Rapid and Quantitative Analysis of Aflatoxin M1 From Milk Using Atmospheric Pressure-Matrix Assisted Laser Desorption/Ionization (AP-MALDI)-Triple Quadrupole Selected Reaction Monitoring.

Background: Aflatoxin M1 (AFM1) is a carcinogenic hydroxylated metabolite commonly found in milk. It is relatively stable toward decontamination procedures posing a major health risk, and it requires an international regulatory mandate of detection at trace levels.

Objective: To develop a high-throughput, reliable, and compliant method for the identification of AFM1 in milk samples using atmospheric pressure-matrix assisted laser desorption/ionization (AP-MALDI) selected reaction monitoring (SRM) quantitation.

Integrated genetic and metabolic landscapes predict vulnerabilities of temozolomide resistant glioblastoma cells.

Metabolic reprogramming and its molecular underpinnings are critical to unravel the duality of cancer cell function and chemo-resistance. Here, we use a constraints-based integrated approach to delineate the interplay between metabolism and epigenetics, hardwired in the genome, to shape temozolomide (TMZ) resistance. Differential metabolism was identified in response to TMZ at varying concentrations in both the resistant neurospheroidal (NSP) and the susceptible (U87MG) glioblastoma cell-lines.

Plausible diagnostic value of urinary isomeric dimethylarginine ratio for diabetic nephropathy.

Altered circulatory asymmetric and symmetric dimethylarginines have been independently reported in patients with end-stage renal failure suggesting their potential role as mediators and early biomarkers of nephropathy. These alterations can also be reflected in urine. Herein, we aimed to evaluate urinary asymmetric to symmetric dimethylarginine ratio (ASR) for early prediction of diabetic nephropathy (DN).

Superfluous glutamine synthetase activity in Chinese Hamster Ovary cells selected under glutamine limitation is growth limiting in glutamine-replete conditions and can be inhibited by serine.

Passaging and expansion of animal cells in lean maintenance medium could result in periods of limitation of some nutrients. Over time, such stresses could possibly result in selection of cells with metabolic changes and contribute to heterogeneity. Here, we investigate whether selection of Chinese Hamster Ovary (CHO) cells under glutamine limitation results in changes in growth under glutamine-replete conditions.

Integrative analysis of rewired central metabolism in temozolomide resistant cells.

An authenticated U87MG clonal glioblastoma cell line was investigated to identify a sub-population of neurospheroidal (NSP) cells within the main epithelial population (U87MG). The NSP cells sorted using Fluorescence Assisted Cell Sorting (FACS) showed varied morphology, 30% lower growth rates, 40% higher IC values for temozolomide drug and could differentiate into the glial cell type (NDx). Metabolite profiling using HR-LCMS identified glucose, glutamine and serine in both populations and tryptophan only in U87MG as growth limiting substrates.

A scalable metabolite supplementation strategy against antibiotic resistant pathogen Chromobacterium violaceum induced by NAD/NADH imbalance.

Background: The leading edge of the global problem of antibiotic resistance necessitates novel therapeutic strategies. This study develops a novel systems biology driven approach for killing antibiotic resistant pathogens using benign metabolites.

Results: Controlled laboratory evolutions established chloramphenicol and streptomycin resistant pathogens of Chromobacterium.

Determination of Triazines and Triazoles in Grapes Using Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization High-Resolution Mass Spectrometry.

A chromatography-free atmospheric pressure matrix-assisted laser desorption/ionization high-resolution mass spectrometry (AP-MALDI HRMS) method is described for the simultaneous and quantitative detection of triazines and triazoles in grapes. The analytes were detected reproducibly with high mass accuracy (mass error within 5 ppm) and further confirmed by collision-induced dissociation fragmentation in tandem MS. The LODs and LOQs for all the analytes were found to be in the nanogram per gram level (15-20 ng/g LOQ).

CHO Cells adapted to inorganic phosphate limitation show higher growth and higher pyruvate carboxylase flux in phosphate replete conditions.

Inorganic phosphate (P ) is an essential ion involved in diverse cellular processes including metabolism. Changes in cellular metabolism upon long term adaptation to P limitation have been reported in E. coli.

Enhanced permeation, leaf retention, and plant protease inhibitor activity with bicontinuous microemulsions.

Bicontinuous microemulsions (BCMEs) have excellent solubulizing properties along with low interfacial tension and aqueous content that can be controlled. In this work, water soluble plant protease inhibitor (PI), well characterized for its activity against insect pests, was incorporated into a BCME system and explored for permeation on hydrophobic leaf surfaces and protease inhibition activity. The bicontinuous nature of the microemulsion containing water:2-propanol:1-butanol (55:35:10 w/w) was characterized using conductivity and self-diffusion coefficient measurements.

Lanthanide phytanates: liquid-crystalline phase behavior, colloidal particle dispersions, and potential as medical imaging agents.

Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy.

Phosphopeptide analysis by directly coupling two-dimensional planar electrochromatography/thin-layer chromatography with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A novel strategy is presented for the fractionation of complex peptide mixtures using two-dimensional planar electrochromatography/thin-layer chromatography (2D PEC/TLC). Phosphopeptides migrate more slowly in the first dimension, based upon their anionic phosphate residues, and certain predominantly acidic phosphopeptides even migrate in the opposite direction, relative to the bulk of the peptides. Phosphopeptides are further distinguished based upon hydrophilicity in the second dimension.

Molecular dynamics simulations of multilayer films of polyelectrolytes and nanoparticles.

We performed molecular dynamics simulations of multilayer assemblies of flexible polyelectrolytes and nanoparticles. The film was constructed by sequential adsorption of oppositely charged polymers and nanoparticles in layer-by-layer fashion from dilute solutions. We have studied multilayer films assembled from oppositely charged polyelectrolytes, oppositely charged nanoparticles, and mixed films containing both nanoparticles and polyelectrolytes.

Molecular dynamics simulations of polyelectrolyte multilayering on a charged particle.

Molecular dynamics simulations of polyelectrolyte multilayering on a charged spherical particle revealed that the sequential adsorption of oppositely charged flexible polyelectrolytes proceeds with surface charge reversal and highlighted electrostatic interactions as the major driving force of layer deposition. Far from being completely immobilized, multilayers feature a constant surge of chain intermixing during the deposition process, consistent with experimental observations of extensive interlayer mixing in these films. The formation of multilayers as well as the extent of layer intermixing depends on the degree of polymerization of the polyelectrolyte chains and the fraction of charge on its backbone.

Molecular dynamics simulations of electrostatic layer-by-layer self-assembly.

Electrostatic assembly of multilayered thin films through sequential adsorption of polyions in layer-by-layer fashion utilizes the strong electrostatic attraction between oppositely charged molecules. We perform molecular dynamics simulations of multilayers of flexible polyelectrolytes around a charged spherical particle. Our simulations establish that the charge reversal after each deposition step is a crucial factor for the steady layer growth.

Ultrathin layered myoglobin-polyion films functional and stable at acidic pH values.

Cross-linking of myoglobin (Mb) promoted by 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide within films of polystyrene sulfonate after layer-by-layer self-assembly provided remarkable stabilization. Cross-linking greatly improved adhesion of the films to fused silica slides and allowed extensive optical studies over a wide pH range. Circular dichroism and visible absorbance spectra showed that Mb retained its native conformation when films were placed in solutions of pH as low as 2 and up to pH 11.