Cholesteryl palmitate

Cholesteryl palmitate crystals in bronchoalveolar lavage fluid smears as a possible prognostic biomarker for chronic interstitial pneumonia: A preliminary study

Background: We observed cholesterol-like crystals (Crystal X) in the bronchoalveolar lavage fluid (BALF) smears of patients with diffuse pulmonary disease. We analyzed the clinical data of patients with and without crystals, and elucidated the structure of Crystal X and its concentration in the BALF. Methods: Two hundred eighty-nine patients with diffuse pulmonary disease who underwent bronchoalveolar lavage (BAL) were analyzed. The relationships between the presence and number of Crystal X in BALF smears and clinical parameters were investigated. Furthermore, structure determination and quantitative analyses of the crystals were performed. Results: Seventy-five (26.0%) patients had Crystal X in their BALF. The crystals were frequently observed in patients with chronic interstitial pneumonia (CIP, 60/160=35.3%). Patients with Crystal X exhibited significantly higher serum Kerbs von Lungren 6 antigen and surfactant protein-D levels (P<0.01) and lower percentage vital capacity (P<0.05) than patients without Crystal X. The number of crystals was significantly correlated with these parameters. The presence of crystals was also associated with a lower survival rate at 1 year after the BAL. The interfacial angles of the crystals were 126㊣2～ and 144㊣2～, different from those of cholesterol monohydrate crystals. Infrared absorption spectrometry showed Crystal X was cholesteryl palmitate. Its concentration was significantly higher in BALF with crystals than in BALF without crystals (P<0.01). Conclusions: Crystal X in the BALF of patients with diffuse pulmonary disease was identified as cholesteryl palmitate, which may be a useful prognostic biomarker for CIP.

Cholesteryl palmitate as a predictor of fetal lung maturity

Cholesteryl palmitate was measured by thin-layer chromatography in 98 amniotic fluid samples obtained from pregnancies ranging from 15 to 40 weeks. Pregnancies complicated by diabetes mellitus or Rh sensitization were excluded. Cholesteryl palmitate concentration increased with gestational age from values less than 5 micrograms/ml at 15 weeks to maximum values of 384 micrograms/ml at term. Seventy-three patients were delivered of their infants within 24 hours of sampling. The mean concentration of cholesteryl palmitate for 55 infants without respiratory distress syndrome was 123.70 +/- 12.21 micrograms/ml (SD). For neonates that developed respiratory distress syndrome (n = 18), the mean concentration was 22.66 +/- 6.16 micrograms/ml (SD). This difference is significant (p less than 0.001). For all patients delivered, respiratory distress syndrome was not seen when the cholesteryl palmitate concentration was greater than 41 micrograms/ml (mean + 3 SD). All infants with a concentration below 38 micrograms/ml developed respiratory distress syndrome. We conclude that measurement of cholesteryl palmitate concentration in amniotic fluid might be another reliable method of assessing fetal lung maturity and may often improve specificity when compared with other tests of fetal lung maturity.

Functionalized magnetic nanomaterials for electrochemical biosensing of cholesterol and cholesteryl palmitate

Synthesis and functionalization of magnetite nanoparticles (Fe₃O₄) was achieved with the view to covalently bind both cholesterol oxidase and cholesterol esterase biorecognition agents for the development of free and total cholesterol biosensors. Prior to enzyme attachment, Fe₃O₄ was functionalized with 3-aminopropyltriethoxysilane (APTES) and polyamidoamine (PAMAM) dendrimer. Characterization of the material was performed by FT-IR and UV spectroscopy, SEM/EDX surface analysis and electrochemical investigations. The response to cholesterol and its palmitate ester was examined using cyclic voltammetry. Optimum analytical performance for the free cholesterol biosensor was obtained using APTES-functionalized magnetite with a sensitivity of 101.9 米A mM^-1 cm^-2, linear range 0.1-1 mM and LOD of 80 米M when operated at 37 ～C. In the case of the total cholesterol biosensor, the best analytical performance was obtained using PAMAM dendrimer-modified magnetite with sensitivity of 73.88 米A mM^-1 cm^-2 and linear range 0.1-1.5 mM, with LOD of 90 米M. A stability study indicated that the free cholesterol biosensors retained average activity of 98% after 25 days while the total cholesterol biosensors retained 85% activity upon storage over the same period. Graphical abstract Schematic representation of cholesterol esterase and oxidase loaded magnetic nanoparticles (Fe₃O₄@APTES or Fe₃O₄@APTES-PAMAM) generating hydrogen peroxide from cholesterol palmitate.

The regional ratio of cholesteryl palmitate to cholesteryl oleate measured by ToF-SIMS as a key parameter of atherosclerosis

Objective: Changes in cholesterol ester (CE) content regulate the progression of atherosclerosis. However, the spatial dynamics of CE subsets and their quantitative changes during lesion progression are not well understood due to a lack of appropriate imaging techniques. In this study, we developed an imaging-based analysis method to map the distribution of CE subsets using time-of-flight secondary ion mass spectrometry (ToF-SIMS).
Methods: Serial sections of atherosclerotic aortic sinuses from apolipoprotein E knock-out mice (n = 15) fed a 0.15% high-fat diet for 12-20 weeks were examined by ToF-SIMS.
Results and conclusion: We found that the ratio of cholesteryl palmitate (Ch-PA) to cholesteryl oleate (Ch-OA) increased by approximately 99% (p = 0.02) as atherosclerosis progressed, whereas the ratios of cholesteryl linoleate (p = 0.09) and cholesteryl stearate (p = 0.22) to Ch-OA did not change significantly. In advanced atherosclerotic plaques, in situ and in-vitro cell death assays showed that local Ch-PA densities were highly correlated with an increase in the number of apoptotic cells. These results suggest that increased Ch-PA may contribute to the formation of a necrotic core by increasing cell death. Our results indicate that the regional ratio of CEs as measured by ToF-SIMS might be a valuable new marker of atherosclerotic progression.

Self-assembly and molecular packing in cholesteryl esters at interfaces

To understand the self-assembly and molecular packing in cholesteryl esters relevant to biological processes, we have studied them at the air-water and air-solid interfaces. Our phase and thickness studies employing imaging ellipsometry and atomic force microscopy along with surface manometry show that the molecular packing of cholesteryl esters at interfaces can be related to Craven's model of packing, given for bulk. At the air-water interface, following Craven's model, cholesteryl nonanoate and cholesteryl laurate exhibit a fluidic bilayer phase. Interestingly, we find the fluidic bilayer phase of cholesteryl laurate to be unstable and it switches to a crystalline bilayer phase. However, according to Craven, only cholesteryl esters with longer chain lengths starting from cholesteryl tridecanoate should show the crystalline bilayer phase. The thickness behavior of different phases was also studied by transferring the films onto a silicon substrate by using the Langmuir-Blodgett technique. Texture studies show that cholesterol, cholesteryl acetate, cholesteryl nonanoate, cholesteryl laurate, and cholesteryl myristate exhibit homogeneous films with large size domains, whereas cholesteryl palmitate and cholesteryl stearate exhibit less homogeneous films with smaller size domains. We suggest that such an assembly of molecules can be related to their molecular structures. Simulation studies may confirm such a relation.