Body mass index, leptin, and ambulatory blood pressure variability in healthy adults

Association of body composition with ambulatory blood pressure among Chinese youths

BACKGROUND

For youths, abnormalities in ambulatory blood pressure (ABP) patterns are known to be associated with increased cardiovascular disease risk and potential target organ damage. Body composition, including indicators such as lean mass index (LMI), fat mass index (FMI), and visceral fat level (VFL), plays a significant role in blood pressure (BP) regulation. However, little is known about the association between these body composition indicators and ABP. Therefore, the present study examined the association between these body composition indicators and BP among Chinese youths.

METHODS

A total of 477 college students aged 17 to 28 years old (mean ± Standard deviation = 18.96 ± 1.21) from a university in Changsha, Hunan Province, China, were included in this study. Body composition indicators were measured with a bioelectrical impedance body composition analyzer, and 24-hour ambulatory blood pressure monitoring (ABPM) was conducted. Multivariable logistic regression was performed to assess the relationship between body composition indicators and abnormal ABP.

RESULTS

The prevalence of abnormal BP, including 24-hour BP, daytime BP, nighttime BP, and clinic BP, were 4.8%, 4.2%, 8.6%, and 10.9%, respectively. After adjusting for potential covariates, LMI [abnormal 24-hour BP (OR = 1.85, 95%CI:1.31, 2.62), abnormal daytime BP (OR = 1.76, 95%CI:1.21, 2.58), abnormal nighttime BP (OR = 1.64, 95%CI:1.25, 2.14), abnormal clinic BP (OR = 1.84, 95%CI:1.38, 2.45)], FMI [abnormal 24-hour BP (OR = 1.20, 95%CI:1.02, 1.41), abnormal daytime BP (OR = 1.30, 95%CI:1.07, 1.57), abnormal nighttime BP (OR = 1.24, 95%CI:1.10, 1.39), abnormal clinic BP (OR = 1.42, 95%CI:1.22, 1.65)], and VFL [abnormal 24-hour BP (OR = 1.22, 95%CI:1.06, 1.39), abnormal daytime BP (OR = 1.29, 95%CI:1.10, 1.51), abnormal nighttime BP (OR = 1.24, 95%CI:1.12, 1.39), abnormal clinic BP (OR = 1.38, 95%CI:1.21, 1.57)] are positively linked to abnormal BP. Additionally, there were significant sex differences in the association between body composition and abnormal BP.

CONCLUSIONS

Our findings suggested maintaining an individual's appropriate muscle mass and fat mass and focusing on the different relations of males' and females' body composition is crucial for the achievement of appropriate BP profiles.

Cardiovascular variability, sociodemographics, and biomarkers of disease: the MIDUS study

Introduction: Like heart rate, blood pressure (BP) is not steady but varies over intervals as long as months to as short as consecutive cardiac cycles. This blood pressure variability (BPV) consists of regularly occurring oscillations as well as less well-organized changes and typically is computed as the standard deviation of multiple clinic visit-to-visit (VVV-BP) measures or from 24-h ambulatory BP recordings (ABPV). BP also varies on a beat-to-beat basis, quantified by methods that parse variation into discrete bins, e.g., low frequency (0.04-0.15 Hz, LF). However, beat-to-beat BPV requires continuous recordings that are not easily acquired. As a result, we know little about the relationship between LF-BPV and basic sociodemographic characteristics such as age, sex, and race and clinical conditions. Methods: We computed LF-BPV during an 11-min resting period in 2,118 participants in the Midlife in the US (MIDUS) study. Results: LF-BPV was negatively associated with age, greater in men than women, and unrelated to race or socioeconomic status. It was greater in participants with hypertension but unrelated to hyperlipidemia, hypertriglyceridemia, diabetes, elevated CRP, or obesity. LF-diastolic BPV (DBPV), but not-systolic BPV (SBPV), was negatively correlated with IL-6 and s-ICAM and positively correlated with urinary epinephrine and cortisol. Finally, LF-DBPV was negatively associated with mortality, an effect was rendered nonsignificant by adjustment by age but not other sociodemographic characteristics. Discussion: These findings, the first from a large, national sample, suggest that LF-BPV differs significantly from VVV-BP and ABPV. Confirming its relationship to sociodemographic risk factors and clinical outcomes requires further study with large and representative samples.

A National Multicenter Study of Leptin and Leptin Receptor Deficiency and Systematic Review

CONTEXT

Homozygous leptin (LEP) and leptin receptor (LEPR) variants lead to childhood-onset obesity.

OBJECTIVE

To present new cases with LEP and LEPR deficiency, report the long-term follow-up of previously described patients, and to define, based on all reported cases in literature, genotype-phenotype relationships.

METHODS

Our cohort included 18 patients (LEP = 11, LEPR = 7), 8 of whom had been previously reported. A systematic literature review was conducted in July 2022. Forty-two of 47 studies on LEP/LEPR were selected.

RESULTS

Of 10 new cases, 2 novel pathogenic variants were identified in LEP (c.16delC) and LEPR (c.40 + 5G > C). Eleven patients with LEP deficiency received metreleptin, 4 of whom had been treated for over 20 years. One patient developed loss of efficacy associated with neutralizing antibody development. Of 152 patients, including 134 cases from the literature review in addition to our cases, frameshift variants were the most common (48%) in LEP and missense variants (35%) in LEPR. Patients with LEP deficiency were diagnosed at a younger age [3 (9) vs 7 (13) years, P = .02] and had a higher median body mass index (BMI) SD score [3.1 (2) vs 2.8 (1) kg/m2, P = 0.02], which was more closely associated with frameshift variants (P = .02). Patients with LEP deficiency were more likely to have hyperinsulinemia (P = .02).

CONCLUSION

Frameshift variants were more common in patients with LEP deficiency whereas missense variants were more common in LEPR deficiency. Patients with LEP deficiency were identified at younger ages, had higher BMI SD scores, and had higher rates of hyperinsulinemia than patients with LEPR deficiency. Eleven patients benefitted from long-term metreleptin, with 1 losing efficacy due to neutralizing antibodies.

Blood pressure variability assessed by office, home, and ambulatory measurements: comparison, agreement, and determinants

The present study compared the blood pressure variability (BPV) among office (OBP), home (HBP), and ambulatory blood pressure (ABP) measurements and assessed their determinants, as well as their agreement in identifying individuals with high BPV. Individuals attending a hypertension clinic had OBP measurements (2-3 visits) and underwent HBP monitoring (3-7 days, duplicate morning and evening measurements) and ABP monitoring (24 h, 20-min intervals). BPV was quantified using the standard deviation (SD), coefficient of variation (CV), and variability independent of the mean (VIM) using all BP readings obtained by each method. A total of 626 participants were analyzed (age 52.8 ± 12.0 years, 57.7% males, 33.1% treated). Systolic BPV was usually higher than diastolic BPV, and out-of-office BPV was higher than office BPV, with ambulatory BPV giving the highest values. BPV was higher in women than men, yet it was not different between untreated and treated individuals. Associations among BPV indices assessed using different measurement methods were weak (r 0.1-0.3) but were stronger between out-of-office BPV indices. The agreement between methods in detecting individuals with high BPV was low (30-40%) but was higher between out-of-office BPV indices. Older age was an independent determinant of increased OBP variability. Older age, female sex, smoking, and overweight/obesity were determinants of increased out-of-office BPV. These data suggest that BPV differs with different BP measurement methods, reflecting different pathophysiological phenomena, whereas the selection of the BPV index is less important. Office and out-of-office BP measurements appear to be complementary methods in assessing BPV.

Factors associated with walking activity in adults with cerebral palsy

BACKGROUND

This prospective study used instrumented gait analysis, patient-reported outcomes, and portable accelerometers to examine walking activity in adults with cerebral palsy (CP).

RESEARCH QUESTION

This study aimed to provide objective data and evaluate factors associated with walking activity in adults with CP.

METHODS

Participants with CP (ages 25-45 years) completed instrumented gait analysis and patient-reported outcomes, including the Patient Reported Outcome Measurement Information System (PROMIS) and Satisfaction with Life Score (SWLS), and wore a StepWatch for 8 days. Average strides per day, stratified by Gross Motor Function Classification System (GMFCS), were compared with nondisabled adults ages 30-39 years utilizing Welch's t-tests with Bonferroni corrections. Correlation coefficients and stepwise multiple linear regression analyses examined relationships between walking activity and GMFCS, gait deviation index (GDI), gait velocity, PROMIS physical function, SWLS, body mass index (BMI), and employment.

RESULTS

Participants included 109 adults with CP, ages 29 ± 4 years, classified at GMFCS levels I/II (73 %) and III/IV (27 %). Compared with nondisabled adults, daily stride count was significantly lower in both groups of adults with CP (p < 0.00025), with a progressive decline according to GMFCS level. Walking activity correlated with PROMIS physical function (r = .42), GDI (r = .48), and gait velocity (r = .58). Association for employment was lower (r = 0.27) but significant, while age, SWLS, and BMI were not individually correlated with walking activity. Stepwise, multiple linear regression modeled with Akaike information criterion explained 40.9 % of the observed variability in walking activity in this cohort of adults with CP.

SIGNIFICANCE

Physical function, as classified by GMFCS or measured by PROMIS and self-selected walking velocity, has the strongest association with and is the most significant predictor of walking activity in adults with CP. After accounting for physical function, a small amount of the variation in walking activity can be explained by GDI, employment, and age.

Normal Variations in Blood Pressure in Ambulatory Blood Pressure Measurements

Aim: Hypertension is very common in primary care patients. The diagnosis of hypertension is made by office measurements and home blood pressure measurements. The aim of this study was to define the normal variation levels of blood pressure in individuals in primary care by using ambulatory blood pressure measurement. Methods: This study was performed in primary care. Individuals who had no hypertension history were included in the study. Subjects were evaluated by using three office measurements, seven days home blood pressure measurements and 24 hours ambulatory blood pressure measurement. The ambulatory blood pressure gave us the variations in blood pressure values. Results: The study started in January 2018 and ended in May 2018. Of the 47 subjects, 70.2% were women and 29.8% were men. The mean age was 41.63±12.00. The most common educational level was elementary school graduates. The most common occupation was housewives. Of the participants, 84.2% were married. At ambulatory blood pressure measurements, 34.0% of the subjects had mean systolic blood pressures 24 hours between 120-129 mmHg. Of the diastolic blood pressure 24 hours mean values, 15.3% had values between 80-89, where 51.0% were between the 71-79 mmHg groups. The mean value of 24 hours variation in systolic blood pressure was 15.75±18.59 (median=11.40, min=8.80, max=106.00). The 24 hours variation in the mean values of diastolic blood pressures was 12.12±10.90 (median=9.70, min=6.80, max=64.00). Conclusion: The results of this study demonstrated that there were high levels of variations in normal blood pressures, which could show candidates for hypertension. Keywords: ambulatory monitoring, blood pressure, variability, primary care

Cardiovascular and Metabolic Crosstalk in the Brain: Leptin and Resistin

Leptin and resistin are cytokines whose plasma levels correlate with adiposity. Leptin is a hormone synthesised and released from adipocytes and can be transported into the brain. Resistin is produced in adipocytes in rodents and in macrophages in humans, particularly macrophages that have infiltrated adipose tissue. Both hormones can act within the brain to influence sympathetic nerve activity. Leptin appears to have a generalised sympatho-excitatory actions whilst resistin appears to increase sympathetic nerve activity affecting the cardiovascular system but inhibits sympathetic nerve activity to brown adipose tissue, which contrasts with leptin. Since both hormones can be elevated in conditions of metabolic dysfunction, interactions/crosstalk between these two hormones in the brain is a real possibility. This review describes the current knowledge regarding such crosstalk within the central nervous system. The evidence suggests that with respect to sympathetic nerve activity, crosstalk between leptin and resistin can elicit enhanced sympatho-excitatory responses to the kidneys. In contrast, with respect to food intake, resistin has weaker effects, but in regard to insulin secretion and thermogenesis, leptin and resistin have opposing actions. Thus, in conditions in which there is increased resistin and leptin levels, the result of crosstalk in the central nervous system could contribute to worse cardiovascular and metabolic complications.

Reduction of 24-h blood pressure variability in extreme obese patients 10 days and 6 months after bariatric surgery depending on pre-existing hypertension

Bariatric surgery is considered as a first line treatment in extreme obese patients to achieve a reduction in health risks. However, after surgical procedure obese patients with normal blood pressure (BP) levels still present residual risk, which may be partly related to lack of correction of BP profile and variability.

AIM

To evaluate short (10 days) and mid-term (6 months) changes of mean values, profile and variability of BP after bariatric surgery in extremely obese patients with and without hypertension.

MATERIALS & METHODS

A follow-up of cross-sectional study was conducted in 90 obese patients (aged 41.7 ± 11.3, BMI = 46.7 ± 5.7 kg/m2), who met the eligibility criteria and underwent bariatric surgery. Each patient underwent 24-h ambulatory BP monitoring with profile and variability estimation before, 10 days and 6 months after the intervention.

RESULTS

Sixty-seven (74.4%) patients had hypertension. Significant decrease from baseline in mean values of systolic and diastolic BP in 10 days (p < .005) and 6 months (p < .005) follow-up were observed only in patients with hypertension. Moreover, only hypertensive subjects revealed significant reduction (p < 0,05) from baseline in 24-h systolic and diastolic BP weighted standard deviation and average real variability after surgical procedure. No changes were found in dipping status.

CONCLUSIONS

Bariatric surgery not only decreased BP levels, but also contributed to reduction in BP variability in early period after intervention mainly in patients with pre-existing hypertension.

Plasma Leptin Concentration and Sympathetic Nervous Activity in Older Adults With Physical Dysfunction

Context

Previous research has shown a positive relationship between plasma leptin and sympathetic nervous activity. High plasma leptin activate inflammatory cytokines and lead to muscle wasting. However, studies have detected low sympathetic nervous activity and high plasma leptin in older adults with muscle wasting, sarcopenia, and frailty. High plasma leptin do not seem to correlate with high sympathetic nervous activity. However, their relationship in older adults remains unclear.

Objective

We investigated the relationship between plasma leptin and sympathetic nervous activity in older adults.

Design, Setting, and Participants

We conducted a cross-sectional study and analyzed the results from 69 participants aged ≥75 years. Sympathetic nervous activity was measured by heart rate variability, obtained from 24-hour Holter monitoring. A functional independence measure (FIM) and Barthel index were used to assess physical function.

Results

The plasma leptin was higher in women (men, 3.4 ± 2.8 ng/mL; women, 6.6 ± 6.5 ng/mL; P = 0.024). Plasma leptin was negatively and substantially related to the FIM (β = −0.233; P = 0.049) and Barthel index (β = −0.298, P = 0.018) after adjustment for covariates. However, the data showed no relationship between the plasma leptin and sympathetic nervous activity.

Conclusions

We could not detect an association between sympathetic nervous activity and plasma leptin in older adults. This might suggest a failure of the feedback system of the sympathetic nervous system, leading to muscle wasting in older adults.

Healthy Lifestyle and Blood Pressure Variability in Young Adults

BACKGROUND

The aim of this study was to assess the relationships between healthy lifestyle metrics and blood pressure variability (BPV) in young and healthy adults.

METHODS

A population-based sample of 1,999 individuals aged 25-41 years was investigated. A lifestyle-score from 0 (most unhealthy) to 7 (most healthy) was calculated by giving one point for each of the following components: never smoking cigarettes, adhering to a healthy diet, performing moderate or intense physical activity, having a body mass index <25 kg/m2, a total cholesterol <200 mg/dl, a glycated hemoglobin <5.7%, or a conventional BP <120/80 mm Hg. Standardized ambulatory 24-hour BP measurements were obtained in all individuals. BPV was defined as the SD of all individual ambulatory BP recordings. We constructed multivariable linear regression models to assess the relationships between the lifestyle-score and BPV. None of the results were adjusted for multiple testing.

RESULTS

Median age was 37 years and 46.8% were men. With increasing lifestyle-score, systolic and diastolic BPV is decreasing linearly (P for trend <0.0001), even after multivariable adjustment. Per 1-point increase in lifestyle-score, the β-coefficient (95% confidence interval) for systolic and diastolic 24-hour BPV was -0.03 (-0.03; -0.02) and -0.04 (-0.05; -0.03), respectively, both P for trend <0.0001. These relationships were attenuated but remained statistically significant after additional adjustment for mean individual BP.

CONCLUSION

In this study of young and healthy adults, adopting a healthy lifestyle was associated with a lower BPV. These associations were independent of mean BP levels.

Central leptin and resistin combined elicit enhanced central effects on renal sympathetic nerve activity

NEW FINDINGS

What is the central question of this study? Leptin and resistin act centrally to increase renal sympathetic nerve activity (RSNA). We investigated whether a combination of resistin and leptin could induce a greater response than either alone. We also used Fos protein to quantify the number of activated neurons in the brain. What is the main finding and its importance? A combination of leptin and resistin induced a greater increase in RSNA than either hormone alone. This was correlated with a greater number of activated neurons in the arcuate nucleus than with either hormone alone. Leptin and resistin act centrally to increase renal sympathetic nerve activity (RSNA). We investigated whether a combination of resistin and leptin could induce a greater response than either alone. Mean arterial pressure, heart rate and RSNA were recorded before and for 3 h after intracerebroventricular saline (control; n = 5), leptin (7 μg; n = 5), resistin (7 μg; n = 4) and leptin administered 15 min after resistin (n = 6). Leptin alone and resistin alone significantly increased RSNA (74 ± 17 and 50 ± 14%, respectively; P < 0.0001 compared with saline). When leptin and resistin were combined, there was a significantly greater increase in RSNA (163 ± 23%) compared with either hormone alone (P < 0.0001). Maximal responses of mean arterial pressure and heart rate were not significantly different between groups. We also used Fos protein to quantify the number of activated neurons in the brain. Compared with controls, there were significant increases in numbers of Fos-positive neurons in the arcuate and hypothalamic paraventricular nuclei when leptin or resistin was administered alone or when they were combined, and in the lamina terminalis when leptin and resistin were combined. Only in the arcuate nucleus was the increase significantly greater compared with either hormone alone. The findings show that a combination of leptin and resistin induces a greater RSNA increase and a greater number of activated neurons in the arcuate nucleus than with either hormone alone. Given that leptin makes an important contribution to the elevated RSNA observed in obese and overweight conditions, the increased concentrations of leptin and resistin may mean that the contribution of leptin to the elevated RSNA in those conditions is enhanced.

Resistin, an Adipokine with Non-Generalized Actions on Sympathetic Nerve Activity

The World Health Organization has called obesity a global epidemic. There is a strong association between body weight gain and blood pressure. A major determinant of blood pressure is the level of activity in sympathetic nerves innervating cardiovascular organs. A characteristic of obesity, in both humans and in animal models, is an increase in sympathetic nerve activity to the skeletal muscle vasculature and to the kidneys. Obesity is now recognized as a chronic, low level inflammatory condition, and pro-inflammatory cytokines are elevated including those produced by adipose tissue. The most well-known adipokine released from fat tissue is leptin. The adipokine, resistin, is also released from adipose tissue. Resistin can act in the central nervous system to influence the sympathetic nerve activity. Here, we review the effects of resistin on sympathetic nerve activity and compare them with leptin. We build an argument that resistin and leptin may have complex interactions. Firstly, they may augment each other as both are excitatory on sympathetic nerves innervating cardiovascular organs; In contrast, they could antagonize each other's actions on brown adipose tissue, a key metabolic organ. These interactions may be important in conditions in which leptin and resistin are elevated, such as in obesity.

Leptin links with plasminogen activator inhibitor-1 in human obesity: the SABPA study

The relationship between obesity and the development of cardiovascular disease is well established. However, the underlying mechanisms contributing to vascular disease and increased cardiovascular risk in the obese remain largely unexplored. Since leptin exerts direct vascular effects, we investigated leptin and the relationship thereof with circulating markers of vascular damage, namely plasminogen activator inhibitor-1 antigen (PAI-1(ag)), von Willebrand factor antigen (vWF(ag)) and urinary albumin-to-creatinine ratio (ACR). The study included a bi-ethnic population of 409 African and Caucasian teachers who were stratified into lean (<0.5) and obese (⩾0.5) groups according to waist-to-height ratio. We obtained ambulatory blood pressure measurements and determined serum leptin levels, PAI-1(ag), vWF(ag) and ACR, as markers of vascular damage. The obese group had higher leptin (P<0.001) and PAI-1(ag) (P<0.001) levels and a tendency existed for higher vWF(ag) (P=0.068). ACR did not differ between the two groups (P=0.21). In single regression analyses positive associations existed between leptin and all markers of vascular damage (all P<0.001) only in the obese group. After adjusting for covariates and confounders in multiple regression analyses, only the association between leptin and PAI-1(ag) remained (R(2)=0.440; β=0.293; P=0.0021). After adjusting for gender, ethnicity and age, additional analyses indicated that leptin also associated with fibrinogen and clot lysis time in both lean and obese groups, which in turn is associated with 24- h blood pressure and pulse pressure. This result provides evidence that elevated circulating leptin may directly contribute to vascular damage, possibly through mechanism related to thrombotic vascular disease.

Blood pressure variability and left ventricular mass index in children

Clinical implications of blood pressure variability (BPV) on subclinical organ damage in children are unknown. The authors sought to explore the potential utility of two newly derived BPV indices: weighted standard deviation (wBPSD) and real average variability (ARV), as well as two standard ambulatory blood pressure indices: average 24-hour systolic blood pressure (SBP) and 24-hour SBP load, to identify children at high risk for left ventricular (LV) hypertrophy (LVH). The study group consisted of 67 consecutive children who were referred to our institution for evaluation of suspected hypertension. LV mass was estimated by M-mode echocardiography using Devereux's formula according to the Penn convention and indexed for height(2.7) . We found a statistically significant, positive correlation between 24-hour wBPSD and LV mass index (LVMI) (ρ=0.389; P=.002) and no correlation between 24-hour ARV and LVMI (P>.05). However, partial correlation analysis of 24-hour wBPSD adjusted for body mass index (BMI) and LVMI showed only a weak correlation (ρ=0.3; P=.022). By using multiple linear regression analysis in a model with LVMI as a dependent variable and 24-hour wBPSD, 24-hour ARV, and BMI as independent variables, only BMI showed statistically significant independent positive associations with LVMI (P=.028). Results of our study showed that currently used BPV indices (24-hour wBPSD and 24-hour ARV) are not clinically reliable parameters to identify children at risk for LVH. Apparent contribution of the 24-hour wBPSD parameter to LVMI is negligible and is secondary to its close correlation with BMI (ρ=0.335 P=.009).

Sympathetic nervous system in obesity-related hypertension: mechanisms and clinical implications

Obesity markedly increases the risk of hypertension and cardiovascular disease, which may be related to activation of the sympathetic nervous system (SNS). Sympathetic overactivity directly and indirectly contributes to blood pressure (BP) elevation in obesity, including stimulation of the renin-angiotensin-aldosterone system (RAAS). The adipocyte-derived peptide leptin suppresses appetite, increases thermogenesis, but also raises SNS activity and BP. Obese individuals exhibit hyperleptinemia but are resistant to its appetite-suppressing actions. Interestingly, animal models of obesity exhibit preserved sympathoexcitatory and pressor actions of leptin, despite resistance to its anorexic and metabolic actions, suggesting selective leptin resistance. Disturbance of intracellular signaling at specific hypothalamic neural networks appears to underlie selective leptin resistance. Delineation of these pathways should lead to novel approaches to treatment. In the meantime, treatment of obesity-hypertension has relied on antihypertensive drugs. Although sympathetic blockade is mechanistically attractive in obesity-hypertension, in practice its effects are disappointing because of adverse metabolic effects and inferior outcomes. On the basis of subgroup analyses of obese patients in large randomized clinical trials, drugs such as diuretics and RAAS blockers appear superior in preventing cardiovascular events in obesity--hypertension. An underused alternative approach to obesity-hypertension is induction of weight loss, which reduces circulating leptin and insulin, partially reverses resistance to these hormones, decreases sympathetic activation and improves BP and other risk factors. Though weight loss induced by lifestyle is often modest and transient, carefully selected pharmacological weight loss therapies can produce substantial and sustained antihypertensive effects additive to lifestyle interventions.

Local renin-angiotensin system and the brain--a continuous quest for knowledge

The ancient renin-angiotensin system (RAS) was discovered more than a hundred years ago by identifying the rate-limiting enzyme of the system and its relevance to blood pressure regulation. Forty years ago, Detlev Ganten et al. postulated the existence of a tissue RAS. In these forty years, he kept developing the knowledge of these systems either directly or by training or attracting the interest of many researchers. Through the present review, we try to highlight recent advancements that originated from the postulation of local brain RAS. Although a large amount of knowledge accumulated, this system continues to intrigue and stimulate the interest and imagination of many researchers.