Role of the sympathetic adrenal system in the pathogenesis of the insulin resistance syndrome

Insulin Resistance and Urolithiasis as a Challenge for a Dietitian

Many obesity and diet-related diseases have been observed in recent years. Insulin resistance (IR), a state of tissue resistance to insulin due to its impaired function, is a common coexisting condition. The most important predisposing factors are excessive visceral fat and chronic low-grade inflammatory response. However, IR’s pathogenesis is not fully understood. Hence, the diagnosis of IR should be carried out carefully because many different diagnostic paths do not always give equivalent results. An additional disease that is often associated with IR is urolithiasis. The common feature of these two conditions is metabolic acidosis and mild inflammation. A patient diagnosed with IR and urolithiasis is a big challenge for a dietitian. It is necessary to check a thorough dietary history, make an appropriate anthropometric measurement, plan a full-fledged diet, and carry out the correct nutritional treatment. It is also essential to conduct proper laboratory diagnostics to plan nutritional treatment, which is often a big challenge for dietitians. The diet’s basic assumptions are based on the appropriate selection of carbohydrates, healthy fats, and wholesome protein sources. It is also essential to properly compose meals, prepare them, and plan physical activities tailored to the abilities. The study aims to summarise the necessary information on IR with concomitant urolithiasis, which may be helpful in dietary practice.

Carotid Arterial Stiffness and Cardiometabolic Profiles in Women with Fibromyalgia

Background: The present study aimed to evaluate the association between FM and cardiometabolic risk factors and carotid arterial stiffness in FM patients. Methods: The cardiometabolic risk profile was defined based on the Adult Treatment Panel III panel. Carotid intimal media thickness (cIMT) and arterial stiffness were assessed using high-resolution ultrasonography. Multivariate logistic analysis was performed to estimate the association between FM and cardiometabolic risk factors. We used a general linear regression to compare the cIMT and carotid beta-index between the participants with and without FM. Pearson’s coefficient was calculated to evaluate the potential correlation between cardiometabolic risk profiles, cIMT, and arterial stiffening in FM. Results: FM participants showed a higher risk of central obesity (odds ratio [OR] = 3.21, 95% confidence interval [CI] 1.49, 6.91), high triglyceride (OR = 4.73, 95% CI 2.29, 9.79), and impaired fasting glucose (IFG) (OR = 4.27, 95% CI 2.07, 8.81) compared to the control group. The FM group exhibited higher beta-index values than the control group (p = 0.003). Although IFG and triglyceride glucose index showed a tendency to correlate with the beta-index, statistical significance was not observed. Conclusions: FM was associated with an increased risk of central obesity, high triglyceride levels, and IFG. Furthermore, advanced arterial stiffness of the carotid artery was observed in FM, which might be correlated with insulin resistance.

Neurogenic Obesity-Induced Insulin Resistance and Type 2 Diabetes Mellitus in Chronic Spinal Cord Injury

The population with SCI is at a significant risk for both insulin resistance and type 2 diabetes mellitus (T2DM) secondary to neurogenic obesity. The prevalence of insulin resistance and T2DM in persons with SCI suggests that disorders of carbohydrate metabolism are at epidemic proportions within the population. However, the true frequency of such disorders may be underestimated because biomarkers of insulin resistance and T2DM used from the population without SCI remain nonspecific and may in fact fail to identify true cases that would benefit from intervention. Furthermore, diet and exercise have been used to help mitigate neurogenic obesity, but results on disorders of carbohydrate metabolism remain inconsistent, likely because of the various ways carbohydrate metabolism is assessed. The objective of this article is to review current literature on the prevalence and likely mechanisms driving insulin resistance and T2DM in persons with SCI. This article also explores the various assessments and diagnostic criteria used for insulin resistance and T2DM and briefly discusses the effects of exercise and/or diet to mitigate disorders of carbohydrate metabolism brought on by neurogenic obesity.

Metabolic syndrome in patients with bipolar disorder: comparison with major depressive disorder and non-psychiatric controls

OBJECTIVE

We aimed to investigate the prevalence of the metabolic syndrome (MetS) and its individual components in subjects with bipolar disorder (BD) compared to those with major depressive disorder (MDD) and non-psychiatric controls.

METHODS

We examined 2431 participants (mean age 44.3±13.0, 66.1% female), of whom 241 had BD; 1648 had MDD; and 542 were non-psychiatric controls. The MetS was ascertained according to NCEP ATP III criteria. Multivariable analyses were adjusted for age, sex, ethnicity, level of education, smoking status and severity of depressive symptoms, and in the case of BD subjects, also for psychotropic medication use.

RESULTS

Subjects with BD had a significantly higher prevalence of MetS when compared to subjects with MDD and non-psychiatric controls (28.4% vs. 20.2% and 16.5%, respectively, p<0.001), also when adjusted for sociodemographic and lifestyle factors (OR 1.52, 95% CI: 1.09-2.12, p=0.02 compared to MDD; OR 1.79, 95% CI: 1.20-2.67, p=0.005 compared to non-psychiatric controls). The differences between BD subjects with controls could partly be ascribed to a higher mean waist circumference (91.0 cm vs. 88.8, respectively, p=0.03). In stratified analysis, the differences in the prevalence of MetS between patients with BD and MDD were found in symptomatic but not in asymptomatic cases.

CONCLUSION

This study confirms a higher prevalence of MetS in patients with BD compared to both MDD patients and controls. Specifically at risk are patients with a higher depression score and abdominal obesity.

Metabolic syndrome and lower urinary tract symptoms

Recently, clinical and epidemiologic data indicating the involvement of metabolic syndrome (MetS) in the pathogenesis and progression of lower urinary tract symptom (LUTS)/benign prostatic hyperplasia (BPH) are reported. This review evaluates the reports on the influence of MetS in the development and progression of LUTS/BPH, and discusses possible clinical implications for the management and treatment of this disease. Recent studies on the epidemiological relationship between MetS and LUTS hypothesize that MetS may be associated with an overactivity of the autonomic nervous system for which hyperinsulinemia, a key element of the MetS, might be responsible. An alternative explanation is that LUTS are associated with chronic ischemia of pelvis resulting from atherosclerotic changes in blood vessels, which leads the production of reactive oxygen species, which can damage the bladder detrusor. Control of autonomic nervous system overactivity and control of chronic bladder ischemia have potential as new targets for LUTS treatment. Studies suggest an association of MetS with LUTS/BPH, although further research is needed to understand how MetS influences LUTS/BPH. MetS should be considered a new domain in basic and clinical research in patients with LUTS/BPH and as a target for treatment.

Insulin resistance, selfish brain, and selfish immune system: an evolutionarily positively selected program used in chronic inflammatory diseases

Insulin resistance (IR) is a general phenomenon of many physiological states, disease states, and diseases. IR has been described in diabetes mellitus, obesity, infection, sepsis, trauma, painful states such as postoperative pain and migraine, schizophrenia, major depression, chronic mental stress, and others. In arthritis, abnormalities of glucose homeostasis were described in 1920; and in 1950 combined glucose and insulin tests unmistakably demonstrated IR. The phenomenon is now described in rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, polymyalgia rheumatica, and others. In chronic inflammatory diseases, cytokine-neutralizing strategies normalize insulin sensitivity. This paper delineates that IR is either based on inflammatory factors (activation of the immune/ repair system) or on the brain (mental activation via stress axes). Due to the selfishness of the immune system and the selfishness of the brain, both can induce IR independent of each other. Consequently, the immune system can block the brain (for example, by sickness behavior) and the brain can block the immune system (for example, stress-induced immune system alterations). Based on considerations of evolutionary medicine, it is discussed that obesity per se is not a disease. Obesity-related IR depends on provoking factors from either the immune system or the brain. Chronic inflammation and/or stress axis activation are thus needed for obesity-related IR. Due to redundant pathways in stimulating IR, a simple one factor-neutralizing strategy might help in chronic inflammatory diseases (inflammation is the key), but not in obesity-related IR. The new considerations towards IR are interrelated to the published theories of IR (thrifty genotype, thrifty phenotype, and others).

The Role of Magnesium in the Pathogenesis and Treatment of Glaucoma

Glaucoma is characterized by chronic optic neuropathy resulting in progressive vision loss. Not only is glaucoma considered as a condition of elevated intraocular pressure (IOP), but also other risk factors may play a role in the pathogenesis of glaucomatous optic nerve damage. Vascular dysregulation in ocular blood flow and oxidative stress are currently suggested as important risk factors for glaucomatous retinal ganglion cell loss. New treatment modalities that improve ocular blood flow and reduce oxidative stress have been investigated in many studies. Magnesium (Mg) is thought to be one of the molecules that has a treatment potential in glaucoma. Mg has been shown to improve blood flow by modifying endothelial function via endothelin-1 (ET-1) and endothelial nitric oxide (NO) pathways. Mg also exhibits neuroprotective role by blocking N-methyl-D-aspartate (NMDA) receptor-related calcium influx and by inhibiting the release of glutamate, and hence protects the cell against oxidative stress and apoptosis. Both improvement in ocular blood flow and prevention of ganglion cell loss would make magnesium a good candidate for glaucoma management. Further studies on the effect of Mg may open a new therapeutic era in glaucoma.

The heart in obesity-hypertension

There is growing recognition that obesity is reaching epidemic proportions throughout the world. In adults, obesity is associated with increased cardiovascular morbidity and mortality. A series of endocrine, metabolic and hemodynamic mechanisms have been responsible for the development of obesity-hypertension. These mechanisms include: a suppressed biologic activity and availability of natriuretic peptide, increased sympathetic adrenergic activity, release of angiotensin ll from adipocytes and activation of the renin-angiotensin-aldosterone system, leptin resistance, chronic hyperleptinemia and hyperinsulinemia. The systemic hemodynamic profile of obesity includes high intravascular volume, increased cardiac output and inappropriately normal peripheral resistance. The cardiovascular adaptations to these changes include changes in vascular responsiveness and concentric-eccentric left ventricular hypertrophy, and may be responsible for increased risk of congestive heart failure, arrhythmia and sudden death.

Insulin resistance possible risk factor for cognitive impairment in fibromialgic patients

To evaluate glucose metabolism and/or insulin resistance (IR) in 96 patients with Fibromyalgia (FM), associated or not to cognitive impairment. We investigated glucose metabolism in 96 FM patients. Enrolled patients were divided into two groups: 48 patients with memory deficit (group A) and 48 without memory deficit (control group). We evaluated glucose and insulin levels after a 2 h-Oral-Glucose-Tolerance-Test (2 h-OGTT) and insulin resistance (IR) by the homeostasis model assessment formula (HOMA). Body Mass Index (BMI), waist-to-hip-ratio (WHR), anxiety level, fasting plasma insulin and Non-Steroidal Anti-Inflammatory agents use were higher in patients with FM with memory impairment; while age, sex, waist circumference, education level, fasting plasma glucose, glycate hemoglobin, triglycerides, blood lipid profile, C- Reactivity-Protein (CRP), blood pressure and smoking habits were similar in both groups. Following OGTT the prevalence of glucose metabolism abnormalities was significantly higher in group A. IR was present in 79% patients, of whom 23% had also impaired glucose tolerance, 4% newly diagnosed diabetes mellitus and 52% IR only. Obesity and overweight prevailed in group A. IR, but not BMI or WHR was associated to an increased risk of memory impairment (OR = 2,6; 95% CI: 1,22-3,7). The results of this study suggest that IR may represent a risk factor for memory impairment in fibromialgic patients.

Heart rate recovery is associated with obesity traits and related cardiometabolic risk factors in children and adolescents

BACKGROUND AND AIMS

Increased vagal activity is associated with obesity and metabolic risk in children and adolescents. The aim of the present cross-sectional study was to examine the association of parasympathetic function, as assessed by heart rate recovery (HRR) from a maximal exercise cycle-ergometer test, with obesity traits and related cardiometabolic risk factors in Spanish children and adolescents.

METHODS AND RESULTS

A sample of 437 Spanish 9-year-old-children and 235 15-year-old-adolescents participated in the study. The variables measured were anthropometric characteristics (height, body mass and waist circumference) and physical activity using the Actigraph accelerometer. Additional measured outcomes included fasting insulin, triglycerides, high-density lipoprotein cholesterol (HDLc) and blood pressure. A metabolic risk score was computed as the mean of the standardised outcomes scores. The HRR was calculated as the difference between peak heart rate and heart rate 1, 3 and 5 min after cessation of the maximal ergometer test. Diastolic blood pressure was associated with all the HRR parameters in 9-year-old-girls. In 9-year-old-boys, the 3-min HRR was inversely associated with systolic blood pressure (p < 0.05) and Homeostasis Model Assessment (HOMA) (p < 0.05). Five minute HRR was inversely associated with waist circumference (p < 0.05), sum of five skinfolds (p < 0.01) and HOMA (p = 0.004). There were no significant associations in adolescents. In 9-year-old-girls, the adjusted 5-min HRR showed significant differences between quartile 2 and 4 of metabolic risk (p = 0.011). In all samples, the adjusted HRR (1-, 3- and 5-min HRR) did not show significant differences across quartiles.

CONCLUSION

HRR was inversely associated with obesity traits and related cardiometabolic risk factors mainly in healthy boys.

Risk of hypertension in patients with bipolar disorder in Taiwan: a population-based study

OBJECTIVE

To examine the prevalence, incidence, and risk factors of hypertension in patients with bipolar disorder in Taiwan.

METHOD

The National Health Research Institute provided a database of 1,000,000 random subjects for study in Taiwan. Study subjects ≥ 18 years or older had at least one service claim during 2005 for either outpatient or inpatient care, with a primary or secondary diagnosis of hypertension combined with antihypertensive drug treatment were identified. We also compared the incidence of hypertension in patients with bipolar disorder and the general population from 2006 through 2010.

RESULTS

The 1-year prevalence of hypertension in patients with bipolar disorder was higher than the general population (18.13% vs. 13.22%, odds ratio, 1.43; 95% confidence interval, 1.25-1.64) in Taiwan. Compared with the general population, patients with bipolar disorder had a higher prevalence of hypertension among 18- to 39-year-olds and 40- to 59-year-olds, in both sexes, and in the group with lower socioeconomic status. The average annual incidence of hypertension in patients with bipolar disorder from 2006 to 2010 was higher than the general population (2.83% vs. 1.99%, risk ratio, 1.40; 95% confidence interval, 1.20-1.62). Patients with bipolar disorder had a higher incidence of hypertension among 18- to 39-year-olds and 40- to 59-year-olds and in both sexes compared with the general population.

CONCLUSIONS

Patients with bipolar disorder had a higher prevalence and a higher incidence of hypertension than those in the general population. Prevention, early detection, and comprehensive treatment of hypertension are important issues for patients with bipolar disorder.

Association of insulin resistance with overactive bladder in female patients

PURPOSE

Metabolic syndrome and obesity have been advocated to be risk factors for the development of overactive bladder (OAB). Additionally, insulin resistance is the underlying mechanism of metabolic syndrome. We aimed to investigate the association of insulin resistance with overactive bladder in female patients.

METHODS

We prospectively conducted the study in our urology department. Female patients aged between 30 and 76 years old applied to our policlinics with or without OAB symptoms were enrolled. One hundred and twenty-two patients with OAB and 62 age-matched controls without OAB were included into the study. Fasting serum insulin, glucose, high-density lipoprotein (HDL-c), and triglycerides levels were measured. Insulin resistance value was obtained via the homeostasis model assessment of insulin resistance (HOMA-IR) calculator. The chi-square and Mann-Whitney U tests were used to compare differences in variables.

RESULTS

Serum insulin level was found higher in female patients with OAB (11.5±6.2 µU/mL) relative to controls (6.4±2.1 µU/mL), statistically significant (P=0.036). In addition, HOMA-IR was significantly found higher in the OAB group, 2.86 (0.76 to 17.04) in comparison to controls, 1.32 (0.67 to 224), P=0.018. High-density lipoprotein cholesterol levels (HDL-c) were significantly found lower in females with OAB.

CONCLUSIONS

Insulin resistance can be associated to overactive bladder and may play significant role in pathogenesis.

Metabolic syndrome in female patients with overactive bladder

OBJECTIVE

To investigate the relevance of metabolic syndrome in the etiopathogenesis of overactive bladder in female patients. It has been shown that obesity has been associated with overactive bladder (OAB), and the metabolic syndrome and insulin resistance have been related to the annual growth rates of prostate and lower urinary tract symptoms.

METHODS

Female patients applying to our policlinics with OAB symptoms or other urologic complaints were enrolled in the study. The International Diabetes Federation criteria were used for the definition of the metabolic syndrome. The chi-square, Student t, and Mann-Whitney U tests and logistic regression analyses were used to compare differences in the variables.

RESULTS

The metabolic syndrome was diagnosed in 201 (64%) of 313 patients with OAB and 73 (35%) of 208 patients without OAB. The difference was statistically significant (P=.002). A larger waist circumference, greater body mass index, low high-density lipoprotein level, and incidence of hypertension were significantly greater statistically in the OAB group than in the controls.

CONCLUSION

The metabolic syndrome correlates highly with OAB in female patients. The metabolic syndrome can be an etiologic pathway for the onset of symptoms.

Prevalence of metabolic syndrome in bipolar patients initiating acute-phase treatment: a 6-month follow up

AIMS

To evaluate the prevalence of metabolic syndrome (MetS) and its correlates in patients with bipolar disorder (BD) during acute-phase treatment in southern China.

METHODS

This study included 148 BD patients presenting with acute mood symptoms and 65 healthy controls at entry. Sociodemographic characteristics were noted for all participants. For patients, lifestyle information (alcohol, smoking, and exercise habits) and clinical characteristics were also collected. Patients were followed up for 6 months after the commencement of pharmacological treatment. Using the Chinese Medical Association Diabetes Branch criteria, MetS prevalence rates were calculated at entry and recalculated for patients at months 1, 3, and 6.

RESULTS

At baseline, MetS was presented in 11.5% of the patients; overweight, 34.5%; low high-density lipoprotein cholesterol, 15.5%; hypertriglyceridemia, 29.1%; hypertension, 14.9%; and hyperglycemia, 5.4%. Compared with controls, the patients had a significantly higher prevalence of MetS and all its components except for hyperglycemia (P < 0.05). In the regression analysis, history of hypertension, presence of diabetes, and alcohol drinking were associated with MetS. During the follow-up period, rates of MetS and overweight increased gradually and stably, hypertriglyceridemia and low high-density lipoprotein cholesterol increased significantly in the first month and then remained stable, and hypertension and hyperglycemia remained stable all the time.

CONCLUSIONS

These data show that MetS is highly prevalent in Chinese BD patients. Weight gain and dyslipidemia result from a short period of treatment. Early interventions for weight gain and dyslipidemia are warranted.

Insulin resistance in tetraplegia but not in mid-thoracic paraplegia: is the mid-thoracic spinal cord involved in glucose regulation?

STUDY DESIGN

Controlled experimental human study.

OBJECTIVES

To assess insulin resistance (IR) in tetraplegia and paraplegia, and the role of the spinal cord (SC) in glucose regulation.

SETTING

Laboratory of Spinal Research, Loewenstein Rehabilitation Hospital.

METHODS

Glucose and insulin levels and the heart rate variation spectral components LF (low frequency), HF (high frequency) and LF/HF were studied at supine rest, head-up tilt and after a standard meal in three groups: 13 healthy subjects, 7 patients with T(4)-T(6) paraplegia and 11 patients with C(4)-C(7) tetraplegia.

RESULTS

Glucose and insulin increased significantly after the meal in all groups (P<0.001). Glucose increased significantly more in the tetraplegia than in the other groups (P<0.01). Increases in insulin level tended to accompany increases in LF/HF after the meal in the tetraplegia and control groups but not in the paraplegia group.

CONCLUSION

Post-prandial IR appears in C(4)-C(7) but not in T(4)-T(6) SC injury. The results of the study, combined with previously published findings, are consistent with the hypotheses that IR is related to activation of the sympathetic nervous system, and that below T(4) the mid-thoracic SC is involved in the regulation of glucose and insulin levels.

Bipolar disorder and the metabolic syndrome: causal factors, psychiatric outcomes and economic burden

Overweight and obesity are highly prevalent in patients with bipolar disorder, and metabolic disorders also affect a significant portion of this population. Obesity and metabolic disorders cause significant economic burden and impair quality of life in both the general population and patients with bipolar disorder. This review examines the relationship between bipolar disorder and the metabolic syndrome, and the associated economic impact. The metabolic syndrome and bipolar disorder appear to share common risk factors, including endocrine disturbances, dysregulation of the sympathetic nervous system, and behaviour patterns, such as physical inactivity and overeating. In addition, many of the commonly used pharmacological treatments for bipolar disorder may intensify the medical burden in bipolar patients by causing weight gain and metabolic disturbances, including alterations in lipid and glucose metabolism, which can result in an increased risk for diabetes mellitus, hypertension, dyslipidaemia, cardiovascular disease and the metabolic syndrome. These medical co-morbidities and obesity have been associated with a worse disease course and likely contribute to the premature mortality observed in bipolar patients. Weight gain is also a major cause of treatment noncompliance, increased use of outpatient and inpatient services and, consequently, higher healthcare costs. Prevention of weight gain and metabolic disturbances or early intervention when these are present in bipolar disorder could result in significant health and economic benefits.

Relation of heart rate with cardiovascular disease in normal-weight individuals: the Chicago Heart Association Detection Project in Industry

The authors investigated the association of resting heart rate (RHR) with cardiovascular disease (CVD) risk factors and mortality among normal-weight individuals. Using data from our cohort (baseline examination in 1967-1973), individuals with a body mass index of 18.5 to 24.9 kg/m(2) (men [n=3724] and women [n=4929] aged 18-39; men [n=1959] and women [n=3735] aged 40-59), were grouped by RHR: <75, 75-84, and > or =85 beats per minute (bpm). A lower RHR was associated with lower mean blood pressure (BP) and cigarette use in each subgroup and total cholesterol (TC) and diabetes in men (P<.05). After a 32-year follow-up, hazard ratios (95% confidence intervals) for CVD mortality for an RHR <75 compared with > or =85 bpm adjusted for age, race, education level, BP, cigarette use, diabetes, and TC were 0.58 (0.34-0.84), 0.73(0.56-0.95), and 0.77 (0.61-0.98) for men aged 18 to 39 and men and women aged 40 to 59, respectively. In women aged 18 to 39, the relationship was not significant. In general, normal-weight individuals with lower RHRs have lower levels of CVD risk factors and mortality.

Inverse correlation between heart rate recovery and metabolic risks in healthy children and adolescents: insight from the National Health and Nutrition Examination Survey 1999-2002

OBJECTIVE

Heart rate recovery (HRR) is a marker for survival. Little is known about the association between HRR and metabolic risks in healthy children or adolescents.

RESEARCH DESIGN AND METHODS

We examined 993 healthy children and adolescents aged 12-19 years with reliable measures of cardiovascular fitness from the National Health and Nutrition Examination Survey 1999-2002. HRR parameters 1-3 min after exercise were calculated from exercise test results. Anthropometric and metabolic risk factors as well as metabolic Z score were obtained.

RESULTS

The HRR parameters were inversely correlated with most of the metabolic risks, including waist circumference, systolic blood pressure (SBP), serum triglycerides, and serum C-reactive protein (CRP) levels, and were positively correlated with serum HDL levels. In multiple linear regression analysis, among the metabolic risks, waist circumference was the only parameter associated with HRR parameters (P = 0.038, 0.001, and 0.001 for 1-, 2-, and 3-min HRR, respectively) in boys. In girls, waist circumference (P = 0.001 and <0.001 for 2- and 3-min HRR, respectively), SBP (P = 0.029 for 1-min HRR), serum glucose (P = 0.021 for 2-min HRR), and serum CRP (P = 0.007 for 2-min HRR) levels were the most important determinants of HRR parameters. The adjusted 1-min HRR did not change across four quartiles of metabolic Z score, while the adjusted 3-min HRR decreased significantly with four quartiles of metabolic Z score.

CONCLUSIONS

Metabolic risks are inversely associated with HRR in healthy children and adolescents. Our finding suggests that there is a link between metabolic risks and autonomic nervous system functions in healthy young ages.

n-3 Polyunsaturated fatty acids, inflammation and obesity-related disease

Obese individuals are at increased risk from a range of metabolic diseases, including insulin resistance, dyslipidaemia and hypertension. Adipose tissue is an important endocrine organ, secreting a range of inflammatory mediators, including tumour necrosis factor a and interleukin 6. Circulating concentrations of these cytokines are increased in obesity and may contribute to the pathogenesis of metabolic diseases. The present review considers the evidence linking inflammation and obesity-related disease. The data show that an inflammatory phenotype, measured by serum sialic acid concentration, identifies individuals with insulin resistance, dyslipidaemia and hypertension. Serum sialic acid concentration increases progressively in obese individuals with none, one or multiple features of the metabolic syndrome, independent of BMI. Supplementation with long-chain n-3 polyunsaturated fatty acids has shown anti-inflammatory effects in studies of both healthy populations and in models of chronic inflammatory conditions. The effect on insulin sensitivity has been varied, with both positive and negative effects. This variability may relate to the metabolic characteristics of the study population; individuals with high background inflammation may derive greater benefits from n-3 polyunsaturated fatty acid supplements, suggesting a possible interaction between diet and phenotype. Future research is needed to fully evaluate the role of anti-inflammatory strategies in the dietary management of obesity.

Effects of a reduced-glycemic-load diet on body weight, body composition, and cardiovascular disease risk markers in overweight and obese adults

BACKGROUND

Lowering the dietary glycemic load and increasing protein intake may be advantageous for weight management.

OBJECTIVE

This randomized controlled trial was designed to evaluate the effects of an ad libitum reduced-glycemic-load (RGL) diet on body weight, body composition, and cardiovascular disease (CVD) risk markers in overweight and obese adults during an initial weight-loss phase (12 wk) and a weight-loss maintenance phase (weeks 24-36).

DESIGN

Subjects were assigned to RGL (n = 43) or low-fat, portion-controlled (control; n = 43) diet groups. The RGL group was instructed to eat until satisfied, maintaining a low carbohydrate intake during weeks 0-2 and adding low-glycemic-index carbohydrate thereafter. Control subjects were instructed to reduce fat intake and decrease portion sizes, with a targeted energy deficit of 500 to 800 kcal/d.

RESULTS

The RGL group had lost significantly more weight than did the control group at week 12 (-4.9 and -2.5 kg, respectively; P = 0.002), but the 2 groups did not differ significantly at week 36 (-4.5 and -2.6 kg, respectively; P = 0.085). Changes in fat mass differed between the groups at week 12 (-1.9 and -0.9 kg, respectively; P = 0.016) but not at week 36 (-2.0 and -1.3 kg, respectively; P = 0.333). At the end of the study, no differences were found in responses for CVD risk markers except a larger mean change in HDL cholesterol in the RGL group than in the control group (3.8 and 1.9 mg/dL, respectively; P = 0.037).

CONCLUSION

These findings provide evidence that an ad libitum RGL diet is a reasonable alternative to a low-fat, portion-controlled eating plan for weight management.

Metabolic syndrome in women with chronic pain

Fibromyalgia is a prevalent syndrome characterized by chronic pain, fatigue, and insomnia. Patients with fibromyalgia commonly have an elevated body mass index and are physically inactive, 2 major risk factors for metabolic syndrome. Yet little is known about the relationship between chronic pain conditions and metabolic disturbances. Our study evaluated the risk for, and neuroendocrine correlates of, metabolic syndrome in this patient population. Women with fibromyalgia (n = 109) were compared with control healthy women (n = 46), all recruited from the community. Metabolic syndrome was identified by using criteria from the Adult Treatment Panel III with glycosylated hemoglobin concentrations substituted for serum glucose. Catecholamine and cortisol levels were determined from 12-hour overnight urine collections. Women with fibromyalgia were 5.56 times more likely than healthy controls to have metabolic syndrome (95% confidence interval, 1.25-24.74). Fibromyalgia was associated with larger waist circumference (P = .04), higher glycosylated hemoglobin (P = .01) and serum triglyceride (P < .001) levels, and higher systolic (P = .003) and diastolic (P = .002) blood pressure. Total and low-density lipoprotein cholesterol were also significantly higher in women with fibromyalgia (P = .001 and .02, respectively), although high-density lipoprotein cholesterol was in the reference range. These associations were not accounted for by age or body mass index. Meeting criteria for more metabolic syndrome components was related to higher urinary norepinephrine (NE)/epinephrine and NE/cortisol ratios (P < .001 and P = .009, respectively). Women with chronic pain from fibromyalgia are at an increased risk for metabolic syndrome, which may be associated with relatively elevated NE levels in conjunction with relatively reduced epinephrine and cortisol secretion.

Effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate metabolism and biomarkers of oxidative stress in men and women with elevated blood pressure

OBJECTIVE

To assess the effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate homeostasis and biomarkers of oxidative stress.

DESIGN

A randomized, double-blind, controlled clinical trial.

SETTING

The trial was conducted at two clinics.

SUBJECTS AND INTERVENTIONS

Ninety-seven men and women with resting systolic blood pressure 130-179 mm Hg and/or diastolic blood pressure 85-109 mm Hg were randomly assigned to consume foods containing oat beta-glucan or control foods for 12 weeks. Resting blood pressures, insulin and glucose values before and after standard breakfast meals, and four biomarkers of oxidative stress were measured before and at the end of the treatment period.

RESULTS

Changes from baseline to week 12 in mean peak insulin and incremental area under the insulin curve differed significantly between groups (P=0.037 and 0.034, respectively), with the beta-glucan group showing declines and the control group remaining essentially unchanged. Blood pressure responses were not significantly different between groups overall. However, in subjects with body mass index above the median (31.5 kg/m(2)), both systolic (8.3 mm Hg, P=0.008) and diastolic (3.9 mm Hg, P=0.018) blood pressures were lowered in the beta-glucan group compared to controls. No significant differences in biomarkers of oxidative stress were observed between treatments.

CONCLUSIONS

The results of the present trial suggest beneficial effects of foods containing beta-glucan from oats on carbohydrate metabolism, and on blood pressure in obese subjects.

The temporal relationship between heart rate recovery immediately after exercise and the metabolic syndrome: the CARDIA study

AIMS

Slower heart rate recovery (HRR) following exercise is associated with the metabolic syndrome, yet the temporal relationship between the two remains unknown. We investigated the cross-sectional and longitudinal associations of slower HRR following a graded exercise treadmill test (GXT) with metabolic syndrome components and LDL-C.

METHODS AND RESULTS

Participants aged 18-30 from the Coronary Artery Risk Development in Young Adults study underwent a symptom-limited maximal GXT at baseline (n = 4319) and 7 years later. HRR was calculated as the difference between maximum heart rate (HR) and HR 2 min after test cessation. Slower baseline HRR was associated with a higher cross-sectional level but not longitudinal (15 year follow-up) increases in blood pressure, triglyceride, waist circumference, and LDL-C. No cross-sectional or longitudinal association was observed between HRR and HDL-C. In contrast, participants with one or two or more metabolic syndrome components (National Cholesterol Education Program III and American Diabetes Association criterion) at baseline examination had significantly larger longitudinal declines in HRR [-3.48 (P < 0.05) and-5.64 bpm (P < 0.001), respectively] from baseline to year 7, when compared with participants without syndrome components (-2.40 bpm).

CONCLUSION

Slower HRR does not precede development of the metabolic syndrome, but appears after syndrome components are present.

Hypertension and the Metabolic Syndrome

The cause of hypertension in the metabolic syndrome is complex and multifactorial and all of the elements of the metabolic syndrome, including obesity, insulin resistance, and the characteristic dyslipidemia probably are involved in mediating changes ultimately resulting in hypertension and modifying its course. Of these elements, obesity may play the most important and pivotal role in creating the conditions that lead to hypertension in the metabolic syndrome. This is not to say that the other elements of the syndrome are less important, and, as we gain more insight into the processes involved, we should be able to better manage the disease and tailor our therapeutic interventions appropriately.

Association between markers of the metabolic syndrome and lower urinary tract symptoms in the Third National Health and Nutrition Examination Survey (NHANES III)

OBJECTIVE

To examine the association of components of the metabolic syndrome with lower urinary tract symptoms (LUTS), which often result from prostate enlargement and heightened tone of prostate and bladder smooth muscle.

DESIGN

Third National Health and Examination Survey (NHANES III), from which LUTS cases and controls were selected.

SUBJECTS

A total of 2372 men aged 60+ y who participated in NHANES III. LUTS cases were men with at least three of these four symptoms: nocturia, incomplete bladder emptying, weak stream, and hesitancy, and who never had noncancer prostate surgery. Controls were men without any of the symptoms and who never had noncancer prostate surgery.

MEASUREMENTS

As part of NHANES III, an oral glucose tolerance test was carried out, glycosylated hemoglobin, HDL and LDL cholesterol, and triglycerides were measured, and history of diabetes mellitus and hypertension were assessed. Logistic regression was used to calculate odds ratios (ORs) after applying sampling weights.

RESULTS

History of diabetes (OR 1.67; 95% confidence interval (CI) 0.72-3.86) and hypertension (OR 1.76; 95% CI 1.20-2.59) appeared to be positively associated with LUTS. The odds of LUTS increased with increasing glycosylated hemoglobin (P-trend = 0.005). No statistically significant associations between fasting or 2-h glucose or fasting insulin and LUTS were observed. However, men classified as having three or more components of the metabolic syndrome had an increased odds of LUTS (OR = 1.80; 95% CI 1.11-2.94).

CONCLUSION

These findings support the role for metabolic perturbations in the etiology of LUTS.

Rosiglitazone improves, while Glibenclamide worsens blood pressure control in treated hypertensive diabetic and dyslipidemic subjects via modulation of insulin resistance and sympathetic activity

BACKGROUND

Type II diabetes is often associated with high blood pressure, elevated sympathetic activity, and high plasma insulin levels. Hypoglycemic agents may negatively interfere with blood pressure control, sympathetic activity, and plasma insulin level; therefore the choice of treatment in type II diabetes may be crucial. We aimed to compare the effects of two hypoglycemic drugs on blood glucose, blood pressure, sympathetic activity, and insulin levels in type II diabetic and hypertensive patients.

METHODS

Forty-eight (24M, 24F) type II diabetic, hypertensive, and hyperlipidemic subjects were enrolled and treated for 4 weeks with an ACE inhibitor (Cilazapril) and a statin (Simvastatin). They were then randomized into two groups to receive a thiazolidinedione (Rosiglitazone; ROS) or a sulfonylurea (Glibenclamide; GLB) for 8 weeks. Blood biochemistry, blood pressure, plasma insulin, endothelial function, and sympathetic skin activity were measured before and after treatment.

RESULTS

A significant drop in systolic and diastolic blood pressure by 6.1 +/- 4.1 mm Hg and 4.2 +/- 1.9 mm Hg respectively; a reduction in plasma insulin concentration by 4.3 +/- 1.9 mU/L and a decline in skin sympathetic activity were observed in the group receiving ROS. The GLB group showed an increase in systolic blood pressure by 3.1 +/- 2.5 mm Hg, no change in diastolic blood pressure, significant elevation in plasma insulin concentration by 2.3 +/- 1.4 mu/L, and augmentation of sympathetic activity. No significant changes in endothelial function were observed in either group.

CONCLUSIONS

Rosiglitazone improved both plasma glucose and blood pressure levels, probably by attenuation of hyperinsulinemia and sympathetic activity, while Glibenclamide worsened blood pressure control possibly by elevation of insulin levels and activation of the sympathetic system.

In situ lipolytic regulation in subjects born small for gestational age

OBJECTIVE

Subjects born small for gestational age (SGA) who are prone to develop insulin resistance in adulthood display an abnormal development pattern of the adipose tissue during fetal and postnatal life. Since the lipolytic activity of the adipose tissue is critical in the development of insulin resistance, the purpose of this study was to investigate whether SGA itself might affect lipolysis regulation.

STUDY DESIGN

We studied the effect of catecholamines, by local injection of isoproterenol, and the effect of insulin, using two-step infusion at 8 and 40 mU/m2/min, on the in situ lipolysis of the subcutaneous abdominal adipose tissue of 23 subjects born SGA and 23 born appropriate for gestational age (AGA), using the microdialysis technique.

RESULTS

Under isoproterenol infusion, the increase in dialysate glycerol concentration was significantly 1.5-fold higher in the SGA than in the AGA group (P=0.02) and induced a 20% increase in the plasma FFA concentration (P=0.04), whereas no significant increase was observed in the AGA group. The antilipolytic action of insulin on dialysate glycerol concentration was similar in both groups throughout the insulin infusion.

CONCLUSION

Subjects born SGA demonstrated a hyperlipolytic reactivity to catecholamines, which might be regarded as an additional deleterious component of the insulin resistance associated with SGA. In contrast, being born SGA does not directly affect the antilipolytic action of insulin, showing that it does not play a major role in causing the long-term metabolic complications associated with reduced fetal growth.

Characteristics of autonomic nervous function in Zucker-fatty rats: investigation by power spectral analysis of heart rate variability

We investigated the characteristics of autonomic nervous function in Zucker-fatty and Zucker-lean rats. For this purpose, a long-term electrocardiogram (ECG) was recorded from conscious and unrestrained rats using a telemetry system, and the autonomic nervous function was investigated by power spectral analysis of heart rate variability (HRV). Although heart rate (HR) in Zucker-fatty rats was lower than that in Zucker-lean rats throughout 24 h, apparent diurnal variation in HR was observed in both strains and HR during the dark period was significantly higher than that in light period. Diurnal variation in locomotor activity (LA) in Zucker-fatty rats was also observed, but LA was lower than that in Zucker lean rats, especially during the dark period. There were no significant differences, however, in high-frequency (HF) power, low-frequency (LF) power, and the LF/HF ratio between Zucker-fatty and Zucker-lean rats. The circadian rhythm of these parameters was mostly preserved in both strains of rats. Moreover, the effect of autonomic blockades on HRV was nearly the same in Zucker-fatty and Zucker-lean rats. These results suggest that the autonomic nervous function of insulin-resistant Zucker-fatty rats remain normal, from the aspect of power spectral analysis of HRV.

Elevated sialic acid, but not CRP, predicts features of the metabolic syndrome independently of BMI in women

AIMS

C-reactive protein (CRP) is a predictor of many diseases including type II diabetes and cardiovascular disease. Fewer studies have similarly shown sialic acid (SA) to be a predictor of obesity-related diseases, but importantly SA shows less intra-individual variability than CRP and acts as an integrated marker of the activity of a number of acute-phase proteins. This study examines the association between both CRP and SA with individual and combined features of the metabolic syndrome.

SUBJECTS

In all, 257 women with a body mass index (BMI) ranging from 25.1 to 54.5 kg/m2 (geometric mean 33.1+/-5.8 kg/m2) and aged 19-71 y (mean 45.6+/-12.1 y) were studied. Subjects had no symptoms of intercurrent infection, known diabetes, treated dyslipidaemia, a chronic inflammatory condition, liver disease or malignancy.

RESULTS

Linear regression demonstrates that both CRP and SA were positively associated with weight, BMI, insulin resistance, dyslipidaemia and hypertension. There was a highly significant (P<0.0001) positive association of both SA and CRP with none, one, two, three or four features of the metabolic syndrome. For a 1 s.d. (4.0 mg/l) increase in CRP, there was a significant increased risk when comparing the odds of having metabolic syndrome (defined as three or more individual features) compared with the remainder of the population (odds ratio=1.7, P<0.0001), but this was not significant after adjustment for BMI. However, for a 1 s.d. (0.34 mmol/l) increase in SA, the odds of having metabolic syndrome compared with those without metabolic syndrome was 2.5 (P<0.0001), and persisted after additional adjustment for BMI (adjusted odds ratio=1.9, P<0.0001).

CONCLUSIONS

While SA and CRP are both univariately associated with individual features of the metabolic syndrome, SA, but not CRP, is significantly associated with the metabolic syndrome, independent of BMI. We conclude that SA identifies a subgroup of overweight individuals with an inflammatory phenotype, who are at the greatest risk of metabolic syndrome.

Extra-adipocyte leptin release in human obesity and its relation to sympathoadrenal function

The link between the human sympathoadrenalmedullary system and the adipocyte hormone leptin is controversial. We measured total and regional norepinephrine spillover, epinephrine secretion rate, and extra-adipocyte leptin release in 22 lean [body mass index (BMI) < 26] and 20 obese (BMI > 28) normotensive men who underwent arterial and central venous catheterization. Because plasma clearance of leptin is primarily by renal removal, for men at steady state we could estimate whole body leptin release to plasma from renal plasma leptin extraction. Whole body leptin release was 1,950 +/- 643 (means +/- SE) ng/min in obese men and 382 +/- 124 ng/min in lean men (P < 0.05). Total and renal norepinephrine spillover rates correlated directly with whole body leptin secretion rate. Leptin is released from multiple nonadipocyte sites, which we tested by use of simultaneous arteriovenous blood sampling. We found a surprisingly large contribution of brain leptin release to the plasma leptin pool, 529 +/- 175 ng/min (> 40% whole body leptin release), with greater leptin release in obese than in lean men, 935 +/- 321 vs. 160 +/- 59 ng/min (P = 0.045). In parallel with leptin measurements, we also quantified brain serotonin turnover and jugular overflow of neuropeptide Y (NPY). Brain serotonin turnover was higher in obese than in lean men, 227 +/- 112 vs. 21 +/- 14 ng/min (P = 0.019), as was overflow of NPY from the brain, 12.9 +/- 1.4 vs. 5.3 +/- 2.2 ng/min (P = 0.042). These results suggest that leptin is released within the brain and at an increased rate in obese humans, in whom activation of brain serotonergic and NPY mechanisms also exists.

Interactive relation of insulin and gender to cardiovascular reactivity in healthy young adults

High levels of insulin may promote hypertension pathogenesis, in part, via enhanced sympathetic nervous system (SNS) activity. This study examined potential interactive relations of fasting insulin levels, gender, and race to cardiovascular reactivity-a correlate of SNS activation. Hemodynamic responses to 4 laboratory challenges were determined by impedance cardiography in 64 healthy young adults (ages 18-26; 48% male; 50% White, 50% African American). Also examined were lipoprotein lipids, central and total adiposity, self-reported dietary factors, and physical activity. High-insulin (>10.2 mU/ml) men showed greater total peripheral resistance and longer pre-ejection period responses than low-insulin ( pound 10.2 mU/ml) men. High-insulin women displayed greater cardiac index responses than high-insulin men. High insulin levels were related to greater percentage body fat, dietary carbohydrate and fat intake, lower high-density lipoprotein (HDL) cholesterol (in men), higher total cholesterol (in women), and a trend toward higher triglycerides. Cardiovascular reactivity findings were unchanged after statistical adjustment for total and HDL cholesterol, triglycerides, percentage body fat, dietary carbohydrates, and fat. The Gender x Insulin (continuous scores) interaction accounted for 7% and 9% of the variance in cardiac index and total peripheral resistance responses, respectively. These results indicate that high insulin levels are associated with greater vascular reactivity in young men and cardiac reactivity in young women. Enhanced cardiovascular reactivity may constitute a biobehavioral dimension of the metabolic syndrome.

Rosiglitazone improves insulin sensitivity and lowers blood pressure in hypertensive patients

OBJECTIVE

To examine the effect of rosiglitazone on insulin resistance and blood pressure in patients with essential hypertension, classified based on abnormalities of their renin-angiotensin system.

RESEARCH DESIGN AND METHODS

A total of 24 hypertensive nondiabetic patients (age 58 +/- 6 years, BMI 30 +/- 5 kg/m2) were studied before and after rosiglitazone treatment. After 2 weeks off antihypertensive medication, subjects received a euglycemic-hyperinsulinemic clamp (40 mU. m(-2). min(-1)) with 6,6-[2H2]glucose infusion, ambulatory blood pressure monitoring, and blood tests for cardiovascular risk factors. Subjects were then placed on rosiglitazone (4 mg orally b.i.d.) and their usual antihypertensive medications (but not ACE inhibitors) for 16 weeks, and baseline tests were repeated.

RESULTS

There was no change in fasting plasma glucose (83 +/- 2 vs. 82 +/- 2 mg/dl, P = 0.60), but fasting insulin decreased (16.1 +/- 1.4 vs. 12.5 +/- 0.9 micro U/ml, P < 0.01). Total glucose disposal during the clamp increased (5.0 +/- 0.4 vs. 5.9 +/- 0.5 mg. kg(-1). min(-1), P < 0.001), with no change in suppression of hepatic glucose output. There were significant decreases in mean 24-h systolic (138 +/- 2 vs. 134 +/- 2 mmHg, P < 0.02) and diastolic (85 +/- 2 vs. 80 +/- 2 mmHg, P < 0.0001) blood pressure, and the decline in systolic blood pressure was correlated with the improvement in insulin sensitivity (r = 0.59, P < 0.005). Triglycerides (135 +/- 16 vs. 89 +/- 8 mg/dl, P < 0.01), LDL cholesterol (129 +/- 6 vs. 122 +/- 8 mg/dl, P = 0.18), and HDL cholesterol (51 +/- 3 vs. 46 +/- 3 mg/dl, P < 0.02) all decreased, with no change in the LDL-to-HDL ratio. Plasminogen activator inhibitor-1 and C-reactive protein also declined significantly.

CONCLUSIONS

Rosiglitazone treatment of nondiabetic hypertensive patients improves insulin sensitivity, reduces systolic and diastolic blood pressure, and induces favorable changes in markers of cardiovascular risk. Insulin sensitizers may provide cardiovascular benefits when used in the treatment of patients with hypertension.

Physical consequences of schizophrenia and its treatment: the metabolic syndrome

Schizophrenia is a life shortening illness. Unnatural causes and natural causes are put forward as reasons for this excess mortality. In terms of the latter, a host of different physical disorders occur with increased frequency in schizophrenia. When taken together, some of these illnesses such as type 2 diabetes mellitus and cardiovascular disorders constitute the Metabolic Syndrome; a characteristic phenotype of those with this syndrome is excessive visceral fat distribution. The exact reasons why this particular syndrome occurs in schizophrenia is as yet unclear though factors such as life style, poor diet and lack of exercise may contribute to it's development. Alternatively, overactivity of the hypothalamic-pituitary-adrenal axis leading to hypercortisolaemia can also result in excessive visceral fat accumulation. This minireview aims to explore the potential role of these issues and medication in terms of the increased morbidity and mortality observed in schizophrenia.

The regulation of human vascular smooth muscle extracellular matrix protein production by alpha- and beta-adrenoceptor stimulation

OBJECTIVE

The sympathetic nervous system (SNS) is commonly activated in hypertension; however, the role of SNS activation in the pathogenesis of cardiovascular structural changes remains poorly defined. In particular, the effect of adrenergic stimulation on extracellular matrix (ECM) protein production by human cardiovascular cells is unknown. The present study thus investigated the direct effect of adrenergic stimulation on ECM protein production by cultured human vascular smooth muscle (VSM) cells.

METHODS AND RESULTS

Exposing human VSM cells to norepinephrine increased collagen protein production by 42%, P < 0.01, when compared to control (unstimulated) cells. This effect was mediated by the alpha1-adrenoceptor, since it was inhibited by the selective alpha1-adrenoceptor antagonist; prazosin (2 micromol/l) and reproduced by the selective alpha1-adrenoceptor agonist; phenylephrine (10 micromol/l). In contrast, beta-adrenoceptor stimulation - isoprenaline (1 micromol/l) or norepinephrine (10 micromol/l) + prazosin (2 micromol/l) - inhibited collagen production by 12%, P < 0.01. This inhibitory effect was mediated via the beta1-adrenoceptor, since it was blocked by atenolol (beta1-adrenoceptor antagonist) but not butoxamine (beta2-adrenoceptor antagonist). Fibronectin, another ECM protein, was similarly regulated by alpha- and beta-adrenoceptor stimulation. Transforming growth factor beta1 (TGFbeta1) mRNA expression by human VSM cells was also significantly influenced by adrenergic stimulation, being increased by phenylephrine (alpha-agonist) and inhibited by isoprenaline (beta-agonist).

CONCLUSIONS

These results uniquely demonstrate the capacity for adrenergic stimulation to directly modulate TGFbeta1 expression and ECM protein synthesis by the human cardiovascular system.

The visceral nervous system and its environments

Starting from the observation of the relationships of the biological system with its environments and of the genetically determined neuronal properties of plasticity and rhythmicity, it is possible to propose a new hypothesis about the functional role and organization of the visceral nervous system based on the physical model of the Dissipative Structure by I. Prigogine. The similarily between the visceral nervous system function and this model is supported by the following observations: (1) The visceral nervous system is a complex system, composed of many interacting units, which works away from thermodynamic equilibrium; (2) the functional organization of the nervous system is strongly dependent on internal and external environmental stimuli; (3) it is characterized by the presence of rhythms and periodic behaviors and (4) the internal order of the system is maintained in the continuous interplay between function, structure and fluctuations. On the basis of the present hypothesis, a few general principles can be formulated: (1) the higher brain centers, the fluid matrix and the external world, are the visceral nervous system natural environments; (2) with which it is plastically interfaced as a thermodynamic dissipative structure; (3) its main functional role is to regulate, distribute and maintain ordered exchanges of matter, energy and information between these environments. The present is a general interpretation of the operations of the visceral nervous system as a whole. In the frame of this interpretation the hypotheses so far formulated, including the homeostatic theory, can be viewed as the description of discrete and complementary aspects of the visceral nervous system functions.

Nutritional factors in the pathobiology of human essential hypertension

Endothelial cells produce vasodilator and vasoconstrictor substances. Dietary factors such as sodium, potassium, calcium, magnesium, zinc, selenium, vitamins A, C, and E, and essential fatty acids and their products such as eicosanoids can influence blood pressure, cardio- and cerebrovascular diseases, and concentrations of blood lipids and atherosclerosis. There might be a close interaction between these dietary factors, sympathetic and parasympathetic nervous systems, the metabolism of essential fatty acids, nitric oxide, prostacyclin, and endothelium in human essential hypertension. A deficiency in any one factor, dietary or endogenous, or alterations in their interactions with each other, can lead to endothelial dysfunction and development of hypertension. Therefore, alterations in the metabolism of essential fatty acids might be a predisposing factor to the development of essential hypertension and insulin resistance.

The adrenal and the metabolic syndrome

This review discusses the possible interrelationships between adrenal steroid hormones and the metabolic syndrome. Abnormal regulation of the hypothalamic-pituitary-adrenal axis has been proposed. Studies in the United Kingdom associated the metabolic syndrome with low birth weight and hyperactivity of the entire axis. In Italy, increased pituitary responsiveness to stimulation with vasopressin and corticotrophin-releasing hormone was demonstrated in women with central obesity. Swedish researchers have reported that increased stress responses of the axis correlated with a less variable but decreased cortisol level. An allele of the glucocorticoid receptor was also associated with various components of the metabolic syndrome. Evidence also suggests that central obesity is associated with an increased peripheral conversion of cortisol to cortisone and subsequent feedback stimulation of the axis. On the other hand, central fat may have an increased local metabolism in the direction of cortisol. Roles for dehydroepiandrosterone and aldosterone in the syndrome have also been proposed.