Piia P Simonen

Publications (3)16.83 Total impact

• Article: The distribution of squalene and non-cholesterol sterols in lipoproteins in type 2 diabetes.

  Piia P Simonen, Helena Gylling, Tatu A Miettinen
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  ABSTRACT: Lipoprotein distribution of non-cholesterol sterols was studied to evaluate in which lipoproteins they are carried in type 2 diabetes with body weight ranging from normal to overweight. Serum and lipoprotein squalene and non-cholesterol sterols were quantitated with gas-liquid chromatography in 33 diabetic subjects separated into normal (BMI < or = 25 kg/m2, n=10) and overweight (BMI > 25 kg/m2, n=23) groups. Two-thirds of the non-cholesterol sterols were carried in LDL and one-fifth in HDL, whereas squalene was mainly in VLDL and LDL in both groups. In overweight versus normal weight subjects, the absorption marker concentrations and ratios to cholesterol in serum and lipoproteins were lower and those of synthesis higher. In both groups the synthesis and absorption markers were interrelated in all lipoproteins suggesting intact regulation of cholesterol metabolism. The absorption marker ratios to cholesterol were mostly carried in HDL (cholestanol) and IDL (campesterol and sitosterol), and synthesis markers in VLDL and IDL regardless of overweight. Synthesis marker ratios were underestimated in serum versus VLDL and IDL, and those of absorption markers in serum versus IDL and HDL (p<0.05 for all). Squalene was related to lathosterol in all lipoprotein fractions (e.g., in LDL r=+0.501, p<0.01) suggesting that in diabetes squalene, too, is an indicator of cholesterol synthesis. The absorption sterols are carried in IDL and HDL, and the synthesis markers in VLDL and IDL regardless of weight. The lipoprotein squalene and non-cholesterol sterol ratios were under- or overestimated in serum, and whether their evaluation in lipoproteins versus in serum only gives better information on cholesterol metabolism should be investigated further also in normal population.
  Atherosclerosis 09/2007; 194(1):222-9. · 3.79 Impact Factor
• Article: Diabetes contributes to cholesterol metabolism regardless of obesity.

  Piia P Simonen, Helena K Gylling, Tatu A Miettinen
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  ABSTRACT: To investigate cholesterol metabolism in obesity with and without diabetes. We performed cross-sectional metabolic studies in obese individuals with and without type 2 diabetes. The study population consisted of 16 obese (BMI >30 kg/m(2)) diabetic subjects with a mean age of 52 +/- 2 years (SE) and 16 nondiabetic control subjects of similar age and weight. Cholesterol absorption efficiency was measured with peroral dual isotopes and cholesterol synthesis with sterol balance. Serum total cholesterol did not differ between the groups, but LDL and HDL cholesterol were significantly lower and VLDL cholesterol and serum total and VLDL triglycerides were higher in the diabetic group than in the control group. Cholesterol absorption efficiency was 29 +/- 1% in diabetic subjects vs. 42 +/- 2% in the control subjects (P < 0.01). Cholesterol synthesis was higher (17 +/- 1 vs. 14 +/- 1 mg. kg(-1). day(-1); P < 0.05) and neutral sterol and bile acid excretion and cholesterol turnover tended to be higher in the diabetic group than in the control group. Blood glucose was positively related to cholesterol synthesis in the diabetic group (r = +0.663, P < 0.01) and in the control group (r = +0.590, P < 0.05), suggesting that the higher blood glucose level, the higher the cholesterol synthesis. In addition, blood glucose was significantly positively related to fecal neutral sterol excretion in both groups. Cholesterol absorption efficiency was lower and cholesterol synthesis was higher in obese subjects with diabetes than in those without diabetes, suggesting that diabetes modulates cholesterol metabolism more than obesity alone.
  Diabetes Care 09/2002; 25(9):1511-5. · 8.09 Impact Factor
• Article: Body weight modulates cholesterol metabolism in non-insulin dependent type 2 diabetics.

  Piia P Simonen, Helena Gylling, Tatu A Miettinen
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  ABSTRACT: Cholesterol metabolism was studied in 64 subjects with type 2 diabetes who had body weight ranging from normal to obese, to find out whether weight interferes with cholesterol metabolism in diabetes. Cholesterol absorption was measured with peroral isotopes and by assaying serum plant sterol and cholestanol to cholesterol ratios, cholesterol synthesis with sterol balance, and measuring serum cholesterol precursor ratios. The study population was divided into normal-weight (body mass index, 24.1 +/- 0.4 kg/m2; mean +/- SEM; n = 20) and obese (31.0 +/- 0.5 kg/m2; n = 44) groups. Despite similar serum cholesterol and blood glucose values, fecal neutral sterol excretion, cholesterol and bile acid synthesis, cholesterol turnover (1649 +/- 78 vs. 1077 +/- 52 mg/d; p < 0.001), and serum cholesterol precursors were higher, and cholesterol absorption % (32 +/- 1 vs. 40 +/- 2%; p < 0.05), serum cholestanol, and plant sterols were lower in the obese vs. the non-obese groups. Serum sex hormone-binding globulin was positively associated with variables of cholesterol absorption, whereas blood glucose, serum insulin, and body mass index were associated with variables of cholesterol synthesis. In multiple stepwise regression analysis, cholesterol absorption percentage (R2 = 24%) and body mass index (R2 = 15%) were the only variables explaining the variability of cholesterol synthesis. Body weight, through its entire range, regulates cholesterol metabolism in type 2 diabetes such that with increasing insulin resistance, cholesterol absorption is lowered and cholesterol synthesis increased.
  Obesity research 06/2002; 10(5):328-35. · 4.95 Impact Factor