ABSTRACT
BACKGROUND: Volatile organic compound (VOC) analysis provides an elegant approach for colorectal cancer screening. An organic compound with a high vapor pressure or volatility can be detected in the headspace of cancer cells or blood samples. Therefore, analyzing VOCs in the blood of rats inoculated with colorectal cancer tissue and in SW480 medium from cultured colorectal cancer cells may provide accurate results. METHODS: After collecting venous blood from rats inoculated with cancer cells at different times, the cancer tissue was removed from the inoculated rats, and the medium was harvested from the cancer cells and cultured in the presence or absence of a chemotherapy drug of intestinal epithelial cells. We used solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) to analyze the headspace of the blood and media to evaluate the VOC profiles. Statistical analysis was conducted using principal component analysis (PCA) and orthogonal partial least-squares analysis (OP-LSDA). RESULTS: The in vivo and in vitro analyses of the colorectal cancer samples revealed a variety of compounds, such as cyclohexanone, 1-hexanol, 2-ethyl-, butylated hydroxytoluene, cyclotrisiloxane, hexamethyl-, pentanoic acid, 2,2,4-trimethyl-3-hydroxy-isobutyl ester and acetone. Butylated hydroxytoluene is unique with regard to its presence during tumor growth and resection; it is also present during tumor cell growth and necrosis. Acetone showed unique trends in the in vivo experimental group. CONCLUSIONS: By analyzing VOC fingerprints related to colorectal cancer (CRC), we found that butylated hydroxytoluene and acetone have unique signatures that may provide the basis for clinical diagnosis and disease assessment.
ABSTRACT
Amyotrophic lateral sclerosis (ALS) is an incurable neurological degenerative disease. It can cause irreversible neurological damage to motor neurons; typical symptoms include muscle weakness and atrophy, bulbar paralysis and pyramidal tract signs. The ALS-mimicking disease cervical spondylotic myelopathy (CSM) presents similar symptoms, but analysis of breath volatile organic compounds (VOCs) can potentially be used to distinguish ALS from CSM. In this study, breath samples were collected from 28 ALS and 13 CSM patients. Subsequently, gas chromatography/mass spectrometry (GCMS) was used to analyze breath VOCs. Principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLSDA) were the statistical methods used to process the final data. We identified 4 compounds with significantly decreased levels in ALS patients compared with CSM controls: (1) carbamic acid, monoammonium salt; (2) 1-alanine ethylamide, (S)-; (3) guanidine, N,N-dimethyl-; and (4) phosphonic acid, (p-hydroxyphenyl)-. Currently, the metabolic origin of the VOCs remains unclear; however, several pathways might explain the decreasing trends observed. The results of this study demonstrate that there are specific VOC profiles associated with ALS and CSM patients that can be used to differentiate between the two. In addition, these metabolites could contribute to a better understanding of the underlying pathophysiological mechanisms of ALS.
