Cholesterol absorption and the metabolic syndrome: a new look at an old area

Dietary cholesterol induces hepatic inflammation and blunts mitochondrial function in the liver of high-fat-fed mice

The present study investigated the role of dietary cholesterol and fat in the development of nonalcoholic fatty liver disease, a common liver disease in metabolic disorders. Mice were fed a diet of regular chow (CH), chow supplemented with 0.2% w/w cholesterol (CHC), high fat (HF, 45kcal%) or HF with cholesterol (HFC) for 17weeks. While both HF and HFC groups displayed hepatic steatosis and metabolic syndrome, only HFC group developed the phenotype of liver injury, as indicated by an increase in plasma level of alanine transaminase (ALT, by 50-80%). There were ~2-fold increases in mRNA expression of tumor necrosis factor α, interleukin 1β and monocyte chemotactic protein 1 in the liver of HFC-fed mice (vs. HF) but no endoplasmic reticulum stress or oxidative stress was observed. Furthermore, cholesterol suppressed HF-induced increase of peroxisome proliferator-activated receptor γ coactivator 1α and mitochondrial transcription factor A expression and blunted fatty acid oxidation. Interestingly, after switching HFC to HF diet for 5weeks, the increases in plasma ALT and liver inflammatory markers were abolished but the blunted of mitochondrial function remained. These findings suggest that cholesterol plays a critical role in the conversion of a simple fatty liver toward nonalcoholic steatohepatitis possibly by activation of inflammatory pathways together with retarded mitochondrial function.

Prevalence of calcified carotid artery atheromas on the panoramic images of patients with syndrome Z, coexisting obstructive sleep apnea, and metabolic syndrome

OBJECTIVES

The objective of this study was to compare the prevalence of calcified carotid artery atheromas (CCAAs) on panoramic images of individuals (n = 31) with obstructive sleep apnea (OSA) with individuals (n = 117) with syndrome Z (SZ: OSA with concomitant metabolic syndrome [MetS]).

STUDY DESIGN

Images of patients with OSA or SZ referred from the Sleep Service to Dentistry were evaluated. Descriptive statistics and t tests (Bonferroni correction) were conducted to determine significant differences between atheroma prevalence and proatherogenic factors (age, apnea-hypopnea index, body mass index, lipid profile, blood pressure, glucose) between OSA and SZ groups.

RESULTS

Individuals with OSA had an atheroma prevalence of 35% and those with SZ 42% (P = .52). Individuals with SZ also had significantly more severe atherogenic profiles (obesity, dyslipidemia, hyperglycemia) than OSA patients (P ≤ .05). Greatest CCAA prevalence (63%) was evidenced by SZ patients with severe OSA and moderate MetS.

CONCLUSION

Individuals with SZ have significantly greater atherogenic burden and slightly higher prevalence of CCAAs when compared with individuals with OSA.

Prevalence of comorbid obstructive sleep apnea and metabolic syndrome: syndrome Z and maxillofacial surgery implications

PURPOSE

To determine the prevalence of the recently identified syndrome Z (SZ), which is the co-occurrence of obstructive sleep apnea (OSA; hypoxia, systemic and pulmonary hypertension, nocturnal arrhythmias) and metabolic syndrome (MetS; increased abdominal girth, hypertriglyceridemia, decreased high-density lipoprotein, hypertension, increased fasting glucose), which places the surgical patient at heightened risk of perioperative complications (myocardial infarction, stroke, pneumonia, wound infection).

MATERIALS AND METHODS

Electronic medical records of 296 male veterans were assessed for the presence of SZ using the American Academy of Sleep Medicine definition of OSA and a modified Adult Treatment Panel III definition of MetS, where obesity was defined by a body mass index of at least 30 kg/m(2) rather than by waist circumference.

RESULTS

SZ was diagnosed in 59% of patients. These individuals commonly exhibited severe OSA and least commonly mild OSA. The more severe the OSA, the more likely (60%) that patients manifested moderate (4 risk markers) or severe (5 risk markers) MetS. Furthermore, with increasing apnea-hypopnea index values, the more severe were the MetS elements.

CONCLUSIONS

The results of this study demonstrate the high prevalence rate of MetS in patients with OSA seeking treatment. Given the risk of perioperative complications, it is suggested that all patients scheduled for maxillofacial surgical procedures to treat OSA be evaluated for SZ.

Metabolic syndrome: pathogenesis, medical care and dental implications

BACKGROUND

The dental literature contains little information about metabolic syndrome (MetS) and its dental implications.

TYPES OF STUDIES REVIEWED

The authors conducted a MEDLINE search for the period 2000 through 2005, using the term "metabolic syndrome" to define its pathophysiology, medical treatment and dental implications.

RESULTS

MetS is the co-occurrence of abdominal obesity, hyper-triglyceridemia, reduced high-density lipoprotein cholesterol levels, hypertension and impaired fasting glucose, which results from consumption of a high-calorie diet and decreased levels of physical activity superimposed on the appropriate genetic setting. Components of MetS synergistically promote the development of atherosclerosis, resulting in myocardial infarction and stroke.

CLINICAL IMPLICATIONS

Deteriorating oral health status is associated with worsening of the atherogenic profile. Tooth loss often results in chewing difficulties because of inadequate occlusive surfaces and may lead to alterations in food selection and dietary quality. This, in turn, adversely affects body composition and nutritional status, both of which are related to vascular health. Dentists should develop treatment plans that preserve and restore the dentition, thus ensuring maximum masticatory efficiency and affording patients the optimum opportunity to consume food that will not foster atherogenesis.

The significance of carotid artery atheromas on panoramic radiographs in the diagnosis of occult metabolic syndrome

OBJECTIVE

Metabolic syndrome (MetS), the co-occurrence of abdominal obesity, hypertriglyceridemia, reduced HDL cholesterol, hypertension, and insulin resistance promotes carotid atherosclerosis and stroke. The objective of this study was to determine if the presence of calcified atheromas detected on panoramic radiographs of individuals free of overt vascular disease may herald occult MetS.

STUDY DESIGN

Ninety-four individuals (mean age 65.6 years) with a calcified atheroma detected by a VA dental clinic were evaluated. A like-aged group was used for comparative analysis.

RESULTS

Fifteen percent of individuals (mean age 64 years) with an atheroma had occult MetS. Mean waist circumference was 116 cm, BMI 32.7 kg/m2, triglycerides 250 mg/dL, HDL cholesterol 35 mg/dL, blood pressure 147/87 mm Hg, and glucose 117 mg/dL. Only 6% of controls had occult MetS but this difference in prevalence was not proven to be statistically significant (P = .059).

CONCLUSION

Some individuals with a calcified atheroma may have undiagnosed MetS and should be referred to their physician because aggressive management may preclude a stroke.