Higher concentration of 25-hydroxycholesterol in treatment-naïve patients with type 2 diabetes compared to healthy individuals.

BACKGROUND: Oxysterols are cholesterol oxidation derivatives with diverse biological activities. However, little is known about the oxysterol levels in treatment-naïve patients with type 2 diabetes. OBJECTIVE: We utilized gas chromatography-mass spectrometry to investigate the potential association between oxysterol concentrations and type 2 diabetes and atherosclerosis in treatment-naïve patients diagnosed with type 2 diabetes. METHODS: This case-control study enrolled 53 eligible patients with type 2 diabetes and 50 healthy volunteers. We compared serum oxysterol concentrations between the two groups; we examined the correlation between the oxysterol concentrations and the carotid plaque score in the type 2 diabetes group. RESULTS: Univariate analysis revealed significant differences in the concentrations of oxysterols (i.e., cholesterol-5α, 6α-epoxide; cholesterol-5ß, 6ß-epoxide; 7ß-hydroxycholesterol; and 25-hydroxycholesterol [25-HC]) and other cardiovascular risk factors between the two groups. The 25-HC concentration was almost twofold greater in the type 2 diabetes group than in the healthy volunteers (median [interquartile range]: 8.52 [6.37-11.26] vs. 4.58 [3.45-5.44] ng/mL). After adjusting for multiple covariates, such as age, body mass index, mean arterial pressure, and triglyceride, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol levels, only the concentration of 25-HC showed a significant association with type 2 diabetes. However, the univariate analysis failed to demonstrate any significant correlation between oxysterol concentrations and the carotid plaque score among individuals with type 2 diabetes. CONCLUSIONS: The levels of various oxysterols differ between treatment-naïve patients with type 2 diabetes and healthy individuals; the 25-HC level differs the most prominently.

[Interaction of Phenytoin with Enteral Formulas, Proteins, and Dietary Fiber in Vitro and in Vivo].

Simultaneous administration of enteral formula and phenytoin in the clinical setting is known to reduce the plasma concentration of phenytoin. In this study, we examined the binding of phenytoin with enteral formulas and its components by quantifying the free phenytoin concentration. Furthermore, we investigated the effect of enteral formulas on gastrointestinal absorption of phenytoin in rats. The free phenytoin rate was reduced in vitro when phenytoin and enteral formula or pectin, a dietary fiber in enteral formulas, were co-administered. In vivo, when phenytoin and the enteral formula Mei Balance R® were co-administered, the time to maximum plasma concentration (Tmax) after oral administration was significantly increased. Moreover, the area under the phenytoin concentration-time curve from time zero to 6 h (AUC0-6 h) was significantly increased by co-administration of phenytoin with the enteral formula PG Soft EJ®. These results showed the gastrointestinal absorption of phenytoin differs according to the type of enteral formula. In addition, we found the first time that plasma phenytoin levels increase when combined with enteral formula. Among the components of enteral formulas, in particular, milk protein delayed the absorption of phenytoin. Moreover, milk protein, casein and carrageenan tended to increase AUC0-6 h. These results suggest the change in phenytoin concentration is due not only to the binding of enteral formula but also to the disintegration of components such as protein. Therefore, when co-administrated of phenytoin and enteral formula, phenytoin must be monitored frequently according to the enteral formula interaction.

Ergosterol increases 7-dehydrocholesterol, a cholesterol precursor, and decreases cholesterol in human HepG2 cells.

Current treatment approaches for hyperlipidemia rely mainly on reducing the cholesterol level by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), which is involved in the presqualene pathway of cholesterol biosynthesis. Finding a compound that instead targets the postsqualene pathway could aid in the treatment of hyperlipidemia and synergistically reduce the cholesterol level when used in conjunction with HMGCR inhibitors. Ergosterol is a fungal sterol that is converted to brassicasterol by 7-dehydrocholesterol reductase (DHCR7). DHCR7 is also a cholesterol biosynthesis enzyme, and thus ergosterol may cause the accumulation of 7-dehydrocholesterol, a precursor of cholesterol and vitamin D3 , by a competitive effect. In this study, we examined the effect of ergosterol on the postsqualene pathway by quantifying cholesterol precursors and related sterols using gas chromatography-mass spectrometry and by conducting quantitative RT-PCR and western blot analysis for human HepG2 hepatoma cells. We found that ergosterol is converted into brassicasterol by the action of DHCR7 from HepG2 cells and that it induced the accumulation of cholesterol precursors (lathosterol, 7-dehydrocholesterol, and desmosterol) and decreased the cholesterol level by altering the mRNA and protein levels of cholesterol biosynthesis enzymes (increase of sterol 8,7-isomerase [EBP] and decrease of DHCR7 and 24-dehydrocholesterol reductase [DHCR24]). These results demonstrate that ergosterol inhibits the postsqualene pathway and may be useful for the prevention of hyperlipidemia.

New Inhibitory Effect of Latilactobacillus sakei UONUMA on the Cholesterol Biosynthesis Pathway in Human HepG2 Cells.

Many pharmaceuticals and dietary foods have been reported to inhibit cholesterol biosynthesis, mainly by inhibiting the presqualene enzyme 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase rather than a postsqualene enzyme. In this study, we examined the inhibitory effects of Latilactobacillus sakei UONUMA on cholesterol biosynthesis, especially postsqualene, in human HepG2 hepatoma cells. We quantified cholesterol and its precursors, and the mRNA and protein levels of enzymes involved in cholesterol biosynthesis. Three L. sakei UONUMA strains exhibited new inhibitory effects on cholesterol biosynthesis and inhibited the mRNA level of sterol-delta24-reductase (DHCR24), which is involved in the postsqualene cholesterol biosynthesis pathway. These strains will be useful for the prevention and treatment of hyperlipidemia.

[Study of blood concentration analysis for formate in acute methanol poisoning].

A 53-year-old woman ingested about 300 mL of 95% methanol. After immediate ethanol antagonist therapy and hemodialysis, she recovered completely. Few days later, the plasma concentration of methanol and formate was measured. A gas chromatography was used for the plasma methanol concentration measurement, and a colorimetric method was used for plasma formate concentration measurement (Formate Colorimetric Assay Kit; BioVision, California, USA). Patient's plasma methanol concentration before hemodialysis was 676.9 mg/dL and plasma formate concentration was 16.9 mg/dL. By removing blood methanol and formate using hemodialysis before formate accumulations in the body, the patient was discharged without any sequelae. We were able to obtain correlation between a gas chromatography and colorimetric method without gas chromatography-mass spectrometry, with good correlation coefficients. The sensitivity was sufficient for analyzing blood sample. Monitoring formate concentration is useful in determining the treatment and evaluating the prognosis of methanol poisoning. We suggest that this colorimetric method is useful in a facility with no access to a gas chromatography in order to measure a plasma formate concentration.