Sympathovagal quotient and resting-state functional connectivity of control networks are related to gut Ruminococcaceae abundance in healthy men

INTRODUCTION

Heart rate variability (HRV), brain resting-state functional connectivity (rsFC), and gut microbiota (GM) are three recognized indicators of health status, whose relationship has not been characterized. We aimed to identify the GM genera and families related to HRV and rsFC, the interaction effect of HRV and rsFC on GM taxa abundance, and the mediation effect of diet on these relationships.

METHODS

Eighty-eight healthy, young Colombian men were included in this cross-sectional study. HRV metrics were extracted from 24-hour Holter monitoring data and the resting functional connectivity strength (FCS) of 15 networks were derived from functional magnetic resonance imaging. Gut microbiota composition was assessed using the sequences of the V3-V4 regions of the 16 S rRNA gene, and diet was evaluated using a food frequency questionnaire. Multivariate linear regression analyses were performed to evaluate the correlations between the independent variables (HRV metrics and FCS) and the dependent variables (GM taxa abundance or alpha diversity indexes). Mediation analyses were used to test the role of diet in the relationship between HRV and GM.

RESULTS

The sympathovagal quotient (SQ) and the FCS of control networks were positively correlated with the abundance of the gut Ruminococcaceae family and an unclassified Ruminococcaceae genus (Ruminococcaceae_unc). Additionally, the interaction between the FCS of the control network and SQ reduced the individual main effects on the Ruminococcaceae_unc abundance. Finally, reduced habitual fiber intake partially mediated the relationship between SQ and this genus.

CONCLUSION

Two indicators of self-regulation, HRV and the rsFC of control networks, are related to the abundance of gut microbiota taxa in healthy men. However, only HRV is related to habitual dietary intake; thus, HRV could serve as a marker of food choice and GM composition in the future.

Safety of High-Intensity, Low-Volume Interval Training or Continuous Aerobic Training in Adults With Metabolic Syndrome

OBJECTIVE

The aim of the study was to evaluate the safety of high-intensity, low-volume interval training (HIIT-low volume) compared with moderate-intensity continuous aerobic training (MICT) in adults with metabolic syndrome.

METHODS

This is a controlled, randomized, clinical trial in patients without history of ischemic heart disease or diabetes, who underwent a supervised, 3 sessions/week, 12-week treadmill exercise program. The HIIT-low volume (n = 29) sessions consisted of 6 intervals with 1-minute, high-intensity phases at 90% of peak oxygen consumption (VO2peak). The MICT (n = 31) trained at 60% of VO2peak for 30 minutes. A new approach to record and classify all clinical events according to possible causality based on Naranjo's algorithm was developed.

RESULTS

Patients were 50.8 ± 6.0 years old, 70% women, with body mass index of 30.6 ± 4.0 kg/m2 and VO2peak of 29.0 ± 6.3 mL·kg-1·min-1. In total, 60 clinical events were recorded in the HIIT-low volume group and 48 in the MICT group, with 59.3% classified as general disease. Only 21 events were classified as adverse reactions possibly related to exercise, without any serious adverse reactions. Both interventions had a similar incidence of musculoskeletal events (incidence rate ratio, 1.1; 95% confidence interval, 0.6-1.8), but HIIT-low volume had a higher incidence of cardiovascular events (incidence rate ratio, 2.9; 95% CI, 0.4-22.8) after adjusting for age, sex, and body mass index (HIIT-low volume: chest pain [n = 1] and symptoms of venous insufficiency of lower limbs [n = 2]; MICT: chest pain [n = 1]).

CONCLUSIONS

The HIIT-low volume and MICT are safe in patients with metabolic syndrome. We recommend a muscle-conditioning program prior to both and to avoid HIIT-low volume in treadmill in patients with venous insufficiency of the lower limbs.Trial registration number NCT03087721.

A novel method for the noninvasive estimation of cardiac output with brachial oscillometric blood pressure measurements through an assessment of arterial compliance

OBJECTIVE

To propose and validate a new method for estimating cardiac output based on the total arterial compliance (Ct) formula that does not need an arterial waveform and to apply it to brachial oscillometric blood pressure measurements (OBPMs).

METHODS

One hundred subjects with normal heart anatomy and function were included. Reference values for cardiac output were measured with echocardiography, and Ct was calculated with a two-element Windkessel model. Then, a statistical model of arterial compliance (Ce) was used to estimate cardiac output. Finally, the measured and estimated cardiac output values were compared for accuracy and reproducibility.

RESULTS

The model was derived from the data of 70 subjects and prospectively tested with the data from the remaining 30 individuals. The mean age of the whole group was 43.4 ± 12.8 years, with 46% women. The average blood pressure (BP) was 107.1/65.0 ± 15.0/9.6 mmHg and the average heart rate was 67.7 ± 11.4 beats/min. The average Ct was 1.39 ± 0.27 mL/mmHg and the average cardiac output was 5.5 ± 1.0 L/min. The mean difference in the cardiac output estimated by the proposed methodology vs. that measured by Doppler echocardiography was 0.022 L/min with an SD of 0.626 L/min. The intraclass correlation coefficient was 0.93, and the percentage error was 19%.

CONCLUSION

Cardiac output could be reliably and noninvasively obtained with brachial OBPMs through a novel method for estimating Ct without the need for an arterial waveform. The new method could identify hemodynamic factors that explain BP values in an ambulatory care setting.

Musclin Is Related to Insulin Resistance and Body Composition, but Not to Body Mass Index or Cardiorespiratory Capacity in Adults

BACKGROUND

We studied whether musclin function in humans is related to glycemic control, body composition, and cardiorespiratory capacity.

METHODS

A cross-sectional study was performed in sedentary adults with or without metabolic syndrome (MS). Serum musclin was measured by enzyme-linked immunosorbent assay. Insulin resistance (IR) was evaluated by the homeostatic model assessment (HOMA-IR). Body composition was determined by dual-energy X-ray absorptiometry and muscle composition by measuring carnosine in the thigh, a surrogate of fiber types, through proton magnetic resonance spectroscopy. Cardiorespiratory capacity was assessed through direct ergospirometry.

RESULTS

The control (n=29) and MS (n=61) groups were comparable in age (51.5±6.5 years old vs. 50.7±6.1 years old), sex (72.4% vs. 70.5% women), total lean mass (58.5%±7.4% vs. 57.3%±6.8%), and peak oxygen consumption (VO2peak) (31.0±5.8 mL O2./kg.min vs. 29.2±6.3 mL O2/kg.min). Individuals with MS had higher body mass index (BMI) (30.6±4.0 kg/m2 vs. 27.4± 3.6 kg/m2), HOMA-IR (3.5 [95% confidence interval, CI, 2.9 to 4.6] vs. 1.7 [95% CI, 1.1 to 2.0]), and musclin (206.7 pg/mL [95% CI, 122.7 to 387.8] vs. 111.1 pg/mL [95% CI, 63.2 to 218.5]) values than controls (P˂0.05). Musclin showed a significant relationship with HOMA-IR (β=0.23; 95% CI, 0.12 to 0.33; P˂0.01), but not with VO2peak, in multiple linear regression models adjusted for age, sex, fat mass, lean mass, and physical activity. Musclin was significantly associated with insulin, glycemia, visceral fat, and regional muscle mass, but not with BMI, VCO2peak, maximum heart rate, maximum time of work, or carnosine.

CONCLUSION

In humans, musclin positively correlates with insulinemia, IR, and a body composition profile with high visceral adiposity and lean mass, but low body fat percentage. Musclin is not related to BMI or cardiorespiratory capacity.

[Predictive validity of a functional classification method in older adultsValidação preditiva de método de classificação funcional em idosos]

Objetivo.

Evaluar la validez predictiva de un método de clasificación funcional (CF) sobre el uso de los servicios de urgencias y hospitalización, mortalidad y costos de la atención en salud en adultos mayores.

Métodos.

Estudio de cohorte retrospectivo que incluyó 2 168 adultos mayores en un programa de atención de las enfermedades crónicas no transmisibles (ECNT) en Medellín (Colombia). Los pacientes fueron estratificados según un método de CF con base en el estado funcional, presencia de factores de riesgo y control de la comorbilidad. Durante un año de seguimiento, se evaluó la validez predictiva de la CF sobre los desenlaces estudiados; se midieron la discriminación y la calibración con el estadístico-C y de Hosmer-Lemeshow (H-L), respectivamente.

Resultados.

El promedio de edad fue 74,6 ± 7,9 años; el 40,8% (n = 884) fueron hombres y 7,7% (n = 168) murieron. El riesgo de muerte (razón de posibilidades [OR, por su sigla en inglés]: 1,767; 3,411; 8,525), hospitalización (OR: 1,397; 2,172; 3,540) y un costo elevado de la atención en salud (OR: 1,703; 2,369; 5,073) aumentaron en la medida que hubo un deterioro en la CF, clases 2B, 3 y 4, respectivamente. El modelo predictivo para el desenlace muerte mostró una buena capacidad de discriminación (estadístico-C = 0,721) y calibración (estadístico de H-L = 10,200; P = 0,251).

Conclusión.

Existe una relación de dosis y respuesta entre el deterioro de la CF y un riesgo más elevado de muerte, hospitalización y costo elevado. La CF tiene validez predictiva para la tasa de mortalidad y podría utilizarse para la estratificación de adultos mayores en programas de atención de las ECNT con miras a dirigir las acciones de intervención.

Pulse wave velocity reference values in 3,160 adults referred to a hypertension clinic for 24-hour ambulatory blood pressure monitoring

Background: Carotid-femoral pulse wave velocity (PWV) is a direct measure of aortic stiffness used in the stratification of cardiovascular risk. Its clinical application in Latin America has been limited by the absence of reference values. The objective of this study was to establish PWV reference values among adults referred to a specialized cardiology center for 24-hour ambulatory blood pressure monitoring (ABPM) in Medellín, Colombia.Methods: A descriptive study of 3,160 records of adult (older than 18 years) patients without pharmacological treatment assessed for PWV using a Mobil-O-Graph® 24-hour PWA device (IEM, Stolberg, Germany) and 24-hour ABPM with hemodynamic parameters based on suspected hypertension or hypotension was conducted. Patient records were categorized by decade of age and sub-divided based on the following 24-hour ABPM categories: normal (< 130/80 mmHg), grade I hypertension (between 130-150/80-90 mmHg), and grade II hypertension (> 150/90 mmHg).Results: PWV increased with age (r = 0,894; p < 0,001) and blood pressure category (ρ = 0,081; p < 0,001); the age-related increase was more pronounced among the patients in the higher blood pressure categories. Measures of central tendency and dispersion regarding PWV are presented, and reference values are proposed from the 90th percentile based on the age and 24-hour ABPM categories.Conclusions: PWV is directly related to age and blood pressure and can be predicted using a simple equation that includes these two variables. To stratify the cardiovascular risk of patients and make clinical decisions, the 90th percentile based on the age and 24-hour ABPM categories is recommended as a cut-off.

[Evaluation of the cost-effectiveness of an integral model of ambulatory treatment in patients with acute coronary syndrome: application of a probabilistic Markov modelAvaliação da relação custo-eficácia de um modelo integral de tratamento ambulatorial em pacientes com síndrome coronariana aguda: aplicação de um modelo probabilístico de Markov]

OBJECTIVE

To evaluate the cost-effectiveness of an integral model of ambulatory treatment in patients who presented an acute coronary syndrome.

METHODS

An economic evaluation was made from a quasi-experimental intervention study, which included 442 patients aged 30 to 70 years who presented an acute coronary syndrome. The intervention group (n = 165) received an integral model of ambulatory treatment based on managed care (disease management), while the control group (n = 277) received conventional cardiovascular rehabilitation. During one year of follow-up, the presentation of cardiovascular events and hospitalizations was evaluated. A probabilistic Markov model was developed. The study perspective was applied within the General System of Health Social Security in Colombia, including the direct health costs; the time horizon was 50 years with discounts of 3.42% for costs and effectiveness; and the measure of effectiveness was quality-adjusted life years (QALYs). A probabilistic and multivariate sensitivity analysis was performed using the Montecarlo simulation.

RESULTS

During the year of follow-up, the direct costs related to the value paid were, on average, USD 2 577 for the control group and USD 2 245 for the intervention group. In the probabilistic sensitivity analysis, 91.3% of the simulations were located in the quadrant corresponding to incremental negative costs and positive incremental effectiveness (evaluated intervention at a lower cost, more effective). In the simulations, an average annual savings per patient of USD 1 215 per QALY was observed.

CONCLUSIONS

The integral model of ambulatory treatment implemented in patients who suffered an acute coronary syndrome was found to be less expensive and more effective compared to conventional care. Considering it is a dominant alternative, it is recommended as a model of care in this population.

Efficacy of high-intensity, low-volume interval training compared to continuous aerobic training on insulin resistance, skeletal muscle structure and function in adults with metabolic syndrome: study protocol for a randomized controlled clinical trial (Intraining-MET)

Background

Evidence of the efficacy of high-intensity, low-volume interval training (HIIT-low volume) in treating insulin resistance (IR) in patients with metabolic disorders is contradictory. In addition, it is unknown whether this effect is mediated through muscle endocrine function, which in turn depends on muscle mass and fiber type composition. Our aims were to assess the efficacy of HIIT-low volume compared to continuous aerobic exercise (CAE) in treating IR in adults with metabolic syndrome (MS) and to establish whether musclin, apelin, muscle mass and muscle composition are mediators of the effect.

Methods

This is a controlled, randomized, clinical trial using the minimization method, with blinding of those who will evaluate the outcomes and two parallel groups for the purpose of showing superiority. Sixty patients with MS and IR with ages between 40 and 60 years will be included. A clinical evaluation will be carried out, along with laboratory tests to evaluate IR (homeostatic model assessment (HOMA)), muscle endocrine function (serum levels of musclin and apelin), thigh muscle mass (by dual energy x-ray absorptiometry (DXA) and thigh muscle composition (by carnosine measurement with proton magnetic resonance spectroscopy (¹H–MRS)), before and after 12 weeks of a treadmill exercise program three times a week. Participants assigned to the intervention (n = 30) will receive HIIT-low volume in 22-min sessions that will include six intervals at a load of 90% of maximum oxygen consumption (VO₂ max) for 1 min followed by 2 min at 50% of VO₂ max. The control group (n = 30) will receive CAE at an intensity of 60% of VO₂ max for 36 min. A theoretical model based on structural equations will be proposed to estimate the total, direct and indirect effects of training on IR and the proportion explained by the mediators.

Discussion

Compared with CAE, HIIT-low volume can be effective and efficient at improving physical capacity and decreasing cardiovascular risk factors, such as IR, in patients with metabolic disorders. Studies that evaluate mediating variables of the effect of HIIT-low volume on IR, such as endocrine function and skeletal muscle structure, are necessary to understand the role of skeletal muscle in the pathophysiology of MS and their regulation by exercise.

Trial registration

NCT03087721. High-intensity Interval, Low Volume Training in Metabolic Syndrome (Intraining-MET). Registered on 22 March 2017, retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2541-7) contains supplementary material, which is available to authorized users.