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Plasmalogens (Pls) are a class of membrane phospholipids which serve a number of essential biological functions. Deficiency of Pls is associated with common disorders such as Alzheimer's disease or ischemic heart disease. A complete lack of Pls due to genetically determined defective biosynthesis gives rise to rhizomelic chondrodysplasia punctata (RCDP), characterized by a number of severe disabling pathologic features and death in early childhood. Frequent cardiac manifestations of RCDP include septal defects, mitral valve prolapse, and patent ductus arteriosus. In a mouse model of RCDP, reduced nerve conduction velocity was partially rescued by dietary oral supplementation of the Pls precursor batyl alcohol (BA). Here, we examine the impact of Pls deficiency on cardiac impulse conduction in a similar mouse model (Gnpat KO). In‐vivo electrocardiographic recordings showed that the duration of the QRS complex was significantly longer in Gnpat KO mice than in age‐ and sex‐matched wild‐type animals, indicative of reduced cardiac conduction velocity. Oral supplementation of BA for 2 months resulted in normalization of cardiac Pls levels and of the QRS duration in Gnpat KO mice but not in untreated animals. BA treatment had no effect on the QRS duration in age‐matched wild‐type mice. These data suggest that Pls deficiency is associated with increased ventricular conduction time which can be rescued by oral BA supplementation.

A small proportion of lean patients develop non-alcoholic fatty liver disease (NAFLD). We aimed to report the histological picture of lean NAFLD in comparison to overweight and obese NAFLD patients. Biopsy and clinical data from 466 patients diagnosed with NAFLD were stratified to groups according to body mass index (BMI): lean (BMI &le, 25.0 kg/m&sup2, n confirmed to be appropriate = 74), overweight (BMI &gt, 25.0 &le, 30.0 kg/m&sup2, n = 242) and obese (BMI &gt, n = 150). Lean NAFLD patients had a higher rate of lobular inflammation compared to overweight patients (12/74, 16.2% vs. 19/242, 7.9%, p = 0.011) but were similar to obese patients (25/150, 16.7%). Ballooning was observed in fewer overweight patients (38/242, 15.7%) compared to lean (19/74, 25.7%, p = 0.014) and obese patients (38/150, 25.3%, p = 0.006). Overweight patients had a lower rate of portal and periportal fibrosis (32/242, 13.2%) than lean (19/74, p = 0.019) and obese patients (37/150, 24.7%, p = 0.016). The rate of cirrhosis was higher in lean patients (6/74, 8.1%) compared to overweight (4/242, 1.7%, p = 0.010) and obese patients (3/150, 2.0% p = 0.027). In total, 60/466, 12.9% patients were diagnosed with non-alcoholic steatohepatitis (NASH). The rate of NASH was higher in lean (14/74, 18.9% p = 0.01) and obese (26/150, 17.3%, p = 0.007) compared to overweight patients (20/242, 8.3%)). Among lean patients, fasting glucose, INR and use of thyroid hormone replacement therapy were independent predictors of NASH in a multivariate model. Lean NAFLD patients were characterized by a severe histological picture similar to obese patients but are more progressed compared to overweight patients. Fasting glucose, international normalized ratio (INR) and the use of thyroid hormone replacement may serve as indicators for NASH in lean patients.

Purple membrane (PM) from Halobacterium salinarum, which comprises bacteriorhodopsin (BR) and lipids only, has been employed by many groups as a model system to study the structure and dynamics of membrane proteins. Although the conformational dynamics of BR within PM has been extensively analyzed with subnanometer resolution by means of diffraction experiments and spectroscopic methods, as well, structural studies of dynamical transitions within single PMs are rare. In this work, we show that tapping-mode atomic force microscopy (TM-AFM) is ideally suited to study dynamical transitions within solid-supported PMs at the nanoscale. Time-dependent AFM analysis of solid-supported PMs shows that redistribution processes take place between a crystalline core region, featuring a height of approximately 5 nm, and a highly mobile rim region (approximately 4 nm in height). Furthermore, we discuss the influence of temperature and substrate on the equilibrium. The experiments are complemented by electrostatic force microscopy (EFM) of PM on mica. Beyond their importance for many physiological processes, dynamical transitions in biological membranes, as observed in this work, are of critical importance for all methods that make use of solid-supported membrane assemblies, either analytical tools or applications.

BACKGROUND Chronic adipose tissue inflammation is a hallmark of obesity, triggering the development of associated pathologies, particularly type 2 diabetes. Long-chain n-3 PUFAs reduce cardiovascular events and exert well-established antiinflammatory effects, but their effects on human adipose tissue inflammation are unknown. OBJECTIVE We investigated whether n-3 PUFAs reduce adipose tissue inflammation in severely obese nondiabetic patients. DESIGN We treated 55 severely obese nondiabetic patients, scheduled to undergo elective bariatric surgery, with 3.36 g long-chain n-3 PUFAs/d (EPA, DHA) or an equivalent amount of butterfat as control, for 8 wk, in a randomized open-label controlled clinical trial. The primary efficacy measure was inflammatory gene expression in visceral and subcutaneous adipose tissue samples (subcutaneous adipose tissue and visceral adipose tissue), collected during surgery after the intervention. Secondary efficacy variables were adipose tissue production of antiinflammatory n-3 PUFA-derived eicosanoids, plasma concentrations of inflammatory markers, metabolic control, and the effect of the Pro12Ala PPARG polymorphism on the treatment response. RESULTS Treatment with n-3 PUFAs, which was well tolerated, decreased the gene expression of most analyzed inflammatory genes in subcutaneous adipose tissue (P < 0.05) and increased production of antiinflammatory eicosanoids in visceral adipose tissue and subcutaneous adipose tissue (P < 0.05). In comparison with control subjects who received butterfat, circulating interleukin-6 and triglyceride concentrations decreased significantly in the n-3 PUFA group (P = 0.04 and P = 0.03, respectively). The Pro12Ala polymorphism affected the serum cholesterol response to n-3 PUFA treatment. CONCLUSIONS Treatment with long-chain n-3 PUFAs favorably modulated adipose tissue and systemic inflammation in severely obese nondiabetic patients and improved lipid metabolism. These effects may be beneficial in the long-term treatment of obesity. This trial was registered at clinicaltrials.gov as NCT00760760.

Obesity is associated with chronic inflammation of the adipose tissue, which contributes to obesity-associated complications such as insulin resistance and type 2 diabetes. Interleukin (IL)-33 acts via its receptor ST2 and is involved in the pathogenesis of inflammatory disorders including atherosclerosis and heart disease. IL-33 has been demonstrated to promote endothelial cell inflammatory response, but also anti-inflammatory and protective actions such as TH2 and M2 polarization of T cells and macrophages, respectively. IL-33 and ST2 have been shown to be expressed in human and murine adipose tissue. Our objective was to investigate alterations in obesity and a possible role of IL-33 in adipose tissue inflammation.We investigated severely obese patients (BMI40 kg m(-2), n=20) and lean to overweight controls (BMI30 kg m(-2); n=20) matched for age and sex, as well as diet-induced obese and db/db mice, in order to determine the impact of obesity on IL-33 and ST2 gene and protein expression levels in adipose tissue and blood, and their correlation with inflammatory and metabolic parameters. Furthermore, we examined the cellular source and location of IL-33 and ST2 in situ.IL-33 and ST2 expression levels were markedly elevated in omental and subcutaneous adipose tissue of severely obese humans and in diet-induced obese mice, but not in leptin receptor-deficient db/db mice. In addition, soluble ST2, but not IL-33 serum levels, were elevated in obesity. The main source for IL-33 in adipose tissue were endothelial cells, which, in humans, exclusively expressed ST2 on their surface. IL-33 expression strongly correlated with leptin expression in human adipose tissue.Expression of IL-33 and its receptor ST2 in human adipose tissue is predominantly detectable in endothelial cells and increased by severe obesity indicating an autocrine action. Thus, the adipose tissue microvasculature could participate in obesity-associated inflammation and related complications via IL-33/ST2.

The first AFM images of strongly bent purple membranes as well as the first single molecule force spectra of bacteriorhodopsins embedded therein are presented. AFM images of purple membranes to date always showed a flat membrane topology. Bacteriorhodopsin variants like BR-D85N and BR-D85T resemble an intermediate state of wild-type BR which is slightly ‘wedge’-shaped. Due to the strong interaction within the 2-D crystalline lattice of the purple membrane, the geometrical anisotropy of the individual bacteriorhodopsins adds up to a macroscopic change in the geometry of the purple membranes. Instead of being flat they appear like domes at physiological conditions. Single molecule force spectroscopy was employed to determine the absolute sign of the membrane curvature. As the bacteriorhodopsins in the center of the dome-like purple membranes are not supported by any solid state substrate, the presented force spectra are the first of non-supported bacteriorhodopsin, resembling the natural occurrence in the halobacterial cell.

Highly oriented monolayers of bacteriorhodopsin (BR) in purple membrane (PM) form are obtained by the reaction of BR-Q3C, where a cysteine was introduced into the N-terminal region, with a gold surface. Single molecule force spectroscopy was used to show that about 50% of the BRs are covalently bound to the surface. The linkage between the cysteine and the gold causes an additional characteristic peak in the force-distance curves to appear. Because several thousand cysteine-gold bonds exist between each PM patch and the surface, the PM is irreversibly bound. Such oriented PM monolayers may serve as an interface between metal surfaces and biomaterials, which may be linked to the PM surface chemically. Photoelectric applications of BR will benefit from the high degree of orientation obtained by this method.

Ultrathin carbon nanomembranes (CNM) have been tested as supports for both cryogenic high-resolution transmission electron microscopy (cryo-EM) as well as atomic force microscopy (AFM) of biological specimens. Purple membrane ( PM) from Halobacterium salinarum, a 2-D crystalline monolayer of bacteriorhodopsin ( BR) and lipids, was used for this study. Due to their low thickness of just 1.6 nm CNM add virtually no phase contrast to the transmission pattern. This is an important advantage over commonly used amorphous carbon support films which become instable below a thickness of similar to 20 nm. Moreover, the electrical conductivity of CNM can be tuned leading to conductive carbon nanomembranes (cCNM). cCNM support films were analyzed for the first time and were found to ideally meet all requirements of cryo-EM of insulating biological samples. A projection map of PM on cCNM at 4 angstrom resolution has been calculated which proves that the structural integrity of biological samples is preserved up to the high-resolution range. CNM have also proven to be suitable supports for AFM analysis of biological samples. PM on CNM was imaged at molecular resolution and single molecule force spectra were recorded which show no differences compared to force spectra of PM obtained with other substrates. This is the first demonstration of a support film material which meets the requirements of both, cryo-EM and AFM, thus enabling comparative structural studies of biomolecular samples with unchanged sample-substrate interactions. Beyond high-resolution cryo-EM of biological samples, cCNM are attractive new substrates for other biophysical techniques which require conductive supports, i.e. scanning tunneling microscopy (STM) and electrostatic force microscopy (EFM).