Simultaneous quantitative LC-MS/MS analysis of 13 apolipoproteins and lipoprotein (a) in human plasma.

Numerous studies have revealed a close correlation between the levels of apolipoproteins (Apos) (including lipoprotein(a) [Lp(a)]) and an increased risk of cardiovascular disease in recent decades. However, clinically, lipid profiling remains limited to the conventional plasma levels of cholesterol, triglyceride, ApoA1, and ApoB, which brings the necessity to quantify more apolipoproteins in human plasma. In this study, we simultaneously quantified 13 apolipoproteins and Lp(a) in 5 µL of human plasma using the LC-MS/MS platform. A method was developed for the precise detection of Lp(a), ApoA1, A2, A5, B, C1, C2, C3, D, E, H, L1, M, and J. Suitable peptides were selected and optimized to achieve clear separation of each peak. Method validation consisting of linearity, sensitivity, accuracy and precision, recovery, and matrix effects was evaluated. The intra-day CV ranged from 0.58% to 14.2% and the inter-day CV ranged from 0.51% to 13.3%. The recovery rates ranged from 89.8% to 113.7%, while matrix effects ranged from 85.4% to 113.9% for all apolipoproteins and Lp(a). Stability tests demonstrated that these apolipoproteins remained stable for 3 days at 4 °C and 7 days at -20 °C. This validated method was successfully applied to human plasma samples obtained from 45 volunteers. The quantitative results of ApoA1, ApoB, and Lp(a) exhibited a close correlation with the results from the immunity transmission turbidity assay. Collectively, we developed a robust assay that can be used for high-throughput quantification of apolipoproteins and Lp(a) simultaneously for investigating related risk factors in patients with dyslipidemia.

Evaluation of plasma phytosterols in sitosterolemia, their kindreds and hyperlipidemia subjects.

BACKGROUND: Patients suffering from sitosterolemia with ABCG5/8 mutation typically present with early-onset or rapidly progressive atherosclerosis. Their kindreds with partial genetic deficiencies of ABCG5/8 are often considered healthy. However, discerning sitosterolemia from its familial kindreds and hyperlipidemia subjects has remained challenging. METHODS: Here we retrospectively recruited seven families including 8 individuals diagnosed with sitosterolemia subjects, and 14 kindreds carrying single gene mutations. Additionally, 17 individuals with hyperlipidemia and 130 healthy controls served as positive and negative controls, respectively. A total of 6 phytosterols combined with cholesterol absorption indices (including sitosterol, campesterol, stigmasterol, and cholestanol) and cholesterol synthesis markers (desmosterol and 7-dehydrocholesterol), was compared across the aforementioned four groups. RESULTS: As expected, the sitosterolemia subjects with double mutations demonstrated significantly elevated levels of sitosterol and other cholesterol absorption indices. Meanwhile, sitosterolemia kindreds with single gene mutation showed a similar pattern of activated cholesterol-absorption ability to the hyperlipidemia group, but not as high as the double mutation group. Notably, the cholesterol-synthesis enzyme 7-dehydrocholesterol reductase displayed an increase in the hyperlipidemia group but a decrease in the sitosterolemia kindred group, suggesting a potential discriminative role of 7-dehydrocholesterol in distinguishing between these two groups. The combination of phytosterols was more valuable than clinical lipid index for sitosterolemia diagnosis. CONCLUSION: Our study revealed mild disruptions of cholesterol absorption capacities in sitosterolemia kindreds with single mutations. Furthermore, the combination of 6 phytosterols proved effective in distinguishing between sitosterolemia, its single mutation carriers, and hyperlipidemia patients.

A facile sol-gel synthesis of low-fusing titanium opaque porcelain using borate-silicate system and its bioactivity.

The titanium opaque porcelain was synthesized through sol-gel using borate-silicate system. The porcelain was characterized by DSC-TG, X-ray diffraction, N2 adsorption-desorption isotherms and scanning electron microscope tests. The results of DSC showed that the nitrates could be decomposed completely when the bioglass xerogel precursor was heat-treated at 760 ℃. The XRD results showed that the Na2Ca3Si6O16 was the major phase of the opaque porcelain. The synthesized opaque porcelain powders had an average particle size of about 5-25 µm with nanopores of around 50-70 nm on the surface. The BET average surface area of the porcelain was 12.67 m2/g, while the average pore diameters for adsorption and desorption were 9.73 and 10.16 nm, respectively. The flexure strength significantly increased from 47.4 MPa to 116.2 MPa with the sintering temperature increasing from 575 ℃ to 600 ℃. The XRD, FTIR and EDS results proved that hydroxyapatite had formed on the porcelain surface after incubation in simulated body fluid.