Involvement of the renin-angiotensin system in obesity: older and newer pathways

Angiotensin-converting enzyme insertion/deletion polymorphism association with obesity and some related disorders in Egyptian females: a case-control observational study

BACKGROUND

According to the WHO report in 2015, obesity is the fifth leading cause of death worldwide, and the prevalence of Egyptian female obesity is 37.5 %. Since obesity is highly influenced by genetics, and adipose tissue renin-angiotensin system is over-activated in obesity, the effect of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism on obesity and related disorders was studied in several populations, because of its effect on ACE activity. Our objective was to study the association of ACE I/D polymorphism with obesity and certain related disorders, namely hypertension, insulin resistance and metabolic syndrome, in Egyptian females.

METHODS

Eighty female volunteers were recruited, blood pressure and body measurements were recorded and a fasting blood sample was obtained for the quantitation of glucose, lipid profile, insulin, leptin and identification of ACE I/D polymorphs. Subjects were grouped based on hypertension and obesity states. Comparisons of continuous parameters were made with independent sample t-test between two groups. The frequencies of ACE genotypes and alleles, and the association between gene polymorphism and metabolic parameters were assessed using chi-square or Fisher's exact test.

RESULTS

Genotype frequencies were in Hardy-Weinberg equilibrium for all groups. Genotype distribution did not differ significantly between controls and cases of all the studied disorders. Although DD carriers had apparently higher parameters of blood pressure, lipid profile and insulin resistance, only diastolic blood pressure was almost significant (p = 0.057). I-carriers were significantly less susceptible to hypertension than DD carriers having normal waist/hip ratio (p = 0.007, OR = 17.29, CI = 1.81-164.96) and normal conicity index (p = 0.024, OR = 7.00, CI = 1.36-35.93). In DD genotype carriers, a significant association was found between insulin resistance and high body mass index (p = 0.004, OR = 8.89, CI = 1.94-40.71), waist circumference (p = 0.003, OR = 9.63, CI = 2.14-43.36) and waist/height ratio (p = 0.034, OR = 6.86, CI = 1.25-37.61), although the variations in percentages between DD and I-carriers were not high enough to conclude an effect of ACE I/D on such an association.

CONCLUSIONS

In this sample of Egyptian females, ACE I/D polymorphism was not significantly associated with obesity nor with any of its related disorders studied. The I allele seemed protective against hypertension in subjects with normal, not high, waist/hip ratio and conicity index compared to DD genotype carriers.

The influence of high versus low sodium intake on blood pressure and haemodynamics in patients with morbid obesity

BACKGROUND

Many patients with morbid obesity (BMI > 40 kg/m) have hypertension. The complex pathophysiological abnormalities linking hypertension to obesity have not been fully clarified, but abnormal sodium handling could be an important mechanism.

METHOD

Therefore, we examined changes in body fluid compartments and haemodynamic responses (at rest and during exercise) after 5 days of a low-sodium diet (90 mmol/day) and 5 days of a high-sodium diet (250 mmol/day) in 12 morbidly obese, hypertensive patients; 12 morbidly obese, normotensive patients and 12 nonobese controls.

RESULTS

High sodium intake as compared to low sodium intake was associated with an increase in plasma volume (obese, hypertensive patients: 5 ± 4%; obese, normotensive patients: 10 ± 11%; nonobese controls: 7 ± 6%), cardiac output (CO) (obese, hypertensive patients: 17 ± 12%; obese, normotensive patients: 20 ± 16%; nonobese controls: 13 ± 14%) and stroke volume (SV) (obese, hypertensive patients: 27 ± 26%; obese, normotensive patients: 27 ± 24%; nonobese controls: 18 ± 27%) in all three groups with no differences between the groups. Despite an increase in CO during high salt intake, 24-h blood pressure (BP) was unchanged in patients and controls as a result of a reduction in total peripheral resistance (obese, hypertensive patients: -11 ± 11%; obese, normotensive patients: -10 ± 12%; nonobese controls: -5 ± 14%). Similar changes were observed during an incremental bicycle exercise test wherein CO and SV were higher, whereas mean arterial BP was unchanged at each exercise level during high sodium intake.

CONCLUSION

Despite substantial increases in CO and SV, we did not observe any significant change in BP during high sodium intake, neither in morbid obese patients nor in lean individuals.

Association of hematological parameters with metabolic syndrome in Beijing adult population: a longitudinal study

The purposes of the study were to estimate the incidence of metabolic syndrome (MetS) and to systematically evaluate the relationship between hematological parameters and MetS in a 5-year follow-up of Beijing adult population. The longitudinal study included 3,180 adults, aged 20-65 years, who attended health check-ups in Beijing Tongren Hospital in 2007 and 2012. Multivariate logistic regression was conducted to explore the associations between hematological parameters and MetS. The 5-year cumulative incidence of MetS in this sample was 10.82 % (14.22 % for males and 7.59 % for females). Among all the hematological parameters, white blood cell count (WBC) was positively associated with MetS for 20-35-year-old (male OR 1.482, 95 % CI 1.169-2.974; female OR 1.398, 95 % CI 1.145-3.011), and 36-50-year-old (male OR 2.012, 95 % CI 1.290-4.010; female OR 3.400, 95 % CI 1.818-4.528) male and female subjects. Alanine aminotransferase (ALT) was significantly associated with the incidence of MetS for males (20-35-year-old OR 2.080, 95 % CI 1.371-3.159; 36-50-year-old OR 2.421, 95 % CI 1.335-3.412; 51-65-year-old OR 4.267, 95 % CI 1.161-6.781). Low-density lipoprotein cholesterol (LDL-C) was positively associated with MetS for 51-65-year-old (male OR 3.078, 95 % CI 2.468-5.131; female OR 2.140, 95 % CI 1.524-4.359) for male and female subjects. WBC is positively associated with MetS for young adults, while LDL-C is positively associated with MetS for elderly people. ALT is positively associated with MetS for males. Our findings provide further evidence in support of using hematological markers for early detection of individuals at risk for MetS.

Uso de medicamentos, glicemia capilar e índice de massa corpórea em pacientes com diabetes mellitus

Objetivou-se relacionar o uso de medicamentos com a glicemia capilar e o índice de massa corpórea em pacientes com diabetes mellitus tipo 2. Estudo transversal realizado entre janeiro e julho de 2009, nos domicílios de 437 pacientes de doze centros de saúde de Fortaleza-CE. Utilizou-se um formulário para o registro das variáveis sociodemográficas e clinicas, glicemia capilar, índice de massa corpórea e uso de medicamentos. Dos pacientes com glicemia capilar normal, 93% não utilizavam antidepressivos / ansiolíticos (p = 0,02). Aproximadamente 99% dos que apresentavam a glicemia capilar elevada não utilizavam cálcio diariamente (p = 0,04). Entre aqueles com índice de massa corpórea normal, 45,5% tomavam diariamente anti-hipertensivos da classe inibidor da ECA (p = 0,03). O uso diário de drogas inibidoras da ECA, antidepressivos / ansiolíticos e cálcio apresentou associação com a glicemia capilar e o índice de massa corpórea, respectivamente. É importante que o enfermeiro avalie o peso corporal e a glicemia capilar dos pacientes com diabetes, em particular daqueles que fazem uso contínuo de medicamentos.

Visceral obesity and metabolic syndrome: two faces of the same medal?

In this review, we have analyzed the role of visceral obesity in the occurrence of metabolic syndrome (MetS). MetS is a common metabolic disorder that has been related recently to the increasing prevalence of obesity. The disorder is defined in various ways, but in the near future a new definition(s) should be applicable worldwide. The pathophysiology has been largely attributed, in the past years, to insulin resistance, although several epidemiological and pathophysiological data now indicate visceral obesity as a main factor in the occurrence of all the components of MetS. In view of this, relationships among visceral obesity, free fatty acids, dyslipidemia and insulin resistance have been reported. In addition, the effects of some adipocytokines and other proinflammatory factors produced by fat accumulation on the occurrence of MetS have been also emphasized. Accordingly, the "hypoadiponectinemia hypothesis" has been proposed as the most interesting to explain the pathophysiology of MetS. The epidemiologic, pathophysiologic and clinical data reported seem to indicate that MetS might be considered a fatal consequence of visceral obesity.