Association between serum cystatin C, monocytes and other inflammatory markers.

BACKGROUND: Cystatin C is a marker of renal function that appears to be associated with inflammation. The aim of the present study was to investigate whether there is any relationship between cystatin C, total and differential leukocyte count and other inflammatory markers. METHODS: Cystatin C, creatinine, high sensitivity C-reactive protein (hs-CRP), haptoglobin, ferritin, serum albumin, glucose, total cholesterol, HDL and triglycerides together with total and differential leukocyte count were determined in 490 adults (46 ± 16 years, 40% men) who underwent a typical health examination. Glomerular filtration rate was estimated by the simplified Modification of Diet in Renal Disease formula. Anthropometric and lifestyle characteristics were also recorded. RESULTS: After adjustment for demographic risk factors, comorbid health conditions and renal function, a positive and independent relationship of serum cystatin C levels with peripheral monocyte blood count (regression coefficient ± SE: 12 ± 3.38, P < 0.001) and white blood count (0.616 ± 0.278, P= 0.027) was evident. In this multiple linear regression analysis, other inflammatory markers (i.e. hs-CRP, haptoglobin, ferritin, albumin) did not seem to affect cystatin C blood levels. CONCLUSION: The results of this study demonstrated that monocytes, which play an important role in chronic inflammation and atherosclerosis, were independently related with cystatin C concentrations. This finding may provide a plausible link for the usefulness of cystatin C in predicting increased cardiovascular risk.

Development, repeatability and validity regarding energy and macronutrient intake of a semi-quantitative food frequency questionnaire: methodological considerations.

BACKGROUND AND AIM: The aim of this work was to evaluate the repeatability and the validity of a food frequency questionnaire (FFQ), and to discuss the methodological framework of such procedures. METHODS AND RESULTS: The semi-quantitative FFQ included 69 questions regarding the frequency of consumption of all main food groups and beverages usually consumed and 7 questions regarding eating behaviors. Five hundred individuals (37 ± 15 yrs, 38% males) were recruited for the repeatability process, while another 432 (46 ± 16 yrs, 40% males) also completed 3-Day Diaries (3DD) for the validation process. The repeatability of the FFQ was adequate for all food items tested (Kendall's tau-b: 0.26-0.67, p < 0.05), energy and macronutrients intake (energy adjusted correlation coefficients ranged between 0.56-0.69, p < 0.05). Moderate validity of the FFQ was observed for "dairy products", "fruit", "alcohol" and "stimulants" (tau-b: 0.31-0.60, p < 0.05), whereas low agreement was shown for "starchy products", "legumes", "vegetables", "meat", "fish", "sweets", "eggs", "fats and oils" (tau-b < 0.30, p < 0.05). The FFQ was also valid regarding energy and macronutrients intake. Sensitivity analyses by sex and BMI category (< or ≥25 kg/m(2)) showed similar validity of the FFQ for all food groups (apart from "fats and oils" intake), as well as energy and nutrient intake. CONCLUSION: The proposed FFQ has proven repeatable and relatively valid for foods' intake, and could therefore be used for nutritional assessment purposes.