Insulin response and changes in composition of non-esterified fatty acids in blood plasma of middle-aged men following isoenergetic fatty and carbohydrate breakfasts

It was previously shown that a high plasma concentration of non-esterified fatty acids (NEFA) persisted after a fatty breakfast, but not after an isoenergetic carbohydrate breakfast, adversely affecting glucose tolerance. The higher concentration after the fatty breakfast may in part have been a result of different mobilization rates of fatty acids. This factor can be investigated as NEFA mobilized from tissues are monounsaturated to a greater extent than those deposited from a typical meal. Twenty-four middle-aged healthy Caucasian men were given oral glucose tolerance tests (OGTT), and for 28 d isoenergetic breakfasts of similar fat composition but of low (L) or moderate (M) fat content. The composition of NEFA in fasting and postprandial plasma was determined on days 1 and 29. No significant treatment differences in fasting NEFA composition occurred on day 29. During the OGTT and 0-1 h following breakfast there was an increase in plasma long-chain saturated NEFA but a decrease in monounsaturated NEFA (mug/100 mug total NEFA; Pg/100 mug total NEFA; P<0.05), expressed as an increase in 18:1 and decreases in 16:0 and 17:0 in treatment M relative to treatment L (P<0.05). Serum insulin attained 35 and 65 mU/l in treatments M and L respectively during this period. Negative correlations were found between 16:0 in fasting plasma and both waist:hip circumference (P=0.0009) and insulin response curve area during OGTT (within treatment M, P=0.0001). It is concluded that a normal postprandial insulin response is associated with a rapid change in plasma saturated:monounsaturated NEFA. It is proposed that this change is the result of a variable suppression of fat mobilization, which may partly account for a large difference in postprandial total plasma NEFA between fatty and carbohydrate meals

Diurnal trends in responses of blood plasma concentrations of glucose, insulin, and C-peptide following high- and low-fat meals and their relation to fat metabolism in healthy middle-aged volunteers

An experiment was conducted in twelve healthy middle-aged volunteers, six of each sex, with a mean BMI of 27 kg/m(2) to detect differences between morning and afternoon in postprandial blood glucose, insulin and C-peptide concentrations. These responses were measured following the consumption of isoenergetic meals that were high or low in fat content, at breakfast and at lunch. Over 4d each subject received the high-carbohydrate (L, 5.5 g mixed fat/meal) and moderately high-fat (M, 33 g mixed fat/meal) breakfasts and lunches, in three combinations (LL, MM, LM), or they fasted at breakfast time and received a moderately high-fat lunch (NM), in three Latin squares. Each evening a standard meal was given. Plasma glucose, insulin and C-peptide responses were greater following L than M meals and within both MM and LL treatments insulin and C-peptide responses were greater following breakfast than following lunch. The incremental C-peptide response to a fatty lunch following a fast at breakfast time (MM) was similar to that to a fatty breakfast, but the incremental insulin response for the same comparison was marginally lower at lunch (P=0.06). The relationship of C-peptide and insulin concentrations was assessed. Plasma glucose response to a fatty lunch was increased by a fatty breakfast. The relationships of these metabolic events with fat metabolism are discussed

Effects of high- and low-fat meals on the diurnal response of plasma lipid metabolite concentrations in healthy middle-aged volunteers

Three experiments were conducted in healthy middle-aged volunteers (six males and six females in Expt 1, six males and two females in Expt 2 and twelve males in Expt 3) with a mean BMI of 27 kg/m(2) to determine whether there is a difference between morning and afternoon dietary fat clearance and utilization, and to determine in what way the fat and starch contents of the meal influence postprandial blood lipid metabolites over 4.5 h. Over 4 days in Expt 1 each subject received isoenergetic, high-carbohydrate (L, 5.5 g mixed fat/meal) and moderately high-fat (M, 33 g mixed fat/meal) breakfasts and lunches, in three combinations (LL, MM, LM), or they fasted at breakfast time and received a high fat lunch (MM) in a randomized and balanced arrangement. Each evening a standard meal was given. The following effects were significant (P < 0.05): plasma triacylglycerol (TAG) responses were greater following RI meals; plasma TAG concentrations were greater in the afternoon than in the morning, following two meats of the same composition, although the postprandial incremental response was less following lunch than following breakfast and peak responses were reached much earlier than after breakfast; a low-fat breakfast, or fasting at breakfast time, delayed the peak TAG response to a M lunch. The plasma concentrations of nonesterified fatty acids (NEFA) and of free glycerol were higher in the afternoon following M meals at breakfast and lunch, especially in males. This response was reduced, by the L breakfast preceding the M lunch. Two M meals in succession lowered plasma HDL-cholesterol concentration. In Expt 2 each subject received a very low-fat (VL) breakfast, followed by a lunch of the same composition. Each of these meals was followed, 110 min from the start of eating, by an infusion of Intralipid 10 % emulsion at the rate of 1 ml/kg body weight over 60 s. Clearance rates of Intralipid were faster in the afternoon than in the morning (P = 0.024). In Expt 3 twelve subjects were randomly allocated to either treatment MM or LM meal patterns, as given in Expt 1. These were given daily for a period of 17 d, during which the change in fasting plasma TAG concentration was similar in both treatments. On days 1, 16 and 17 responses were measured to the M lunch and to a glucose tolerance test (GTT), conducted 2 h 17 min after lunch. The post-lunch responses confirmed those found in Expt 1; but immediately following the glucose dose there was an abrupt increase in plasma TAG that was greater in treatment LM than in treatment MM (P = 0.025), whereas plasma NEFA concentration decreased rapidly in both treatments at that time (P = 0.00066)

Effect of breakfast fat content on glucose tolerance and risk factors of atherosclerosis and thrombosis

Twenty-four middle-aged healthy men were given a low-fat high-carbohydrate (5.5 g fat; L), or a moderately-fatty, (25.7 g fat; M) breakfast of similar energy contents for 28 d. Other meals were under less control. An oral glucose tolerance test (OGTT) was given at 09.00 hours on day 1 before treatment allocation and at 13.30 hours on day 29. There were no significant treatment differences in fasting serum values, either on day 1 or at the termination of treatments on day 29. The following was observed on day 29: (1) the M breakfast led to higher OGTT C-peptide responses and higher areas under the curves (AUC) of OGTT serum glucose and insulin responses compared with the OGTT responses to the L breakfast (P < 0.05); (2) treatment M failed to prevent OGTT glycosuria, eliminated with treatment L; (3) serum non-esterified fatty acid (NEFA) AUC was 59% lower with treatment L than with treatment M, between 09.00 and 13.20 hours (P < 0.0001), and lower with treatment L than with treatment M during the OGTT (P = 0.005); (4) serum triacylglycerol (TAG) concentrations were similar for both treatments, especially during the morning, but their origins were different during the afternoon OGTT when the Svedberg flotation unit 20-400 lipid fraction was higher with treatment L than with treatment M (P = 0.016); plasma apolipoprotein B-48 level with treatment M was not significantly greater than that with treatment L (P = 0.086); (5) plasma tissue plasminogen-activator activity increased after breakfast with treatment L (P = 0.0008), but not. with treatment M (P = 0.80). Waist:hip circumference was positively correlated with serum insulin and glucose AUC and with fasting LDL-cholesterol, Waist:hip circumference and serum TAG and insulin AUC were correlated with factors of thrombus formation; and the OGTT NEFA and glucose AUC were correlated. A small difference in fat intake at breakfast has a large influence on circulating diurnal NEFA concentration, which it is concluded influences adversely glucose tolerance up to 6 h later

Ultra-short silicon-organic hybrid (SOH) modulator for bidirectional polarization-independent operation

We propose a bidirectional, polarization-independent, recirculating IQ-modulator scheme based on the silicon-organic hybrid (SOH) platform. We demonstrate the viability of the concept by using an SOH Mach-Zehnder modulator, operated at 10 GBd BPSK and 2ASK-2PSK

Silicon-Organic Hybrid (SOH) and Plasmonic-Organic Hybrid (POH) integration

Silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) integration combines organic clectro-optic materials with silicon photonic and plasmonic waveguides, The concept enables fast and power-efficient modulators that support advanced modulation formats such as QPSK and 16QAM

Silicon-Organic Hybrid (SOH) and Plasmonic-Organic Hybrid (POH) integration

Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, nei-ther silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonic-organic hybrid integration, which combine SOI waveguides and plasmonic nanostructures with organic electro-optic cladding materials

Reach-scale bankfull channel types can exist independently of catchment hydrology

© 2020 John Wiley &amp; Sons, Ltd. Reach-scale morphological channel classifications are underpinned by the theory that each channel type is related to an assemblage of reach- and catchment-scale hydrologic, topographic, and sediment supply drivers. However, the relative importance of each driver on reach morphology is unclear, as is the possibility that different driver assemblages yield the same reach morphology. Reach-scale classifications have never needed to be predicated on hydrology, yet hydrology controls discharge and thus sediment transport capacity. The scientific question is: do two or more regions with quantifiable differences in hydrologic setting end up with different reach-scale channel types, or do channel types transcend hydrologic setting because hydrologic setting is not a dominant control at the reach scale? This study answered this question by isolating hydrologic metrics as potential dominant controls of channel type. Three steps were applied in a large test basin with diverse hydrologic settings (Sacramento River, California) to: (1) create a reach-scale channel classification based on local site surveys, (2) categorize sites by flood magnitude, dimensionless flood magnitude, and annual hydrologic regime type, and (3) statistically analyze two hydrogeomorphic linkages. Statistical tests assessed the spatial distribution of channel types and the dependence of channel type morphological attributes by hydrologic setting. Results yielded 10 channel types. Nearly all types existed across all hydrologic settings, which is perhaps a surprising development for hydrogeomorphology. Downstream hydraulic geometry relationships were statistically significant. In addition, cobble-dominated uniform streams showed a consistent inverse relationship between slope and dimensionless flood magnitude, an indication of dynamic equilibrium between transport capacity and sediment supply. However, most morphological attributes showed no sorting by hydrologic setting. This study suggests that median hydraulic geometry relations persist across basins and within channel types, but hydrologic influence on geomorphic variability is likely due to local influences rather than catchment-scale drivers. © 2020 John Wiley &amp; Sons, Ltd