Publications by authors named "Ngee S Chong"

Article Synopsis
  • This study explores the effectiveness of a two-dimensional gas chromatography-flame ionization detection (GC×GC-FID) method for identifying 12 psychoactive drugs in urine, including popular substances like cocaine and methamphetamine.
  • The method achieved clear separation of these drugs within 8 minutes using a specific column setup, demonstrating better results than traditional configurations.
  • Validation showed high accuracy and precision for drug detection, with very low detection limits and effective recovery rates, proving its usefulness for quick forensic drug testing.
View Article and Find Full Text PDF

Based on previous studies showing abnormalities in the intestinal pathophysiology characterized by disruption in the gut barrier functions, and alteration in the intestinal microbial load and composition, we set out in the study to examine the expression of genes that might be involved in mediating these changes in Townes sickle cell disease (SCD) mice at 6 months old compared to non-SCD control mice. Using qPCR on total RNA isolated from the intestine, we found downregulation of the TJ genes JAM-A, Occludin, and ZO-1 in both the small intestine and colon. E-Cadherin and MUC2 were also downregulated.

View Article and Find Full Text PDF

Polycyclic aromatic hydrocarbons (PAHs) are a class of compounds containing multiple aromatic rings formed during incomplete combustion. Since many of them are known mutagens and carcinogens, PAHs found in the particulate matter (PM) from the wildfire smoke may pose significant health risks to the wildland firefighters. It is pivotal to determine the levels of PAHs in the PM to evaluate the health effects of their inhalation exposure.

View Article and Find Full Text PDF

We showed in the present study that, not unlike in adult patients with sickle cell disease (SCD), Townes mice exhibit increases in serum intestinal fatty acid binding proteins and lipopolysaccharides (LPS), together with a breach in the intestinal barrier. These abnormalities increased rapidly after the induction of vaso-occlusive crisis (VOC). We also confirmed higher intestinal microbial density in SCD.

View Article and Find Full Text PDF

The thermal desorption/pyrolysis-direct analysis in real time-mass spectrometry (TD/Py-DART-MS) method was developed for the analysis of fibers in this study. The fiber samples were pyrolyzed with a temperature gradient and the pyrolysis products were determined by DART-MS. The pyrogram from the TD/Py-DART-MS fiber analysis was found to be associated with the physical properties such as the melting points.

View Article and Find Full Text PDF

In order to assess the human exposure risks from the release of contaminants from water pipes made of polyvinyl chloride (PVC), experiments were carried out by subjecting the PVC pipe material to burning and leaching conditions followed by analysis of the emission and leachate samples. The emissions of burning pipes were analyzed by both infrared spectrometry and gas chromatography-mass spectrometry (GC-MS). The emission test results indicate the presence of chlorinated components including chlorine dioxide, methyl chloride, methylene chloride, allyl chloride, vinyl chloride, ethyl chloride, 1-chlorobutane, tetrachloroethylene, chlorobenzene, and hydrogen chloride were detected in the emissions of burning PVC pipes.

View Article and Find Full Text PDF

The use of electronic cigarettes (E-cig) is popular because of the perception that they are less addictive and safer compared to the traditional cigarettes. Nevertheless, there are still harmful effects associated with chemicals emitted from E-cig. Identifying the sources of the emitted compounds can be challenging because of the differences in the design of E-cig devices and the variability in the composition of E-cig liquids used in these devices.

View Article and Find Full Text PDF

Bidi, an indigenous form of cigarette in South Asian countries, is popular because of its low cost and multi-flavored variants. Although recent studies have shown that bidi smokers suffer from various adverse health effects including cancer, research on bidi smoke composition and exposure levels is still very limited. In this research, the vapor and particulate phases of bidi were characterized using gas chromatography coupled with mass spectrometry (GC-MS) and Fourier-transform infrared spectrometry (FTIR).

View Article and Find Full Text PDF

Not unlike many cancer types, acute myeloid leukemia (AML) exhibits many metabolic changes and reprogramming, causing changes in lipid metabolism. Some of the distinct molecular abnormalities associated with AML also modify the metabolic changes. Both processes result in changes in the production of endogenous volatile organic compounds (VOCs).

View Article and Find Full Text PDF