1.
HPLC with spectrophotometric or mass spectrometric detection for quantifying very-long chain fatty acids in human plasma and its association with cardiac risk factors.
Shrestha, R, Chen, Z, Gao, Z, Chen, Y, Okada, E, Ukawa, S, Nakagawa, T, Nakamura, K, Tamakoshi, A, Chiba, H, et al
Annals of clinical biochemistry. 2021;(5):400-410
Abstract
BACKGROUND We developed and compared two liquid chromatography methods, one with UV/Visible spectrophotometric detection (HPLC) and the other with mass spectrometric detection (LC-MS), for quantifying very-long chain fatty acids (VLCFA) in human plasma. Association of VLCFA with various cardiovascular risk factors were evaluated. METHOD Fasting blood samples were collected from 541 human volunteers (242 men and 299 women; mean age ±SD, 58.9 ± 12.4 years), including 429 and 112 individuals with and without hypertriglyceridemia, respectively. Esterified VLCFA were saponified and derivatized with 2-nitrophenylhydrazine. Separation of VLCFA species was achieved with C4 Mightysil column (HPLC) and Ascentis Express Phenyl-Hexyl column (LC-MS) followed by spectrophotometric and selected-reaction monitoring mode of mass spectrometric detection, respectively. RESULTS The HPLC assay of VLCFA was precise with intra-assay imprecision of 2.5% to 6.9% and inter-assay imprecision of 3.2% to 9.5%. Moreover, there was an excellent correlation (r > 0.96) between HPLC and LC-MS methods. The 95 percentile reference intervals (RI; upper limit) of VLCFA were determined to be 41.3 µmol/L in healthy volunteers. Plasma VLCFA were significantly correlated with triglycerides (Spearman's ρ = 0.306, P < 0.001) and total cholesterol (Spearman's ρ = 0.251, P < 0.001). All species of VLCFA were significantly elevated in hypertriglyceridaemic individuals compared with control. CONCLUSION We established LC-based assays of VLCFA with either spectrophotometry or mass spectrometry as a detection system. Hypertriglyceridaemia is significantly associated with elevated concentration of each species of VLCFA.
2.
Statins Reduce Epicardial Adipose Tissue Attenuation Independent of Lipid Lowering: A Potential Pleiotropic Effect.
Raggi, P, Gadiyaram, V, Zhang, C, Chen, Z, Lopaschuk, G, Stillman, AE
Journal of the American Heart Association. 2019;(12):e013104
Abstract
Background High epicardial adipose tissue (EAT) attenuation (Hounsfield units [ HUs] ) on computed tomography is considered a marker of inflammation and is associated with an increased risk of cardiovascular events. Statins reduce the volume of EAT , but it is unknown whether they affect EAT HUs . Methods and Results We reviewed the chest computed tomographic scans of 420 postmenopausal women randomized to either 80 mg of atorvastatin or 40 mg of pravastatin daily and rescanned after 1 year to measure change in coronary artery calcium score. EAT HUs were measured near the proximal right coronary artery and remote from any area of coronary artery calcium. Computed tomographic images were also queried for subcutaneous adipose tissue (SubQ) attenuation ( HUs ) change over time. The mean patients' age was 65±6 years. The baseline EAT HU value was higher than the SubQ HU value (-89.4±24.0 HU versus -123.3±30.4 HU ; P<0.001). The EAT HU value decreased significantly in the entire cohort (-5.4±29.7 HU [-6% change]; P<0.001), but equally in the patients given atorvastatin and pravastatin (-6.35+31 HU and -4.55+28 HU ; P=0.55). EAT HU change was not associated with change in total cholesterol, low-density lipoprotein cholesterol, coronary artery calcium, and EAT volume (all P=not significant). Change in high-density lipoprotein cholesterol was marginally associated with EAT HU change ( P=0.07). Statin treatment did not induce a change in SubQ HUs . Conclusions Statins induced a decrease in EAT HUs over time, independent of intensity of low-density lipoprotein cholesterol lowering. The positive effect on EAT and the neutral effect on SubQ suggest that statins induced a decrease in metabolic activity in EAT by reduction in cellularity, vascularity, or inflammation. The clinical significance of the observed change in EAT HUs remains to be demonstrated.