Identification of Dimethyldioctadecylammonium Ion (m/z 550.6) and Related Species (m/z 522.6, 494.6) as a Source of Contamination in Mass Spectrometry

Chemical contamination can be one of the more common problems encountered when performing trace-level analysis regardless of the analytical technique. Minimizing or eliminating background interferences can be a difficult task, so knowledge of the chemical composition of these contaminants can prove invaluable when it comes to identifying the source. Once the source is identified, proper steps may be taken to reduce or eliminate it. In this study, we report the identity of some commonly seen contaminants (m/z 550.6, 522.6, and 494.6) in electrospray ionization (ESI) mass spectrometry (MS). Through MS, tandem MS, accurate-mass, and high-resolution measurements we have identified these background contaminants as being quaternary ammonium species that contain long-chain hydrocarbon groups, where m/z 550.6 is a dimethyldioctadecylammonium ion (C18, C18) and m/z 522.6 and 494.6 are similar in nature but have shorter alkyl-chain groups. The lipophilic nature of these compounds and the fact that they have molecular weights similar to lysophospholipids make them a frequent contaminant in lipidomic studies. The likely sources of these compounds are commonly used personal and household products

Bone Marrow Microenvironment in Multiple Myeloma Progression

Substantial advances have been made in understanding the biology of multiple myeloma (MM) through the study of the bone marrow (BM) microenvironment. Indeed, the BM niche appears to play an important role in differentiation, migration, proliferation, survival, and drug resistance of the malignant plasma cells. The BM niche is composed of a cellular compartment (stromal cells, osteoblasts, osteoclasts, endothelial cells, and immune cells) and a noncellular compartment including the extracellular matrix (ECM) and the liquid milieu (cytokines, growth factors, and chemokines). In this paper we discuss how the interaction between the malignant plasma cell and the BM microenvironment allowed myeloma progression through cell homing and the new concept of premetastatic niche

High-protein paternal diet confers an advantage to sons in sperm competition

Parental environment can widely influence offspring phenotype, but paternal effects in the absence of parental care remain poorly understood. We asked if protein content in the larval diet of fathers affected paternity success and gene expression in their sons. We found that males reared on high-protein diet had sons that fared better during sperm competition, suggesting that postcopulatory sexual selection is subject to transgenerational paternal effects. Moreover, immune response genes were downregulated in sons of low-protein fathers, while genes involved in metabolic and reproductive processes were upregulated

Global Epigenetic Regulation of MicroRNAs in Multiple Myeloma

Epigenetic changes frequently occur during tumorigenesis and DNA hypermethylation may account for the inactivation of tumor suppressor genes in cancer cells. Studies in Multiple Myeloma (MM) have shown variable DNA methylation patterns with focal hypermethylation changes in clinically aggressive subtypes. We studied global methylation patterns in patients with relapsed/refractory MM and found that the majority of methylation peaks were located in the intronic and intragenic regions in MM samples. Therefore, we investigated the effect of methylation on miRNA regulation in MM. To date, the mechanism by which global miRNA suppression occurs in MM has not been fully described. In this study, we report hypermethylation of miRNAs in MM and perform confirmation in MM cell lines using bisulfite sequencing and methylation-specific PCR (MSP) in the presence or absence of the DNA demethylating agent 5-aza-2′-deoxycytidine. We further characterized the hypermethylation-dependent inhibition of miR-152, -10b-5p and -34c-3p which was shown to exert a putative tumor suppressive role in MM. These findings were corroborated by the demonstration that the same miRNAs were down-regulated in MM patients compared to healthy individuals, alongside enrichment of miR-152-, -10b-5p, and miR-34c-3p-predicted targets, as shown at the mRNA level in primary MM cells. Demethylation or gain of function studies of these specific miRNAs led to induction of apoptosis and inhibition of proliferation as well as down-regulation of putative oncogene targets of these miRNAs such as DNMT1, E2F3, BTRC and MYCBP. These findings provide the rationale for epigenetic therapeutic approaches in subgroups of MM

Inhibiting the oncogenic translation program is an effective therapeutic strategy in multiple myeloma

Published in final edited form as: Sci Transl Med. 2017 May 10; 9(389). https://doi.org/10.1126/scitranslmed.aal2668.Multiple myeloma (MM) is a frequently incurable hematological cancer in which overactivity of MYC plays a central role, notably through up-regulation of ribosome biogenesis and translation. To better understand the oncogenic program driven by MYC and investigate its potential as a therapeutic target, we screened a chemically diverse small-molecule library for anti-MM activity. The most potent hits identified were rocaglate scaffold inhibitors of translation initiation. Expression profiling of MM cells revealed reversion of the oncogenic MYC-driven transcriptional program by CMLD010509, the most promising rocaglate. Proteome-wide reversion correlated with selective depletion of short-lived proteins that are key to MM growth and survival, most notably MYC, MDM2, CCND1, MAF, and MCL-1. The efficacy of CMLD010509 in mouse models of MM confirmed the therapeutic relevance of these findings in vivo and supports the feasibility of targeting the oncogenic MYC-driven translation program in MM with rocaglates

On the Formation of Collective Memories: The Role of a Dominant Narrator.

To test our hypothesis that conversations can contribute to the formation of collective memory, we asked participants to study stories and to recall them individually (pregroup recollection), then as a group (group recounting), and then once again individually (postgroup recollection). One way that postgroup collective memories can be formed under these circumstances is if unshared pregroup recollections in the group recounting influences others\u27 postgroup recollections. In the present research, we explored (using tests of recall and recognition) whether the presence of a dominant narrator can facilitate the emergence of unshared pregroup recollections in a group recounting and whether this emergence is associated with changes in postgroup recollections. We argue that the formation of a collective memory through conversation is not inevitable but is limited by cognitive factors, such as conditions for social contagion, and by situational factors, such as the presence of a narrator