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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hyperinsulinemia and increased sympathetic nervous system (SNS) activity are thought to be pathophysiological links between obesity and hypertension. In the present study, we examined the relation among heart rate (HR), blood pressure (BP), and percent body fat (hydrodensitometry or DEXA), fasting plasma insulin concentration, and muscle sympathetic nerve activity (MSNA, microneurography) in male, normotensive whites (n=42) and Pima Indians (n=77). Pima Indians have a high prevalence of obesity and hyperinsulinemia but a relatively low prevalence of hypertension. Compared with whites, Pima Indian men had a higher percent body fat (28% versus 21%) and higher fasting insulin concentrations (210 versus 132 pmol/L) but lower MSNA (27 versus 33 bursts/min) (all P<0.001). In both ethnic groups, HR and BP were positively related to percent body fat and MSNA, and both were significant independent determinants of HR and BP in multiple regression analyses. However, MSNA was positively related to percent body fat and the fasting insulin concentration in whites (r=0.60 and r=0.47, both P<0.01) but not in Pima Indians (r=0.15 and r=0.03, NS) (P<0.01 for ethnic differences in the slope of the regression lines). These results confirm the physiological importance of the SNS in normal BP regulation but indicate that the roles of hyperinsulinemia and increased SNS activity as mediators for the relation between obesity and hypertension can differ between different ethnic groups. The lack of an increase in SNS activity with increasing adiposity and insulinemia in Pima Indians may contribute to the low prevalence of hypertension in this population.
Hypertension 2000 Oct
PMID:Ethnic differences in insulinemia and sympathetic tone as links between obesity and blood pressure. 1104 Feb 31

Animal models for insulin resistance and type 2 diabetes are required for the study of the mechanism of these phenomena and for a better understanding of diabetes complications in human populations. Type 2 diabetes is a syndrome that affects 5-10% of the adult population. Hyperinsulinaemia, hypertriglyceridaemia, decreased high-density lipoprotein (HDL) cholesterol levels, obesity and hypertension, all form a cluster of risk factors that increase the risk of coronary artery disease, and are known as insulin resistance syndrome or syndrome X. The gerbil, Psammomys obesus is characterized by primary insulin resistance and is a well-defined model for dietary induced type 2 diabetes. Weanling Psammomys and Albino rats were held individually for several weeks on high energy (HE) and low energy (LE) diets in order to determine the development of metabolic changes leading to diabetes. Feeding Psammomys on HE diet resulted in hyperglycaemia (303 +/- 40 mg/dl), hyperinsulinaemia (194 +/- 31 microU/ml) and a moderate elevation in body weight, obesity and plasma triglycerides. Albino rats on HE diet demonstrated an elevation in plasma insulin (30 +/- 4 microU/ml), hypertriglyceridaemia (170 +/- 11 mg/dl), an elevation in body weight and obesity, but maintained normoglycaemia (98 +/- 6 mg/dl). Psammomys represent a model that is similar to human populations, with primary insulin resistance expressed in young age, which leads to a high percentage of adult type 2 diabetes. Examples for such populations are the Pima Indians, Australian Aborigines and many other Third World populations. The results indicate that the metabolism of Psammomys is well adapted towards life in a low energy environment, where Psammomys takes advantage of its capacity for a constant accumulation of adipose tissue that will serve for maintenance and breeding in periods of scarcity. This metabolism known as 'thrifty metabolism', is compromised at a high nutrient intake.
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PMID:Psammomys obesus and the albino rat--two different models of nutritional insulin resistance, representing two different types of human populations. 1166 19

Insulin resistance is a key factor in the pathogenesis of type 2 diabetes mellitus and a co-factor in the development of dyslipidaemia, hypertension and atherosclerosis. The causes of insulin resistance include factors such as obesity and physical inactivity, and there may also be genetic factors. The mechanism of obesity-related insulin resistance involves the release of factors from adipocytes which exert a negative effect on glucose metabolism: free fatty acids, tumour necrosis factor-alpha and the recently discovered hormone, resistin. The two resulting abnormalities observed consistently in glucose-intolerant states are impaired suppression of endogenous glucose production, and impaired stimulation of glucose uptake. Among the genetic factors, a polymorphism (Pro12Ala) in the peroxisome proliferator-activated receptor (PPAR) gamma is associated with a reduced risk of type 2 diabetes mellitus and increased insulin sensitivity, primarily that of lipolysis. On the other hand, the association with insulin resistance of a common polymorphism (Gly972Arg) in the insulin receptor substrate 1, long believed to be a plausible candidate gene, is weak at best. This polymorphism may instead be associated with reduced insulin secretion, which, in view of the recent recognition of the insulin signalling system in beta-cells, results in the development of a novel pathogenic concept. Finally, fine-mapping and positional cloning of the susceptibility locus on chromosome 2 resulted in the identification of a polymorphism (UCSNP-43 G/A) in the calpain-10 gene. In non-diabetic Pima Indians, this polymorphism was associated with insulin resistance of glucose disposal. The pharmacological treatment of insulin resistance has recently acquired a novel class of agents: the thiazolidinediones. They act through regulation of PPARgamma-dependent genes and probably interfere favourably with factors released from adipocytes which mediate obesity-associated insulin resistance.
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PMID:Insulin resistance and insulin sensitizers. 1168 68

As the white adipose tissue, especially abdominal fat is an endocrine organ secreting adipocytokines, which induce insulin resistance, hypertension, and arteriosclerotic diseases, reduction of the abdominal fat is important. But effect of the diet therapy differs in each individual, because of the difference of energy expenditure. Since the relationship between the missense mutation (Trp64Arg) of the beta 3-adrenergic receptor (beta 3-AR) gene and low energy expenditure in the obese Pima Indians was made clear, gene polymorphisms that mediate body weight are reported one after another. We also reported that one third of Japanese have the Trp64Arg mutation of beta 3-AR gene, which may produce obesity or difficulties in weight loss. Here we introduce the obesity-related genes, and report the importance of Tailor-made diet therapy based on molecular genetics to improve obesity.
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PMID:[The tailor-made diet therapy to improve obesity]. 1180 27

The combination of insulin resistance, dyslipidemia, hypertension, and obesity has been described as a "metabolic syndrome" that is a strong determinant of type 2 diabetes. Factor analysis was used to identify components of this syndrome in 1,918 Pima Indians. Prospective analyses were conducted to evaluate associations of identified factors with incidence of diabetes. Factor analysis identified 4 factors that accounted for 79% of the variance in the original 10 variables. Each of these factors reflected a proposed component of the metabolic syndrome: insulinemia, body size, blood pressure, and lipid metabolism. Among 890 originally nondiabetic participants with follow-up data, 144 developed diabetes in a median follow-up of 4.1 years. The insulinemia factor was strongly associated with diabetes incidence (incidence rate ratio [IRR] for a 1-SD difference in factor scores = 1.81, P < 0.01). The body size and lipids factors also significantly predicted diabetes (IRR 1.52 and 1.37, respectively, P < 0.01 for both), whereas the blood pressure factor did not (IRR 1.11, P = 0.20). Identification of four unique factors with different associations with incidence of diabetes suggests that the correlations among these variables reflect distinct metabolic processes, about which substantial information may be lost in the attempt to combine them into a single entity.
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PMID:Components of the "metabolic syndrome" and incidence of type 2 diabetes. 1235 57

The hypothalamo-pituitary-adrenal axis and sympathetic nervous system (SNS) interact to maintain cardiovascular and metabolic homeostasis, especially during stress. Pima Indians have a low SNS activity, which may contribute to both their increased risk of obesity and reduced risk of hypertension. Although glucocorticoids inhibit SNS activity, Pima Indians are not hypercortisolemic compared with Caucasians. This does not exclude the possibility that the SNS is more responsive to an inhibitory effect of cortisol in the former than in the latter group. We measured fasting plasma ACTH and cortisol and muscle SNS activity [muscle sympathetic nervous system activity (MSNA), microneurography] in 58 males [27 Pimas/31 Caucasians]. Seven Pimas and 12 Caucasians were randomized to a double-blind, placebo-controlled, cross-over study to examine the effect of overnight partial chemical adrenalectomy (metyrapone) followed by cortisol replacement (hydrocortisone) on plasma ACTH, cortisol, and MSNA. There were no ethnic differences in fasting plasma ACTH or cortisol, but MSNA adjusted for percent body fat was lower in Pimas than in Caucasians (P < 0.006). No correlation was found between fasting cortisol and basal MSNA. Administration of metyrapone did not lead to significant changes in MSNA. In response to a hydrocortisone infusion, MSNA decreased in Pima Indians (P = 0.03) but not in Caucasians (P = 0.7). Our data indicate that the low SNS activity that predisposes Pima Indians to obesity is not due to a tonic inhibitory effect of cortisol. However, an acute release of cortisol is likely to more effectively contain sympathoexcitation during stress in Pima Indians than in Caucasians, which may be an important mechanism of cardioprotection in this Native American population.
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PMID:Effect of cortisol on muscle sympathetic nerve activity in Pima Indians and Caucasians. 1284 68

The angiotensin-converting enzyme gene (ACE) insertion/deletion polymorphism was determined in 211 Mexican healthy individuals belonging to different Mexican ethnic groups (98 Mestizos, 64 Teenek, and 49 Nahuas). ACE polymorphism differed among Mexicans with a high frequency of the D allele and the D/D genotype in Mexican Mestizos. The D/D genotype was absent in Teenek and present in only one Nahua individual (2.0%). When comparisons were made, we observed that Caucasian, African, and Asian populations presented the highest frequencies of the D allele, whereas Amerindian (Teenek and Pima) and Australian Aboriginals showed the highest frequencies of the I allele. The distribution of I/D genotype was heterogeneous in all populations: Australian Aboriginals presented the lowest frequency (4.9%), whereas Nahuas presented the highest (73.4%). The present study shows the frequencies of a polymorphism not analyzed previously in Mexican populations and establishes that this polymorphism distinguishes the Amerindian populations of other groups. On the other hand, since ACE alleles have been associated with genetic susceptibility to developing cardiovascular diseases and hypertension, knowledge of the distribution of these alleles could help to define the true significance of ACE polymorphism as a genetic susceptibility marker in the Amerindian populations.
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PMID:Angiotensin-converting enzyme gene (ACE) insertion/deletion polymorphism in Mexican populations. 1501 37

Type 2 diabetes mellitus (DM) has traditionally been considered a disease of adults. However, in the last 2 decades, it is increasingly being reported in children and adolescents. Obesity is a strong correlate, and the increasing prevalence of obesity and poor physical activity is precipitating type 2 DM at younger ages in the ethnic groups at risk. Indians and other South Asians are among the ethnic groups particularly prone to insulin resistance and type 2 DM, the other racial groups being some American Indian tribes like the Pima Indians, Mexican Americans,Pacific Islanders and African Americans,among others. The WHO has predicted that India will have the greatest number of diabetic individuals in the world by the year 2025. Type 2 DM starting during adolescence puts the individual at risk for major morbidity and even mortality right during the productive years of life. The microvascular complications of DM (nephropathy, retinopathy, neuropathy) are brought on at an early age. In addition, type 2 DM and obesity are two components of a metabolic syndrome of insulin resistance, the other features of which include hypertension, dyslipidemia and hypercoagulability of blood. All these conditions together increase the risk for cardiovascular and cerebrovascular mortality and morbidity (i.e., myocardial infarction and stroke). The resulting economic burden will be enormous. Type 2 DM and the insulin resistance syndrome are to a large extent preventable. Adoption of a healthy eating and physical activity pattern has resulted in decreasing the development of DM in a few recent studies from various parts of the world. A concerted,multi-pronged effort is needed, involving the general public, pediatricians and general physicians, teachers and schools, the media,the government and professional medical bodies, to generate a momentum towards the goal of prevention of type 2 DM and the insulin resistance syndrome in the young population of India.
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PMID:IAP National Task Force for Childhood Prevention of Adult Diseases: insulin resistance and Type 2 diabetes mellitus in childhood. 1518 Dec 95

Pima Indians in the United States and Mexico share a common genetic background but have very different lifestyles. Comparisons were made of the frequency of obesity, diabetes, hypertension, and kidney disease in these geographically separated but susceptible populations. Mexican Pimas had higher levels of physical activity, less obesity, and a lower prevalence of diabetes than their US Pima counterparts. Mean blood pressure rose with worsening glucose tolerance, and the prevalence of elevated urinary albumin excretion was higher in patients with diabetes than in those without, regardless of whether they lived in the United States or Mexico. These findings illustrate the importance of lifestyle in the development of diabetes and in the subsequent occurrence of diabetic kidney disease.
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PMID:Impact of lifestyle on prevalence of kidney disease in Pima Indians in Mexico and the United States. 1601 93

Adiponectin has demonstrated insulin-sensitizing, antiatherogenic, and anti-inflammatory properties, and may be an important risk factor for coronary heart disease and diabetes. Relatively few previous studies of plasma adiponectin have included sizable numbers of African Americans. The objective of the study was to investigate plasma concentrations of adiponectin and correlates of these concentrations in African Americans. This was a cross-sectional analysis that took place within the Hypertension Genetic Epidemiology Network. This study included 211 normotensive offspring (aged 22-37 years) of hypertensive siblings recruited by the Hypertension Genetic Epidemiology Network Birmingham, AL, field center. In addition to measuring plasma adiponectin, demographic and lifestyle data were collected, and anthropometric, clinical, and laboratory measurements were obtained. Mean plasma adiponectin concentration was 5.5+/-3.8 microg/mL. Adiponectin was 55% higher in women than in men: 6.5+/-4.4 vs 4.2+/-2.5 microg/mL, respectively (P<.0001). In a multivariable analysis, high-density lipoprotein cholesterol concentration was positively associated and male sex and insulin concentration were negatively associated with plasma adiponectin concentration. Plasma adiponectin concentrations in these African Americans were lower than those reported in other racial/ethnic groups, including Japanese, whites, and Pima Indians. The directions of the associations of plasma adiponectin with other factors were in agreement with results in other racial/ethnic groups.
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PMID:Plasma adiponectin concentrations and correlates in African Americans in the Hypertension Genetic Epidemiology Network (HyperGEN) study. 1761 43


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