Hawthorn total flavonoids ameliorate ambient fine particulate matter-induced insulin resistance and metabolic abnormalities of lipids in mice.

Recent studies have shown a strong correlation between ambient fine particulate matter (PM2.5) exposure and diabetes risk, including abnormal lipid accumulation and systemic insulin resistance (IR). Hawthorn total flavonoids (HF) are the main groups of active substances in Hawthorn, which showed anti-hyperlipidemic and anti-hyperglycemic effects. Therefore, we hypothesized that HF may attenuate PM2.5-induced IR and abnormal lipid accumulation. Female C57BL/6 N mice were randomly assigned to the filtered air exposure (FA) group, concentrated PM2.5 exposure (PM) group, PM2.5 exposure maintained on a low-dose HF diet (LHF) group, and PM2.5 exposure maintained on a high-dose HF diet (HHF) group for an 8-week PM2.5 exposure using a whole-body exposure device. Body glucose homeostasis, lipid profiles in the liver and serum, and enzymes responsible for hepatic lipid metabolism were measured. We found that exposure to PM2.5 impaired glucose tolerance and insulin sensitivity. In addition, triacylglycerol (TAG) in serum elevated, whereas hepatic TAG levels were decreased after PM2.5 exposure, accompanied by inhibited fatty acid uptake, lipogenesis, and lipolysis in the liver. HF administration, on the other hand, balanced the hepatic TAG levels by increasing fatty acid uptake and decreasing lipid export, leading to alleviated systemic IR and hyperlipidemia in PM2.5-exposed mice. Therefore, HF administration may be an effective strategy to protect against PM2.5-induced IR and metabolic abnormalities of lipids.

Dimethyl sulfoxide (DMSO) is a stabilizing co-solvent for G-quadruplex DNA.

We report the effect of dimethyl sulfoxide (DMSO) on the stability of the four-stranded structures formed by the oligodeoxyribonucleotides d[5'-AGGG(TTAGGG)3-3'] (HTel), d[5'-(GGGT)3GGG-3'] (G3T), d[5'-GGTTGGTGTGGTTGG-3] (TBA), d[5'-GGGGTTTTGGGG-3'] (Oxy-1.5), and d[5'-TGGGGT-3'] (TG4T). In these measurements, influence of the co-solvent was assessed by the change in the mid-point of the heat-induced unfolding, Tm, by monitoring the change in the UV absorption of the sample. Increasing concentrations of DMSO led to an increase in the Tm from the folded to unfolded states. We have also studied the effect of the denaturant urea and mixtures of urea and DMSO on the stability of the intramolecular HTel and the intermolecular TG4T G-quadruplexes. Consistent with earlier data, we found that urea destabilized the folded G-quadruplex structure; the Tm decreases with increasing urea concentration. However, in solutions containing both urea and DMSO, we observed that the two co-solvents off-set the destabilizing and stabilizing effect, respectively, of one another. That is, in solutions containing urea, increasing concentrations of DMSO led to the increase of the Tm of the G-quadruplex structure. This effect is observed in solutions containing sodium, potassium, or ammonium as the ion that stabilizes the folded G-quadruplex structure. The complementary effect of the two co-solvents presumably arises from differential interactions between urea and DMSO and the oligonucleotide or the cations involved in the stabilization of the G-quadruplexes. These results highlight the importance of co-solutes and co-solvents in systems containing guanine-rich DNA, particularly experimental processes that require DMSO.