Ngee Sing Chong | Middle Tennessee State University (original) (raw)

Papers by Ngee Sing Chong

The Lancet Regional Health - Americas

Annals of Hematology

Based on previous studies showing abnormalities in the intestinal pathophysiology characterized b... more 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. In contrast, gene encoding claudin-2 that mediates increase permeability to water and ions was upregulated in the small intestine. Claudin-2 upregulation is usually also associated with ongoing inflammation. Intestinal epithelium also includes Paneth cells that produce antimicrobial peptides (AMPs) that regulate intestinal microbial community. We also found that the expression of the genes encoding the AMPs defensin-α4 was reduced in the small intestine and colon and defensin-α1 in the colon in the SCD mice. Our findings are novel and provide direction for further studies into the characteristics and mechanisms of the intestinal pathophysiologic changes observed in SCD.

Forensic Chemistry, Feb 1, 2023

Journal of Food Composition and Analysis

Academic Journal of Chemistry, 2021

Due to the high cost of feedstock and catalyst in biodiesel production, the viability of the biod... more Due to the high cost of feedstock and catalyst in biodiesel production, the viability of the biodiesel industry has been dependent on government subsidies or tax incentives. In order to reduce the cost of production, food wastes including eggshells and oyster shells have been used to prepare calcium oxide (CaO) catalysts for the transesterification reaction of biodiesel synthesis. The shells were calcined at 1000 °C for 4 hours to obtain CaO powders which were investigated as catalysts for the transesterification of waste cooking oil. The catalysts were characterized by Fourier Transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and X-ray fluorescence (XRF) spectroscopy. Reaction parameters such as methanol-to-oil molar ratio, CaO catalyst concentration, and reaction time were evaluated and optimized for the percentage conversion of cooking oil to biodiesel esters. The oyster-based CaO showed better catalytic activity when compar...

Chlorine dioxide has been used to replace traditional water treatments, deactivate Anthracis baci... more Chlorine dioxide has been used to replace traditional water treatments, deactivate Anthracis bacillus, and remediate various molds and bacteria. This study aims to analyze the products of the gas phase reaction between chlorine dioxide and malodorous compounds produced during putrefaction. The study focuses on the reactions between chlorine dioxide and three specific chemicals: cadaverine (amine), 2-hexanone (ketone), and cyclohexyl mercaptan (thiol). The analysis of the gas phase reaction products is carried out using a Varian 7000 Fourier Transform infrared spectrometer (FTIR) with a 2.4 m gas cell. The measurement of most reaction by-products requires spectral resolution of 0.5 cm-1 because the spectra of most gas phase standards are available for spectral resolutions of 0.5 cm-1 or 0.25 cm-1 only.The reaction between cadaverine and chlorine dioxide resulted in the rapid formation of ammonia gas. The GC-MS analysis of the reaction between chlorine dioxide and cadaverine showed th...

British Journal of Haematology, 2021

We showed in the present study that, not unlike in adult patients with sickle cell disease (SCD),... more 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. These findings support the concept that SCD and/or its complications, and not hospitalisation or medications, are responsible for the intestinal pathophysiological changes. The present results provide the basis for use of Townes mice to further elucidate the mechanistic relationship between intestinal pathophysiology and VOC.

Analytical Chemistry, 2019

The thermal desorption/pyrolysis-direct analysis in real time-mass spectrometry (TD/Py-DART-MS) m... more 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. At the same time, the TD/Py-DART-MS allows the analyst to obtain the chemical information such as polymeric backbone structures and dyes on the fiber. The pyrolysis profiles of common polymeric fibers in textile materials such as cotton, cellulose triacetate (CT), poly(caprolactam) (nylon 6), poly(hexamethylene adipamide) (nylon 6/6), poly(acrylonitrile) (PAN), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(propylene) (PP), and polytrimethylene terephthalate (PTT) and their respective characteristic mass spectra were reported in this study. The fibers from 40 commercial textile samples were analyzed by TD/Py-DART-MS method and the statistical methods including principal component analysis (PCA) and Pearson product moment correlation (PPMC) were applied to classify and associate the fibers based on their mass spectral data. The strong correlation between the reference fiber mass spectral profiles and tested fiber mass spectral profiles was observed by using PPMC method and the identification accuracy was 97.5%. When combined the mass spectral and pyrogram data, the types of fibers including the blended fibers were identified effectively. The TD/Py-DART-MS method also demonstrated the promising capability for the identification of dyes on fibers. Overall, the TD/Py-DART-MS method requires small sample size and minimal sample preparation but offers reproducible and multi-dimensional information for the fiber evidence rapidly (i.e., ~6.7 min). Since the proposed method is simple to perform and the data are easy to interpret, this approach may significantly contribute to the fiber identification and comparison procedures in forensic settings with high sample throughput potential.

ACS Omega, 2019

The use of electronic cigarettes (E-cig) is popular because of the perception that they are less ... more 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. In this study, the emission profiles from impurity-free E-liquids containing only propylene glycol and glycerol in various percentage ratios along with two commercially available Eliquids were evaluated using gas chromatography−mass spectrometry (GC−MS). This study approach allows the elucidation of the transformation pathways of the major emitted compounds without the confounding effects of existing impurities or flavor ingredients added to E-liquids. Analysis of the vapor phases of E-cig emissions detected toxicants such as acetaldehyde, acrolein, benzaldehyde, as well as benzene, toluene, ethylbenzene, and xylene (BTEX) compounds. The amount of glycerol in the E-liquids has a major effect on the concentration of these hazardous compounds emitted because the concentration of these chemicals increased with increasing glycerol percentage in the E-liquid. Acetaldehyde and acrolein increased by 175-fold and 28-fold, respectively, when the glycerol composition was increased from 0 to 80%. Benzaldehyde, naphthalene, diphenyl ether, and glycerol along with menthol and nicotine that were present in the commercial E-liquids were also detected in the aerosol condensates. The cascade impactor data on the distribution of the nicotine and menthol in different size fractions from >2.5 to <2.5 μm allow the estimates of the extent of toxicant deposition in different parts of the pulmonary system including the oropharynx region, the trachea as well as inside the alveoli and bronchioles. In summary, users of E-cig are exposed to harmful chemicals even if the E-liquids contain only propylene glycol and glycerol without flavorings, nicotine, or impurities. Furthermore, this study shows that E-liquids containing higher percentages of glycerol will produce higher levels of toxicants compared to E-liquids with similar percentages of propylene glycol. This finding has important implications to E-cigarette vendors and manufacturers, consumers, and regulatory agencies.

BMC Chemistry, 2019

Bidi, an indigenous form of cigarette in South Asian countries, is popular because of its low cos... more 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). The amounts of nicotine, cotinine, indole, substituted phenols, substituted pyridines, and phytol found in different size fractions of the particulate matter collected using a cascade impactor were reported. Due to the low combustibility of the tendu leaf in bidi, a six-second puff interval was used to sample the smoke constituents for analysis. Significant levels of carbon monoxide, hydrogen cyanide, and hydrocarbons like ethylene, methane and 1, 3-butadiene were detected in the mainstream bidi smoke. In addition, 3-methylpyridine, cotinine, α-amyrin, and β-amyrin were also present at high levels in bidi smoke. Despite having less tobacco compared to conventional cigarette, bidi smokers are potentially exposed to significantly higher concentrations of nicotine due to the greater puffing frequency. The non-porous nature and higher moisture content of tendu leaf in bidis compared to cigarette wrapping paper led to higher levels of carbon monoxide and tar in bidi smoke compared to regular cigarette smoke. Results of this study indicate the presence of harmful and carcinogenic chemicals in the mainstream bidi smoke that could be harmful to human health.

Frontiers in Chemistry, 2018

Journal of breath research, Jan 4, 2018

Not unlike many cancer types, acute myeloid leukemia (AML) exhibits many metabolic changes and re... more 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). The increasing availability of highly sensitive methods for detecting trace chemicals provides the opportunity to investigate the role of patient-specific VOC finger-prints as biomarkers for detecting early relapse or minimal residual disease in AML. Since VOC production is reliant on metabolic activities, when combined with currently available methods, VOC analysis may identify within a group of patients with flow cytometric or molecular evidence of residual disease those most at risk for disease relapse.

Tennessee S Business, 2008