34 research outputs found
Identification of leptomeningeal metastasis-related proteins in cerebrospinal fluid of patients with breast cancer by a combination of MALDI-TOF, MALDI-FTICR and nanoLC-FTICR MS
Leptomeningeal metastasis (LM) is a devastating complication occurring in 5% of breast cancer patients. However, the current gold standard of diagnosis, namely microscopic examination of the cerebrospinal fluid (CSF), is false-negative in 25% of patients at the first lumbar puncture. In a previous study, we analyzed a set of 151 CSF samples (tryptic digests) by MALDI-TOF and detected peptide masses that were differentially expressed in breast cancer patients with LM. In the present study, we obtain for a limited number of samples exact masses for these peptides by MALDI-FTICR MS measurements. Identification of these peptides was performed by electrospray FTICR MS after separation by nano-scale LC. The database results were confirmed by targeted high mass accuracy measurements of the fragment ions in the FTICR cell. The combination of automated high-throughput MALDI-TOF measurements and analysis by FTICR MS leads to the identification of 17 peptides corresponding to 9 proteins. These include proteins that are operative in host-disease interaction, inflammation and immune defense (serotransferrin, alpha 1-antichymotrypsin, hemopexin, haptoglobin and transthyretin). Several of these proteins have been mentioned in the literature in relation to cancer. The identified proteins alpha1-antichymotrypsin and apolipoprotein E have been described in relation to Alzheimer's disease and brain cancer
XMS: Cross-Platform Normalization Method for Multimodal Mass Spectrometric Tissue Profiling
An In vitro Study on the Postinfection Activities of Hydrated Lime and Lime Sulphur against Apple Scab (Venturia inaequalis)
An In Vitro Study of the Nature of Protective Activities of Copper Sulphate, Copper Hydroxide and Copper Oxide Against Conidia of Venturia inaequalis
Absorption mode FTICR mass spectrometry imaging
Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here, we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image, and then, these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode “Datacubes” for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast
SORI excitation : Collisional and radiative processes
Theoretical modeling of sustained off-resonance irradiation
collision-induced dissociation (SORI-CID) experiments in Fourier
transform ion cyclotron resonance (FT-ICR) mass spectrometry is
described in the present paper. Manipulation of various analytical
expressions yield the result that the average laboratory frame
collision energy is equal to 2/3 of the maximum kinetic energy in SORI.
Survival yields (the fraction of nondecomposed molecular ions) as a
function of excitation time, collision energy, and source temperature
have been considered: results of MassKinetics-type reaction kinetics
modeling were compared with experimental results obtained by Guo et al.
(Int. J. Mass Spectrom. 2003, 225, 71-82). The results show that
radiative cooling has a major influence in SORI-CID. They also suggest
that collisional cooling is significant only at very low (less than
0.02 eV) center of mass collision energy; therefore it has a very small
influence on the SORI process. Survival yield curves showed excellent
agreement between experiments and calculations optimizing two
parameters only (collisional energy-transfer efficiency and radiative
cooling rate). Using leucine enkephalin as a model compound, the
results indicate 0.128 +/- 0.021 energy deposition in a single
collision and 7.5 +/- 0.5 s(-1) infrared cooling rate. We also present
that these two physical parameters cannot be properly deconvoluted.
This effect shows the importance of the parallel consideration of
different physical processes
Treatment of fluoroacetate by a Pseudomonas fluorescens biofilm grown in membrane aerated biofilm reactor
Fluorinated organic compounds have widespread applications, and their accumulation in the environment is a concern. Biofilm reactors are an effective technology for the treatment of contaminated wastewater, yet almost no research has been conducted on the effectiveness of biofilms for the biodegradation of fluorinated aliphatic compounds. In this paper we describe experiments undertaken to investigate the degradation of fluoroacetate using a membrane aerated biofilm reactor (MABR) by Pseudomonas fluorescens DSM8341. The concentration of fluoroacetate in the medium influenced biofilm structure, with less dense biofilm observed at lower fluoroacetate loading rates. As biofilm thickness increased, oxygen utilization decreased, probably as a consequence of increased resistance to oxygen transfer. Furthermore, most of the biofilm was anaerobic, since oxygen penetration depth was less than 1000 μm. Biofilm performance, in terms of fluoroacetate removal efficiency, was improved by decreasing the fluoroacetate loading rate, however increasing the intramembrane oxygen pressure had little effect on biofilm performance. A mathematical model showed that while fluoroacetate does not penetrate the entire biofilm, the defluorination intermediate metabolite glycolate does, and consequently the biofilm was not carbon limited at the biofilm−membrane interface where oxygen concentrations were highest. The model also showed the accumulation of the free fluoride ion within the biofilm. Overflow metabolism of glycolate was identified to be most likely a result of a combination of oxygen limitation and free fluoride ion inhibition. The study demonstrated the potential of MABR for treating wastewater streams contaminated with organofluorine compounds.Science Foundation Irelan