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Dear Sir,

Metabolic syndrome (MS) is a complex of factors characterized by abnormal glucose and lipid metabolism, and is a common cause of atherosclerosis-related diseases. Recent studies have indicated that subjects characterized by MS had thicker intima-media complex in the carotid artery compared with age-matched controls [1, 2]. Furthermore, MS was found to exert effects on carotid structure and function independent of its individual components and other known cardiovascular risk factors [2]. It is well known that visceral obesity, partly mediated by several adipocytokines possessing biological activity in the vascular system, is closely associated with MS [3] and may exaggerate carotid atherosclerosis (CA).

However, to our knowledge, the clinical significance of adiposity and adipocytokines on the development of CA has not been well documented in MS subjects. This study therefore examined the relationships of such clinical variables to the development of CA in Japanese males with MS. MS was diagnosed according to the National Cholesterol Education Program–Adult Treatment Panel III criteria [4] using a modified waist circumference of >85 cm vs. 102 cm, as proposed by the Japan Society for the Study of Obesity [5]. Adiposity was evaluated by computed tomography at umbilical level to measure abdominal subcutaneous and visceral fat areas (SFA and VFA respectively) [6]. Intima-media thickness (IMT) of the common carotid artery was measured with high-resolution B-mode ultrasonography (SSA-370A; Toshiba, Tokyo, Japan) [7]. Plaque score (PS) was determined as the sum of maximum thickness of all plaques on the near and far walls of vessels [7].

A total of 98 consecutive Japanese men with MS (mean ± SD: aged 56.5 ± 14.4 years, BMI 26.4 ± 5.6 kg m−2, blood pressure 133.0 ± 19.4/81.0 ± 10.9 mmHg, waist circumference 91.9 ± 15.2 cm) were assessed, and 67 had type 2 diabetes. Fasting blood samples were used to measure serum adiponectin (5.5 ± 3.0 μg mL−1) by an enzyme-linked immunosorbent assay kit (Otsuka Pharmaceutical Co., Tokushima, Japan), tumour necrosis factor (TNF)-α (18.5 ± 6.2 pg mL−1) by an enzyme-amplified sensitivity immunoassay kit (TFB Inc., Tokyo, Japan), leptin (6.5 ± 7.0 ng mL−1) by radioimmunoassay, as well as measurements of immunoreactive insulin (57.8 ± 48.2 pmol L−1), HbA1c (7.5 ± 2.3%), triglycerides (1.72 ± 0.94 mmol L−1), total cholesterol (5.11 ± 1.03 mmol L−1), HDL cholesterol (0.85 ± 0.26 mmol L−1) and plasma glucose (7.16 ± 2.73 mmol L−1).

Positive correlations were observed between the VFA/SFA ratio and IMT (r = 0.248; P = 0.024) and between VFA/SFA and PS (r = 0.361; P =0.0008). Significant association of VFA with IMT (r = 0.239; P = 0.029) was also found, although not with PS (P = 0.72). TNF-α concentrations were significantly correlated with PS (r = 0.251; P =0.036). No relationships were observed between other variables, except for age and IMT or PS. Multiple regression analysis showed VFA/SFA (β =0.302; P = 0.013), TNF-α (β = 0.253; P = 0.022), and age (β = 0.257; P = 0.033) were independent determinants of PS.

Our results suggest the VFA/SFA ratio, rather than VFA alone, might be a more reliable indicator of the development and progression of CA in the management of Japanese males with MS. This may be partly due to the fact that Japanese tend to have higher VFA/SFA ratios than Caucasians [8]. Adipocytokines other than TNF-α were not correlated with CA, consistent with a recent report demonstrating no observed relationship between adiponectin and IMT, while TNF-α was correlated with IMT in Japanese type 2 diabetics [9]. Future prospective longitudinal studies using larger populations will be required to support these results.

Conflict of interest statement

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  2. Conflict of interest statement
  3. References

No conflict of interest was declared.

Y. Murase, A. Asano, J. Kobayashi, N. Yamaaki, H. MabuchiFrom the Molecular Genetics of Cardiovascular Disorders, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan

References

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  2. Conflict of interest statement
  3. References
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