Kinetics and plasma concentrations of 26-hydroxycholesterol in baboons

Biosynthesis and extrinsic toxicity of copper oxide nanoparticles against cattle parasites: An eco-friendly approach

Plant extracts' ability to collect metals and decrease metal ions makes them a superior candidate for the biosynthesis of nanoparticles; hence, they are referred to as bio-nano factories since both living and dead dried biomass are employed to produce metallic nanoparticles. The antiparasitic activity of biosynthesized copper oxide nanoparticles (CuO NPs) was examined against cow tick larvae (Rhipicephalus microplus, Haemaphysalis bispinosa, and Hippobosca maculata). These parasitic larvae were treated with various concentrations of methanolic leaf extract of A. marmelos (MLE-AM) and biosynthesized CuO NPs for 24 h. CuO NPs were synthesized quickly using A. marmelos leaf extract, and nanoparticle synthesis was identified within 15 min. The results from characteristic XRD, FTIR, SEM, EDX, and TEM analyses confirmed the biosynthesis of CuO NPs. The presence of 26-Hydroxycholesterol was discovered as the predominant chemical present in the GC-MS analysis of MLE-AM. The maximum efficacy was observed in biosynthesized CuO NPs against R. microplus larvae, H. bispinosa adults, and Hip. maculata larvae (LC₅₀ = 4.30, 9.50, and 11.13 mg/L; and LC₉₀ = 8.30, 19.57, and 21.65 mg/L; and 6.219, 6.547, and 2.587). Overall, the bio-fabrication of CuO NPs has the potential to develop better and safer antiparasitic control techniques.

Oxysterols in heart failure

Oxysterols are biologically active molecules that result from the oxidation of cholesterol. Several oxysterols are found in macrophages and macrophage-derived 'foam cells' in atherosclerotic tissue. Lipophilic oxysterols penetrate cell membranes and, therefore, their concentrations can reach harmful levels in endothelial and smooth muscle cells located in close proximity to the atherosclerotic plaques or inflammatory zones. New findings suggest that the effects of oxysterols on cardiomyocytes can lead to cell hypertrophy and death. This may make oxysterols one of the major factors precipitating morbidity in atherosclerosis-induced cardiac diseases and inflammation-induced heart complications. The pathological actions of oxysterols on muscle cells were shown to depend on dysfunctional Ca(2+) signaling; however, the mechanisms of the effects remain to be elucidated. Understanding the effects of oxysterols could lead to therapies that modulate malfunction of cardiomyocytes. This review discusses the experimental findings and the relevance of oxysterols to heart failure, and suggests strategies for important future investigations.

Programming of initial steps in bile acid synthesis by breat-feeding vs. Formula-feeding in the baboon

We tested the hypothesis that breast- vs. formula-feeding differentially affects the enzymatic activity of three sterol hydroxylases critical in the initial steps of bile acid formation. Thirty baboons were either breast-fed or formula-fed for the first 14 wk of life before weaning to baboon chow. At 14 and 34 wk of age, liver biopsies were assayed for cholesterol 7alpha-hydroxylase (CYP7A1), 27-hydroxycholesterol-7alpha-hydroxylase (CYP7B1), and cholesterol 27-hydroxylase (CYP27A1). We also determined the kinetics of 3H-27-hydroxycholesterol (27-OHC) turnover in vivo at both ages. At 14 wk of age, hepatic CYP7A1 activity was low but sevenfold higher among formula-fed vs. breast-fed baboons. By 34 wk, CYP7A1 activity had increased nearly 10-fold in both infant diet groups, and the sevenfold difference in CYP7A1 between previously breast- and formula-fed animals persisted. There were no differences in CYP7B1 activities between infant diet groups at either 14 or 34 wk of age although the activity increased in both groups by about 50% from 14 to 34 wk. CYP27A1 activity also increased between 14 and 34 wk of age, and, compared with CYP7A1, relatively small differences in CYP27A1 activity due to infant diet were observed at each age. Plasma 27-OHC turnover had a half-time of 2-4 min. We had previously reported that after weaning, the total bile acid synthesis rate was higher among baboons that were formula-fed than among breast-fed animals. The present results suggest that this difference is most likely due to significantly higher CYP7A1 activity among formula-fed vs. breast-fed animals.

Chromatographic behavior of oxygenated derivatives of cholesterol

Oxygenated derivatives of cholesterol have important functions in many biochemical processes. These oxysterols are difficult to study because of their low physiological concentrations, the facile formation of cholesterol autoxidation artifacts, and lack of information on their chromatographic behavior. Focusing on metabolites and autoxidation products of cholesterol, we have documented the chromatographic mobilities of 35 oxysterols under a variety of conditions: eight solvent systems for thin-layer chromatography on silica gel, several mobile phases for reversed-phase high-performance liquid chromatography (HPLC), and two types of stationary phase for capillary gas chromatography (GC) using trimethylsilyl derivatives. Notable differences in selectivity could be obtained by modifying the stationary or mobile phases. Separations of oxysterol pairs isomeric at side-chain carbons or C-7 were achieved on normal-phase, reversed-phase, chiral, or silver-ion HPLC columns. Chromatographic behavior is also described for side-chain hexadeuterated and heptafluorinated oxysterols, which are useful as standards in isotope dilution analyses and autoxidation studies, respectively. The overall results are relevant to many problems of oxysterol analysis, including the initial separation of oxysterols from cholesterol, determination of highly polar and nonpolar oxysterols, separation of isomeric pairs, selection of derivatization conditions for GC analysis, and quantitation of the extent of cholesterol autoxidation.