Studies in animals have documented that, compared with glucose, dietary fructose induces dyslipidemia and insulin resistance. To assess the relative effects of these dietary sugars during sustained consumption in humans, overweight and obese subjects consumed glucose-or fructose-sweetened beverages providing 25% of energy requirements for 10 weeks. Although both groups exhibited similar weight gain during the intervention, visceral adipose volume was significantly increased only in subjects consuming fructose. Fasting plasma triglyceride concentrations increased by approximately 10% during 10 weeks of glucose consumption but not after fructose consumption. In contrast, hepatic de novo lipogenesis (DNL) and the 23-hour postprandial triglyceride AUC were increased specifically during fructose consumption. Similarly, markers of altered lipid metabolism and lipoprotein remodeling, including fasting apoB, LDL, small dense LDL, oxidized LDL, and postprandial concentrations of remnant-like particle-triglyceride and -cholesterol significantly increased during fructose but not glucose consumption. In addition, fasting plasma glucose and insulin levels increased and insulin sensitivity decreased in subjects consuming fructose but not in those consuming glucose. These data suggest that dietary fructose specifically increases DNL, promotes dyslipidemia, decreases insulin sensitivity, and increases visceral adiposity in overweight/obese adults. IntroductionStudies investigating the effects of fructose consumption in humans and animals have been comprehensively reviewed (1-4), and while strong evidence exists that consumption of diets high in fructose results in increased de novo lipogenesis (DNL), dyslipidemia, insulin resistance, and obesity in animals, direct experimental evidence that consumption of fructose promotes DNL, dyslipidemia, insulin resistance, glucose intolerance, and obesity in humans is lacking. Thus, we have investigated and compared the biological effects of the 2 major simple sugars in the diet, glucose and fructose, on BW and regional fat deposition and on indices of lipid and carbohydrate metabolism in older, overweight and obese men and women.We sought to answer the following questions: (a) Does consumption of fructose with an ad libitum diet promote greater BW gain and have differential effects on regional adipose deposition and adipose gene expression compared with consumption of glucose with an ad libitum diet? (b) Does consumption of fructose induce dyslipidemia compared with consumption of glucose? (c) Is fructose-induced hypertriglyceridemia the result of increased rates

SummaryPhotosystem II (PSII) is a huge membrane-protein complex consisting of 20 different subunits with a total molecular mass of 350 kDa for a monomer, and catalyzes light-driven water oxidation at its catalytic center, the oxygen-evolving complex (OEC) [1][2][3] . The structure of PSII has been analyzed at 1.9 Å resolution by synchrotron radiation X-rays, which revealed that OEC is a Mn4CaO5 cluster organized in an asymmetric, "distorted-chair" form 4 . This structure was further analyzed with femtosecond X-ray free electron lasers (XFEL), providing the "radiation damage-free" 5 structure. The mechanism of O=O bond formation, however, remains obscure due to the lack of intermediate state structures. Here we report the structural changes of PSII induced by 2-flash (2F) illumination at room temperature at a resolution of 2.35 Å using time-resolved serial femtosecond crystallography (TR-SFX) with an XFEL provided by the SPring-8 angstrom compact free-electron laser (SACLA). Isomorphous differenceFourier map between the 2F and dark-adapted states revealed two areas of apparent changes; they are around QB/non-heme iron and the Mn4CaO5 cluster. The changes around the QB/non-heme iron region reflected the electron and proton transfers induced by the 2F-illumination. In the region around the Mn4CaO5 cluster, a water molecule located 3.5 Å from the Mn4CaO5 cluster disappeared from the map upon 2Fillumination, leading to a closer distance between another water molecule and O4, suggesting also the occurrence of proton transfer. Importantly, the 2F-dark isomorphous difference Fourier map showed an apparent positive peak around O5, a unique μ3-oxo-bridge located in the quasi-center of Mn1 and Mn4 4,5 . This suggests an insertion of a new oxygen atom (O6) close to O5, providing an O=O distance of 1.5 Å between these two oxygen atoms. This provides a mechanism for the O=O bond formation 4 consistent with that proposed by Siegbahn 6,7 . Fig. 1a shows organization of the electron transfer chain of PSII in a pseudo-C2 symmetry by two subunits D1 and D2. The water-oxidation reaction proceeds via the Si-state cycle 8 (with i=0-4), where dioxygen is produced in the transition of S3→(S4)→S0 (Fig. 1b). The high-resolution structures of PSII analyzed so far were for the dark-stable S1 state 4,5 , although a few studies on the low-resolution intermediate S-state structures have been reported by TR-SFX [9][10][11] . During the revision of our manuscript, Young et al. reported a 2F-illuminated state structure at 2.25 Å resolution where no apparent changes around O5 were observed 12 , although estimations of the resolution could yield somewhat different values so that small movement of some water molecules may escape the detection. In order to achieve resolution high enough to uncover small structural changes induced by flash illuminations yet allowing Si-state transition to proceed efficiently, we determined the optimal crystal size of PSII with a maximum length of 100 µm, which diffracted up to a resolution of 2.1 Å by a SACLA-XFEL ...

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Consumption of HFCS-sweetened beverages for 2 wk at 25% E increased risk factors for cardiovascular disease comparably with fructose and more than glucose in young adults.

Background-Remnant lipoproteins are atherogenic, but assays of remnants have not been available in routine clinical laboratories because of the lack of practical and validated methods. A simple and reliable method for such an assay, using an immunochemical approach, has recently been developed. This study prospectively examined whether remnant lipoprotein levels in fasting serum, measured by our method, may have prognostic value in patients with coronary artery disease (CAD). Methods and Results-Remnant lipoprotein levels in fasting serum were measured in 135 patients with CAD by an immunoaffinity mixed gel containing anti-apolipoprotein (apo) A-1 and anti-apoB-100 monoclonal antibodies. Patients were followed up for Յ36 months until occurrence of 1 of the following clinical coronary events: recurrent or refractory angina pectoris requiring coronary revascularization, nonfatal myocardial infarction, or cardiac death. Kaplan-Meier analysis demonstrated a significantly higher probability of developing coronary events in patients with the highest tertile of remnant levels (Ͼ5.1 mg cholesterol/dL; 75th percentile of distribution of remnant levels) than in those with the lowest tertile of remnant levels (Յ3.3 mg cholesterol/dL; 50th percentile of the distribution). Higher levels of remnants were a significant and independent predictor of developing coronary events in multivariate Cox hazard analysis including the following covariates: extent of coronary artery stenosis, age, sex, smoking, hypertension, diabetes mellitus, hypercholesterolemia, low HDL cholesterol, and hypertriglyceridemia. Conclusions-Higher levels of remnant lipoproteins in fasting serum predict future coronary events in patients with CAD independently of other risk factors. Thus, measurement of fasting remnant levels, assessed by the current immunoseparation method, may be helpful in assessment of CAD risk. (Circulation. 1999;99:2858-2860.)

Remnant lipoprotein levels were independently associated with abnormal endothelium-dependent vasomotor function in large and resistance coronary arteries in humans, indicating that remnant lipoproteins may impair endothelial vasomotor function in human coronary arteries. The decrease in coronary nitric oxide bioactivity may be responsible in part for the inhibitory effects of remnant lipoproteins.

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Since Zilversmit first proposed postprandial lipemia as the most common risk of cardiovascular disease, chylomicrons (CM) and CM remnants have been thought to be the major lipoproteins which are increased in the postprandial hyperlipidemia. However, it has been shown over the last two decades that the major increase in the postprandial lipoproteins after food intake occurs in the very low density lipoprotein (VLDL) remnants (apoB100 particles), not CM or CM remnants (apoB48 particles). This finding was obtained using the following three analytical methods; isolation of remnant-like lipoprotein particles (RLP) with specific antibodies, separation and detection of lipoprotein subclasses by gel permeation HPLC and determination of apoB48 in fractionated lipoproteins by a specific ELISA. The amount of the apoB48 particles in the postprandial RLP is significantly less than the apoB100 particles, and the particle sizes of apoB48 and apoB100 in RLP are very similar when analyzed by HPLC. Moreover, CM or CM remnants having a large amount of TG were not found in the postprandial RLP. Therefore, the major portion of the TG which is increased in the postprandial state is composed of VLDL remnants, which have been recognized as a significant risk for cardiovascular disease.