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

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)

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

Using trace element and halide isotopes to understand salinization mechanisms of groundwaters from an arid aquifer

Saline groundwaters are common to inland Australia, yet many aspects of their hydrochemical evolution remain uncertain. The saline groundwaters in the alluvial aquifers of the Darling River have previously been found to exhibit broad similarity in traditional hydrochemical and isotopic tracers. By contrast, trace element isotopes (δ7Li, δ11B and 87Sr/86Sr) and halide isotopes (δ37Cl and δ81Br) provide evidence of more complex hydrogeochemical processes.Hydrochemical evolution was found to be dependent on proximity to theDarling River and depth even though all groundwaters from this aquifer were found to be saline. The differing signatures highlighted the discovery of adeeper palaeo-groundwater system containing heavier trace element and halide isotope values. The measurement of these isotopes has permitted delineation of groundwater end-members and salinization mechanisms that would have otherwise not been identified

Assessing Initial Conditions for Chloride Transport Across Low- permeability Argillaceous Rocks, Wellenberg, Switzerland

Information about fluid evolution and solute transport in a low-permeability metamorphic rock sequence has been obtained by comparing chloride concentrations and chlorine isotope ratios of pore water, groundwater, and fluid inclusions. The similarity of d37Cl values in fluid inclusions and groundwater suggests a closed-system evolution during the metamorphic overprint, and signatures established at this time appear to form the initial conditions for chloride transport after exhumation of the rock sequence

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

Recent Deformation in the Bottom Sediments of Western and Southeastern Lake Ontario and its Association with Major Structures and Seismicity

Geophysical surveys, undertaken in the Toronto-Burlington corridor of western Lake Ontario and in the Rochester Basin of southeastern Lake Ontario, revealed the presence of features affecting the young lake-bottom sediments. In the western part of the lake, they include inferred pop-ups in bedrock, and plumose structures, dark linear patterns, and linear belts of circular to elliptical signatures in the modern mud. In southeastern Lake Ontario the glacial and post-glacial sediments display vertical separations of on the order of 10-15 m. Pop-ups are tectonically-induced structures. The features in the modern mud commonly parallel the orientation of P-stresses measured in Paleozoic rocks nearby and, along with the pop-ups, are spatially related to an aeromagnetic lineament. Furthermore, all of these features occur within a seismically active belt. The vertical displacements of the layered glacial and post-glacial sediments, within the Rochester Basin, are located along the southern margin of the postulated WSW extension of the seismically active St. Lawrence rift system and are interpreted to be due to faulting. The geologically young age of the sediments affected by the various deformational features, along with the characteristics of the features themselves, suggest that the lake-bottom sediments surveyed in this study may have recorded the effects of neotectonic processes.Des levés géophysiques effectués dans le corridor Toronto-Burlington, dans l'ouest du lac Ontario, a révélé la présence d'éléments qui altèrent les jeunes sédiments lacustres du fond. Dans la partie ouest du lac, dans la roche en place, il s'agit de structures de soulèvement (pop-ups) et, dans les boues récentes, de structures plumeuses, de réseaux de traits sombres et de zones linéaires de tracés circulaires à elliptiques. Dans la partie sud-est du lac Ontario, il y a dans les sédiments glaciaires et postglaciaires des rejets verticaux de l'ordre de 10 à 15 m. Les structures de soulèvement sont d'origine tectonique. Les formes dans les boues récentes, généralement parallèles à l'orientation des contraintes de compression mesurées dans les roches paléozoïques voisines, sont spatialement reliés, comme les structures de soulèvement, à un linéament aéromagnétique. De plus, toutes ces formes se trouvent dans une zone sismique active. Les rejets verticaux dans les sédiments glaciaires et postglaciaires stratifiés, à l'intérieur du basssin de Rochester, sont localisés le long de la bordure sud du prolongement présumé WSW du système actif du rift du Saint-Laurent et sont probablement attribuables à la formation de failles. La jeunesse des sédiments altérés par les déformations et les caractéristiques des déformations mêmes laissent croire que ces sédiments ont probablement enregistré les effets de processus néotectoniques.Geophysikalische Vermessungen, die im Toronto Burlington-Korridor des westlichen Ontariosees und im Rochester-Becken des sùdôstlichen Ontariosees durchgefùhrt wurden, deckten die Anwesenheit von Elementen auf, welche auf die jungen Seegrundsedimente einwirken. Im westlichen Teil des Sees bestehen sie aus Hebungen im anste-henden Gestein und im modernen Schlamm aus federartigen Strukturen, dunklen linearen Mustern und linearen Gùrteln mit kreisformigen bis ellipsenfôrmigen Umrissen. Im sùdôstlichen Ontariosee gibt es in den glazialen und postglazialen Sedimenten verti-kale Verwùrfe der GrôRenordnung von 10-15 m. Die Hebungen sind tektonischen Ursprungs. Die Formen im modernen Schlamm liegen im allgemeinen paralell zu der Orientierung der in den benachbarten palàozoischen Felsen gemessenen P-Stresse und sind zusammen mit den Hebungen ràumlich mit einem aeromagnetischen Lineament verbunden. AuRerdem treten aile dièse Formen innerhalb eines seismisch aktiven Gùrtels auf. Die vertikalen Verstellungen der geschichteten glazialen und postglazialen Sedimente innerhalb des Rochester-Beckens werden entlang des sùdlichen Rands der angenommenen WSW-Verlàngerung des seismisch aktiven Sankt-Lorenz-Spaltensystems lokalisiert. Das geologisch relativ junge Alter der durch die verschiedenen Verformungen Iàf3t vermu-ten, daB die in dieser Studie gemessenen Seegrundsedimente moglicherweise die Wirkungen neotektonischer Prozesse aufgezeichnet haben