Plasma levels of IGF-I are higher and plasma levels of IGFBP-3 are lower in patients with lung cancer than in control subjects. If these findings can be confirmed in prospective studies, measuring levels of IGF-I and IGFBP-3 in blood may prove useful in assessing lung cancer risk.

Aims/hypothesis: The aim of this study was to further elucidate the relationship between resistin and insulin sensitivity, body fat distribution and the metabolic syndrome in humans. Methods: We measured plasma resistin levels in 177 non-diabetic subjects (75 male, 102 female; age 32-75 years). BMI, waist circumference, blood pressure, lipids, glucose, plasminogen-activator inhibitor 1 (PAI-1), adiponectin and leptin levels were also measured. The insulin sensitivity index (S I ) was quantified using Bergman's minimal model. Intra-abdominal fat (IAF) and subcutaneous fat (SQF) areas were quantified by CT scan. Presence of metabolic syndrome criteria was determined using the National Cholesterol Education Program Adult Treatment Panel III guidelines. Results: When subjects were divided into categories based on BMI (< or ≥27.5 kg/m 2 ) and S I (< or ≥ 7×10 −5 min −1 [pmol/l] −1 ), resistin levels did not differ between the lean, insulinsensitive (n=53, 5.36±0.3 ng/ml), lean, insulin-resistant (n=67, 5.70±0.4 ng/ml) and obese, insulin-resistant groups (n=48, 5.94±0.4 ng/ml; ANOVA p=0.65). Resistin correlated with age (r=−0.22, p<0.01), BMI (r=0.16, p=0.03) and SQF (r=0.19, p=0.01) but not with S I

Insulin‐like growth factors (IGFs) and IGF binding proteins (IGFBPs) play an important role in cell growth and differentiation. Clinical and epidemiological studies have indicated that measuring IGFs and IGFBPs in blood has potential implications in assessing growth‐related abnormalities and risks of certain types of cancer. To facilitate the application, we reported a large collection of reference ranges of IGFs and IGFBPs in normal population and evaluations of these molecules in serum and plasma as well as the impact of freeze‐thaw cycles on the measurement. IGF‐I, IGFBP‐3 and ALS showed a similar pattern of change associated with age. Levels of these molecules were low at birth and increased with age through puberty. After puberty the levels declined slowly with age. Overall, IGF‐I, IGFBP‐3 and ALS were slightly higher in females than in males. Free IGF‐I accounted for about 1% of the total IGF‐I and its variation with age was similar to total IGF‐I. IGF‐II levels were also increased with age from birth to puberty, but became stable after puberty. There was little difference in IGF‐II levels between genders. IGFBP‐2 levels declined with age from birth to puberty. Levels of IGFBP‐6 in contrast were increased with age. These IGF binding proteins were higher in males than in females. IGFs, IGFBP‐3 and ALS were 5‐10% higher in serum than in plasma. IGFBP‐2 and IGFBP‐6 differed substantially between serum and plasma. Freeze‐thaw treatment up to five cycles had little impact on plasma levels of IGFs and IGFBP‐3. Our observations suggest that levels of IGFs and their binding proteins are varied with age, gender, and types of specimen and that these variations need to be taken into consideration when IGFs and their binding proteins are utilized in clinic and research. J. Clin. Lab. Anal. 13:166–172, 1999. © 1999 Wiley‐Liss, Inc.

Although the acid-labile subunit (ALS) of the approximately 150-kDa insulin-like growth factor (IGF)-binding protein (IGFBP) complex was described over a decade ago, details of ALS physiology have remained largely uncertain. We evaluated antibodies to synthetic human ALS and constructed a noncompetitive ALS enzyme-linked immunosorbent assay. Whereas uncomplexed ALS is directly measured, determination of total levels required sample pretreatment with SDS, which was found to optimally dissociate complexed ALS and significantly enhance ALS immunoreactivity. ALS in random adult sera was approximately 50% uncomplexed, and samples devoid of complexed ALS by immunoaffinity separation contained about 54% of the total levels. Serum ALS fractionated by gel filtration high performance liquid chromatography eluted in a single peak at approximately 150 kDa with IGF-I and IGFBP-3, but appeared at about 400-500 kDa after sample acidification and fractionation under acidic condition. The unexpected shift in ALS immunoreactivity remained unchanged when acid-neutralized or SDS-treated samples were fractionated under neutral pH and was reproducible when the 150-kDa complex was isolated, treated with acid or SDS, and rechromatographed. ALS in adult sera more tightly correlated with IGFBP-3 than IGF-I or IGF-II. The total levels (mean +/- SD) were 16.7 +/- 3.7 mg/L in 22 normal subjects, 28.3 +/- 8.1 mg/L in 20 acromegalic patients, and 9.5 +/- 3.8 in 32 GH-deficient adults. Little or no ALS was detectable in amniotic fluid, cerebrospinal fluid, seminal plasma, or milk, whereas high levels were present in synovial fluid. The development of ALS enzyme-linked immunosorbent assay should greatly facilitate further investigations of this unique glycoprotein.

Background: Of the 3 circulating multimeric forms of adiponectin, the high-molecular-weight (HMW) form, as measured by size-exclusion and/or immunoblotting techniques, is a better index of insulin sensitivity for monitoring health and disease than is total adiponectin. We aimed to develop a simple ELISA to measure HMW adiponectin.