Home About us Contact
|
Home About us Contact | ||
|
|
||
Several Drawbacks (several + drawback)
Selected AbstractsDiagnosing PNH with FLAER and multiparameter flow cytometryCYTOMETRY, Issue 3 2007D. Robert Sutherland Abstract Background: PNH is an acquired hematopoietic stem cell disorder leading to a partial or absolute deficiency of all glycophosphatidyl-inositol (GPI)-linked proteins. The classical approach to diagnosis of PNH by cytometry involves the loss of at least two GPI-linked antigens on RBCs and neutrophils. While flow assays are more sensitive and specific than complement-mediated lysis or the Hams test, they suffer from several drawbacks. Bacterial aerolysin binds to the GPI moiety of cell surface GPI-linked molecules and causes lysis of normal but not GPI-deficient PNH cells. FLAER is an Alexa488-labeled inactive variant of aerolysin that does not cause lysis of cells. Our goals were to develop a FLAER-based assay to diagnose and monitor patients with PNH and to improve detection of minor populations of PNH clones in other hematologic disorders. Methods: In a single tube assay, we combined FLAER with CD45, CD33, and CD14 allowing the simultaneous analysis of FLAER and the GPI-linked CD14 structure on neutrophil and monocyte lineages. Results: Comparison to standard CD55 and CD59 analysis showed excellent agreement. Because of the higher signal to noise ratio, the method shows increased sensitivity in our hands over single (CD55 or CD59) parameter analysis. Using this assay, we were able to detect as few as 1% PNH monocytes and neutrophils in aplastic anemia, that were otherwise undetectable using CD55 and CD59 on RBC's. We also observed abnormal FLAER staining of blast populations in acute leukemia. In these cases, the neutrophils stained normally with FLAER, while the gated CD33bright cells failed to express normal levels of CD14 and additionally showed aberrant CD45 staining and bound lower levels of FLAER. Conclusion: FLAER combined with multiparameter flow cytometry offers an improved assay for diagnosis and monitoring of PNH clones and may have utility in detection of unsuspected myeloproliferative disorders. © 2007 Clinical Cytometry Society [source] Active immunization with IL-1 displayed on virus-like particles protects from autoimmune arthritisEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2008Gunther Spohn Abstract IL-1 is an important mediator of inflammation and a major cause of tissue damage in rheumatoid arthritis (RA). Therapeutic administration of recombinant IL-1 receptor antagonist (IL-1Ra) is efficacious in reducing clinical symptoms of disease, but suffers from several drawbacks, including the need for frequent administrations of large amounts. Here, we show that immunization of mice with either IL-1, or IL-1, chemically cross-linked to virus-like particles (VLP) of the bacteriophage Q, elicited a rapid and long-lasting autoantibody response. The induced Ab efficiently neutralized the binding of the respective IL-1 molecules to their receptors in vitro and their pro-inflammatory activities in vivo. In the collagen-induced arthritis model, both vaccines strongly protected mice from inflammation and degradation of bone and cartilage. Moreover, immunization with either vaccine showed superior efficacy than daily administrations of high amounts of IL-1Ra. In the T and B cell-independent collagen Ab transfer model, immunization with the IL-1, vaccine strongly protected from arthritis, whereas immunization with the IL-1, vaccine had no effect. Our results suggest that active immunization with IL-1,, and especially IL-1, conjugated to Q, VLP, might become an efficacious and cost-effective new treatment option for RA and other systemic IL-1-dependent inflammatory disorders. [source] A closed-loop proposal for hydrogen generation using steel waste and a prototype solar concentratorINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2009Abdul-Majeed Azad Abstract An economically viable and environmental-friendly method of generating PEM grade hydrogen has been proposed and is by the reaction of certain metals with steam, appropriately called ,metal,steam reforming',MSR. The drawbacks of conventional processes (hydrogen and carbothermic reduction schemes) are overcome by resorting to solution-based reduction schemes and are made economically feasible using iron oxides from steel industry's mill-scale waste. A novel aqueous-based room temperature technique using sodium borohydride (NaBH4) as the reducing agent has been developed that produces highly active nanoscale iron particles (,40,nm). By using hydrazine as an inexpensive and, compared with NaBH4, more stable reductant, body centered cubic iron particles with ,5,nm edges were obtained via solvothermal process under mild conditions from acid digested mill-scale waste. The nanoscale zerovalent iron (nZVI) powder showed improved kinetics and greater propensity for hydrogen generation than the coarser microscale iron. The rate constants for the MSR were obtained for all the reduction schemes employed in this work and are given by khydrogen=0.0158,min,1kcarbon=0.0248,min,1ksodiumborohydride=0.0521,min,1 and khydrazine=0.1454,min,1, assuming first order kinetics. Another innovative effort converted the magnetite waste directly into nZVI under solvothermal conditions, thus obviating the sluggish and time-consuming acid dissolution step. This particular aspect has significant ramification in terms of time and cost of making the iron precursor. To initiate and sustain the somewhat endothermic MSR process, a solar concentrator consisting of a convex polyacrylic bowl with reflective aluminum coating was fabricated and evaluated. This unique combination of mill-scale waste as iron source, hydrazine as reductant, mild process conditions and solar energy as the MSR actuator obviates several drawbacks plaguing the grand scheme of producing and delivering pure and humidified H2 to a PEMFC stack. Copyright © 2008 John Wiley & Sons, Ltd. [source] New attempts to quantify concentric needle electromyographyMUSCLE AND NERVE, Issue S11 2002Masahiro Sonoo MD, PhDArticle first published online: 4 JUN 200 Abstract Quantitative motor unit potential (MUP) analysis, which is a leading method of quantitative evaluation of concentric needle electromyography, has several inherent limitations. First, the most essential features of neurogenic or myogenic changes manifest as recruitment abnormalities, rather than as changes in MUP morphology. Second, two factors related to MUP sampling, focusing and level of contraction, greatly influence the parameters of sampled MUPs. Third, the MUP duration, considered to be the cardinal parameter in MUP analysis, has several drawbacks, including low stability and low discriminant sensitivity. We developed a new MUP parameter, the size index (SI), which is calculated from the MUP amplitude and area/amplitude ratio (thickness). The SI remained almost constant during electrode movements, as demonstrated by manual scanning of MUPs. It is a stable and robust parameter and achieved an extremely high ability to discriminate between normal and large neurogenic MUPs. It identifies features related to the sound produced by the MUP on the audio monitor, which is often used by trained electromyographers for qualitative assessments of MUPs. © 2002 Wiley Periodicals, Inc. Muscle Nerve Supplement 11: S98,S102, 2002 [source] Toward a better analysis of secreted proteins: the example of the myeloid cells secretomePROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 11 2007Mireille Chevallet Abstract The analysis of secreted proteins represents a challenge for current proteomics techniques. Proteins are usually secreted at low concentrations in the culture media, which makes their recovery difficult. In addition, culture media are rich in salts and other compounds interfering with most proteomics techniques, which makes selective precipitation of proteins almost mandatory for a correct subsequent proteomics analysis. Last but not least, the non-secreted proteins liberated in the culture medium upon lysis of a few dead cells heavily contaminate the so-called secreted proteins preparations. Several techniques have been used in the past for concentration of proteins secreted in culture media. These techniques present several drawbacks, such as coprecipitation of salts or poor yields at low protein concentrations. Improved techniques based on carrier-assisted TCA precipitation are described and discussed in this report. These techniques have been used to analyze the secretome of myeloid cells (macrophages, dendritic cells) and enabled to analyze proteins secreted at concentrations close to 1,ng/mL, thereby allowing the detection of some of the cytokines (TNF, IL-12) secreted by the myeloid cells upon activation by bacterial products. [source] PEAKS: powerful software for peptide de novo sequencing by tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2003Bin Ma A number of different approaches have been described to identify proteins from tandem mass spectrometry (MS/MS) data. The most common approaches rely on the available databases to match experimental MS/MS data. These methods suffer from several drawbacks and cannot be used for the identification of proteins from unknown genomes. In this communication, we describe a new de novo sequencing software package, PEAKS, to extract amino acid sequence information without the use of databases. PEAKS uses a new model and a new algorithm to efficiently compute the best peptide sequences whose fragment ions can best interpret the peaks in the MS/MS spectrum. The output of the software gives amino acid sequences with confidence scores for the entire sequences, as well as an additional novel positional scoring scheme for portions of the sequences. The performance of PEAKS is compared with Lutefisk, a well-known de novo sequencing software, using quadrupole-time-of-flight (Q-TOF) data obtained for several tryptic peptides from standard proteins. Copyright © 2003 John Wiley & Sons, Ltd. [source] Comparison between micellar liquid chromatography and capillary zone electrophoresis for the determination of hydrophobic basic drugs in pharmaceutical preparationsBIOMEDICAL CHROMATOGRAPHY, Issue 1 2007S. Torres-Cartas Abstract The determination of highly hydrophobic basic compounds by means of conventional reversed-phase liquid chromatographic methods has several drawbacks. Owing to the characteristics of micellar liquid chromatography (MLC) and capillary electrophoresis (CE), these techniques could be advantageous alternatives to reversed-phase chromatographic methods for the determination of these kinds of compounds. The objective of this study was to develop and compare MLC and CE methods for the determination of antipsychotic basic drugs (amitryptiline, haloperidol, perphenazine and thioridazine) in pharmaceutical preparations. The chromatographic determination of the analytes was performed on a Kromasil C18 analytical column; the mobile phase was 0.04 m cetyltrimethylammonium bromide (CTAB), at pH 3, containing 5% 1-butanol, at a flow rate of 1 mL/min. The CE separation was performed in a fused-silica capillary with a 50 mm tris-(hydroxymethyl)-aminomethane buffer, pH 7, at an applied voltage of 20 kV, using barbital as internal stardard. The proposed methods are suitable for a reliable quantitation of these compounds in the commercial tablets and drops in terms of accuracy and precision and require a very simple pre-treatment of the samples. By comparing the performance characteristics and experimental details of the MLC and CE methods we conclude that CE seems to be slightly better than MLC in the determination of highly hydrophobic compounds in pharmaceuticals in terms of resolution and economy, taking into account that the limits of detection are not a handicap in pharmaceutical samples. Copyright © 2006 John Wiley & Sons, Ltd. [source] Fast chiral separation of drugs using columns packed with sub-2 ,m particles and ultra-high pressureCHIRALITY, Issue 3 2010Davy Guillarme Abstract The use of columns packed with sub-2 ,m particles in liquid chromatography with very high pressure conditions (known as UHPLC) was investigated for the fast enantioseparation of drugs. Two different procedures were evaluated and compared using amphetamine derivatives and ,-blockers as model compounds. In one case, cyclodextrins (CD) were directly added to the mobile phase and chiral separations were carried out in less than 5 min. However, this strategy suffered from several drawbacks linked to column lifetime and low chromatographic efficiencies. In the other case, the analysis of enantiomers was carried out after a derivatization procedure using two different reagents, 2,3,4-tri-O-acetyl-,- D -arabinopyranosyl isothiocyanate (AITC) and N -,-(2,4-dinitro-5-fluorophenyl)- L -alaninamide (Marfey's reagent). Separation of several amphetamine derivatives contained within the same sample was achieved in 2,5 min with high efficiency and selectivity. The proposed approach was also successfully applied to the enantiomeric purity determination of (+)-(S)-amphetamine and (+)-(S)-methamphetamine. Similar results were obtained with ,-blockers, and the separation of 10 enantiomers was carried out in less than 3 min, whereas the individual separation of several ,-blocker enantiomers was performed in 1 min or less. Chirality, 2010. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||