Hemostatic response to postprandial lipemia before and after exercise training

Metabolic Responses to Eight Weeks of Consuming Cottonseed Oil v. Olive Oil in Adults with Dyslipidemia, a Randomized Trial

BACKGROUND

Differences in metabolic responses between diets rich in monounsaturated (MUFA) and polyunsaturated fats (PUFA) could affect energy balance and weight maintenance. The present study was a secondary analysis to investigate 8-week diet interventions rich in either PUFA (cottonseed oil (CSO)) or MUFA (olive oil (OO)) on metabolic responses in adults with dyslipidemia.

METHODS

Forty-one adults with dyslipidemia completed this randomized trial consisting of an 8-week partial-outpatient feeding trial. Provided foods accounted for ~60% of their daily energy needs, with ~30% of energy needs provided by CSO (n=20) or OO (n=21). At pre- and post-diet intervention visits, participants consumed a high saturated fat (SFA) meal (35% daily energy needs, 47.9% from SFA), and fasting and 3.5h postprandial indirect calorimetry was used to measure energy expenditure (EE) and substrate oxidation.

RESULTS

No changes were observed in fasting measures. The OO group had greater increases in postprandial EE (p=0.002); however, there were no differences in substrate oxidation between groups. A lack of metabolic flexibility was found in both groups, which was partially explained by changes in insulin sensitivity (homeostasis model assessment of insulin resistance (HOMA-IR)).

CONCLUSIONS

The results of the present study show OO, but not CSO, diet enrichment improves EE following the occasional high SFA meal, which may improve weight maintenance over time. Registered at clinicaltrials.gov (NCT04397055). This article is protected by copyright. All rights reserved.

Effect of Prior Exercise on Postprandial Lipemia: An Updated Meta-Analysis and Systematic Review

The purpose of this systematic review was to synthesize the results from current literature examining the effects of prior exercise on the postprandial triglyceride (TG) response to evaluate current literature and provide future direction. A quantitative review was performed using meta-analytic methods to quantify individual effect sizes. A moderator analysis was performed to investigate potential variables that could influence the effect of prior exercise on postprandial TG response. Two hundred and seventy-nine effects were retrieved from 165 studies for the total TG response and 142 effects from 87 studies for the incremental area under the curve TG response. There was a moderate effect of exercise on the total TG response (Cohen's d = -0.47; p < .0001). Moderator analysis revealed exercise energy expenditure significantly moderated the effect of prior exercise on the total TG response (p < .0001). Exercise modality (e.g., cardiovascular, resistance, combination of both cardiovascular and resistance, or standing), cardiovascular exercise type (e.g., continuous, interval, concurrent, or combined), and timing of exercise prior to meal administration significantly affected the total TG response (p < .001). Additionally, exercise had a moderate effect on the incremental area under the curve TG response (Cohen's d = -0.40; p < .0001). The current analysis reveals a more homogeneous data set than previously reported. The attenuation of postprandial TG appears largely dependent on exercise energy expenditure (∼2 MJ) and the timing of exercise. The effect of prior exercise on the postprandial TG response appears to be transient; therefore, exercise should be frequent to elicit an adaptation.

Potential Physiological and Cellular Mechanisms of Exercise That Decrease the Risk of Severe Complications and Mortality Following SARS-CoV-2 Infection

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has unmasked mankind's vulnerability to biological threats. Although higher age is a major risk factor for disease severity in COVID-19, several predisposing risk factors for mortality are related to low cardiorespiratory and metabolic fitness, including obesity, cardiovascular disease, diabetes, and hypertension. Reaching physical activity (PA) guideline goals contribute to protect against numerous immune and inflammatory disorders, in addition to multi-morbidities and mortality. Elevated levels of cardiorespiratory fitness, being non-obese, and regular PA improves immunological function, mitigating sustained low-grade systemic inflammation and age-related deterioration of the immune system, or immunosenescence. Regular PA and being non-obese also improve the antibody response to vaccination. In this review, we highlight potential physiological, cellular, and molecular mechanisms that are affected by regular PA, increase the host antiviral defense, and may determine the course and outcome of COVID-19. Not only are the immune system and regular PA in relation to COVID-19 discussed, but also the cardiovascular, respiratory, renal, and hormonal systems, as well as skeletal muscle, epigenetics, and mitochondrial function.

Daily Step Count and Postprandial Fat Metabolism

INTRODUCTION

Two benefits of acute exercise are the next day's lowering of the postprandial plasma triglyceride response to a high-fat meal and increased fat oxidation. However, if activity levels (daily steps) are very low, these acute adaptations to exercise do not occur. This phenomenon has been termed "exercise resistance." This study sought to systematically reduce daily step number and identify the range of step counts that elicit "exercise resistance."

METHODS

Ten participants completed three, 5-d trials in a randomized, crossover design with differing levels of step reduction. After 2 d of controlled activity, participants completed 2 d of LOW, LIMITED, or NORMAL steps (2675 ± 314, 4759 ± 276, and 8481 ± 581 steps per day, respectively). Participants completed a 1-h bout of running on the evening of the second day. High-fat tolerance tests were performed on the next morning, and postprandial responses were compared.

RESULTS

After LOW and LIMITED, postprandial incremental area under the curve (AUC) of plasma triglyceride was elevated 22%-23% compared with NORMAL (P < 0.05). Whole body fat oxidation was also significantly lower (16%-19%, P < 0.05, respectively) in LOW and LIMITED compared with NORMAL. No significant differences were found between LOW and LIMITED.

CONCLUSION

Two days of step reduction to approximately 2500-5000 steps per day in young healthy individuals impairs the ability of an acute bout of exercise to increase fat oxidation and attenuate postprandial increases in plasma triglycerides. This suggests that "exercise resistance" occurs in individuals taking approximately 5000 or fewer steps per day, whereas 8500 steps per day protects against exercise resistance in fat metabolism. It seems that fat metabolism is influenced more by the inhibitory effects of inactivity than by the stimulating effects derived from 1 h of moderate-intensity running.

The chronic effect of physical activity on postprandial triglycerides in postmenopausal women: A randomized controlled study

Objective

This study examined the chronic effect of increased physical activity on postprandial triglycerides in older women.

Methods

Twenty-six women, aged 72 ± 5 years (mean ± SD), participated in this study. Participants in the physical activity group (n = 11) were asked to increase their activities above their usual lifestyle levels for 12 weeks. Participants in the control group (n = 15) maintained their usual lifestyle for 12 weeks. All participants rested and consumed a standardized breakfast after a 24-h period of physical activity avoidance at baseline, 4 weeks, and 12 weeks. Blood samples were collected in the fasted state (0 h) and at 2, 4, and 6 h after breakfast.

Results

The average increased time spent in self-selected activities per day was 1.1 ± 19.3 min over the 12 weeks compared with the baseline in the physical activity group. There was no difference in the postprandial time-averaged triglyceride area under the curve at baseline (1.59 ± 0.81 vs. 1.39 ± 0.67 mmol/L, p = 0.515) or over the 12-week intervention (1.78 ± 1.00 vs. 1.31 ± 0.67 mmol/L, p = 0.212) between the physical activity and control groups.

Conclusion

Postprandial triglyceride concentrations were not reduced after performing self-selected activities under free-living conditions in older women when these responses were determined 24 h after the last physical activity bout. (Trial registration ID: UMIN000037420).

FDP-E induces adipocyte inflammation and suppresses insulin-stimulated glucose disposal: effect of inflammation and obesity on fibrinogen Bβ mRNA

Obesity is associated with increased fibrinogen production and fibrin formation, which produces fibrin degradation products (FDP-E and FDP-D). Fibrin and FDPs both contribute to inflammation, which would be expected to suppress glucose uptake and insulin signaling in adipose tissue, yet the effect of FDP-E and FDP-D on adipocyte function and glucose disposal is completely unknown. We tested the effects of FDPs on inflammation in 3T3-L1 adipocytes and primary macrophages and adipocyte glucose uptake in vitro. High-fat-fed mice increased hepatic fibrinogen mRNA expression ninefold over chow-fed mice, with concomitant increases in plasma fibrinogen protein levels. Obese mice also displayed increased fibrinogen content of epididymal fat pads. We treated cultured 3T3-L1 adipocytes and primary macrophages with FDP-E, FDP-D, or fibrinogen degradation products (FgnDP-E). FDP-D and FgnDP-E had no effect on inflammation or glucose uptake. Cytokine mRNA expression in RAW264.7 macrophage-like cells and 3T3-L1 adipocytes treated with FDP-E induced inflammation with maximal effects at 100 nM and 6 h. Insulin-stimulated 2-deoxy-d-[3H]glucose uptake was reduced by 71% in adipocytes treated with FDP-E. FDP-E, but not FDP-D or FgnDP-E, induces inflammation in macrophages and adipocytes and decreases glucose uptake in vitro. FDP-E may contribute toward obesity-associated acute inflammation and glucose intolerance, although its chronic role in obesity remains to be elucidated.

High-intensity exercise training for the prevention of type 2 diabetes mellitus

Aerobic exercise training and diet are recommended for the primary prevention of type 2 diabetes mellitus and cardiovascular disease. The American Diabetes Association (ADA) recommends that adults with prediabetes engage in ≥ 150 minutes per week of moderate activity and target a 7% weight loss. However, traditional moderate-intensity (MI) exercise training programs are often difficult to sustain for prediabetic adults; a commonly cited barrier to physical activity in this population is the "lack of time" to exercise. When matched for total energy expenditure, high-intensity (HI) exercise training has a lower overall time commitment compared with traditional low-intensity (LI) or MI exercise training. Several recent studies comparing HI exercise training with LI and MI exercise training reported that HI exercise training improves skeletal muscle metabolic control and cardiovascular function in a comparable and/or superior way relative to LI and MI exercise training. Although patients can accrue all exercise benefits by performing LI or MI activities such as walking, HI activities represent a time-efficient alternative to meeting physical activity guidelines. High-intensity exercise training is a potent tool for improving cardiometabolic risk for prediabetic patients with limited time and may be prescribed when appropriate.

The latest on the effect of prior exercise on postprandial lipaemia

This review examines the effect of prior exercise on postprandial triacylglycerol (pTAG) concentrations, an independent risk factor for cardiovascular diseases. Numerous studies have shown that a single bout of exercise reduces pTAG concentrations; however, several modulators such as exercise energy expenditure/deficit, mode of exercise (aerobic/resistance/high intensity/intermittent exercise or combinations), type of meal (moderate or high fat), time frame between exercise and meal and target group may individually or in conjunction influence this effect. On the other hand, at least for aerobic exercise, training reduces pTAG concentrations transiently (~2 days); therefore, exercise sessions should be frequent enough to maintain this clinically significant improvement. For the healthy population, it seems that a subject's preference and ability determine which type of exercise to undertake to attenuate pTAG concentrations; an energy expenditure of ~30 kJ/kg of body mass (or ~2-2.5 MJ) not combined with a corresponding increase in energy intake is required; for resistance or intermittent exercise, for those following a moderate rather than a high-fat diet, and for those with obesity (expressed as kJ/kg of body mass), a smaller energy expenditure is probably sufficient. More studies are needed to investigate dose-response/plateau effects, as well as the threshold of energy expenditure in those with diabetes mellitus and other high-risk populations. Finally, investigation of the underlying mechanisms may be clinically helpful in individualizing the appropriate intervention.

The effect of aerobic exercise intensity on attenuation of postprandial lipemia is dependent on apolipoprotein E genotype

OBJECTIVE

To investigate the effect of aerobic exercise intensity on postprandial lipemia according to allelic variants of the apolipoprotein E gene.

METHODS

Three groups of 10 healthy men each were formed based genotyping of the APOE gene, rested or performed 500 Kcal tests in a random sequence separated by a minimum 48 h interval, as follows: (a) no exercise (control), (b) intense intermittent exercise, (c) moderate continuous exercise. Each test series was completed 30-min before ingestion of a high-fat meal (1 g fat/kg). Venous blood was collected before and at 1, 2, 3 and 4 h after the high-fat meal. Postprandial lipemia was assessed using the area under the curve approach as well as the kinetic profile of mean lipid variables. Statistical significance was adopted at P ≤ 0.05 level.

RESULTS

The main results show that, in the moderate continuous exercise, total postprandial cholesterolemia was higher in ɛ4 than in ɛ2 carriers, whereas under intense intermittent exercise, total and LDL cholesterolemia were higher in ɛ4 than in ɛ2 and ɛ3 carriers. There was no difference in the lipemic profile of the subjects across APOE genotypes at baseline.

CONCLUSION

Moderate and intense exercise were effective in attenuating PPL in both ɛ2 and ɛ3 subjects, with ɛ2 subjects being more susceptible to the lipid lowering effect of moderate training than ɛ3 subjects. Carriers of the ɛ4 allele, however, showed no attenuation of postprandial lipemia.

Effects of exercise training on molecular markers of lipogenesis and lipid partitioning in fructose-induced liver fat accumulation. J Nutr Metab. 2012;2012:181687. [PMID: 21860785 PMCID: PMC3155796 DOI: 10.1155/2012/181687]

The present study was designed to investigate the impact of exercise training on lipogenic gene expression in liver and lipid partitioning following the ingestion of a high fructose load. Female rats were exercise-trained for 8 wk or kept sedentary before being submitted to a fasting/refeeding protocol. Rats were further subdivided as follow: rats were fasted for 24 h, refed a standard diet for 24 h, starved for another 24 h, and refed with a standard or a high-fructose diet 24 h before sacrifice. Fructose refeeding was associated with an increase in hepatic lipid content, endocannabinoid receptor 1, sterol regulatory element-binding protein1c, and stearoyl-CoA desaturase1 gene expression in both Sed and TR rats. However, desaturation indexes measured in liver (C16 : 1/C16 : 0 and C18 : 1/C18 : 0) and plasma (C18 : 1/C18 : 0) were higher (P < 0.01) in TR than in Sed rats following fructose refeeding. It is concluded that exercise training does not significantly affect fat accumulation and the molecular expression of genes involved in lipogenesis after fasting and fructose refeeding but does modify the partitioning of lipids so as to provide more unsaturated fatty acids in liver without affecting liver fat content.

The influence of intense intermittent versus moderate continuous exercise on postprandial lipemia

INTRODUCTION

Postprandial lipemia is characterized by an increased concentration of circulating lipids after fat intake and is an independent risk factor for cardiovascular disease. Exercise is known to reduce postprandial lipemia and its negative clinical outcomes.

OBJECTIVE

This study investigated the effect of intense intermittent versus moderate continuous exercise using the same energy expenditure in postprandial lipemia.

MATERIALS AND METHODS

Twenty healthy men (aged 21.5 ± 3.5 years) performed a random sequence of either rest or 500 Kcal tests separated by a minimum 48 h interval as follows: (a) no exercise (control), (b) intense intermittent exercise, or (c) moderate continuous exercise. Each test series was completed 30 min before ingestion of a high-fat meal (1 g fat/kg). Venous blood was collected before and at 1, 2, 3 and 4 hours after the high-fat meal. Postprandial lipemia was assessed using the area under the curve approach as well as a kinetic profile of mean lipid variables. Statistical significance was tested at the p<0.05 level.

RESULTS

With both statistical approaches, intense intermittent and moderate continuous exercises were both effective in reducing postprandial triglycerides; however, only intense intermittent exercise reduced the levels of postprandial very low density lipoprotein. Intense intermittent and continuous exercise produced lower levels of insulinemia using the area under the curve analysis only.

CONCLUSION

Intense intermittent or continuous exercise with an energy expenditure of 500 kcal completed 30 min before ingestion of high-fat meal reduced postprandial lipid levels to different levels in physically active men. Understanding these relevant differences will enable clinicians to provide the best exercise prescription for patients.

Effects of different protein sources on plasminogen inhibitor-1 and factor VII coagulant activity added to a fat-rich meal in type 2 diabetes

BACKGROUND

Exaggerated postprandial triglyceride concentration is believed to be atherogenic, and to influence the risk of thrombosis. Both elevated plasminogen inhibitor 1 (PAI-1) and increased factor VII coagulant activity (FVIIc) are potential important contributors to the increased risk of cardiovascular disease in type 2 diabetes.

AIM

We aimed to investigate the effect of adding four different protein types (i.e. casein, whey, cod, and gluten) to a fat-rich meal on postprandial responses of PAI-1 and FVIIc in type 2 diabetic patients.

METHODS

Twelve type 2 diabetic patients ingested four isocaloric test meals in random order. The test meals contained 100 g of butter and 45 g of carbohydrate in combination with 45 g of casein (Cas-meal), whey (Whe-meal), cod (Cod-meal), or gluten (Glu-meal), respectively. Plasma concentrations of PAI-1 and FVIIc were measured before meal, and at regular intervals for 8-h postprandially.

RESULTS

The postprandial PAI-1 concentration decreased significantly by 49% to 56% in response to the four test meals. There were no significant differences between the outcomes from the four test-meals. The FVIIc levels decreased by 8% to 11% after the meals. Again, we observed no significant differences in outcomes between the four protein-enriched meals.

CONCLUSIONS

The four proteins casein, whey, cod, and gluten, added to a fat-rich meal, all decreased the PAI-1 and FVIIc concentrations postprandially in type 2 diabetic subjects. However, postprandial levels of PAI-1 and FVIIc were not acutely influenced by the protein source.

Beta-arrestin inhibits CAMKKbeta-dependent AMPK activation downstream of protease-activated-receptor-2

Background

Proteinase-activated-receptor-2 (PAR₂) is a seven transmembrane receptor that can activate two separate signaling arms: one through Gαq and Ca²⁺ mobilization, and a second through recruitment of β-arrestin scaffolds. In some cases downstream targets of the Gαq/Ca²⁺ signaling arm are directly inhibited by β-arrestins, while in other cases the two pathways are synergistic; thus β-arrestins act as molecular switches capable of modifying the signal generated by the receptor.

Results

Here we demonstrate that PAR₂ can activate adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy balance, through Ca²⁺-dependent Kinase Kinase β (CAMKKβ), while inhibiting AMPK through interaction with β-arrestins. The ultimate outcome of PAR₂ activation depended on the cell type studied; in cultured fibroblasts with low endogenous β-arrestins, PAR₂ activated AMPK; however, in primary fat and liver, PAR₂ only activated AMPK in β-arrestin-2^-/- mice. β-arrestin-2 could be co-immunoprecipitated with AMPK and CAMKKβ under baseline conditions from both cultured fibroblasts and primary fat, and its association with both proteins was increased by PAR₂ activation. Addition of recombinant β-arrestin-2 to in vitro kinase assays directly inhibited phosphorylation of AMPK by CAMKKβ on Thr172.

Conclusions

Studies have shown that decreased AMPK activity is associated with obesity and Type II Diabetes, while AMPK activity is increased with metabolically favorable conditions and cholesterol lowering drugs. These results suggest a role for β-arrestin in the inhibition of AMPK signaling, raising the possibility that β-arrestin-dependent PAR₂ signaling may act as a molecular switch turning a positive signal to AMPK into an inhibitory one.

Effect of intensity of resistance exercise on postprandial lipemia

The purpose of this study is to determine whether moderate-intensity resistance exercise (MOD) lowers postprandial lipemia (PPL) as much as high-intensity resistance exercise (HI) of equal work. Ten healthy men performed three trials, each conducted over 2 days. On day 1 of each treatment, they either did not exercise (CON), performed 3 sets of 16 repetitions of 10 exercises at 50% of 8 repetitions maximum (MOD), or performed 3 sets of 8 repetitions of 10 exercises at 100% of 8 repetitions maximum (HI). On the morning of day 2 at 15.5 h postexercise, participants ate a high-fat meal. Venous blood samples were collected, and metabolic rate was measured at rest and 3 h postprandial. HI reduced fasting triglyceride (TG) and TG area under the curve (AUC) (36%, P = 0.011 and 35%, P = 0.014) compared with CON. MOD tended to reduce fasting TG and TG AUC (21%, P = 0.054 and 26%, P = 0.052) compared with CON, but MOD and HI did not differ in fasting TG or TG AUC. Incremental TG AUC did not differ among treatments. MOD and HI did not change resting metabolic rate. HI increased fat oxidation at rest (21%, P = 0.021) and at 3 h postprandial (39%, P = 0.009) relative to CON. MOD tended to increase fat oxidation at rest (18%, P = 0.060) relative to CON. Fat oxidation and metabolic rate did not differ in MOD and HI. MOD and HI increased the fasting quantitative insulin-sensitivity check index (4%, P = 0.001 and P = 0.004) relative to CON. As MOD and HI resulted in similar reductions in PPL and increases in fat oxidation, resistance exercise intensity does not influence PPL.

Assessing individual metabolic responsiveness to a lipid challenge using a targeted metabolomic approach

The development of assessment techniques with immediate clinical applicability is a priority for resolving the growing epidemic in metabolic disease. Many imbalances in diet-dependent metabolism are not detectable in the fasted state. Resolving the high inter-individual variability in response to diet requires the development of techniques that can detect metabolic dysfunction at the level of the individual. The intra- and inter-individual variation in lipid metabolism in response to a standardized test meal was determined. Following an overnight fast on three different days, three healthy subjects consumed a test meal containing 40% of their daily calories. Plasma samples were collected at fasting, and 1, 3, 6, and 8 h after the test meal. Plasma fatty acid (FA) concentrations within separated lipid classes and lipoprotein fractions were measured at each time point. The intra-individual variation within each subject across three days was lower than the inter-individual differences among the three subjects for over 50% of metabolites in the triacylglycerol (TG), FA, and phosphatidylcholine (PC) lipid classes at 6 h, and for 25-50% of metabolites across lipid classes at 0, 1, 3, and 8 h. The consistency of response within individuals was visualized by principal component analysis (PCA) and confirmed by ANOVA. Three representative metabolites that discriminated among the three individuals in the apolipoprotein B (ApoB) fraction, TG16:1n7, TG18:2n6, and PC18:3n3, are discussed in detail. The postprandial responses of individuals were unique within metabolites that were individual discriminators (ID) of metabolic phenotype. This study shows that the targeted metabolomic measurement of individual metabolic phenotype in response to a specially formulated lipid challenge is possible even without lead-in periods, dietary and lifestyle control, or intervention over a 3-month period in healthy free-living individuals.

Reproducibility of postprandial lipemia tests and validity of an abbreviated 4-hour test

Postprandial lipemia test (PPLT) results are predictive of cardiovascular disease risk. However, their reproducibility must be established before they can be clinically useful. Therefore, we investigated PPLT reproducibility by testing 9 men and women (body mass index, 20-41 kg/m(2); age, 21-40 years) on 4 separate occasions (n = 36 PPLTs total) separated by 1 week. Furthermore, because PPLTs are time consuming, we assessed the validity of an abbreviated PPLT. During the PPLT, venous blood was obtained before and every hour for 8 hours after a high-fat meal, which consisted of ice cream and heavy cream (approximately 800 kcal, 71% fat calories). Total and triglyceride-rich lipoprotein (TRL) triglyceride concentrations were measured in plasma. Total area under the curve (AUC) for total triglycerides was highly reproducible (within-subject coefficient of variation, 8%; intraclass correlation coefficient, 0.82); however, reproducibility was low for total triglyceride incremental AUC and both total and incremental TRL triglyceride AUCs (within-subject coefficients of variation, 20%-31%; intraclass correlation coefficients, 0.28-0.54). Four-hour lipemic responses were highly predictive of 8-hour responses (R(2) = 0.89-0.96, P Collapse

Key Words

• high-fat meal
• fat tolerance test
• triglyceride-rich lipoprotein
• lipid metabolism

Collapse

MESH Headings

• Adult
• Area Under Curve
• Female
• Humans
• Hyperlipidemias/blood
• Linear Models
• Lipoproteins/blood
• Male
• Postprandial Period
• Reproducibility of Results
• Time Factors
• Triglycerides/blood

Collapse

Grants

• M01 RR000036-431425 NCRR NIH HHS
• AG-00078 NIA NIH HHS
• HD-0145901 NICHD NIH HHS
• M01 RR000036 NCRR NIH HHS
• P30 DK056341 NIDDK NIH HHS
• P30 DK056341-07 NIDDK NIH HHS
• T32 AG000078-25 NIA NIH HHS
• K12 HD001459 NICHD NIH HHS
• R01 DK037948-14 NIDDK NIH HHS
• DK-37948 NIDDK NIH HHS
• T32 AG000078-24 NIA NIH HHS
• K12 HD001459-01 NICHD NIH HHS
• R01 DK037948 NIDDK NIH HHS
• DK-56341 NIDDK NIH HHS
• RR-00036 NCRR NIH HHS
• T32 AG000078 NIA NIH HHS

Collapse

Affiliation(s)

Edward P Weiss Division of Geriatrics and Nutritional Science, Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA.
David A Fields
Bettina Mittendorfer
M A Dorien Haverkort
Samuel Klein

Collapse

A low-glycemic-index diet reduces plasma plasminogen activator inhibitor-1 activity, but not tissue inhibitor of proteinases-1 or plasminogen activator inhibitor-1 protein, in overweight women

BACKGROUND

The development of obesity has been suggested to involve plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of proteinases-1 (TIMP-1). Plasma PAI-1 is elevated in obesity. A low-glycemic-index (LGI) diet may have a beneficial effect on obesity through a decrease in plasma PAI-1, but whether it affects plasma TIMP-1 in healthy humans has not been studied.

OBJECTIVE

We investigated whether a 10-wk intake of an LGI or a high-glycemic-index (HGI), high-carbohydrate, low-fat, ad libitum diet is associated with decreases in plasma PAI-1 and TIMP-1 concentrations in overweight women.

DESIGN

Forty-four overweight women [body mass index (BMI; in kg/m2): 27.5+/-0.23] were randomly assigned to consume an HGI or an LGI diet for 10 wk. A subgroup of 29 women was assigned to participate in an additional 4-h meal test on the last day of the 10-wk intervention.

RESULTS

PAI-1 activity decreased after 10 wk of the LGI diet and was significantly different between groups. Changes in PAI-1 antigen followed the same trend, but no significant difference was observed between groups. No difference in plasma TIMP-1 concentrations was observed between groups. PAI-1 and TIMP-1 concentrations after the 4-h meal test were not significantly different between groups.

CONCLUSION

An LGI diet reduces fasting plasma PAI-1 activity and therefore may be useful for diminishing the adverse cardiovascular effects of obesity. This trial was registered at clinicaltrials.gov as NCT00324090.

Aerobic exercise bout effects on gene transcription in the rat soleus

PURPOSE

This study was designed to identify changes in gene transcription that occur in the soleus muscle of untrained, 10-wk-old rats after a single aerobic exercise bout, and to identify which families of genes are most likely affected.

METHODS

Rats were either run for 2 h and killed 1 h after exercise, or they remained sedentary and were killed at a matched time. Soleus muscles from each animal were examined using DNA microarrays, four genes related to RONS were analyzed by PCR, and two proteins were checked by Western blot analysis.

RESULTS

The microarray identified 52 genes significantly altered by the exercise. The major gene families altered were metabolism, apoptosis, muscle contraction, transcription/cell signaling, tissue generation, and inflammation. Real-time PCR was performed on four genes (NFkappaB, TNFalpha, Atf3, and Mgst1), and the results from PCR analysis agreed with the microarray results. NFkappaB and TNFalpha were unaltered, whereas Atf3 was upregulated and Mgst1 was downregulated in the exercised soleus muscles. NFkappaB protein level was not different between the two groups, whereas Atf3 protein level was elevated in the exercise group according to Western blot analysis.

CONCLUSIONS

These data suggest that 1 h after a 2-h run at approximately 65% of VO2max, the soleus muscle undergoes significant gene-transcript changes. Also, the genes examined with the real-time PCR matched the microarray results and the measured protein concentration concentrations agreed with gene-transcript data at the 1-h postexercise time point.