A fast, fully validated GC-MS method using a simplified pretreatment for the quantification of short and branched chain fatty acids in human stool.

The study of short (SCFAs) and branched chain fatty acids (BCFAs) in human stool related to gastrointestinal diseases, gut microbiota, metabolism, and diet has dramatically increased. As a result, a fast, reliable method with minimal pretreatment is needed for quantification of these metabolites (acetic, propionic, isobutyric, butyric, isovaleric, valeric, and caproic acid) in stool. Therefore, a GC-MS method meeting this criterion was developed.

A dilute-and-shoot flow-injection tandem mass spectrometry method for quantification of phenobarbital in urine.

Rationale: Liquid chromatography/tandem mass spectrometry (LC/MS/MS) is the gold standard of urine drug testing. However, current LC-based methods are time consuming, limiting the throughput of MS-based testing and increasing the cost. This is particularly problematic for quantification of drugs such as phenobarbital, which is often analyzed in a separate run because they must be negatively ionized.

A Simple and Rapid LC-MS/MS Method for the Determination of BMCL26 a Novel Anti-Parasitic Agent in Rat Plasma.

BMCL26 is a potential drug derived from nimesulide, which has exhibited the substantial anti-parasitic activity in various cell lines. To conduct various pharmacological and toxicological properties of this drug, we developed and validated a rapid LC-MS/MS method for its quantification in accordance with the FDA guidelines. Protein precipitation with 0.

A rapid LC-MS/MS method for quantification of CSUOH0901, a novel antitumor agent, in rat plasma.

CSUOH0901, a novel anticancer derivative of nimesulide, exhibits very promising anticancer activities in various cancer cell lines. In order to support further pharmacological and toxicological studies of this promising anticancer drug candidate, an LC-MS/MS method was developed and validated in accordance with the US Food and Drug Administration guidelines. The drug molecules were extracted from plasma samples by protein precipitation and then analyzed with LC-ESI-MS/MS.

Development and validation of a rapid LC-MS/MS method for the determination of JCC76, a novel antitumor agent for breast cancer, in rat plasma and its application to a pharmacokinetics study.

JCC76 is a novel nimesulide analog that selectively inhibits the human epidermal growth factor receptor 2 (HER2) overexpressing breast cancer cell proliferation and tumor progression. To support further pharmacological and toxicological studies of JCC76, a novel and rapid method using liquid chromatography and electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) has been developed and validated for the quantification of the compound in rat plasma. A C₁₈ column was used for chromatographic separation, and the mobile phase was aqueous ammonium formate (pH 3.

An LC-ESI-MS method for the quantitative analysis of bile acids composition in fecal materials.

In this work, a liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) method was developed and validated for quantification of bile acids in fecal materials. Co-eluting matrix impurities in fecal materials have been shown to greatly suppress the ionization of analytes in mass spectrometry, which is known as the matrix effect. To correct large quantitative errors caused by the matrix effect, we developed a scheme that combined the standard addition method with internal standard (SA-IS).

Sumoylation of vimentin354 is associated with PIAS3 inhibition of glioma cell migration.

The invasive phenotype of glioblastoma multiforme (GBM) is a hallmark of malignant process, yet the molecular mechanisms that dictate this locally invasive behavior remain poorly understood. Over-expression of PIAS3 effectively changes cell shape and inhibits GBM cell migration. We focused on the molecular target(s) of PIAS3 stimulated sumoylation, which play an important role in the inhibition of GBM cell motility.

Genotyping single-nucleotide polymorphisms by matrix-assisted laser desorption/ionization time-of-flight-based mini-sequencing.

Currently, there is a critical need to develop high-throughput, low-cost, and accurate methods for genotyping of single-nucleotide polymorphisms (SNPs). The matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometrically based technique represents a new promising approach to SNP analysis. We have developed a new MALDI-TOF-based mini-sequencing assay, termed "VSET," for genotyping of SNPs.

A matrix of 3,4-diaminobenzophenone for the analysis of oligonucleotides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A new matrix of 3,4-diaminobenzophenone (DABP) was demonstrated to be advantageous in the analysis of oligonucleotides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. With DABP as a matrix, intact oligonucleotide ions can be readily produced with lower laser powers, resulting in better detection limits, less fragmentation and fewer alkali metal ion adducts compared with the results obtained with conventional matrices. Importantly, minimal fragmentation and fewer alkali metal ion adducts were seen even at low concentrations of oligonucleotides.

Detection of mononucleotide repeat sequence alterations in a large background of normal DNA for screening high-frequency microsatellite instability cancers.

Purpose: Mutations in mononucleotide repeat sequence (MRS) are good indicators of high-frequency microsatellite instability (MSI-H) cancers, but it has been a challenge to detect such mutations in a large background of wild-type DNA; as in this setting, PCR errors often generate false positive mutant alleles. In this study, we developed a general strategy, referred to as probe clamping primer extension-PCR (PCPE-PCR), to detect MRS alterations in a large background of wild-type DNA.

Experimental Design: In PCPE-PCR, genomic DNA is first subjected to PCPE, in which mutant single-strand DNA molecules are preferentially produced.

Using oxidized carbon nanotubes as matrix for analysis of small molecules by MALDI-TOF MS.

Oxidized carbon nanotubes are tested as a matrix for analysis of small molecules by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Compared with nonoxidized carbon nanotubes, oxidized carbon nanotubes facilitate sample preparation because of their higher solubility in water. The matrix layer of oxidized carbon nanotubes is much more homogeneous and compact than that of nonoxidized carbon nanotubes.

Carbon nanotubes as adsorbent of solid-phase extraction and matrix for laser desorption/ionization mass spectrometry.

A method with carbon nanotubes functioning both as the adsorbent of solid-phase extraction (SPE) and the matrix for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) to analyze small molecules in solution has been developed. In this method, 10 microL suspensions of carbon nanotubes in 50% (vol/vol) methanol were added to the sample solution to extract analytes onto surface of carbon nanotubes because of their dramatic hydrophobicity. Carbon nanotubes in solution are deposited onto the bottom of tube with centrifugation.

Determination of basic pharmaceuticals in human serum by hydrophilic interaction capillary electrochromatography.

Hydrophilic interaction capillary electrochromatography (HI-CEC) for the determination of basic pharmaceuticals spiked in human serum is described. The organic modifier content, ionic strength, and pH value of the mobile phase as well as the applied voltage are optimized for separation and elution of these drug analytes. Excellent separation was achieved for drugs using a mobile phase composition of 80% v/v acetonitrile in 100 mM triethylamine phosphate (TEAP) buffer at pH 2.

Tazobactam inactivation of SHV-1 and the inhibitor-resistant Ser130 -->Gly SHV-1 beta-lactamase: insights into the mechanism of inhibition.

The increasing number of bacteria resistant to combinations of beta-lactam and beta-lactamase inhibitors is creating great difficulties in the treatment of serious hospital-acquired infections. Understanding the mechanisms and structural basis for the inactivation of these inhibitor-resistant beta-lactamases provides a rationale for the design of novel compounds. In the present work, SHV-1 and the Ser(130) --> Gly inhibitor-resistant variant of SHV-1 beta-lactamase were inactivated with tazobactam, a potent class A beta-lactamase inhibitor.

Carbon nanotubes as assisted matrix for laser desorption/ionization time-of-flight mass spectrometry.

Analysis of low molecular weight compounds with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) has been developed by using carbon nanotubes obtained from coal by arc discharge as the matrix. The carbon nanotube matrix functions as substrate to trap analytes of peptides, organic compounds, and beta-cyclodextrin deposited on its surface. It has been found that carbon nanotubes can transfer energy to the analyte under laser irradiation, which makes analytes well desorbed/ionized, and the interference of intrinsic matrix ions can be eliminated.

Immobilized metal-ion chelating capillary microreactor for peptide mapping analysis of proteins by matrix assisted laser desorption/ ionization-time of flight-mass spectrometry.

Peptide mass mapping analysis, utilizing a regenerable enzyme microreactor with metal-ion chelated adsorption of enzyme, combined with matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) was developed. Different procedures from the conventional approaches were adopted to immobilize the chelator onto the silica supports, that is, the metal chelating agent of iminodiacetic acid (IDA) was reacted with glycidoxypropyltrimethoxysilane (GLYMO) before its immobilization onto the inner wall of the fused-silica capillary pretreated with NH(4)HF(2). The metal ion of copper and subsequently enzyme was specifically adsorbed onto the surface to form the immobilized enzyme capillary microreactor, which was combined with MALDI-TOF-MS to apply for the mass mapping analysis of nL amounts of protein samples.

Matrix-assisted laser desorption/ionization time-of-flight analysis of low-concentration oligonucleotides and mini-sequencing products.

A new sample preparation procedure has been developed to improve the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis of low-concentration oligonucleotides. In this method, a few microL of the oligonucleotide solutions are first dispensed and allow drying and shrinking to a small spot on an anchoring target. Thereafter, a small volume (0.

Capillary electrochromatographic separation of enantiomers on chemically bonded type of cellulose derivative chiral stationary phases with a positively charged spacer.

Positively charged chiral stationary phases (CSPs) were prepared for capillary electrochromatography (CEC) separation of enantiomers by chemically immobilizing cellulose derivatives onto diethylenetriaminopropylated silica (DEAPS) with tolylene-2,4-diisocyanate (TDI) as a spacer reagent. Anodic electroosmotic mobility was observed in both nonaqueous and aqueous mobile phases due to the positively charged amines on the surface of the prepared CSPs. For comparison, the traditionally used 3-aminopropyl silica (APS) was also adopted as the base material instead of DEAPS to prepare CSP.

Unilamellar liposomes covalently coupled on silica gel for liquid chromatography.

Silica gel was used as a support for the covalent coupling of liposomes, which could overcome drawbacks of soft gel beads in column efficiency and separation speed. The influences of the concentration of added dimethylaminopyridine and reaction time on the chloroformate activation reaction of silica gel were investigated. Temperature and pH for covalent coupling of liposomes on the activated silica gel were also optimized.

A method for the analysis of low-mass molecules by MALDI-TOF mass spectrometry.

We report a novel method termed matrix suppressed laser desorption/ionization to improve the analysis of low-mass molecules by MALDI-TOF mass spectrometry. In this method, the surfactant of cetrimonium bromide (CTAB) is added to the conventional matrix of alpha-cyano-4-hydroxycinnamic acid solution to prepare the MALDI samples. During the MALDI process, the presence of CTAB could substantially or even completely suppress the matrix-related ion background.

Detection of tumor mutations in the presence of excess amounts of normal DNA.

Mutations are important markers in the early detection of cancer. Clinical specimens such as bodily fluid samples often contain a small percentage of mutated cells in a large background of normal cells. Thus, assays to detect mutations leading to cancer need to be highly sensitive and specific.