Martin Nordal Petersen

Genetic Polymorphisms and Weight Loss in Obesity: A Randomised Trial of Hypo-Energetic High- versus Low-Fat Diets

Objectives: To study if genes with common single nucleotide polymorphisms (SNPs) associated with obesity-related phenotypes influence weight loss (WL) in obese individuals treated by a hypo-energetic low-fat or high-fat diet. Design: Randomised, parallel, two-arm, open-label multi-centre trial. Setting: Eight clinical centres in seven European countries. Participants: 771 obese adult individuals. Interventions: 10-wk dietary intervention to hypo-energetic (−600 kcal/d) diets with a targeted fat energy of 20%–25% or 40%–45%, completed in 648 participants. Outcome Measures: WL during the 10 wk in relation to genotypes of 42 SNPs in 26 candidate genes, probably associated with hypothalamic regulation of appetite, efficiency of energy expenditure, regulation of adipocyte differentiation and function, lipid and glucose metabolism, or production of adipocytokines, determined in 642 participants. Results: Compared with the noncarriers of each of the SNPs, and after adjusting for gender, age, baseline weight and centre, heterozygotes showed WL differences that ranged from −0.6 to 0.8 kg, and homozygotes, from −0.7 to 3.1 kg. Genotype-dependent additional WL on low-fat diet ranged from 1.9 to −1.6 kg in heterozygotes, and from 3.8 kg to −2.1 kg in homozygotes relative to the noncarriers. Considering the multiple testing conducted, none of the associations was statistically significant. Conclusions: Polymorphisms in a panel of obesity-related candidate genes play a minor role, if any, in modulating weight changes induced by a moderate hypo-energetic low-fat or high-fat diet.

Randomized, multi-center trial of two hypo-energetic diets in obese subjects: high- versus low-fat content

Objective:To investigate whether a hypo-energetic low-fat diet is superior to a hypo-energetic high-fat diet for the treatment of obesity.Design:Open-label, 10-week dietary intervention comparing two hypo-energetic (−600 kcal/day) diets with a fat energy percent of 20–25 or 40–45.Subjects:Obese (BMI ⩾30 kg/m2) adult subjects (n=771), from eight European centers.Measurements:Body weight loss, dropout rates, proportion of subjects who lost more than 10% of initial body weight, blood lipid profile, insulin and glucose.Results:The dietary fat energy percent was 25% in the low-fat group and 40% in the high-fat group (mean difference: 16 (95% confidence interval (CI) 15–17)%). Average weight loss was 6.9 kg in the low-fat group and 6.6 kg in the high-fat group (mean difference: 0.3 (95% CI −0.2 to 0.8) kg). Dropout was 13.6% (n=53) in the low-fat group and 18.3% (n=70) in the high-fat group (P=0.001). Among completers, more subjects lost >10% in the low-fat group than in the high-fat group ((20.8%, n=70) versus (14.7%, n=46), P=0.02). Fasting plasma total, low-density lipoprotein- and high-density lipoprotein-cholesterol decreased in both groups, but more so in the low-fat group than in the high-fat group. Fasting plasma insulin and glucose were lowered equally by both diets.Conclusions:The low-fat diet produced similar mean weight loss as the high-fat diet, but resulted in more subjects losing >10% of initial body weight and fewer dropouts. Both diets produced favorable changes in fasting blood lipids, insulin and glucose.

Changes in body composition during weight loss in obese subjects in the NUGENOB study: comparison of bioelectrical impedance vs. dual-energy X-ray absorptiometry.

AIM We studied the accuracy of bioelectrical impedance analysis (BIA) to assess changes in body composition during moderate weight loss in obese subjects. METHODS Estimates of changes in fat mass (FM) and fat-free mass (FFM) by BIA were compared with those by dual-energy X-ray absorptiometry (DXA) as the reference method during a 10-week standardized weight-loss intervention. In obese women (age: 20-50 years, mean BMI: 33.8 kg/m(2)) participating in a European multicentre trial (nutrient-gene interactions in human obesity [NUGENOB]), body composition was assessed by BIA (Bodystat QuadScan 4000) and DXA (Lunar DPX-IQ at two centres, Hologic QDR 2000 at another centre) at baseline (n=131) and at week 10 (n=105) after a mean weight loss of -5.7 kg. RESULTS At baseline, BIA significantly overestimated FFM and underestimated FM (by 1-3 kg on average) compared with DXA, and the limits of agreement were wide (mean ± 7-8.5 kg). For body-composition changes, although biases were generally non-significant, the limits of agreement were also wide (mean ± 3.7-4.6 kg). An FFM prediction equation for BIA data was developed in subjects scanned with Lunar instruments and cross-validated in an independent sample of 31 obese women undergoing similar weight loss. However, no major improvement in limits of agreement was found. CONCLUSION During moderate diet-induced weight loss, the use of BIA leads to estimates of changes in body composition at the individual level that can differ substantially from those assessed by DXA, indicating that BIA and DXA cannot be used interchangeably. However, BIA in this context may be used for assessing changes in body composition at group level.

Photonics in switching: enabling technologies and subsystem design

This paper describes recent research activities and results in the area of photonic switching carried out within the framework of the EU-funded e-Photon/ONe+ network of excellence, Virtual Department on Optical Switching. Technology aspects of photonics in switching and, in particular, recent advances in wavelength conversion, ring resonators, and packet switching and processing subsystems are presented as the building blocks for the implementation of a high-performance router for the next-generation Internet.

Impaired Fat-induced Thermogenesis in Obese Subjects: The NUGENOB Study

Objectives: To study energy expenditure before and 3 hours after a high‐fat load in a large cohort of obese subjects (n = 701) and a lean reference group (n = 113).

Agreement Between Fasting and Postprandial LDL Cholesterol Measured with 3 Methods in Patients with Type 2 Diabetes Mellitus

BACKGROUND LDL cholesterol (LDL-C) is a modifiable cardiovascular disease risk factor. We used 3 LDL-C methods to study the agreement between fasting and postprandial LDL-C in type 2 diabetes (T2DM) patients. METHODS We served 74 T2DM patients a standardized meal and sampled blood at fasting and 1.5, 3.0, 4.5, and 6.0 h postprandially. We measured LDL-C by use of modified β quantification (MBQ), the Friedewald equation (FE), and a direct homogeneous assay (DA). We evaluated agreement using 95% limits of agreement (LOA) within ±0.20 mmol/L (±7.7 mg/dL). RESULTS LDL-C concentrations at all postprandial times disagreed with those at fasting for all methods. In 66 patients who had complete measurements with all LDL-C methods, maximum mean differences (95% LOA) in postprandial vs fasting LDL-C were -0.16 mmol/L (-0.51; 0.19) [-6.2 mg/dL (-19.7; 7.3)] with MBQ at 3 h; -0.36 mmol/L (-0.89; 0.17) [-13.9 mg/dL (-34; 6.6)] with FE at 4.5 h; and -0.24 mmol/L (-0.62; 0.05) [-9.3 mg/dL (-24; 1.9)] with DA at 6.0 h. In postprandial samples, FE misclassified 38% of patients (two-thirds of statin users) into lower Adult Treatment Panel III (ATP III) risk categories. Greater disagreement between fasting and postprandial LDL-C was observed in individuals with postprandial triglyceride concentrations >2.08 mmol/L (>184 mg/dL) and in women (interactions: P ≤ 0.038). CONCLUSIONS Differences up to 0.89 mmol/L (34 mg/dL) between fasting and postprandial LDL-C concentrations, with postprandial LDL-C concentrations usually being lower, were found in T2DM by 3 different LDL-C methods. Such differences are potentially relevant clinically and suggest that, irrespective of measurement method, postprandial LDL-C concentrations should not be used to assess cardiovascular disease risk.

Link Design Rules for Cost-Effective Short-Range Radio Over Multimode Fiber Systems

Referring to short-range radio over multimode fiber links, we find out important guidelines for the realization of cost-effective intensity modulated directly detected systems. Since the quality of todays connectors is considerably higher than in the past, we demonstrate that two important parameters of the system are the finite detecting area of the photodiode and the laser frequency chirp. Furthemore, we show that the use of the central launch technique inherently determines a lower impact of modal noise fluctuations with respect to the offset launch one. This makes CL more convenient for short-range applications, where the transmittable bandwidth does not constitute the main limitation.

Sustained postprandial decrease in plasma levels of LDL cholesterol in patients with type-2 diabetes mellitus

Objective. Low density lipoprotein cholesterol (LDL‐C) is an independent and modifiable risk factor for development of cardiovascular disease (CVD). Postprandial lipid metabolism has been linked to CVD, but little is known about the postprandial LDL‐C profile in patients with type‐2 diabetes (T2DM). We aimed to study the postprandial levels of LDL‐C in T2DM patients. Material and methods. After an overnight fast, 74 T2DM patients, mean age approximately 60 years, were served a standard fat‐rich meal of 3,515 kJ containing 54 % fat, 13 % protein and 33 % carbohydrates. Only drinking water was allowed postprandially. Blood samples were drawn at times 0 (fasting), 1.5, 3.0, 4.5 and 6.0 h (postprandial). In all samples, LDL‐C was measured with modified beta quantification (separation by ultracentrifugation followed by measurement of infranate high density lipoprotein cholesterol (HLD‐C) using a homogeneous assay). Results. At all postprandial times, levels of LDL‐C showed highly significant (p<0.005) decreases compared to time 0 (mean [95 % CI] maximum change in LDL‐C levels at 3.0 h: −0.16 mmol/L [−0.12; −0.20]; p<0.001). Independently of fasting LDL‐C levels and ongoing statin therapy, LDL‐C decreased significantly more in female compared to male patients postprandially (mean [95 % CI] maximum unadjusted change versus time 0 in LDL‐C for men [n = 56] at 3.0 h: −0.14 mmol/L [−0.19; −0.10], p<0.001; for women [n = 18] at 4.5 h: −0.26 mmol/L [−0.35; −0.18], p<0.001; −0.14 mmol/L [−0.24; −0.05], p = 0.005 between genders for the mean [95 % CI] fasting adjusted difference at 4.5 h in the change versus time 0 in LDL‐C; gender by time interaction: p = 0.007 (repeated measures mixed model)). Conclusions. In T2DM patients served a fat‐rich meal, levels of LDL‐C decreased significantly more in women compared to men postprandially, irrespective of fasting levels or ongoing statin therapy. This might have implications in the atherosclerotic process and on any difference in the risk of CVD between genders.

Compact all-optical parity calculator based on a single all-active Mach Zehnder interferometer with all-SOA amplified feedback

An all-optical signal processing circuit capable of parity calculations is demonstrated using a single integrated all-active SOA-based MZI, exploiting the integrated SOAs for feedback amplification.

Noise filtering in a multi-channel system using a tunable liquid crystal photonic bandgap fiber

This paper reports on the first application of a liquid crystal infiltrated photonic bandgap fiber used as a tunable filter in an optical transmission system. The device allows low-cost amplified spontaneous emission (ASE) noise filtering and gain equalization with low insertion loss and broad tunability. System experiments show that the use of this filter increases for times the distance over which the optical signal-to-noise ratio (OSNR) is sufficient for error-free transmission with respect to the case in which no filtering is used.