A transgenic model of visceral obesity and the metabolic syndrome

The adverse metabolic consequences of obesity are best predicted by the quantity of visceral fat. Excess glucocorticoids produce visceral obesity and diabetes, but circulating glucocorticoid levels are normal in typical obesity. Glucocorticoids can be produced locally from inactive 11-keto forms through the enzyme 11beta hydroxysteroid dehydrogenase type 1 (11beta HSD-1). We created transgenic mice overexpressing 11beta HSD-1 selectively in adipose tissue to an extent similar to that found in adipose tissue from obese humans. These mice had increased adipose levels of corticosterone and developed visceral obesity that was exaggerated by a high-fat diet. The mice also exhibited pronounced insulin-resistant diabetes, hyperlipidemia, and, surprisingly, hyperphagia despite hyperleptinemia. Increased adipocyte 11beta HSD-1 activity may be a common molecular etiology for visceral obesity and the metabolic syndrome.

Changes in the isoprenoid pathway in syndrome X

This study assessed the changes in digoxin and some other metabolites of the isoprenoid pathway in metabolic syndrome X presenting with multiple lacunar state. There was an increase in plasma HMG CoA reductase activity with a consequent increase in serum digoxin, which caused a reduction in RBC membrane Na+-K+ ATPase activity. There was an increase in serum tryptophan and its metabolites and a decrease in tyrosine and its metabolites. Serum magnesium was decreased with consequent alteration in the metabolism of glycosaminoglycans and glycolipids. Increase in dolichol, another product of the isoprenoid pathway resulted in alteration in glycoprotein metabolism. Changes in the composition of membrane glycosaminoglycans, glycoproteins and cholesterol:phospholipid ratio were also observed in this disorder leading to decreased lysosomal stability. Decrease in ubiquinone, another isoprenoid metabolite resulted in alteration in the free radical generation. Membrane Na+-K+ ATPase inhibition due to digoxin, altered membrane structure, increased tryptophan catabolites and decreased tyrosine catabolites can lead on to increased intracellular calcium and reduced intracellular magnesium which can account for the symptoms of syndrome X.

PPARgamma and atherosclerosis: effects on cell growth and movement

Atherosclerosis is a major vascular complication of diabetes and the primary cause of mortality in persons with this disease. Metabolic abnormalities related to the Insulin Resistance Syndrome or Metabolic Syndrome may importantly contribute to the increased risk of atherosclerosis associated with diabetes. Thiazolidinediones (TZDs) are oral insulin sensitizers in broad clinical use that enhance insulin-stimulated glucose uptake into skeletal muscle. TZDs can also improve cardiovascular risk factors and exert direct effects on vascular cells to potentially retard the atherosclerotic process. Direct vascular effects of TZDs likely result from their activity as ligands for the nuclear receptor, PPARgamma. All of the major cell types in the vasculature express PPARgamma, including intimal macrophages and vascular smooth muscle cells (VSMCs) in human atheroma. TZDs block VSMC growth by inducing cell cycle arrest in G1 through an inhibition of retinoblastoma protein phosphorylation. Migration of monocytes and VSMCs is also inhibited by TZDs, possibly through decreased matrix metalloproteinase production. Activation of PPARgamma by TZDs in macrophages induces ABCA1 transporter expression to promote reverse cholesterol transport. These antiatherogenic activities may also occur in vivo because TZDs have been shown to inhibit lesion formation in several animal models. Thus, TZD activation of PPARgamma may protect against atherosclerosis both by normalizing proatherogenic metabolic abnormalities of the insulin resistance/diabetes milieu and through an inhibition of vascular cell growth and movement.

Benefits of sustained moderate weight loss in obesity

Over the last few years, weight loss has been recognised as a key factor in the control and prevention of coronary heart disease, hypertension, type 2 diabetes, hyperlipidaemia, cardiorespiratory failure and other chronic degenerative diseases. It has been shown that even a modest loss of 5% of initial body weight can reduce, eliminate or prevent these disorders in a large proportion of overweight patients. The early benefits of weight loss can be explained by the direct effects of a low calorie diet, but the long-term effects can only partially be attributed to diet, physical exercise or behavioural modifications. Long-term studies have shown that a sustained moderate weight loss of 10% improves glycemic control as a result of reduced insulin resistance, the better control or prevention of hypertension, increased HDL-and decreased LDL-cholesterol and VLDL triglycerides, improved diastolic function and the propagation of a cardiac stimulus that reduces the risk of ventricular arrhythmias. The health benefits of modest weight loss are particularly evident and useful when excess body fat is a major health hazard, as in the case of class III obesity (BMI > 40 kg/m2), which is often characterised by prevalent visceral fat accumulation. Baseline serum glucose, cholesterol, triglyceride, uric acid and blood pressure levels are usually higher in the upper body than is the case in peripheral obesity, and tend to decrease more in response to moderate weight loss. A therapeutic programme aimed at obtaining a gradual and moderate weight loss avoids the complications due to the rapid weight loss associated with inappropriate, unbalanced diets or even more harmful treatments. These complications include cholelithiasis and the subsequent risk of cholecystitis, lean body mass loss and a stable decrease in energy expenditure with a high probability of regaining weight (weight cycling syndrome). In conclusion, a large number of obese patients may be sensitive to a modest weight loss even without the achievement of ideal body weight. Sustained moderate weight loss by itself is definitely beneficial in obesity (especially "malignant" and "morbid" obesity), but also in diabetes, hypertension, hyperlipidaemia, cardiorespiratory diseases and other chronic degenerative diseases associated with any degree of excess body fat.

Complications of HIV: lipodystrophy, anemia, renal, cardiovascular, and bone diseases

Diagnosis of a human immunodeficiency virus (HIV) infection has long been associated with a short life expectancy, with care centered on the treatment and prevention of opportunistic infections and symptom management. As progress has been made through better understanding of the virus, and improved medications and treatments, persons with HIV are living longer, more productive lives. In addition to the scientific breakthroughs in treating the HIV-infected patient, more is also being learned about the long-term effects of the treatments and the virus, such as lipodystrophy syndrome. Comorbid diseases are also becoming more common in patients with HIV, such as anemia, bone disease, renal disease, and cardiac disease, which may be the result of metabolic complications or HIV itself. There is a vast array of comorbid diseases and adverse effects of medications in persons with HIV disease; and information regarding these issues is constantly changing as research continues to show more about their pathophysiology and treatment options. The most common comorbid disorders will be explored. A detailed explanation of the lipodystrophy syndrome and its common metabolic manifestations will be presented, including current research. In addition, the etiology, clinical findings, diagnosis, and treatment of the most common comorbid diseases associated with anemia and the bone, renal, and cardiovascular systems will be presented as they relate to the HIV-infected patient. All of the descriptions are designed for the primary care provider, who may be in contact with an HIV-infected patient whose differential diagnoses consist of one or more of these disorders.

Sleep disordered breathing--a new component of syndrome x?

Sleep disordered breathing (SDB) is a complication of obesity estimated to occur in about 4-6% of overweight individuals. These respiratory disturbances during sleep incorporate a number of conditions including snoring, upper airway resistance syndrome and obstructive sleep apnoea syndrome (OSAS). It is thought that as well as having deleterious effects on sleep quality these conditions may also promote cardiovascular and hormonal changes leading to an elevated blood pressure and an increased incidence of cardiovascular morbidity. Evidence reviewed here points to an alteration in sympathovagal balance, baroreceptor sensitivity, insulin resistance and leptin, growth hormone and lipid levels. Whether these changes are a consequence of the associated obesity or the SDB itself remains to be proven.

Insulin resistance syndrome and type 2 diabetes mellitus

Patients with type 2 diabetes mellitus have an elevated risk of morbidity and mortality from cardiovascular disease. This risk is partly attributable to an increased prevalence of classic coronary artery disease risk factors and partly because of hyperglycemia itself and a highly atherogenic lipid profile. The altered composition of lipoproteins and lipids in type 2 diabetic patients, termed diabetic dyslipidemia, is characterized by: (1) elevated levels of triglyceride; (2) normal levels of total and low-density lipoprotein cholesterol (LDL-C); (3) reduced levels of high-density lipoprotein cholesterol (HDL-C); (4) elevated levels of apolipoprotein B; (5) a preponderance of small, dense LDL particles; and (6) increased levels of cholesterol-rich very-low-density lipoprotein. In most cases, diabetic dyslipidemia is preceded by hyperinsulinemia resulting from insulin resistance. Because patients with type 2 diabetes and insulin resistance are at a markedly increased risk of atherosclerosis, and because strict control of glycemia has proved beneficial in reducing microangiopathy but not macroangiopathy, treatment of diabetic dyslipidemia should be aggressive. Target levels have, therefore, been set at <2.6 mmol/L (100 mg/dL) for LDL-C, <2.3 mmol/L [200 mg/dL] for triglycerides, and >1.15 mmol/L (45 mg/dL) for HDL-C. Trial data suggest that these target levels are likely to be achieved with statins, if necessary, in combination with fibrates or nicotinic acid derivatives. Furthermore, in large-scale clinical trials (eg, Scandinavian Simvastatin Survival Study [4S] and the Cholesterol and Recurrent Events [CARE] study), it has been demonstrated that lipid lowering can appreciably reduce cardiovascular events in diabetic patients.

Metabolic syndrome in severely obese patients

BACKGROUND

The authors assessed the prevalence of diabetes, hypertension, dyslipidemia and metabolic syndrome in patients with a high degree of obesity.

METHODS

A retrospective investigation was planned in a cohort of obese patients with a wide range of body mass index (BMI) referred to a large University Hospital for weight loss.

RESULTS

An increase in prevalence of diabetes and hypertension with increase in the degree of obesity was observed, while the prevalence of dyslipidemia and metabolic syndrome appeared to be independent of the BMI values.

CONCLUSION

In severely obese patients a still unknown factor which affects differently glucose and lipid metabolism cannot be excluded.

A high-fructose diet induces insulin resistance but not blood pressure changes in normotensive rats

Rats fed a high-fructose diet represent an animal model for insulin resistance and hypertension. We recently showed that a high-fructose diet containing vegetable oil but a normal sodium/potassium ratio induced mild insulin resistance with decreased insulin receptor substrate-1 tyrosine phosphorylation in the liver and muscle of normal rats. In the present study, we examined the mean blood pressure, serum lipid levels and insulin sensitivity by estimating in vivo insulin activity using the 15-min intravenous insulin tolerance test (ITT, 0.5 ml of 6 microg insulin, iv) followed by calculation of the rate constant for plasma glucose disappearance (Kitt) in male Wistar-Hannover rats (110-130 g) randomly divided into four diet groups: control, 1:3 sodium/potassium ratio (R Na:K) diet (C 1:3 R Na:K); control, 1:1 sodium/potassium ratio diet (CNa 1:1 R Na:K); high-fructose, 1:3 sodium/potassium ratio diet (F 1:3 R Na:K), and high-fructose, 1:1 sodium/potassium ratio diet (FNa 1:1 R Na:K) for 28 days. The change in R Na:K for the control and high-fructose diets had no effect on insulin sensitivity measured by ITT. In contrast, the 1:1 R Na:K increased blood pressure in rats receiving the control and high-fructose diets from 117 +/- 3 and 118 +/- 3 mmHg to 141 +/- 4 and 132 +/- 4 mmHg (P < 0.05), respectively. Triacylglycerol levels were higher in both groups treated with a high-fructose diet when compared to controls (C 1:3 R Na:K: 1.2 +/- 0.1 mmol/l vs F 1:3 R Na:K: 2.3 +/- 0.4 mmol/l and CNa 1:1 R Na:K: 1.2 +/- 0.2 mmol/l vs FNa 1:1 R Na:K: 2.6 +/- 0.4 mmol/l, P < 0.05). These data suggest that fructose alone does not induce hyperinsulinemia or hypertension in rats fed a normal R Na:K diet, whereas an elevation of sodium in the diet may contribute to the elevated blood pressure in this animal model.

Rapid fusion of granules with neutrophil cell membranes in hypertensive patients may increase vascular damage

In essential hypertension (EHT) the presence of a metabolic syndrome increases the risk of cardiovascular disease. A cell membrane abnormality is implicated but its role in cardiovascular disease is unclear. Neutrophil accumulation, which occurs by beta2-integrin (CD11b/CD18) expression, followed by release of proinflammatory factors from primary vesicles is an important factor in vascular damage. CD11b and CD69 expression on neutrophils from normal controls and EHT patients was determined by fluorescence-activated cell scanning. Neutrophils were activated with phorbol myristate acetate (PMA). Protein kinase C (PKC) and calpain were inhibited with bisindolylmaleimide and E64d, respectively. In EHT patients CD11b was not increased on neutrophils at rest. However, EHT neutrophils more readily expressed CD11b on incubation in phosphate-buffered saline and more cells went on to exocytose primary granules indicated by expression of CD69. Stimulation with PMA caused more rapid activation in EHT neutrophils with expression of CD11b, followed rapidly by exocytosis of primary granules. Bisindolylmaleimide slowed but did not prevent CD11b expression, which, together with primary granule exocytosis, continued to be faster in EHT neutrophils. E64d also slowed but did not prevent either CD11b expression or primary granule exocytosis, but this inhibitor did abolish the difference between NC and EHT neutrophils. The membrane abnormality in EHT may contribute to cardiovascular risk by increasing the rate of vesicle fusion with the cell membrane to increase neutrophil accumulation and release of inflammatory agents at sites of vascular damage. Calpain activation may be the rate-limiting component that is abnormal.

[Studies on the incidence and clinical significance of the metabolic syndrome in postmenopausal women in Lodz region]

In menopausal period increased prevalence of lipid metabolism disorders, atherosclerosis, carbohydrate metabolism disorders, cardiovascular diseases is observed.

AIM OF STUDY

Evaluation of prevalence of obesity, overweight, hypertension, carbohydrate and lipid metabolism disorders in population of women aged 45-65, treated in Menopause Diagnostic and Treatment Center Polish Mother's Memorial Hospital--Research Institute in Lodz. 2081 women, aged 45-65 were studied. In all of them diseases history, body mass index (BMI), blood pressure (twice), total cholesterol, triglycerides, fasting blood glucose levels were obtained. The highest percentage of obese women was noted in small villages (39%), whereas 21% of women from cities have BMI > or = 30 kg/m2. On the other side only 18.4% women living in cities have normal body weight, although in small villages there are 34.6% women from this group. Overweighted women percentage is similar among women living in small villages and cities. Hypertension prevalence did not depend on place of living, but obese women have hypertension more frequently. In study group diabetes mellitus was diagnosed in 4.8% of women and impaired glucose tolerance in 7%. Almost 2/3 of diabetes mellitus cases was first time diagnosed. Fasting blood glucose (FBG) level > or = 125 mg/dl was noted in 62 women (3%), values 111-124 mg/dl in 124 (6%), and in other 1895 women (91%) FBG was < or = 110 mg/dl. FBG level over 124 mg/dl and diabetes mellitus was more frequent in obese women. Women with hypercholesterolemia mostly (63.2%) have BMI > 25 kg/m2. Our study revealed that hypercholesterolemia prevalence did not differ with no statistical significance between women living in cities, towns and small villages. Elevated triglycerides level over 2.26 mmol/l was noted in 14.5% studied women, whereas there was no correlation between triglycerides level and body weight and place of living. Main health problem of women in perimenopausal period is obesity and lipid metabolism disorders detected in significant number of studied patients. Most cases of undiagnosed diabetes mellitus indicate that complex evaluation of health status of women in perimenopausal period is obligatory procedure.

[Evaluation of selected X syndrome factors during hormonal replacement therapy]

Estrogen deficiency after menopause leads to characteristics changes in the hormonal profile, which may influence lipid carbohydrate and calcium-phosphate metabolism and some elements of homeostasis.

AIM OF STUDY

To evaluate the influence of hormone replacement therapy with 2 mg estradiol valerate and 0,15 mg levonorgestrel on carbohydrate and lipid metabolism in women after menopause during 12 months of follow-up. We examined 101 women, mean age 52.9 +/- 4.6 years (range from 44 to 65). HRT was applied in 67 women whereas 34 women were without treatment. All of them had no carbohydrate disturbances. All women underwent clinical examination, and body mass index (BMI), fasting blood glucose, insulin, total cholesterol and triglycerides levels were obtained. At 1 and 2 hours after 75 g glucose challenge (75OGTT) glucose and insulin levels were obtained. During hormone replacement therapy all women noted release or significant decrease of climacteric symptoms. Total cholesterol level was decreased, whereas triglycerides did not change. After 12 months of treatment there was also a significant decrease of all factors relating to carbohydrate metabolism--fasting glucose and insulin, insulin/glucose ratio and area under glucose and insulin curves. In our study--after 6 months of follow-up fasting insulin level, area under glucose and insulin curves were increased whereas fasting blood glucose level remained unchanged. Among women without HRT there were no significant changes in selected lipid parameters and BMI. Triglyceride levels decreased (albeit insignificantly) but, total cholesterol levels did not change. After 12 months glucose level did not change, although other carbohydrate parameters were increased. 1) In the study group there was a statistically significant decrease in total cholesterol levels whereas triglycerides remained unchanged. 2) HRT we significantly decreased of insulin resistance and fasting blood glucose levels as compared with non-group HRT. 3) The present results indicate HRT-induced improvement of lipid and carbohydrate metabolism. 4) Long-term HRT is necessary to improve carbohydrate metabolism.

[Thiazolidinediones--a new class of oral antidiabetic drugs]

The discovery of a new class of oral antidiabetic drugs was stimulated by difficulties with the treatment currently available for patients with type 2 diabetes mellitus. Thiazolidinediones can lower blood glucose values due to their special insulin-sensitiser effect. In this way, these drugs seem to be very effective in the treatment of type 2 diabetic patients with characteristics of metabolic syndrome. The intracellular action caused by thiazolidinediones differs markedly from that of other oral antidiabetic drugs available. Apart from antihyperglycaemic effect, thiazolidinediones have further beneficial effects in experimental diabetes which require corroboration by clinical studies. Troglitazone was the first drug which reached the market. Unfortunately, this drug was withdrawn soon due to its hepatotoxicity. Rosiglitazone proved to be much safer in clinical studies. Pioglitazone is being tested nowadays in clinical studies. Thiazolidinediones have been already listed among oral antidiabetic drugs in international therapeutical guidelines. Nevertheless, further clinical studies and experiences are needed to determine the final exact indication of thiazolidinediones for the treatment of type 2 diabetic patients.

[Study on syndrome pattern in insulin resistant model rats]

OBJECTIVE

To explore the Syndrome pattern in insulin resistant model rats.

METHODS

Eight Sprague-Dawley (SD) rats were induced to insulin resistance (IR) by 60% high-sucrose forage.

RESULTS

The correlative co-efficient of some biological and internal changes were clusterly analyzed and divided into 3 groups, which was closely related with phleg tubidity, blood stasis and internal toxin types respectively. The phlegm turbidity type was characterized by high content of blood lipid (triglyceride, total cholesterol) and high concentration of glycated serum protein; the blood stasis type was characterized by tendency of high viscosity and high coagulant state, the blood pressure increased, prothrombin time shortened, fibrinogen content raised and RBC and platelet count increased; while the internal toxin type was characterized by high content of glucose, insulin and the elevation of tumor necrosis factor.

CONCLUSION

The combined Syndrome of phlegm turbidity, blood stasis and internal toxin is the Syndrome-pattern in insulin resistant model rat. This observation provides theoretic basis for clinical and experimental studies of TCM.

Visceral obesity and metabolic syndrome

There is increasing evidence for the existence of a condition consisting of a cluster of metabolic disorders which include insulin resistance, alterations in glucose and lipid metabolism, increased blood pressure and visceral obesity. The metabolic syndrome is now the favoured definition of the cluster. Each single component of the cluster increases the cardiovascular risk, but the combination of factors is much more important. Insulin resistance is the most frequently associated factor to the singular components of the syndrome: most authors believe that it may be the common aetiological factor. However, visceral obesity seems to be the main driving factor by means of the increased production of free fatty acids whose activity, in turn, might interfere with the action of insulin. Some questions exist about the syndrome because of the frequent lack in the cluster of one of the factors. This does not mean that the missing factor does not belong to the syndrome, but only that it is not yet clinically evident. Weight gain has been shown to be a strong predictor of the metabolic syndrome. This aspect gives strength to treatment and prevention because it means that losing weight or stopping weight increase might reduce the risk of a future appearance of a factor that is still not evident. Interventions to treat visceral obesity by means of losing weight seem to be the most efficacious way to treat the metabolic syndrome thus improving the most widespread cardiovascular risk factor in western countries.