No abstract

2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate was designed to replace perfluorooctanoic acid (PFOA), which has been mostly phased out of U.S. production due to environmental persistence, detectable human and wildlife serum concentrations, and reports of systemic toxicity. In rodent models, PFOA exposure suppresses T cell-dependent antibody responses (TDAR) and vaccine responses in exposed humans. To determine replacement compound effects on TDAR and related parameters, male and female C57BL/6 mice were gavaged with 0, 1, 10, or 100 mg/kg/day for 28 days. Mice immunized with antigen on day 24were evaluated for TDAR and splenic lymphocyte subpopulations five days later. Serum and urine were collected for test compound concentrations and liver peroxisome proliferation was measured. Relative liver weight at 10 and 100 mg/kg and peroxisome proliferation at 100 mg/kg were increased in both sexes. TDAR was suppressed in females at 100 mg/kg. T lymphocyte numbers were increased in males at 100 mg/kg; B lymphocyte numbers were unchanged in both sexes. Females had less serum accumulation and higher clearance than males, and males had higher urine concentrations than females at all times and doses. While this PFOA-replacement compound appears less potent at suppressing TDAR relative to PFOA, it produces detectable changes in parameters affected by PFOA; further studies are necessary to determine its full immunomodulatory profile and potential synergism with other per-and polyfluoroalkyl substances of environmental concern.

Aflatoxin B has been shown to bind to proteins through a dialdehyde intermediate under physiological conditions. The proposed structure of this adduct has been published showing a Schiff base interaction, but adequate verification using structural elucidation instrumental techniques has not been performed. In this work, we synthesized the aflatoxin B amino acid adduct under alkaline conditions, and the formation of a new product was determined using high performance liquid chromatography-time-of-flight mass spectrometry. The resulting accurate mass was used to generate a novel proposed chemical structure of the adduct in which the dialdehyde forms a pyrrole ring with primary amines rather than the previously proposed Schiff base interaction. The pyrrole structure was confirmed using H,C, correlation spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond correlation NMR and tandem mass spectrometry. Reaction kinetics show that the reaction is overall second order and that the rate increases as pH increases. Additionally, this study shows for the first time that aflatoxin B dialdehyde forms adducts with phosphatidylethanolamines and does so through pyrrole ring formation, which makes it the first aflatoxin-lipid adduct to be structurally identified. Furthermore, oxidation of the pyrrole adduct produced a product that was 16 m/z heavier. When the aflatoxin B-lysine (ε) adduct was oxidized, it gave a product with an accurate mass, mass fragmentation pattern, and H NMR spectrum that match aflatoxin B-lysine, which suggest the transformation of the pyrrole ring to a pyrrolin-2-one ring. These data give new insight into the fate and chemical properties of biological adducts formed from aflatoxin B as well as possible interferences with known aflatoxin B exposure biomarkers.

Heterotrimeric G proteins were originally discovered through efforts to understand the effects of hormones, such as glucagon and epinephrine, on glucose metabolism. On the other hand, many cellular metabolites, including glucose, serve as ligands for G protein-coupled receptors. Here we investigate the consequences of glucose-mediated receptor signaling, and in particular the role of a Gα subunit Gpa2 and a non-canonical Gβ subunit, known as Asc1 in yeast and RACK1 in animals. Asc1/RACK1 is of particular interest because it has multiple, seemingly unrelated, functions in the cell. The existence of such “moonlighting” operations has complicated the determination of phenotype from genotype. Through a comparative analysis of individual gene deletion mutants, and by integrating transcriptomics and metabolomics measurements, we have determined the relative contributions of the Gα and Gβ protein subunits to glucose-initiated processes in yeast. We determined that Gpa2 is primarily involved in regulating carbohydrate metabolism while Asc1 is primarily involved in amino acid metabolism. Both proteins are involved in regulating purine metabolism. Of the two subunits, Gpa2 regulates a greater number of gene transcripts and was particularly important in determining the amplitude of response to glucose addition. We conclude that the two G protein subunits regulate distinct but complementary processes downstream of the glucose-sensing receptor, as well as processes that lead ultimately to changes in cell growth and metabolism.

Dysregulation of cellular metabolism is now a well-recognized hallmark of cancer. Studies investigating the metabolic features of cancer cells have shed new light onto processes in cancer cell biology and have identified many potential novel treatment options. The advancement of mass spectrometry-based metabolomics has improved the ability to monitor multiple metabolic pathways simultaneously in various experimental settings. However, questions still remain as to how certain steps in the metabolite extraction process affect the metabolic profiles of cancer cells. Here, we use ultra-high-performance liquid chromatography–high-resolution mass spectrometry (UHPLC–HRMS) untargeted metabolomics to investigate the effects of different detachment and lysis methods on the types and abundances of metabolites extracted from MDA-MB-231 cells through the use of in-house standards libraries and pathway analysis software. Results indicate that detachment methods (trypsinization vs. scraping) had the greatest effect on metabolic profiles whereas lysis methods (homogenizer beads vs. freeze–thaw cycling) had a lesser, though still significant, effect. No singular method was clearly superior over others, with certain metabolite classes giving higher abundances or lower variation for each detachment–lysis combination. These results indicate the importance of carefully selecting sample preparation methods for cell-based metabolomics to optimize the extraction performance for certain compound classes.

No abstract

Effective and reliable training aids for victim recovery canine teams is essential for law enforcement and investigative purposes. Without adequate training aids, the rate of recovery for sub surface or surface human remains deposition using canine teams may be adversely affected and result in confusing information. The composition of three commercially available canine training aids that purportedly generate volatile components responsible for the odor of human decomposition is relatively simple and not closely related to those compounds experimentally determined to be present at the site of surface or sub-surface human remains. In this study, these different commercial formulations were chemically characterized using six different sampling approaches, including two applications of direct liquid injection, solid-phase microextraction (SPME), purge and trap, ambient preconcentration/thermal desorption, and cryogenic preconcentration/thermal desorption. Direct liquid injections resulted in the fewest number of detected compounds, while a cryogen based thermal desorption method detected the greatest number of compounds in each formulation. Based solely upon the direct liquid injection analysis, Pseudo™ Scent I was composed of approximately 29±4% and 71±5% of 2-pyrrolidinone and 4-aminobutanoic acid, respectively. This same analysis showed that Pseudo™ Scent II was composed of approximately 11±1, 11±1, 24±5, and 54±7% of putrescine, cadaverine, 2-pyrrolidinone, and 4-aminobutanoic acid, respectively. Headspace analysis was conducted to more closely simulate the process whereby a canine's nose would capture a volatiles profile. More compounds were detected using the headspace sampling method; however, the vast majority was not consistent with current data on human decomposition. Additionally, the three formulations were tested in outdoor and indoor scenarios by a double-blinded canine team, using a certified and specifically trained victim recovery canine with multiple confirmed recoveries, to determine if the formulations would be recognized by that canine as being related to human decomposition. The canine used in this study did not provide a positive response to any of the formulations tested in either test scenario. The implications for locating residual human decomposition odor in the absence of recoverable material are discussed in light of these data.

Aflatoxin B1 (AFB1) is a class 1 carcinogen and a common food contaminant worldwide with widely uncontrolled human exposure. The ability of organic acids to transform AFB1 into a known detoxified form, aflatoxin B2a (AFB2a), was investigated using high performance liquid chromatography-electrospray ionisation-time of flight mass spectrometry (HPLC/ESI/TOF/MS). The identity of the transformation product was confirmed by accurate mass measurement, chromatographic separation from other aflatoxins, H(1)-nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Of the weak acids tested, citric acid was found to be the most effective for AFB2a formation. At room temperature, 1 M citric acid was able to convert > 97% of AFB1 to AFB2a over 96 h of treatment. Up to 98% transformation was achieved by boiling AFB1 in the presence of citric acid for 20 min. AFB1 hydration after ingestion was explored by spiking AFB1 into simulated gastric fluid containing citric acid. Under these conditions, > 71% of AFB1 was hydrated to AFB2a and did not show any reversion to the parent compound after being transferred to a neutral solution. These results provide a basis for a practical and effective method for detoxification of AFB1 in contaminated foods.