Bound leptin and sympathetic outflow in nonobese men

Leptin exists in a free form and a receptor-bound form. Protein-bound rather than free leptin levels may be associated with regulation of muscle sympathetic nerve activity (MSNA). We determined MSNA and bound leptin concentrations in 25 men [age, 29 +/- 6 yr, body mass index (BMI), 24 +/- 3 kg/m(2)]. Baroreflex sensitivity was measured using phenylephrine and nitroprusside infusions. We measured bound leptin in patients with central (multiple system atrophy, n = 8; age, 59 +/- 8 yr; BMI, 23 +/- 2 kg/m(2)) and peripheral autonomic failure (pure autonomic failure, n = 4; age, 71 +/- 10 yr; BMI, 25 +/- 3 kg/m(2)). MSNA was correlated with protein-bound leptin concentrations (r(2) = 0.35; P < 0.01) but not with free leptin levels (r(2) = 0.09). MSNA at baseline was 15 +/- 2 bursts x minutes(-1) in subjects with lower and 24 +/- 3 bursts x minutes(-1) in subjects with higher bound leptin concentrations (P < 0.05). Blood pressure as well as baroreflex regulation of heart rate and MSNA was similar in both groups. Phenylephrine and nitroprusside responses were similar. Patients with multiple system atrophy and autonomic failure featured similar bound leptin levels. We conclude that protein-bound rather than free leptin levels are correlated with basal sympathetic outflow in normotensive, nonobese men. This relationship cannot be explained by a direct central nervous effect of protein-bound leptin. Instead, protein-bound leptin may increase sympathetic vasomotor tone indirectly via a baroreflex mechanism.     

Learning-based parametrized model predictive control for trajectory tracking

This article is concerned with the tracking of nonequilibrium motions with model predictive control (MPC). It proposes to parametrize input and state trajectories of a dynamic system with basis functions to alleviate the computational burden in MPC. As a result of the parametrization, an optimization problem with fewer variables is obtained, and the memory requirements for storing the reference trajectories are reduced. The article also discusses the generation of feasible reference trajectories that account for the system's dynamics, as well as input and state constraints. In order to cope with repeatable disturbances, which may stem from unmodeled dynamics for example, an iterative learning procedure is included. The approach relies on a Kalman filter that identifies the repeatable disturbances based on previous trials. These are then included in the system's model available to the model predictive controller, which compensates them in subsequent trials. The proposed approach is evaluated on a quadcopter, whose task is to balance a pole, while flying a predefined trajectory.     

Plasma erythropoietin levels in anaemic and non-anaemic patients with chronic liver diseases

AIM: To investigate the serum erythropoietin (Epo) levels in patients with chronic liver diseases and to compare to subjects with iron-deficiency anaemia and healthy controls. METHODS: We examined 31 anaemic (ALC) and 22 non-anaemic (NALC) cirrhotic patients, 21 non- anaemic subjects with chronic active hepatitis (CAH), 24 patients with iron-deficiency anaemia (ID) and 15 healthy controls. Circulating Epo levels (ELISA; R and D Systems, Europe Ltd, Abingdon, UK) and haemoglobin (Hb) concentration were determined in all subjects. RESULTS: Mean+/-SD of Epo values was 26.9+/-10.8 mU/mL in ALC patients, 12.5+/-8.0 mU/mL in NALC subjects, 11.6+/-6.3 mU/mL in CAH patients, 56.4+/-12.7 mU/mL in the cases of ID and 9.3+/-2.6 mU/mL in controls. No significant difference (P>0.05) was found in Epo levels between controls, CAH and NALC patients. ALC individuals had higher Epo levels (P<0.01) than these groups whereas ID subjects had even higher levels (P<0.001) than patients suffering from ALC. CONCLUSION: Increased Epo values in cirrhotics, are only detectable when haemoglobin was lesser than 12 g/dL. Nevertheless, this rise in value is lower than that observed in anaemic patients with iron-deficiency and appears blunted and inadequate in comparison to the degree of anaemia.     

Review on Graphene-, Graphene Oxide-, Reduced Graphene Oxide-Based Flexible Composites: From Fabrication to Applications

In the new era of modern flexible and bendable technology, graphene-based materials have attracted great attention. The excellent electrical, mechanical, and optical properties of graphene as well as the ease of functionalization of its derivates have enabled graphene to become an attractive candidate for the construction of flexible devices. This paper provides a comprehensive review about the most recent progress in the synthesis and applications of graphene-based composites. Composite materials based on graphene, graphene oxide (GO), and reduced graphene oxide (rGO), as well as conducting polymers, metal matrices, carbon–carbon matrices, and natural fibers have potential application in energy-harvesting systems, clean-energy storage devices, and wearable and portable electronics owing to their superior mechanical strength, conductivity, and extraordinary thermal stability. Additionally, the difficulties and challenges in the current development of graphene are summarized and indicated. This review provides a comprehensive and useful database for further innovation of graphene-based composite materials.     

Pulmonary atresia with intact ventricular septum: A quantitative cineventriculographic study of the right and left ventricular function

Summary Quantitative cineventriculographic measurements (ventricular volumes, ejection fraction, and myocardial mass) were obtained in 15 neonates with pulmonary atresia and intact ventricular septum. There was a wide dimensional range for the right ventricle, from a reduced through normal to enlarged. A restrictive tricuspid valve (less than 12 mm) was associated with a small or diminutive right ventricle. A normal function of the right ventricle was present only in those cases with normal-sized chambers. The left ventricular end-diastolic volume was always greater than normal. The ejection fraction was normal only if a normal myocardial mass was present. Additional abnormalities were frequent in the myocardium of both ventricles, such as extreme thinning of the wall of the right ventricle and hypoplasia or fibroelastosis of the left ventricle. All these factors can lead to a poor surgical prognosis despite good anatomical correction.     

Impact of endoscopic surveillance of Barrett's esophagus on survival of patients with esophageal adenocarcinoma

In an attempt to reduce mortality from oesophageal adenocarcinoma, it has been recommended to enroll patients with Barrett's oesophagus in endoscopic surveillance programs in order to detect malignant degeneration at an early and possibly curable stage. The aim of this study was to assess the impact of endoscopic biopsy surveillance on the outcome of Barrett's adenocarcinoma. From November 1992 to December 2000, 328 patients with histologically proven oesophageal adenocarcinoma were referred to our department. One hundred of these patients had Barrett's adenocarcinoma. In 12 (12%) patients, cancer was discovered during endoscopic surveillance for Barrett's metaplasia. The prevalence of gastro-oesophatgeal reflux disease in the Barrett's group was 38.8% versus 8.1% (P < 0.01) of non-Barrett's patients. In the surveyed group, there were 9 (75%) early stage tumours (Tis-1N0), versus 10 (11.4%, P < 0.01) in the non-surveyed patients. Three out of five surveyed patients operated on for high grade dysplasia proved to have invasive carcinoma in the oesophagectomy specimen. All surveyed patients were alive after a median follow-up period of 50 months; the median survival in the non-surveyed group was 24 +/- 3 months (P < 0.01). Endoscopic surveillance of Barrett's oesophagus allows early detection of malignant degeneration and better long-term survival than in non-surveyed patients.