lipoprotein fractions.     

Binge drinking among college students: a comparison of California with other states

The aim of the present study was to describe the expression and distribution of bone morphogenetic protein (BMP) in odontogenic tumors by immunohistochemistry using monoclonal antibody against bovine BMP (BMPMcAb). Eight types of odontogenic tumors (44 cases), including ameloblastoma (20 cases), cementifying fibroma (8 cases), benign cementoblastoma (5 cases), dentinoma (3 cases), compound odontoma (2 cases), adenomatoid odontogenic tumor (2 cases), calcifying epithelial odontogenic tumor (2 cases) and odontogenic fibroma (2 cases), were studied. The results showed that, according to the immunostaining pattern of BMPMcAb, tumors could be classified into two types: all cementifying fibromas, benign cementoblastomas, dentinomas, odontogenic fibromas, and compound odontomas demonstrated a positive reaction, whereas all ameloblastomas, adenomatoid odontogenic tumors, and calcifying epithelial odontogenic tumors were negative. BMPMcAb-positive odontogenic tumors were those tumors with formation of enamel, dentin, cementum or bone. Therefore, BMP might play an important role in the formation of calcified dental tissues and the development of odontogenic tumors contaning such tissues.     

Lateral current flow in thyristors with partially shorted cathodes—I: Two-terminal operation

The influence of a partial short in the cathode of a thyristor on current flow in the high-impedance region is investigated in the first of a two-part paper, primarily for two-terminal operation. First, this short is simulated by a resistance R connected between gate and cathode and included in the equations governing current flow. Secondly, an effective current gain, modified by a shorting dot (SD), is calculated showing, not only current but also geometrical dependence. Thirdly, the lateral current flow in the gated p-region is calculated, for two-terminal operation, from a digital computer solution of a non-linear differential equation—which in principle applies for both two- and three-terminal operation—yielding the current flow into the SD. Some speculations on the influence of gold doping on this lateral current flow are offered and are reconciled with measured differences.     

The influence of anisotropic stress on the electrical characteristics of GaAs1-xPx diodes

Anisotropic stress has been applied on shallow light emitting GaAsP junctions with stylii of relatively small radius of curvature made of diamond and—for the purpose of extracting the emitted radiation—of glass. It was found that the induced current changes, which were restricted to the (q/2kT) slope region of the forward bias current voltage characteristic and which is dominated by the Generation Recombination (GR)_current in the junction, were reversible. The currents flowing in the (q/kT) forward bias—light emitting—region and reverse bias region were not affected by stress. No changes in the spectral output in the (q/kT) region could be observed.In sharp contrast the near uniaxial stresses caused by glass stylii with large radii of curvature to which large forces were applied resulted in measurable (reversible) band gap changes as detected by the emitted radiation yet, despite the much higher stresses throughout the diode area, did not affect the currents in the GR domain. Highly anisotropic stress fields, though not necessarily high stresses seem therefore essential in the creation and/or changes of GR centres. An empirical relation of the excess stress induced electric currents with force F derived from experimental data is utilised to extract a theoretical relationship between local concentration of stress induced GR centres and elastic deformation energy. The theory confirms the requirement of an anisotropic stress field for the creation of these excess GR centres in the junction.     

Role of lipopolysaccharide and a major outer membrane protein from Francisella tularensis in the induction of immunity against tularemia

A crude outer membrane preparation from Francisella tularensis Live Vaccine Strain (LVS) was used to immunize mice. Immunized mice were completely protected from a F. tularensis challenge. We evaluated the role of two major outer membrane antigens in the induction of protective immunity, namely lipopolysaccharide and an outer membrane protein FopA. We presented FopA to the immune system using an aromatic amino acid-dependent Salmonella typhimurium as a vector. Although mice mounted an immune response to cloned FopA no significant protection was induced. However, LPS immunized mice were completely protected. We conclude that LPS is a major protective antigen whereas FopA has a limited or no role in the induction of protective immunity.     

Exploiting Model Structure to Solve the Dynamics of a Macro Model

This paper considers alternative numerical approaches to solvingthe time-path of a nonlinear representative agent model.     

Citrus phenylpropanoids and defence against pathogens. Part I: Metabolic profiling in elicited fruits

Penicillium spp. are among the major postharvest pathogens of citrus fruit. Induction of natural resistance in fruits constitutes one of the alternatives to chemical fungicides. Here, we investigated the involvement of the phenylpropanoid pathway in the induction of resistance in Navelate oranges by examining changes in the metabolic profile of upon eliciting citrus fruits. By using both HPLC-PDA-FD and HPLC-PDA-QTOF–MS allowed the identification of several compounds that seem to be relevant for induced resistance. In elicited fruits, a greater diversity of phenolic compounds was observed in the flavedo (outer coloured part of the peel) when compared to the albedo (inner white part). Moreover, only small changes were detected in the most abundant citrus flavonoids. The coumarin scoparone was among the compounds with the highest induction upon elicitation. Two other highly induced compounds were identified as citrusnin A and drupanin aldehyde. All three compounds are known to exert antimicrobial activity. Our results suggest that phenylpropanoids and their derivatives play an important role in the induction of resistance in citrus fruit.     

Gate current flow in thyristors with partially shorted cathodes—two and three terminal operation

A knowledge of lateral gate current flow including the current drawn off into the shorting dot (SD) is crucial in assessing the stability of operation of thyristors. Following two recent papers the non-linear differential equation y″ + yy′ ? Cy = 0 governing y(ζ), the normalised lateral gate current flow as a function of ζ, the normalised co-ordinate parallel to the cathode junction, is further investigated. Although analytical solutions have so far proved elusive, improved results have now been obtained for two terminal (2T) operation with the use of second order approximations. The Non-Cauchy boundary conditions inherent in the problem have thus been bypassed. This has also assisted in the accurate numerical solution for three terminal (3T) operation and a series of curves are presented. The influence of sheet resistance ($\text{?}\text{W}$) clearly emerges, and the assumption previously made of approximately constant gate current is shown to hold only for low values of ($\text{?}\text{W}$). The influence of gate current flow upon turn-on area is once more discussed, and the minimum gate current required to switch the device is derived.