Longitudinal weight differences, gene expression and blood biomarkers in BMI-discordant identical twins.

BACKGROUND: Body mass index (BMI) discordant monozygotic (MZ) twins allow an examination of the causes and consequences of adiposity in a genetically controlled design. Few studies have examined longitudinal BMI discordance in MZ pairs. OBJECTIVES: The aim of this work was to study the development over time of BMI discordance in adolescent and adult MZ twin pairs and to examine lifestyle, metabolic, inflammatory and gene expression differences associated with concurrent and long-term BMI discordance in MZ pairs. SUBJECTS/METHODS: BMI data from 2775 MZ twin pairs, collected in eight longitudinal surveys and a biobank project between 1991 and 2011, were analyzed to characterize longitudinal discordance. Lifestyle characteristics were compared within discordant pairs (ΔBMI⩾3 kg m(-2)) and biomarkers (lipids, glucose, insulin, C-reactive protein, fibrinogen, interleukin (IL)-6, tumor necrosis factor-α and soluble IL-6 receptor and liver enzymes aspartate aminotransferase, alanine aminotransferase and gamma glutamyl transferase) and gene expression were compared in peripheral blood from discordant pairs who participated in the Netherlands Twin Register biobank project. RESULTS: The prevalence of discordance ranged from 3.2% in 1991 (mean age=17, s.d.=2.4) to 17.4% (N=202 pairs) in 2009 (mean age=35, s.d.=15) and was 16.5% (N=174) among pairs participating in the biobank project (mean age=35, s.d.=12). Of the 699 MZ pairs with BMI data from 3 to 5 time points, 17 pairs (2.4%) were long-term discordant (at all available time points; mean follow-up range=6.4 years). Concurrently discordant pairs showed significant differences in self-ratings of which twin eats most (P=2.3 × 10(-13)) but not in leisure time exercise activity (P=0.28) and smoking (P>0.05). Ten out of the 14 biomarkers showed significantly more unfavorable levels in the heavier of twin of the discordant pairs (P-values <0.001); most of these biomarker differences were largest in longitudinally discordant pairs. No significant gene expression differences were identified, although high ranking genes were enriched for Gene Ontology terms highlighting metabolic gene regulation and inflammation pathways. CONCLUSIONS: BMI discordance is uncommon in adolescent identical pairs but increases with higher pair-mean of BMI at older ages, although long-term BMI discordance is rare. In discordant pairs, the heavier twin had a more unfavorable blood biomarker profile than the genetically matched leaner twin, in support of causal effects of obesity.

Association of depressive disorders, depression characteristics and antidepressant medication with inflammation.

Growing evidence suggests that immune dysregulation may be involved in depressive disorders, but the exact nature of this association is still unknown and may be restricted to specific subgroups. This study examines the association between depressive disorders, depression characteristics and antidepressant medication with inflammation in a large cohort of controls and depressed persons, taking possible sex differences and important confounding factors into account. Persons (18-65 years) with a current (N = 1132) or remitted (N = 789) depressive disorder according to DSM-IV criteria and healthy controls (N = 494) were selected from the Netherlands Study of Depression and Anxiety. Assessments included clinical characteristics (severity, duration and age of onset), use of antidepressant medication and inflammatory markers (C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α)). After adjustment for sociodemographics, currently depressed men, but not women, had higher levels of CRP (1.33 versus 0.92 mg l(-1), P<0.001, Cohen's d = 0.32) and IL-6 (0.88 versus 0.72 pg ml(-1), P = 0.01, Cohen's d = 0.23) than non-depressed peers. Associations reduced after considering lifestyle and disease indicators--especially body mass index--but remained significant for CRP. After full adjustment, highest inflammation levels were found in depressed men with an older age of depression onset (CRP, TNF-α). Furthermore, inflammation was increased in men using serotonin-norepinephrine reuptake inhibitors (CRP, IL-6) and in men and women using tri- or tetracyclic antidepressants (CRP), but decreased among men using selective serotonin reuptake inhibitors (IL-6). In conclusion, elevated inflammation was confirmed in depressed men, especially those with a late-onset depression. Specific antidepressants may differ in their effects on inflammation.

Preparation of lyophilized partial thromboplastin time reagent composed of synthetic phospholipids: usefulness for monitoring heparin therapy.

To contribute to the development of a reference reagent for monitoring heparin therapy, a lyophilized partial thromboplastin time (PTT) reagent was prepared from synthetic dioleoylphosphatidylcholine, dioleoylphosphatidylserine, and dioleoylphosphatidylethanolamine, with colloidal silica as activator. The reagent, coded 91/558, was contained in sealed glass ampoules; it deteriorated in a heat degradation experiment, but its activity remained constant for at least 4 years when stored at -70 degrees C. Within- and between-run precision with this reagent complied with the requirements proposed by the International Committee for Standardization in Haematology (ICSH) Panel on PTT. The response of this reagent and of two other reagents to heparin added to pooled normal plasma was nonlinear. Citrated samples from 58 patients receiving intravenous heparin and from 24 apparently healthy volunteers were tested with reagent 91/558, with Automated APTT (Organon Teknika), with Manchester APTT reagent, with an antifactor Xa assay, and with an anti-factor IIa assay. The correlation of APTT with anti-Xa and anti-IIa activity was poor. The best correlation was observed between reagent 91/558 and the Organon Teknika reagent. Correlations were improved when individual patients' samples were replaced by pooled plasmas from heparinized patients, in whom the effect of oral anticoagulation was minimal. These results suggest that preparation of a lyophilized synthetic phospholipid reagent is feasible for use in monitoring heparin therapy.

Effect of synthetic phospholipids on the response of the activated partial thromboplastin time to heparin.

The activated partial thromboplastin time (aPTT) is the most popular test for monitoring of heparin therapy. The purpose of the present study was to show that an aPTT reagent with good response to heparin can be prepared from synthetic phosphoglycerides. Mixed liposomes were prepared from synthetic dioleoylphosphatidylserine (DOPS), dioleoylphosphatidylcholine (DOPC), and dioleoylphosphatidylethanolamine (DOPE). These liposomes were used in an aPTT test system with kaolin as activator, to evaluate their procoagulant activity in the absence and presence of heparin. For comparison, mixtures of purified non-synthetic phospholipids were prepared and tested with the same systems. The aPTT and its response to heparin were influenced by the phospholipid class composition and concentration. The presence of phosphatidylserine (PS) was required to reduce the aPTT of normal plasma to values between 30 and 40s. The presence of phosphatidylethanolamine (PE) in mixed liposomes could modulate the response to heparin. At low PE/PS liposome concentrations (approximately 40 microM), a relatively low response was observed. At high liposome concentrations (approximately 1 mM), the response to heparin increased with the mole fraction of phosphatidylethanolamine. The results obtained with non-synthetic phospholipid mixtures were similar to those obtained with the synthetic phosphoglycerides. Optimal concentrations of DOPS, DOPE and DOPC were found with which an almost linear response to heparin and to low molecular weight heparin (Fragmin) was observed. Using a mixed liposome consisting of 12 microM DOPS/12 microM DOPC/16 microM DOPE, a doubling of the base-line aPTT was achieved at approximately 0.2 IU/ml of heparin, and at approximately 1.0 IU/ml of Fragmin.(ABSTRACT TRUNCATED AT 250 WORDS)