Physiology - Research Publications
Now showing items 1-12 of 367
The Impact of Frailty on the Effectiveness and Safety of Intensive Glucose Control and Blood Pressure-Lowering Therapy for People With Type 2 Diabetes: Results From the ADVANCE Trial
(AMER DIABETES ASSOC, 2021-07-01)
OBJECTIVE: To develop a frailty index (FI) and explore the relationship of frailty to subsequent adverse outcomes on the effectiveness and safety of more intensive control of both blood glucose and blood pressure (BP), among participants with type 2 diabetes in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial. RESEARCH DESIGN AND METHODS: Cox proportional hazard models were used to estimate the effectiveness and safety of intensive glucose control and BP intervention according to frailty (defined as FI >0.21) status. The primary outcomes were macro- and microvascular events. The secondary outcomes were all-cause mortality, cardiovascular mortality, severe hypoglycemia, and discontinuation of BP treatment due to hypotension/dizziness. RESULTS: There were 11,140 participants (mean age, 65.8 years; 42.5% women, 25.7% frail). Frailty was an independent predictor of all primary outcomes and secondary outcomes. The effect of intensive glucose treatment on primary outcomes showed some evidence of attenuation in the frail: hazard ratios for combined major macro- and microvascular events 1.03 (95% CI 0.90-1.19) in the frail versus 0.84 (95% CI 0.74-0.94) in the nonfrail (P = 0.02). A similar trend was observed with BP intervention. Severe hypoglycemia rates (per 1,000 person-years) were higher in the frail: 8.39 (6.15-10.63) vs. 4.80 (3.84-5.76) in nonfrail (P < 0.001). There was no significant difference in discontinuation of BP treatment between frailty groups. CONCLUSIONS: It was possible to retrospectively estimate frailty in a trial population, and this FI identified those at higher risk of poor outcomes. Participants with frailty had some attenuation of benefit from intensive glucose-lowering and BP-lowering treatments.
Polygenic risk scores predict diabetes complications and their response to intensive blood pressure and glucose control
AIMS/HYPOTHESIS: Type 2 diabetes increases the risk of cardiovascular and renal complications, but early risk prediction could lead to timely intervention and better outcomes. Genetic information can be used to enable early detection of risk. METHODS: We developed a multi-polygenic risk score (multiPRS) that combines ten weighted PRSs (10 wPRS) composed of 598 SNPs associated with main risk factors and outcomes of type 2 diabetes, derived from summary statistics data of genome-wide association studies. The 10 wPRS, first principal component of ethnicity, sex, age at onset and diabetes duration were included into one logistic regression model to predict micro- and macrovascular outcomes in 4098 participants in the ADVANCE study and 17,604 individuals with type 2 diabetes in the UK Biobank study. RESULTS: The model showed a similar predictive performance for cardiovascular and renal complications in different cohorts. It identified the top 30% of ADVANCE participants with a mean of 3.1-fold increased risk of major micro- and macrovascular events (p = 6.3 × 10-21 and p = 9.6 × 10-31, respectively) and a 4.4-fold (p = 6.8 × 10-33) higher risk of cardiovascular death. While in ADVANCE overall, combined intensive blood pressure and glucose control decreased cardiovascular death by 24%, the model identified a high-risk group in whom it decreased the mortality rate by 47%, and a low-risk group in whom it had no discernible effect. High-risk individuals had the greatest absolute risk reduction with a number needed to treat of 12 to prevent one cardiovascular death over 5 years. CONCLUSIONS/INTERPRETATION: This novel multiPRS model stratified individuals with type 2 diabetes according to risk of complications and helped to target earlier those who would receive greater benefit from intensive therapy.
Phosphoproteomics reveals conserved exercise-stimulated signaling and AMPK regulation of store-operated calcium entry
Exercise stimulates cellular and physiological adaptations that are associated with widespread health benefits. To uncover conserved protein phosphorylation events underlying this adaptive response, we performed mass spectrometry-based phosphoproteomic analyses of skeletal muscle from two widely used rodent models: treadmill running in mice and in situ muscle contraction in rats. We overlaid these phosphoproteomic signatures with cycling in humans to identify common cross-species phosphosite responses, as well as unique model-specific regulation. We identified > 22,000 phosphosites, revealing orthologous protein phosphorylation and overlapping signaling pathways regulated by exercise. This included two conserved phosphosites on stromal interaction molecule 1 (STIM1), which we validate as AMPK substrates. Furthermore, we demonstrate that AMPK-mediated phosphorylation of STIM1 negatively regulates store-operated calcium entry, and this is beneficial for exercise in Drosophila. This integrated cross-species resource of exercise-regulated signaling in human, mouse, and rat skeletal muscle has uncovered conserved networks and unraveled crosstalk between AMPK and intracellular calcium flux.
Response of 1,5-anhydroglucitol level to intensive glucose- and blood-pressure lowering interventions, and its associations with clinical outcomes in the ADVANCE trial
AIMS: To evaluate 1,5-anhydroglucitol (1,5-AG) according to clinical outcomes and assess the effects of glucose- and blood pressure-lowering interventions on change in 1,5-AG levels in people with type 2 diabetes. METHODS: We measured 1,5-AG in 6826 stored samples at baseline and in a random subsample of 684 participants at the 1-year follow-up visit in the ADVANCE trial. We examined baseline 1,5-AG [< 39.7, 39.7-66.2, ≥ 66.2 μmol/L (<6, 6-10, ≥10 μg/mL)] and microvascular and macrovascular events and mortality using Cox regression models during 5 years of follow-up. Using an intention-to-treat approach, we examined 1-year change in 1,5-AG (mean and percent) in response to the glucose- and blood pressure-lowering interventions in the subsample. RESULTS: Low 1,5-AG level [<39.7 μmol/L vs ≥ 66.2 μmol/L (<6 μg/mL vs ≥10 μg/mL)] was associated with microvascular events (hazard ratio 1.28, 95% confidence interval 1.03-1.60) after adjustment for risk factors and baseline glycated haemoglobin (HbA1c); however, the associations for macrovascular events and mortality were not independent of HbA1c. The glucose-lowering intervention was associated with a significant 1-year increase in 1,5-AG (vs standard control) of 6.69 μmol/L (SE 2.52) [1.01 μg/mL (SE 0.38)], corresponding to an 8.26% (SE 0.10%) increase from baseline. We also observed an increase in 1,5-AG of similar magnitude in response to the blood pressure intervention independent of the glucose-lowering effect. CONCLUSIONS: Our results suggest that 1,5-AG is a marker of risk in adults with type 2 diabetes, but only for microvascular events independently of HbA1c. We found that 1,5-AG was improved (increased) in response to an intensive glucose-lowering intervention, although the independent effect of the blood pressure-lowering intervention on 1,5-AG suggests potential non-glycaemic influences.
Elevated maternal linoleic acid reduces circulating leptin concentrations, cholesterol levels and male fetal survival in a rat model.
KEY POINTS: Linoleic acid consumption is increasing in Western populations. We investigated whether elevated linoleic acid in pregnancy was deleterious to mothers or offspring. Maternal and fetal body and organ weights were not affected by elevated linoleic acid consumption. Maternal lipids and leptin were altered following elevated linoleic acid consumption. Male offspring numbers were reduced following elevated linoleic acid consumption. ABSTRACT: Dietary intakes of linoleic acid (LA) have increased dramatically in Western populations, including in women of reproductive age. Pro-inflammatory effects of LA may have detrimental effects on maternal and offspring outcomes. We aimed to investigate whether consumption of a maternal diet with elevated LA altered maternal inflammatory or metabolic markers during pregnancy, fetal growth and/or the sex ratio of the offspring. Female Wistar Kyoto rats consumed a diet high in LA (HLA) (6.21% of energy) or a diet low in LA (LLA) (1.44% of energy) for 10 weeks prior to mating and during pregnancy. Pregnant rats were killed at embryonic day 20 (E20). There were no differences in maternal or fetal body weights or organ weights in the HLA group compared to the LLA group. There was no difference in maternal circulating cytokine concentrations between dietary groups. In the maternal liver, IL-1α concentrations were significantly lower, and TNF-α and IL-7 significantly higher in the HLA group. Total plasma cholesterol, LDL-cholesterol, HDL cholesterol and the total:HDL cholesterol ratio were lower in dams fed the HLA diet. mRNA expression of sterol regulatory element binding transcription factor 1 (SREBF-1) and leptin in maternal adipose tissue was lower in the HLA group, as were circulating leptin concentrations. The proportion of male fetuses was lower and circulating prostaglandin E metabolite concentrations were increased in the HLA group. In conclusion, consumption of a maternal diet high in linoleic acid alters cholesterol metabolism and prostaglandin E metabolite concentrations, which may contribute to the reduced proportion of male offspring.
Exercise initiated during pregnancy in rats born growth restricted alters placental mTOR and nutrient transporter expression
KEY POINTS: Fetal growth is dependent on effective placental nutrient transportation, which is regulated by mammalian target of rapamycin (mTOR) complex 1 modulation of nutrient transporter expression. These transporters are dysregulated in pregnancies affected by uteroplacental insufficiency and maternal obesity. Nutrient transporters and mTOR were altered in placentae of mothers born growth restricted compared to normal birth weight dams, with maternal diet- and fetal sex-specific responses. Exercise initiated during pregnancy downregulated mTOR protein expression, despite an increase in mTOR activation in male associated placentae, and reduced nutrient transporter gene abundance, which was also dependent on maternal diet and fetal sex. Limited changes were characterized with exercise initiated before and continued throughout pregnancy in nutrient transporter and mTOR expression. Maternal exercise during pregnancy differentially regulated mTOR and nutrient transporters in a diet- and sex-specific manner, which likely aimed to improve late gestational placental growth and neonatal survival. ABSTRACT: Adequate transplacental nutrient delivery is essential for fetoplacental development. Intrauterine growth restriction and maternal obesity independently alter placental nutrient transporter expression. Although exercise is beneficial for maternal health, limited studies have characterized how the timing of exercise initiation influences placental nutrient transport. Therefore, this study investigated the impact of maternal exercise on placental mechanistic target of rapamycin (mTOR) and nutrient transporter expression in growth restricted mothers and whether these outcomes were dependent on maternal diet or fetal sex. Uteroplacental insufficiency or sham surgery was induced on embryonic day (E) 18 in Wistar-Kyoto rats. F1 offspring were fed a chow or high-fat diet from weaning and at 16 weeks were randomly allocated to an exercise protocol: sedentary, exercised prior to and during pregnancy, or exercised during pregnancy only. Females were mated with normal males (20 weeks) and F2 placentae collected at E20. Exercise during pregnancy only, reduced mTOR protein expression in all groups and increased mTOR activation in male associated placentae. Exercise during pregnancy only, decreased the expression of amino acid transporters in a diet- and sex-specific manner. Maternal growth restriction altered mTOR and system A amino acid transporter expression in a sex- and diet-specific manner. These data highlight that maternal exercise initiated during pregnancy alters placental mTOR expression, which may directly regulate amino acid transporter expression, to a greater extent than exercise initiated prior to and continued during pregnancy, in a diet- and fetal sex-dependent manner. These findings highlight that the timing of exercise initiation is important for optimal placental function.
Use of the waist-to-height ratio to predict cardiovascular risk in patients with diabetes: Results from the ADVANCE-ON study
AIMS: Patients with type 2 diabetes have a high risk of cardiovascular disease (CVD). Central obesity has been particularly associated with this risk relationship. We aimed to evaluate waist to height ratio (WHtR) as a predictor of risk in such patients. METHODS: WHtR was evaluated as a predictor of the risk of CVD and mortality amongst 11 125 participants with type 2 diabetes in the ADVANCE and ADVANCE-ON studies, and was compared with body mass index (BMI), waist circumference and waist hip ratio (WHR). Primary outcome was a composite of death from CVD, non-fatal myocardial infarction or non-fatal stroke. Secondary outcomes were myocardial infarction, stroke, cardiovascular death and death from any cause. Cox models were used, with bootstrapping to compare associations between anthropometric measures for the primary outcome. RESULTS: Median follow-up time was 9.0 years. There was a positive association between WHtR and adverse outcomes. The hazard ratio (HR) (confidence interval), per SD higher WHtR, was 1.16 (1.11-1.22) for the primary endpoint, with no heterogeneity by sex or region, but a stronger effect in individuals aged 66 years or older. The other 3 anthropometric measurements showed similar associations, although there was evidence that WHtR marginally outperformed BMI and WHR. Based on commonly used BMI cut-points, the equivalent WHtR cut-points were estimated to be 0.55 and 0.6, with no evidence of a difference across subgroups. CONCLUSIONS: In patients with diabetes, WHtR is a useful indicator of future adverse risk, with similar effects in different population subgroups.
Sex differences in risk factors for cognitive decline and dementia, including death as a competing risk, in individuals with diabetes: Results from the ADVANCE trial
AIM: To estimate the associations between risk factors and cognitive decline (CD)/dementia, and the sex differences in these risk factors in individuals with type 2 diabetes, while accounting for the competing risk of death. MATERIALS AND METHODS: The Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial of 11,140 individuals with type 2 diabetes was used to estimate the odds of CD/dementia using multinomial logistic regression. RESULTS: During a median 5-year follow-up, 1827 participants (43.2% women) had CD/dementia (1718 with CD only; 21 with dementia only; 88 with CD and dementia), and 929 (31.0% women) died without CD/dementia. Women had lower odds of CD/dementia than men (odds ratio [OR] [95% confidence interval], 0.88 [0.77, 1.00]); older age, higher total cholesterol, HbA1c, waist circumference, waist-to-height ratio, moderately increased albumin-creatinine ratio, stroke/transient ischaemic attack and retinal disease were each associated with greater odds of CD/dementia; higher years at education completion, baseline cognitive function, taller stature and current alcohol use were inversely associated. Higher waist circumference (women-to-men ratio of ORs [ROR], 1.05 [1.00, 1.10] per 5 cm) and presence of anxiety/depression (ROR, 1.28 [1.01, 1.63]) were associated with greater ORs for CD/dementia in women than men. CONCLUSIONS: Several risk factors were associated with CD/dementia. Higher waist circumference and mental health symptoms were more strongly associated with CD/dementia in women than men. Further studies should examine the mechanisms that underlie these sex differences.
Cardiac mechanical efficiency is preserved in primary cardiac hypertrophy despite impaired mechanical function
(ROCKEFELLER UNIV PRESS, 2021-08-02)
Increased heart size is a major risk factor for heart failure and premature mortality. Although abnormal heart growth subsequent to hypertension often accompanies disturbances in mechano-energetics and cardiac efficiency, it remains uncertain whether hypertrophy is their primary driver. In this study, we aimed to investigate the direct association between cardiac hypertrophy and cardiac mechano-energetics using isolated left-ventricular trabeculae from a rat model of primary cardiac hypertrophy and its control. We evaluated energy expenditure (heat output) and mechanical performance (force length work production) simultaneously at a range of preloads and afterloads in a microcalorimeter, we determined energy expenditure related to cross-bridge cycling and Ca2+ cycling (activation heat), and we quantified energy efficiency. Rats with cardiac hypertrophy exhibited increased cardiomyocyte length and width. Their trabeculae showed mechanical impairment, evidenced by lower force production, extent and kinetics of shortening, and work output. Lower force was associated with lower energy expenditure related to Ca2+ cycling and to cross-bridge cycling. However, despite these changes, both mechanical and cross-bridge energy efficiency were unchanged. Our results show that cardiac hypertrophy is associated with impaired contractile performance and with preservation of energy efficiency. These findings provide direction for future investigations targeting metabolic and Ca2+ disturbances underlying cardiac mechanical and energetic impairment in primary cardiac hypertrophy.
Sex-specific associations between cardiovascular risk factors and myocardial infarction in patients with type 2 diabetes: TheADVANCE-ONstudy
AIM: To examine possible sex differences in the excess risk of myocardial infarction (MI) consequent to a range of conventional risk factors in a large-scale international cohort of patients with diabetes, and to quantify these potential differences both on the relative and absolute scales. MATERIALS AND METHODS: Eleven thousand and sixty-five participants (42% women) with type 2 diabetes in the ADVANCE trial and its post-trial follow-up study, ADVANCE-ON, were included. Cox regression models were used to estimate hazard ratios (HRs) for associations between risk factors and MI (fatal and non-fatal) by sex, and the women-to-men ratio of HRs (RHR). RESULTS: Over a median of 9.6 years of follow-up, 719 patients experienced MI. Smoking status, smoking intensity, higher systolic blood pressure (SBP), HbA1c, total and LDL cholesterol, duration of diabetes, triglycerides, body mass index (BMI) and lower HDL cholesterol were associated with an increased risk of MI in both sexes. Furthermore, some variables were associated with a greater relative risk of MI in women than men: RHRs were 1.75 (95% CI: 1.05-2.91) for current smoking, 1.53 (1.00-2.32) for former smoking, 1.18 (1.02-1.37) for SBP, and 1.13 (95% CI, 1.003-1.26) for duration of diabetes. Although incidence rates of MI were higher in men (9.3 per 1000 person-years) compared with women (5.8 per 1000 person-years), rate differences associated with risk factors were greater in women than men, except for HDL cholesterol and BMI. CONCLUSIONS: In patients with type 2 diabetes, smoking, higher SBP and longer duration of diabetes had a greater relative and absolute effect in women than men, highlighting the importance of routine sex-specific approaches and early interventions in women with diabetes.
Role of omega-6 and omega-3 fatty acids in fetal programming.
Maternal nutrition plays a critical role in fetal development and can influence adult onset of disease. Linoleic acid (LA) and alpha-linolenic acid (ALA) are major omega-6 (n-6) and n-3 polyunsaturated fatty acids (PUFA), respectively, that are essential in our diet. LA and ALA are critical for the development of the fetal neurological and immune systems. However, in recent years, the consumption of n-6 PUFA has increased gradually worldwide, and elevated n-6 PUFA consumption may be harmful to human health. Consumption of diets with high levels of n-6 PUFA before or during pregnancy may have detrimental effects on fetal development and may influence overall health of offspring in adulthood. This review discusses the role of n-6 PUFA in fetal programming, the importance of a balance between n-6 and n-3 PUFAs in the maternal diet, and the need of further animal models and human studies that critically evaluate both n-6 and n-3 PUFA contents in diets.
The effect of high maternal linoleic acid on endocannabinoid signalling in rodent hearts.
(Cambridge University Press (CUP), 2020-12)
The endocannabinoid system (ECS), modulated by metabolites of linoleic acid (LA), is important in regulating cardiovascular function. In pregnancy, LA is vital for foetal development. We investigated the effects of elevated LA in H9c2 cardiomyoblasts in vitro and of a high linoleic acid (HLA, 6.21%) or low linoleic acid (LLA, 1.44%) diet during pregnancy in maternal and offspring hearts. H9c2 cell viability was reduced following LA exposure at concentrations between 300 and 1000 µM. HLA diet decreased cannabinoid receptor type 2 (CB2) mRNA expression in foetal hearts from both sexes. However, HLA diet increased CB2 expression in maternal hearts. The mRNA expression of fatty acid amide hydrolase (FAAH) in foetal hearts was higher in females than in males irrespective of diet and N-acyl phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) mRNA expression showed an interaction between diet and sex. Data indicate that a high LA diet alters cell viability and CB2 expression, potentially influencing cardiac function during pregnancy and development of the offspring's heart.