Design and characteristic of trials included in our meta-analysis.

<p>Design and characteristic of trials included in our meta-analysis.</p

Summary of the relative risks of grade 3 or worse toxicity assessed.

<p>Summary of the relative risks of grade 3 or worse toxicity assessed.</p

Accurate Determination of Protein Methionine Oxidation by Stable Isotope Labeling and LC-MS Analysis

Methionine (Met) oxidation is a major modification of proteins, which converts Met to Met sulfoxide as the common product. It is challenging to determine the level of Met sulfoxide, because it can be generated during sample preparation and analysis as an artifact. To determine the level of Met sulfoxide in proteins accurately, an isotope labeling and LC-MS peptide mapping method was developed. Met residues in proteins were fully oxidized using hydrogen peroxide enriched with ¹⁸O atoms before sample preparation. Therefore, it was impossible to generate Met sulfoxide as an artifact during sample preparation. The molecular weight difference of 2 Da between Met sulfoxide with the ¹⁶O atom and Met sulfoxide with the ¹⁸O atom was used to differentiate and calculate the level of Met sulfoxide in the sample originally. Using a recombinant monoclonal antibody as a model protein, much lower levels of Met sulfoxide were detected for the two susceptible Met residues with this new method compared to a typical peptide mapping procedure. The results demonstrated efficient elimination of the analytical artifact during LC-MS peptide mapping for the measurement of Met sulfoxide. This method can thus be used when accurate determination of the level of Met sulfoxide is critical

Chemotherapy Plus Best Supportive Care versus Best Supportive Care in Patients with Non-Small Cell Lung Cancer: A Meta-Analysis of Randomized Controlled Trials

<div><p>Background</p><p>The use of chemotherapy has been proposed to increase the effectiveness of best supportive care (BSC) in patients with non-small cell lung cancer (NSCLC). Previous trials reported inconsistent findings regarding the efficacy and safety of chemotherapy on overall survival (OS) and treatment-related mortality. We performed a systematic review and meta-analysis to evaluate the effects of chemotherapy plus BSC versus BSC alone on survival of patients with NSCLC.</p> <p>Methodology and Principal Findings</p><p>We systematically searched PubMed, EmBase, and the Cochrane Central Register of Controlled Trials for relevant literature. All eligible studies included patients with NSCLC who had received chemotherapy and BSC or BSC alone. All eligible studies measured at least 1 of the following outcomes: OS or treatment-related mortality. Overall, patients that received chemotherapy plus BSC had significant longer OS than those that received BSC alone (HR, 0.76; 95%CI, 0.69–0.84; P<0.001). Additionally, chemotherapy plus BSC as compared to BSC alone resulted in a 28% RR reduction (95%CI: 12–40; P = 0.001) in 6-month mortality, 11% RR reduction (95%CI: 8–15; P<0.001) in 12-month mortality, and 5% RR reduction (95%CI: 1–8; P = 0.02) in 2-year mortality. Toxicity was greater in patients that received chemotherapy plus BSC.</p> <p>Conclusion/Significance</p><p>Chemotherapy plus BSC increased the OS and reduced the 6-month, 12-month, and 2-year mortality of NSCLC patients.</p> </div

Accurate Determination of Protein Methionine Oxidation by Stable Isotope Labeling and LC-MS Analysis

Methionine (Met) oxidation is a major modification of proteins, which converts Met to Met sulfoxide as the common product. It is challenging to determine the level of Met sulfoxide, because it can be generated during sample preparation and analysis as an artifact. To determine the level of Met sulfoxide in proteins accurately, an isotope labeling and LC-MS peptide mapping method was developed. Met residues in proteins were fully oxidized using hydrogen peroxide enriched with ¹⁸O atoms before sample preparation. Therefore, it was impossible to generate Met sulfoxide as an artifact during sample preparation. The molecular weight difference of 2 Da between Met sulfoxide with the ¹⁶O atom and Met sulfoxide with the ¹⁸O atom was used to differentiate and calculate the level of Met sulfoxide in the sample originally. Using a recombinant monoclonal antibody as a model protein, much lower levels of Met sulfoxide were detected for the two susceptible Met residues with this new method compared to a typical peptide mapping procedure. The results demonstrated efficient elimination of the analytical artifact during LC-MS peptide mapping for the measurement of Met sulfoxide. This method can thus be used when accurate determination of the level of Met sulfoxide is critical

Ranking the Susceptibility of Disulfide Bonds in Human IgG1 Antibodies by Reduction, Differential Alkylation, and LC−MS Analysis

One of the basic structural features of human IgG1 is the arrangement of the disulfide bond structure, 4 inter chain disulfide bonds in the hinge region and 12 intra chain disulfide bonds associated with twelve individual domains. Disulfide bond structure is critical for the structure, stability, and biological functions of IgG molecules. It has been known that inter chain disulfide bonds are more susceptible to reduction than intra chain disulfide bonds. However, a complete ranking of the susceptibility of disulfide bonds in IgG1 molecules is lacking. A method including reduction, differential alkylation, and liquid chromatography−mass spectrometry (LC−MS) analysis was developed and employed to investigate the complete ranking order of the susceptibility of disulfide bonds in two recombinant monoclonal antibodies. The results confirmed that inter chain disulfide bonds were more susceptible than intra chain disulfide bonds. In addition, it was observed that the disulfide bonds between the light chain and heavy chain were more susceptible than disulfide bonds between the two heavy chains. The upper disulfide bond of the two inter heavy chain disulfide bonds was more susceptible than the lower one. Furthermore, disulfide bonds in the CH2 domain were the most susceptible to reduction. Disulfide bonds in VL, CL, VH, and CH1 domains had similar and moderate susceptibility, while disulfide bonds in the CH3 domain were the least susceptible to reduction. Interestingly, a difference between IgG1κ and IgG1λ was also observed. The difference in the susceptibility of inter light heavy chain disulfide bonds and inter heavy chain disulfide bonds was smaller in IgG1κ than in IgG1λ. The intra chain disulfide bonds in the Fab region of IgG1κ were also less susceptible than disulfide bonds in the Fab region of IgG1λ

Subgroup analysis of overall survival, 12-month mortality, and 2-year mortality after treatment with chemotherapy and best supportive care.

<p>Subgroup analysis of overall survival, 12-month mortality, and 2-year mortality after treatment with chemotherapy and best supportive care.</p

Identification process for eligible studies.

<p>Identification process for eligible studies.</p

Determination of Deamidation Artifacts Introduced by Sample Preparation Using ¹⁸O-Labeling and Tandem Mass Spectrometry Analysis

The sites and levels of Asn deamidation in proteins are often determined by LC–MS analysis of peptides obtained from enzymatic digestion. However, deamidation that occurs during sample preparation steps results in overestimation of the original level of deamidation. The inherent deamidation and those introduced by sample preparation can be differentiated by preparing samples in ¹⁸O water. When using H₂¹⁸O, the formation of isoAsp and Asp by Asn deamidation during sample preparation results in a molecular weight increase of 3 Da due to the incorporation of the ¹⁸O atom to the side chains of isoAsp or Asp; in contrast, inherent deamidation only results in a molecular weight increase of 1 Da. In addition, up to two ¹⁸O atoms can also be incorporated into the peptide C-terminal carboxyl group during enzymatic digestion. Therefore, the 2 Da molecular weight difference at the deamidation sites can only be used to differentiate deamidation that occurs prior to or during sample preparation under conditions that a fixed number of ¹⁸O atoms are incorporated into the peptide C-terminal carboxyl groups. Otherwise, it is challenging to apply this procedure because of the resulting complicated isotopic distributions. Here, a new procedure of using ¹⁸O-water for sample preparation coupled with tandem mass spectrometry (MS/MS) was established to calculate the deamidation artifacts. In this method, b ions were used for the calculation of Asn deamidation that occurred prior to or during sample preparation, which eliminated the complicated factor of various number of ¹⁸O-atoms to the peptide carboxyl groups. This procedure has the potential to be applied under the general peptide mapping conditions

Comparison of 6-month mortality (A), 12-month mortality (B), and 2-year mortality (C) between chemotherapy plus best supportive care and best supportive care alone.

<p>Comparison of 6-month mortality (A), 12-month mortality (B), and 2-year mortality (C) between chemotherapy plus best supportive care and best supportive care alone.</p