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Starved lubrication is an important strategy for minimizing the amount of lubricant needed, and also inevitably occurs during idling and fail-safe lubrication. In this regime, however, the flow of the lubricant and the related friction coefficients are yet to be fully understood. This research aims to make fundamental contributions to the understanding of contact mechanics of partially lubricated contacts. Recent experiments with a pin-on-disk tribometer examined the microscopic behavior of partially filled gaps. Using a new experimental setup on a macroscale, new insights into partially filled gaps with rough surfaces were gained. This work presents the systematic analyses of the lubricant flow, friction coefficients, and other variables over a wide range of friction parameters. Distinct friction behaviors were observed, and similar effects occur on both the micro and macroscale. The experimental results show that a typical Stribeck characteristic is visible regarding not only the relative velocity, but also regarding the lubricant filling level in the gap. The fluid exhibits a variety of flow patterns for various velocities and viscosities. The patterns relate to different friction regimes, such as dry friction and mixed lubrication. It is concluded that the filling level is a valid parameter for regulating the transition from dry friction to hydrodynamic lubrication. These findings are quantified regarding the filling level and it is shown that for the identification of the friction regimes the filling level is an independent parameter in addition to the established parameters like speed, viscosity and pressure.

Rett syndrome (RTT) is a severe neurodevelopmental disorder typically arising from spontaneous mutations in the X-chromosomal methyl-CpG binding protein 2 (MECP2) gene. The almost exclusively female Rett patients show an apparently normal development during their first 6-18 months of life. Subsequently, cognitive- and motor-impairment, hand stereotypies, loss of learned skills, epilepsy, and irregular breathing manifest. Early mitochondrial impairment and oxidative challenge are considered to facilitate disease progression. Along this line, we recently confirmed in vitro that acute treatment with the vitamin E-derivative Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, ameliorates cellular redox balance, and improves hypoxia tolerance in male MeCP2-deficient (Mecp2-/y) mouse hippocampus. Pursuing these promising findings, we performed a preclinical study to define the merit of systemic Trolox administration. Blinded, placebo-controlled in vivo treatment of male mice started at postnatal day 10-11 and continued for ~40 days. Compounds (vehicle only, 10 mg/kg or 40 mg/kg Trolox) were injected intraperitoneally every 48h. Detailed phenotyping revealed that in Mecp2-/y mice, blood glucose levels, lipid peroxidation, synaptic short-term plasticity, hypoxia tolerance, and certain forms of environmental exploration were improved by Trolox. Yet, body weight and size, motor function, and the rate and regularity of breathing did not improve. In conclusion, in vivo Trolox treatment partially ameliorated a subset of symptoms of the complex Rett phenotype, thereby confirming a partial merit of the vitamin E-derivative based pharmacotherapy. Yet, it also became evident that frequent animal handling and the route of drug administration are critical issues to be optimized in future trials.

ABSTRACT Complete biodegradation of the abundant and persistent fluoroaromatics requires enzymatic cleavage of an arylic C–F bond, probably the most stable single bond of a biodegradable organic molecule. While in aerobic microorganisms defluorination of fluoroaromatics is initiated by oxygenases, arylic C–F bond cleavage has never been observed in the absence of oxygen. Here, an oxygen-independent enzymatic aryl fluoride bond cleavage is described during the complete degradation of 4-fluorobenzoate or 4-fluorotoluene to CO2 and HF in the denitrifying Thauera aromatica: the ATP-dependent defluorination of 4-fluorobenzoyl-coenzyme A (4-F-BzCoA) to benzoyl-coenzyme A (BzCoA) and HF, catalyzed by class I BzCoA reductase (BCR). Adaptation to growth with the fluoroaromatics was accomplished by the downregulation of a promiscuous benzoate-CoA ligase and the concomitant upregulation of 4-F-BzCoA-defluorinating/dearomatizing BCR on the transcriptional level. We propose an unprecedented mechanism for reductive arylic C–F bond cleavage via a Birch reduction-like mechanism resulting in a formal nucleophilic aromatic substitution. In the proposed anionic 4-fluorodienoyl-CoA transition state, fluoride elimination to BzCoA is favored over protonation to a fluorinated cyclic dienoyl-CoA. IMPORTANCE Organofluorides are produced as pesticides, pharmaceuticals, and other chemicals and comprise approximately one quarter of all organic compounds in the pharmaceutical and agricultural sectors; they are considered a growing class of environmentally relevant persistent pollutants. Especially in the case of fluoroaromatics, biodegradation is hampered by the extreme stability of the arylic C–F bond. In aerobic microorganisms, degradation proceeds via oxygenase-dependent C–F bond cleavage reactions, whereas the enzymes involved in the degradation of fluoroaromatics at anoxic sites are unknown. Here we report a strategy for the complete biodegradation of a fluoroaromatic to CO2 and HF in a denitrifying bacterium via activation to a CoA ester, followed by oxygen-independent arylic C–F bond cleavage catalyzed by an ATP-dependent enzyme. This reaction, in conjunction with a transcriptional adaptation to fluorinated growth substrates, is essential for the anoxic biodegradation of 4-fluorobenzoate/4-F-toluene and probably other fluoroaromatics.

Lead halide perovskite solar cells have shown a tremendous rise in power conversion efficiency with reported record efficiencies of over 20% making this material very promising as a low cost alternative to conventional inorganic solar cells. However, due to a differently severe “hysteretic” behaviour during current density-voltage measurements, which strongly depends on scan rate, device and measurement history, preparation method, device architecture, etc., commonly used solar cell measurements do not give reliable or even reproducible results. For the aspect of commercialization and the possibility to compare results of different devices among different laboratories, it is necessary to establish a measurement protocol which gives reproducible results. Therefore, we compare device characteristics derived from standard current density-voltage measurements with stabilized values obtained from an adaptive tracking of the maximum power point and the open circuit voltage as well as characteristics extracted from time resolved current density-voltage measurements. Our results provide insight into the challenges of a correct determination of device performance and propose a measurement protocol for a reliable characterisation which is easy to implement and has been tested on varying perovskite solar cells fabricated in different laboratories.

Introduction. To evaluate the impact of the eye lens status and oil side effects on the outcome of vitreoretinal surgery in retinal detachment with proliferative vitreoretinopathy (PVR) and a temporary silicone oil tamponade (SOT). Methods. 101 eyes were analyzed retrospectively and 103 eyes prospectively in regard to their retinal reattachment success rate and key factors for the outcome. Subgroup analysis of 27 eyes with Scheimpflug lens photography (SLP) before and after retinal reattachment service with SOT was performed. For SLP (65% phakic eyes) a Pentacam densitometry reference body with 3 mm diameter was chosen and 3 segments (anterior/mid/posterior) were evaluated separately after a quality check. Results. The retinal reattachment rate was highest in the prospective pseudophakic group (p=0.039). Lens transparency loss occurred earlier in middle aged patients than in younger patients. Besides the nucleus, layers posterior and anterior to it showed specific transparency changes. The emulsification rate was higher when eyes had been operated on in the anterior chamber before retinal reattachment service. Conclusions. Retinal reattachment surgery seems to benefit from preoperative cataract removal. We found significant lens changes in the nucleus as well as in the layers anterior and posterior to it. This corresponds to the histology of the lens epithelium published before.

Periodontal ligament stem cells (PDLSCs) are lacking membrane CD14, which is an important component of lipopolysaccharide (LPS) signaling through toll-like receptor (TLR) 4. In the present study we investigated the effect of soluble CD14 on the response of human PDLSCs to LPS of Porphyromonas (P.) gingivalis. Human PDLSCs (hPDLSCs) were stimulated with P. gingivalis LPS in the presence or in the absence of soluble CD14 (sCD14) and the production of interleukin (IL)-6, chemokine C-X-C motif ligand 8 (CXCL8), and chemokine C-C motif ligand 2 (CCL2) was measured. The response to P. gingivalis LPS was compared with that to TLR4 agonist Escherichia coli LPS and TLR2-agonist Pam3CSK4. The response of hPDLSCs to both P. gingivalis LPS and E. coli LPS was significantly enhanced by sCD14. In the absence of sCD14, no significant difference in the hPDLSCs response to two kinds of LPS was observed. These responses were significantly lower compared to that to Pam3CSK4. In the presence of sCD14, the response of hPdLSCs to P. gingivalis LPS was markedly higher than that to E. coli LPS and comparable with that to Pam3CSK4. The response of hPdLSCs to bacterial LPS is strongly augmented by sCD14. Local levels of sCD14 could be an important factor for modulation of the host response against periodontal pathogens.

PURPOSE:To evaluate the efficacy of the virtual reality training simulator Eyesi to prepare surgeons for performing pars plana vitrectomies and its potential to predict the surgeons' performance. METHODS:In a preparation phase, four participating vitreoretinal surgeons performed repeated simulator training with predefined tasks. If a surgeon was assigned to perform a vitrectomy for the management of complex retinal detachment after a surgical break of at least 60 hours it was randomly decided whether a warmup training on the simulator was required (n = 9) or not (n = 12). Performance at the simulator was measured using the built-in scoring metrics. The surgical performance was determined by two blinded observers who analyzed the video-recorded interventions. One of them repeated the analysis to check for intra-observer consistency. The surgical performance of the interventions with and without simulator training was compared. In addition, for the surgeries with simulator training, the simulator performance was compared to the performance in the operating room. RESULTS:Comparing each surgeon's performance with and without warmup trainingshowed a significant effect of warmup training onto the final outcome in the operating room. For the surgeries that were preceeded by the warmup procedure, the performance at the simulator was compared with the operating room performance. We found that there is a significant relation. The governing factor of low scores in the simulator were iatrogenic retinal holes, bleedings and lens damage. Surgeons who caused minor damage in the simulation also performed well in the operating room. CONCLUSIONS:Despite the large variation of conditions, the effect of a warmup training as well as a relation between the performance at the simulator and in the operating room was found with statistical significance. Simulator training is able to serve as a warmup to increase the average performance.

Rett syndrome is an X chromosome-linked neurodevelopmental disorder associated with cognitive impairment, motor dysfunction and breathing irregularities causing intermittent hypoxia. Evidence for impaired mitochondrial function is also accumulating. A subunit of complex III is among the potentially dys-regulated genes, the inner mitochondrial membrane is leaking protons, brain ATP levels seem reduced, and Rett patient blood samples confirm increased oxidative damage. We therefore screened for mitochondrial dysfunction and impaired redox balance. In hippocampal slices of a Rett mouse model (Mecp2−/y) we detected an increased FAD/NADH baseline-ratio indicating intensified oxidization. Cyanide-induced anoxia caused similar decreases in FAD/NADH ratio and mitochondrial membrane potential in both genotypes, but Mecp2−/y mitochondria seemed less polarized. Quantifying cytosolic redox balance with the genetically-encoded optical probe roGFP1 confirmed more oxidized baseline conditions, a more vulnerable redox-balance, and more intense responses of Mecp2−/y hippocampus to oxidative challenge and mitochondrial impairment. Trolox treatment improved the redox baseline of Mecp2−/y hippocampus and dampened its exaggerated responses to oxidative challenge. Microarray analysis of the hippocampal CA1 subfield did not detect alterations of key mitochondrial enzymes or scavenging systems. Yet, quantitative PCR confirmed a moderate upregulation of superoxide dismutase 1 in Mecp2−/y hippocampus, which might be a compensatory response to the increased oxidative burden. Since several receptors and ion-channels are redox-modulated, the mitochondrial and redox changes which already manifest in neonates could contribute to the hyperexcitability and diminished synaptic plasticity in MeCP2 deficiency. Therefore, targeting cellular redox balance might qualify as a potential pharmacotherapeutic approach to improve neuronal network function in Rett syndrome.

The ordering kinetics in free and supported L10 nanoparticles was studied by means of lattice-based kinetic Monte-Carlo simulations. Starting from a fully disordered particle of Wulff shape, the simulations show that the nucleation of ordered domains is starting quickly on various (100) facets but is retarded in the particle volume due to the lack of vacancies compared with a thin film geometry. If a substrate is present, we do not find significant differences in the ordering behavior. This holds true, even if we impose a massively increased thermodynamic driving force for interface segregation, because the nucleation of ordered domains on free facets is significantly faster than the bulk diffusion of the segregating species to the interface. In cases where wetting of the substrate or surface facetting occurs, we find that diffusional atomic motion on the surface goes along with an enhanced long-range order.

This commentary reviews the role of the Alzheimer amyloid peptide Aβ on basal synaptic transmission, synaptic short-term plasticity, as well as short- and long-term potentiation in transgenic mice, with a special focus on N-terminal truncated Aβ4-42. Aβ4-42 is highly abundant in the brain of Alzheimer’s disease (AD) patients. It demonstrates increased neurotoxicity compared to full length Aβ, suggesting an important role in the pathogenesis of AD. Transgenic Tg4-42 mice, a model for sporadic AD, express human Aβ4-42 in Cornu Ammonis (CA1) neurons, and develop age-dependent hippocampal neuron loss and neurological deficits. In contrast to other transgenic AD mouse models, the Tg4-42 model exhibits synaptic hyperexcitability, altered synaptic short-term plasticity with no alterations in short- and long-term potentiation. The outcomes of this study are discussed in comparison with controversial results from other AD mouse models.

A novel long-wavelength vertical-cavity surface-emitting laser (VCSEL) structure based on a subwavelength high-contrast grating (HCG) as the output mirror has been realized. By design, these devices are highly polarization stable, are single mode at large apertures, and solve the VCSEL-mirror problem at long wavelengths in an elegant way. With cost-effective mass fabrication in mind, the top HCG reflector consists of amorphous silicon on isolator (amorphous silica). The single-mode laser emission is tailored to be around 1320-nm wavelength, targeting applications in high-speed optical data transmission, particularly those for passive optical networks. We report single-mode emission for devices with apertures as large as 11 $\mu\hbox{m}$ operating in continuous wave with output powers in excess of 0.4 mW. Pulsed operation with output powers up to 4 mW at room temperature is demonstrated as well. This is the first electrically pumped VCSEL structure realized in this wavelength regime utilizing an HCG mirror.

The volute is one of the key components of a centrifugal compressor. The design of the volute not only impacts the compressor efficiency but also influences the operating range. The detailed flow simulation presented here helps to better understand the volute flow mechanisms and provide design guidance in volute design to meet performance goals. In this study, the viscous Navier-Stokes equations are used to simulate the flow inside the vaneless diffuser and volute. The detailed flow structures for different volute tongue geometries are studied in detail. The numerical calculations are compared with experimental data and good agreement is found. The results also suggest direction for further investigations in volute design.

Obwohl in Deutschland seit über 40 Jahren bilingualer Unterricht erteilt wird, sind die empirischen Untersuchungen zu seiner Lernwirksamkeit zumeist jüngeren Datums. Der vorliegende Artikel stellt die aus Sicht der Verfasser wichtigsten Untersuchungen vor und diskutiert sie kritisch. Während die Ergebnisse hinsichtlich des Fremdsprachen-Kompetenzzuwachses durch bilingualen Unterricht als weitgehend gesichert gelten, liegen zum fachlich-geographischen Kompetenzzuwachs nach wie vor keine eindeutigen Erkenntnisse vor. Unterschiedlich fällt auch die Beantwortung der Frage aus, ob der bilinguale Geographieunterricht ein besonderes Potential für den Erwerb interkultureller Kompetenzen bietet. Neben der kritischen Analyse empirischer Untersuchungen skizzieren wir in diesem Beitrag ein Kompetenzmodell für den bilingualen Geographieunterricht, das den Belangen der Geographie stärker Rechnung tragen soll. Trotz der vielen offenen Fragen plädieren wir für ein starkes Engagement unseres Faches in der Diskussion zum bilingualen Unterricht, denn aus ureigenem Interesse der Geographie sprechen eine Reihe von Gründen für eine besondere Berücksichtigung dieser Unterrichtsform. Vermittlung von zeitgemäßer raumbezogener Handlungskompetenz erfordert heute einen multiperspektivischen Zugang auch mittels fremdsprachiger Quellen und Personen.

Background and study aims: Endoscopic implantation of a duodenal-jejunal bypass liner (DJBL) is a novel bariatric technique to induce weight loss and remission of type 2 diabetes mellitus. Placement of the DJBL mimics the bypass component of the Roux-en-Y gastric bypass (RYGB) procedure. In this observational study, we evaluated improvement of glycemic control and weight loss in the course of the treatment (0 – 24 weeks after DJBL implantation) and analyzed accompanying gut hormone responses. Patients and methods: 12 obese individuals with type 2 diabetes were selected for DJBL implantation. Body weight, fat mass, and fasting plasma levels of glucose, insulin, C-peptide, and glycated hemoglobin (HbA1c), were analyzed at 0, 1, 4 and 24 weeks post-implant. Fasting ghrelin, gastric inhibitory peptide (GIP), and glucagon-like peptide (GLP-1) were determined at 0, 1 and 4 weeks post-implant. Results: Besides significant weight loss, fat mass, fasting insulin, and homeostasis model assessment-estimated insulin resistance (HOMA-IR) index were also significantly decreased after DJBL implantation and a 42 % reduction was found in diabetes medication (P

Intestinal chemosensory receptors and transporters are able to detect food-derived molecules and are involved in the modulation of gut hormone release. Gut hormones play an important role in the regulation of food intake and the control of gastrointestinal functioning. This mechanism is often referred to as "nutrient sensing". Knowledge of the distribution of chemosensors along the intestinal tract is important to gain insight in nutrient detection and sensing, both pivotal processes for the regulation of food intake. However, most knowledge is derived from rodents, whereas studies in man and pig are limited, and cross-species comparisons are lacking.To characterize and compare intestinal expression patterns of genes related to nutrient sensing in mice, pigs and humans.Mucosal biopsy samples taken at six locations in human intestine (n = 40) were analyzed by qPCR. Intestinal scrapings from 14 locations in pigs (n = 6) and from 10 locations in mice (n = 4) were analyzed by qPCR and microarray, respectively. The gene expression of glucagon, cholecystokinin, peptide YY, glucagon-like peptide-1 receptor, taste receptor T1R3, sodium/glucose cotransporter, peptide transporter-1, GPR120, taste receptor T1R1, GPR119 and GPR93 was investigated. Partial least squares (PLS) modeling was used to compare the intestinal expression pattern between the three species.The studied genes were found to display specific expression patterns along the intestinal tract. PLS analysis showed a high similarity between human, pig and mouse in the expression of genes related to nutrient sensing in the distal ileum, and between human and pig in the colon. The gene expression pattern was most deviating between the species in the proximal intestine. Our results give new insights in interspecies similarities and provide new leads for translational research and models aiming to modulate food intake processes in man.

August 2011 − London’s burning. Vier Tage lang kommt es zunächst in verschiedenen Stadtteilen Londons und später auch in anderen britischen Städten zu den größten Aufständen und Plünderungen der Nachkriegsgeschichte. Konservative Medien und Politik sind sich schnell einig: Der Abschaum, der sich für die Verwüstungen und Plünderungen verantwortlich zeigt, gehört mit aller Härte aus den Straßen gefegt. Die Aufständischen stellen keine politischen Forderungen. Entgegen hegemonialer Deutungen, die den riots eine politische Dimension absprechen, fragt der Artikel, inwiefern sich hier eine neue Qualität des Politischen und politischer Subjektivität zeigt, die wir mit den vertrauten repräsentationspolitischen Deutungsmustern nicht verstehen können.

Progressive familial intrahepatic cholestasis (PFIC) is a group of severe genetic cholestatic liver diseases of early life. PFIC types 1 and 2 are characterized by cholestasis and a low to normal serum gamma-glutamyltransferase (GGT) activity, whereas in PFIC type 3, the serum GGT activity is elevated. PFIC types 1 and 2 occur due to mutations in loci at chromosome 18 and chromosome 2, respectively. The pathophysiology of PFIC type 1 is not well understood. PFIC types 2 and 3 are caused by transport defects in the liver affecting the hepatobiliary secretion of bile acids and phospholipids, respectively. Benign recurrent intrahepatic cholestasis (BRIC) is linked to a mutation in the same familial intrahepatic cholestasis 1 locus at chromosome 18. Defects of bile acid synthesis may be difficult to differentiate from these transport defects.Intrahepatic cholestasis of pregnancy (ICP) appears to be related to these cholestatic diseases. For example, heterozygosity in families with PFIC type 3 is associated with ICP, but ICP has also been reported in families with BRIC.In Dubin-Johnson syndrome there is no cholestasis; only the hepatobiliary transport of conjugated bilirubin is affected. This, therefore, is a mild disease, and patients have a normal lifespan.

Maternal diet is associated with the development of metabolism-related and other non-communicable diseases in offspring. Underlying mechanisms, functional profiles, and molecular markers are only starting to be revealed. Here, we explored the physiological and molecular impact of maternal Western-style diet on the liver of male and female offspring. C57BL/6 dams were exposed to either a low fat/low cholesterol diet (LFD) or a Western-style high fat/high cholesterol diet (WSD) for six weeks before mating, as well as during gestation and lactation. Dams and offspring were sacrificed at postnatal day 14, and body, liver, and blood parameters were assessed. The impact of maternal WSD on the pups' liver gene expression was characterised by whole-transcriptome microarray analysis. Exclusively male offspring had significantly higher body weight upon maternal WSD. In offspring of both sexes of WSD dams, liver and blood parameters, as well as hepatic gene expression profiles were changed. In total, 686 and 604 genes were differentially expressed in liver (p≤0.01) of males and females, respectively. Only 10% of these significantly changed genes overlapped in both sexes. In males, in particular alterations of gene expression with respect to developmental functions and processes were observed, such as Wnt/beta-catenin signalling. In females, mainly genes important for lipid metabolism, including cholesterol synthesis, were changed. We conclude that maternal WSD affects physiological parameters and induces substantial changes in the molecular profile of the liver in two-week-old pups. Remarkably, the observed biological responses of the offspring reveal pronounced sex-specificity.

High fat meal challenges are known to induce postprandial low-grade inflammation and endothelial dysfunction. This assumption is largely based on studies performed in older populations or in populations with a progressed disease state and an appropriate control meal is often lacking. Young healthy individuals might be more resilient to such challenges. We therefore aimed to characterize the vascular and inflammatory response after a high fat meal in young healthy individuals.In a double-blind randomized cross-over intervention study, we used a comprehensive phenotyping approach to determine the vascular and inflammatory response after consumption of a high fat shake and after an average breakfast shake in 20 young healthy subjects. Both interventions were performed three times.Many features of the vascular postprandial response, such as FMD, arterial stiffness and micro-vascular skin blood flow were not different between shakes. High fat/high energy shake consumption was associated with a more pronounced increase in blood pressure, heart rate, plasma concentrations of IL-8 and PBMCs gene expression of IL-8 and CD54 (ICAM-1), whereas plasma concentrations of sVCAM1 were decreased compared to an average breakfast.Whereas no difference in postprandial response were observed on classical markers of endothelial function, we did observe differences between consumption of a HF/HE and an average breakfast meal on blood pressure and IL-8 in young healthy volunteers. IL-8 might play an important role in dealing with high fat challenges and might be an early marker for endothelial stress, a stage preceding endothelial dysfunction.

Landscape simulators are widely applied in landscape ecology for generating landscape patterns. These models can be divided into two categories: pattern-based models that generate spatial patterns irrespective of the processes that shape them, and process-based models that attempt to generate patterns based on the processes that shape them. The latter often tend toward complexity in an attempt to obtain high predictive precision, but are rarely used for generic or theoretical purposes. Here we show that a simple process-based simulator can generate a variety of spatial patterns including realistic ones, typifying landscapes fragmented by anthropogenic activities. The model "G-RaFFe" generates roads and fields to reproduce the processes in which forests are converted into arable lands. For a selected level of habitat cover, three factors dominate its outcomes: the number of roads (accessibility), maximum field size (accounting for land ownership patterns), and maximum field disconnection (which enables field to be detached from roads). We compared the performance of G-RaFFe to three other models: Simmap (neutral model), Qrule (fractal-based) and Dinamica EGO (with 4 model versions differing in complexity). A PCA-based analysis indicated G-RaFFe and Dinamica version 4 (most complex) to perform best in matching realistic spatial patterns, but an alternative analysis which considers model variability identified G-RaFFe and Qrule as performing best. We also found model performance to be affected by habitat cover and the actual land-uses, the latter reflecting on land ownership patterns. We suggest that simple process-based generators such as G-RaFFe can be used to generate spatial patterns as templates for theoretical analyses, as well as for gaining better understanding of the relation between spatial processes and patterns. We suggest caution in applying neutral or fractal-based approaches, since spatial patterns that typify anthropogenic landscapes are often non-fractal in nature.

In humans, plasma amino acid concentrations of branched-chain amino acids (BCAA) and aromatic amino acids (AAA) increase in states of obesity, insulin resistance and diabetes. We here assessed whether these putative biomarkers can also be identified in two different obesity and diabetic mouse models. C57BL/6 mice with diet-induced obesity (DIO) mimic the metabolic impairments of obesity in humans characterized by hyperglycemia, hyperinsulinemia and hepatic triglyceride accumulation. Mice treated with streptozotocin (STZ) to induce insulin deficiency were used as a type 1 diabetes model. Plasma amino acid profiling of two high fat (HF) feeding trials revealed that citrulline and ornithine concentrations are elevated in obese mice, while systemic arginine bioavailability (ratio of plasma arginine to ornithine + citrulline) is reduced. In skeletal muscle, HF feeding induced a reduction of arginine levels while citrulline levels were elevated. However, arginine or citrulline remained unchanged in their key metabolic organs, intestine and kidney. Moreover, the intestinal conversion of labeled arginine to ornithine and citrulline in vitro remained unaffected by HF feeding excluding the intestine as prime site of these alterations. In liver, citrulline is mainly derived from ornithine in the urea cycle and DIO mice displayed reduced hepatic ornithine levels. Since both amino acids share an antiport mechanism for mitochondrial import and export, elevated plasma citrulline may indicate impaired hepatic amino acid handling in DIO mice. In the insulin deficient mice, plasma citrulline and ornithine levels also increased and additionally these animals displayed elevated BCAA and AAA levels like insulin resistant and diabetic patients. Therefore, type 1 diabetic mice but not DIO mice show the "diabetic fingerprint" of plasma amino acid changes observed in humans. Additionally, citrulline may serve as an early indicator of the obesity-dependent metabolic impairments.

Cytochromes P450 (CYP, P450) are a large family of heme-active-site proteins involved in many catalytic processes, including steroidogenesis. In humans, four primary enzymes are involved in the metabolism of almost all xenobiotics. Among these enzymes, CYP3A4 is responsible for the inactivation of the majority of used drugs which makes this enzyme an interesting target for many fields of research, especially pharmaceutical research. Since the late 1970s, attempts have been made to construct and develop electrochemical sensors for the determination of substrates. This paper is concerned with the establishment of such a CYP3A4-containing biosensor. The sensor was constructed by adsorption of alternating layers of sub-nanometer gold particle-modified PAMAM (poly-amido-amine) dendrimers of generation 4.0, along with the enzyme by a layer-by-layer assembly technique. Atomic force microscopy (AFM), quartz crystal microbalance (QCM), and Fourier-transformed infrared spectroscopy (FTIR) were employed to elucidate the sensor assembly. Additionally, the biosensor was tested by cyclic voltammetry using caffeine as a substrate.

Bone adaptation after total hip arthroplasty is associated with the change in internal load environment, and can result in compromised bone stock, which presents a considerable challenge should a revision procedure be required. Under the assumption of a generic mechano-regulatory algorithm for governing bone adaptation, the aim of this study was to understand the contribution of subject specific loading conditions towards explaining the local periprosthetic remodelling variations in patients. CT scans of 3 consecutive THA patients were obtained and used for the construction of subject specific finite element models using verified musculoskeletal loading and physiological boundary conditions. Using either strain energy density or equivalent strain as mechano-transduction signals, predictions of bone adaptation were compared to DEXA derived BMD changes from 7 days to 12 months post-implantation. Individual changes in BMD of up to 33.6% were observed within the 12 month follow-up period, together with considerable inter-patient variability of up to 26%. Estimates of bone adaptation using equivalent strain and balanced loading conditions led to the best agreement with in vivo measured BMD, with RMS errors of only 3.9%, 7.3% and 7.3% for the individual subjects, compared to errors of over 10% when the loading conditions were simplified.This study provides evidence that subject specific loading conditions and physiological boundary constraints are essential for explaining inter-patient variations in bone adaptation patterns. This improved knowledge of the rules governing the adaptation of bone following THA helps towards understanding the interplay between mechanics and biology for better identifying patients at risk of excessive or problematic periprosthetic bone atrophy.

Red meat consumption is associated with an increased colon cancer risk. Heme, present in red meat, injures the colon surface epithelium by luminal cytotoxicity and reactive oxygen species. This surface injury is overcompensated by hyperproliferation and hyperplasia of crypt cells. Transcriptome analysis of mucosa of heme-fed mice showed, besides stress- and proliferation-related genes, many upregulated lipid metabolism-related PPARα target genes. The aim of this study was to investigate the role of PPARα in heme-induced hyperproliferation and hyperplasia. Male PPARα KO and WT mice received a purified diet with or without heme. As PPARα is proposed to protect against oxidative stress and lipid peroxidation, we hypothesized that the absence of PPARα leads to more surface injury and crypt hyperproliferation in the colon upon heme-feeding. Heme induced luminal cytotoxicity and lipid peroxidation and colonic hyperproliferation and hyperplasia to the same extent in WT and KO mice. Transcriptome analysis of colonic mucosa confirmed similar heme-induced hyperproliferation in WT and KO mice. Stainings for alkaline phosphatase activity and expression levels of Vanin-1 and Nrf2-targets indicated a compromised antioxidant defense in heme-fed KO mice. Our results suggest that the protective role of PPARα in antioxidant defense involves the Nrf2-inhibitor Fosl1, which is upregulated by heme in PPARα KO mice. We conclude that PPARα plays a protective role in colon against oxidative stress, but PPARα does not mediate heme-induced hyperproliferation. This implies that oxidative stress of surface cells is not the main determinant of heme-induced hyperproliferation and hyperplasia.

BackgroundIntakes of n-3 polyunsaturated fatty acids (PUFAs), especially EPA (C20:5n-3) and DHA (C22:6n-3), are known to prevent fatal coronary heart disease (CHD). The effects of n-6 PUFAs including arachidonic acid (C20:4n-6), however, remain unclear. δ-5 and δ-6 desaturases are rate-limiting enzymes for synthesizing long-chain n-3 and n-6 PUFAs. C20:4n-6 to C20:3n-6 and C18:3n-6 to C18:2n-6 ratios are markers of endogenous δ-5 and δ-6 desaturase activities, but have never been studied in relation to incident CHD. Therefore, the aim of this study was to investigate the relation between these ratios as well as genotypes of FADS1 rs174547 and CHD incidence.MethodsWe applied a case-cohort design within the CAREMA cohort, a large prospective study among the general Dutch population followed up for a median of 12.1 years. Fatty acid profile in plasma cholesteryl esters and FADS1 genotype at baseline were measured in a random subcohort (n = 1323) and incident CHD cases (n = 537). Main outcome measures were hazard ratios (HRs) of incident CHD adjusted for major CHD risk factors.ResultsThe AA genotype of rs174547 was associated with increased plasma levels of C204n-6, C20:5n-3 and C22:6n-3 and increased δ-5 and δ-6 desaturase activities, but not with CHD risk. In multivariable adjusted models, high baseline δ-5 desaturase activity was associated with reduced CHD risk (P for trend = 0.02), especially among those carrying the high desaturase activity genotype (AA): HR (95% CI) = 0.35 (0.15-0.81) for comparing the extreme quintiles. High plasma DHA levels were also associated with reduced CHD risk.ConclusionIn this prospective cohort study, we observed a reduced CHD risk with an increased C20:4n-6 to C20:3n-6 ratio, suggesting that δ-5 desaturase activity plays a role in CHD etiology. This should be investigated further in other independent studies.

Spreading depression (SD) is characterized by a sustained near-complete depolarization of neurons, a massive depolarization of glia, and a negative deflection of the extracellular DC potential. These electrophysiological signs are accompanied by an intrinsic optical signal (IOS) which arises from changes in light scattering and absorption. Even though the underlying mechanisms are unclear, the IOS serves as non-invasive tool to define the spatiotemporal dynamics of SD in brain slices. Usually the tissue is illuminated by white light, and light reflectance or transmittance is monitored. Using a polychromatic, fast-switchable light source we now performed temporo-spectral recordings of the IOS associated with hypoxia-induced SD-like depolarization (HSD) in rat hippocampal slices kept in an interface recording chamber. Recording full illumination spectra (320-680 nm) yielded distinct reflectance profiles for the different phases of HSD. Early during hypoxia tissue reflectance decreased within almost the entire spectrum due to cell swelling. HSD was accompanied by a reversible reflectance increase being most pronounced at 400 nm and 460 nm. At 440 nm massive porphyrin absorption (Soret band) was detected. Hypotonic solutions, Ca(2+)-withdrawal and glial poisoning intensified the reflectance increase during HSD, whereas hypertonic solutions dampened it. Replacement of Cl(-) inverted the reflectance increase. Inducing HSD by cyanide distorted the IOS and reflectance at 340-400 nm increased irreversibly. The pronounced changes at short wavelengths (380 nm, 460 nm) and their cyanide sensitivity suggest that block of mitochondrial metabolism contributes to the IOS during HSD. For stable and reliable IOS recordings during HSD wavelengths of 460-560 nm are recommended.

The ability of subjects to respond to nutritional challenges can reflect the flexibility of their biological system. Nutritional challenge tests could be used as an indicator of health status but more knowledge on metabolic and immune responses of different subjects to nutritional challenges is needed. The aim of this study was to compare the responses to high-fat challenges varying in fat type in subjects with different metabolic risk phenotypes.In a cross-over design 42 men (age 50-70 y) consumed three high-fat shakes containing saturated fat (SFA), monounsaturated fat (MUFA) or n-3 polyunsaturated (PUFA). Men were selected on BMI and health status (lean, obese or obese diabetic) and phenotyped with MRI for adipose tissue distribution. Before and 2 and 4 h after shake consumption blood was drawn for measurement of expression of metabolic and inflammation-related genes in peripheral blood mononuclear cells (PBMCs), plasma triglycerides (TAG), glucose, insulin, cytokines and ex vivo PBMC immune response capacity. The MUFA and n-3 PUFA challenge, compared to the SFA challenge, induced higher changes in expression of inflammation genes MCP1 and IL1β in PBMCs. Obese and obese diabetic subjects had different PBMC gene expression and metabolic responses to high-fat challenges compared to lean subjects. The MUFA challenge induced the most pronounced TAG response, mainly in obese and obese diabetic subjects.The PBMC gene expression response and metabolic response to high-fat challenges were affected by fat type and metabolic risk phenotype. Based on our results we suggest using a MUFA challenge to reveal differences in response capacity of subjects.ClinicalTrials.gov NCT00977262.

Regular physical activity positively influences whole body energy metabolism and substrate handling in exercising muscle. While it is recognized that the effects of exercise extend beyond exercising muscle, it is unclear to what extent exercise impacts non-exercising muscles. Here we investigated the effects of an acute endurance exercise bouts on gene expression in exercising and non-exercising human muscle. To that end, 12 male subjects aged 44-56 performed one hour of one-legged cycling at 50% W(max). Muscle biopsies were taken from the exercising and non-exercising leg before and immediately after exercise and analyzed by microarray. One-legged cycling raised plasma lactate, free fatty acids, cortisol, noradrenalin, and adrenalin levels. Surprisingly, acute endurance exercise not only caused pronounced gene expression changes in exercising muscle but also in non-exercising muscle. In the exercising leg the three most highly induced genes were all part of the NR4A family. Remarkably, many genes induced in non-exercising muscle were PPAR targets or related to PPAR signalling, including PDK4, ANGPTL4 and SLC22A5. Pathway analysis confirmed this finding. In conclusion, our data indicate that acute endurance exercise elicits pronounced changes in gene expression in non-exercising muscle, which are likely mediated by changes in circulating factors such as free fatty acids. The study points to a major influence of exercise beyond the contracting muscle.

Colon cancer is a major cause of cancer deaths in Western countries and is associated with diets high in red meat. Heme, the iron-porphyrin pigment of red meat, induces cytotoxicity of gut contents which injures surface cells leading to compensatory hyperproliferation of crypt cells. This hyperproliferation results in epithelial hyperplasia which increases the risk of colon cancer. In humans, a high red-meat diet increases Bacteroides spp in feces. Therefore, we simultaneously investigated the effects of dietary heme on colonic microbiota and on the host mucosa of mice. Whole genome microarrays showed that heme injured the colonic surface epithelium and induced hyperproliferation by changing the surface to crypt signaling. Using 16S rRNA phylogenetic microarrays, we investigated whether bacteria play a role in this changed signaling. Heme increased Bacteroidetes and decreased Firmicutes in colonic contents. This shift was most likely caused by a selective susceptibility of gram-positive bacteria to heme cytotoxic fecal water, which is not observed for gram-negative bacteria, allowing expansion of the gram-negative community. The increased amount of gram-negative bacteria most probably increased LPS exposure to colonocytes, however, there is no appreciable immune response detected in the heme-fed mice. There was no functional change in the sensing of the bacteria by the mucosa, as changes in inflammation pathways and Toll-like receptor signaling were not detected. This unaltered host-microbe cross-talk indicates that the changes in microbiota did not play a causal role in the observed hyperproliferation and hyperplasia.

BACKGROUND AND AIMS: High protein (HP) diets are suggested to positively modulate obesity and associated increased prevalence of non-alcoholic fatty liver (NAFLD) disease in humans and rodents. The aim of our study was to detect mechanisms by which a HP diet affects hepatic lipid accumulation. METHODS: To investigate the acute and long term effect of high protein ingestion on hepatic lipid accumulation under both low and high fat (HF) conditions, mice were fed combinations of high (35 energy%) or low (10 energy%) fat and high (50 energy%) or normal (15 energy%) protein diets for 1 or 12 weeks. Effects on body composition, liver fat, VLDL production rate and the hepatic transcriptome were investigated. RESULTS: Mice fed the HP diets displayed a lower body weight, developed less adiposity and decreased hepatic lipid accumulation, which could be attributed to a combination of several processes. Next to an increased hepatic VLDL production rate, increased energy utilisation due to enhanced protein catabolic processes, such as transamination, TCA cycle and oxidative phosphorylation was found upon high protein ingestion. CONCLUSION: Feeding a HP diet prevented the development of NAFLD by enhancing lipid secretion into VLDL particles and a less efficient use of ingested calories.

It would very much seem as though the avant-garde in post-war Germany had initially lost sight of the previously politically grounded programmatic narratives. Moreover, it seemed quite obsolete to insist on the destruction of the affirmative. After all, had it not been the Nazis who had pursued such destruction far more successfully than the avant-gardes before them, albeit with completely opposite goals in mind? For this reason, it seemed so compelling to regard the restoration of the avant-garde via the renewed recourse to the autonomy of art as an expression of an anti-fascist stance. The linkage of emancipation of individual subjectivity and radical social change called for by the avant-gardes now collapses once again. In the years that followed, the conservative cultural position repeatedly turned on attempts to closely link aesthetic innovation with social change. This taming of a recalcitrant art was followed in the early 1970s, after a brief intermezzo at the end of the 1960s, by talk of the failure of the avant-garde, before being subjected to outrageous defamation ten years later (particularly in architecture). The question of whether today the universalization of the aesthetic has indirectly realized the hopes of the avant-gardes of an aesthetics of and in lived practice, will be the subject of my remarks.

AIMS/HYPOTHESIS: Bile acid sequestrants (BAS) reduce plasma glucose levels in type II diabetics and in murine models of diabetes but the mechanism herein is unknown. We hypothesized that sequestrant-induced changes in hepatic glucose metabolism would underlie reduced plasma glucose levels. Therefore, in vivo glucose metabolism was assessed in db/db mice on and off BAS using tracer methodology. METHODS: Lean and diabetic db/db mice were treated with 2% (wt/wt in diet) Colesevelam HCl (BAS) for 2 weeks. Parameters of in vivo glucose metabolism were assessed by infusing [U-(13)C]-glucose, [2-(13)C]-glycerol, [1-(2)H]-galactose and paracetamol for 6 hours, followed by mass isotopologue distribution analysis, and related to metabolic parameters as well as gene expression patterns. RESULTS: Compared to lean mice, db/db mice displayed an almost 3-fold lower metabolic clearance rate of glucose (p = 0.0001), a ∼300% increased glucokinase flux (p = 0.001) and a ∼200% increased total hepatic glucose production rate (p = 0.0002). BAS treatment increased glucose metabolic clearance rate by ∼37% but had no effects on glucokinase flux nor total hepatic or endogenous glucose production. Strikingly, BAS-treated db/db mice displayed reduced long-chain acylcarnitine content in skeletal muscle (p = 0.0317) but not in liver (p = 0.189). Unexpectedly, BAS treatment increased hepatic FGF21 mRNA expression 2-fold in lean mice (p = 0.030) and 3-fold in db/db mice (p = 0.002). CONCLUSIONS/INTERPRETATION: BAS induced plasma glucose lowering in db/db mice by increasing metabolic clearance rate of glucose in peripheral tissues, which coincided with decreased skeletal muscle long-chain acylcarnitine content.

Excessive intake of dietary fat is known to be a contributing factor in the development of obesity. In this study, we determined the dose-dependent effects of dietary fat on the development of this metabolic condition with a focus on changes in gene expression in the small intestine. C57BL/6J mice were fed diets with either 10, 20, 30 or 45 energy% (E%) derived from fat for four weeks (n = 10 mice/diet). We found a significant higher weight gain in mice fed the 30E% and 45E% fat diet compared to mice on the control diet. These data indicate that the main shift towards an obese phenotype lies between a 20E% and 30E% dietary fat intake. Analysis of differential gene expression in the small intestine showed a fat-dose dependent gradient in differentially expressed genes, with the highest numbers in mice fed the 45E% fat diet. The main shift in fat-induced differential gene expression was found between the 30E% and 45E% fat diet. Furthermore, approximately 70% of the differentially expressed genes were changed in a fat-dose dependent manner. Many of these genes were involved in lipid metabolism-related processes and were already differentially expressed on a 30E% fat diet. Taken together, we conclude that up to 20E% of dietary fat, the small intestine has an effective 'buffer capacity' for fat handling. From 30E% of dietary fat, a switch towards an obese phenotype is triggered. We further speculate that especially fat-dose dependently changed lipid metabolism-related genes are involved in development of obesity.

Depot-dependent differences in adipose tissue physiology may reflect specialized functions and local interactions between adipocytes and surrounding tissues. We combined time-resolved microarray analyses of mesenteric- (MWAT), subcutaneous- (SWAT) and epididymal adipose tissue (EWAT) during high-fat feeding of male transgenic ApoE3Leiden mice with histology, targeted lipidomics and biochemical analyses of metabolic pathways to identify differentially regulated processes and site-specific functions. EWAT was found to exhibit physiological zonation. De novo lipogenesis in fat proximal to epididymis was stably low, whereas de novo lipogenesis distal to epididymis and at other locations was down-regulated in response to high-fat diet. The contents of linoleic acid and alpha-linolenic acid in EWAT were increased compared to other depots. Expression of the androgen receptor (Ar) was higher in EWAT than in MWAT and SWAT. We suggest that Ar may mediate depot-dependent differences in de novo lipogenesis rate and propose that accumulation of linoleic acid and alpha-linolenic acid in EWAT is favored by testosterone-mediated inhibition of de novo lipogenesis and may promote further elongation and desaturation of these polyunsaturated fatty acids during spermatogenesis.

Suomeen kulkeutui 1990-luvun alussa Phytophthora cactorum -mikrobi, jota voidaan kutsua jo vakiintuneeksi vieraslajiksi. Sata vuotta aiemmin Eurooppaan levisi strobusmäntyjen mukana Cronartium ribicola, joka aiheuttaa valkomännyn tervasroson 5-neulasmännyillä. Aikanaan maahamme on tullut taimien mukana kaksi, Amerikasta kotoisin olevaa sientä Neofabrea populi ja Entoleuca mammata, jotka aiheuttavat lähinnä hybridihaavalla kuoripoltteeksi ja haavanrosoksi nimetyt taudit. Eviran kasvintarkastuslaboratorio löysi Amerikassa tammenäkkikuolemaa ja Euroopassa heiden ja varpukasvien versopoltetta aiheuttavaa P. ramorum -mikrobia ensimmäisen kerran vuonna 2004. Sitä löytyi paitsi tuontitaimista, myös Suomessa tuotetuilta alppiruusuilta. Uusin vieraslaji on P. plurivora, joka tartutuskokeissa on osoittautunut erittäin haitalliseksi monille kasveille. Lepänruosteen aiheuttava Melampsoridium hiratsukanum on tuhonnut Suomessa lepän lehtiä vuodesta 1997. Muita tulokaslajeja ovat Dothistroma septosporum ja Chalara fraxinea. Ensinmainittu aiheuttaa punavyökariste-taudin, jonka esiintyminen meillä varmennettiin 2008. C. fraxinea puolestaan liitetään saarnensurmaksi nimettyyn tautiin.

BACKGROUND: Biomarkers that allow detection of the onset of disease are of high interest since early detection would allow intervening with lifestyle and nutritional changes before the disease is manifested and pharmacological therapy is required. Our study aimed to improve the phenotypic characterization of overweight but apparently healthy subjects and to identify new candidate profiles for early biomarkers of obesity-related diseases such as cardiovascular disease and type 2 diabetes. METHODOLOGY/PRINCIPAL FINDINGS: In a population of 56 healthy, middle-aged overweight subjects Body Mass Index (BMI), fasting concentration of 124 plasma proteins and insulin were determined. The plasma proteins are implicated in chronic diseases, inflammation, endothelial function and metabolic signaling. Random Forest was applied to select proteins associated with BMI and plasma insulin. Subsequently, the selected proteins were analyzed by clustering methods to identify protein clusters associated with BMI and plasma insulin. Similar analyses were performed for a second population of 20 healthy, overweight older subjects to verify associations found in population I. In both populations similar clusters of proteins associated with BMI or insulin were identified. Leptin and a number of pro-inflammatory proteins, previously identified as possible biomarkers for obesity-related disease, e.g. Complement 3, C Reactive Protein, Serum Amyloid P, Vascular Endothelial Growth Factor clustered together and were positively associated with BMI and insulin. IL-3 and IL-13 clustered together with Apolipoprotein A1 and were inversely associated with BMI and might be potential new biomarkers. CONCLUSION/ SIGNIFICANCE: We identified clusters of plasma proteins associated with BMI and insulin in healthy populations. These clusters included previously reported biomarkers for obesity-related disease and potential new biomarkers such as IL-3 and IL-13. These plasma protein clusters could have potential applications for improved phenotypic characterization of volunteers in nutritional intervention studies or as biomarkers in the early detection of obesity-linked disease development and progression.

The peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcription factor involved in the regulation of a variety of processes, ranging from inflammation and immunity to nutrient metabolism and energy homeostasis. PPARα serves as a molecular target for hypolipidemic fibrates drugs which bind the receptor with high affinity. Furthermore, PPARα binds and is activated by numerous fatty acids and fatty acid-derived compounds. PPARα governs biological processes by altering the expression of a large number of target genes. Accordingly, the specific role of PPARα is directly related to the biological function of its target genes. Here, we present an overview of the involvement of PPARα in lipid metabolism and other pathways through a detailed analysis of the different known or putative PPARα target genes. The emphasis is on gene regulation by PPARα in liver although many of the results likely apply to other organs and tissues as well.

BackgroundStudies in mice have shown that PPARalpha is an important regulator of hepatic lipid metabolism and the acute phase response. However, little information is available on the role of PPARalpha in human liver. Here we set out to compare the function of PPARalpha in mouse and human hepatocytes via analysis of target gene regulation.Methodology/principal findingsPrimary hepatocytes from 6 human and 6 mouse donors were treated with PPARalpha agonist Wy14643 and gene expression profiling was performed using Affymetrix GeneChips followed by a systems biology analysis. Baseline PPARalpha expression was similar in human and mouse hepatocytes. Depending on species and time of exposure, Wy14643 significantly induced the expression of 362-672 genes. Surprisingly minor overlap was observed between the Wy14643-regulated genes from mouse and human, although more substantial overlap was observed at the pathway level. Xenobiotics metabolism and apolipoprotein synthesis were specifically regulated by PPARalpha in human hepatocytes, whereas glycolysis-gluconeogenesis was regulated specifically in mouse hepatocytes. Most of the genes commonly regulated in mouse and human were involved in lipid metabolism and many represented known PPARalpha targets, including CPT1A, HMGCS2, FABP1, ACSL1, and ADFP. Several genes were identified that were specifically induced by PPARalpha in human (MBL2, ALAS1, CYP1A1, TSKU) or mouse (Fbp2, lgals4, Cd36, Ucp2, Pxmp4). Furthermore, several putative novel PPARalpha targets were identified that were commonly regulated in both species, including CREB3L3, KLF10, KLF11 and MAP3K8.Conclusions/significanceOur results suggest that PPARalpha activation has a major impact on gene regulation in human hepatocytes. Importantly, the role of PPARalpha as master regulator of hepatic lipid metabolism is generally well-conserved between mouse and human. Overall, however, PPARalpha regulates a mostly divergent set of genes in mouse and human hepatocytes.

BACKGROUND:Excessive exposure to dietary fats is an important factor in the initiation of obesity and metabolic syndrome associated pathologies. The cellular processes associated with the onset and progression of diet-induced metabolic syndrome are insufficiently understood. PRINCIPAL FINDINGS:To identify the mechanisms underlying the pathological changes associated with short and long-term exposure to excess dietary fat, hepatic gene expression of ApoE3Leiden mice fed chow and two types of high-fat (HF) diets was monitored using microarrays during a 16-week period. A functional characterization of 1663 HF-responsive genes reveals perturbations in lipid, cholesterol and oxidative metabolism, immune and inflammatory responses and stress-related pathways. The major changes in gene expression take place during the early (day 3) and late (week 12) phases of HF feeding. This is also associated with characteristic opposite regulation of many HF-affected pathways between these two phases. The most prominent switch occurs in the expression of inflammatory/immune pathways (early activation, late repression) and lipogenic/adipogenic pathways (early repression, late activation). Transcriptional network analysis identifies NF-kappaB, NEMO, Akt, PPARgamma and SREBP1 as the key controllers of these processes and suggests that direct regulatory interactions between these factors may govern the transition from early (stressed, inflammatory) to late (pathological, steatotic) hepatic adaptation to HF feeding. This transition observed by hepatic gene expression analysis is confirmed by expression of inflammatory proteins in plasma and the late increase in hepatic triglyceride content. In addition, the genes most predictive of fat accumulation in liver during 16-week high-fat feeding period are uncovered by regression analysis of hepatic gene expression and triglyceride levels. CONCLUSIONS:The transition from an inflammatory to a steatotic transcriptional program, possibly driven by the reciprocal activation of NF-kappaB and PPARgamma regulators, emerges as the principal signature of the hepatic adaptation to excess dietary fat. These findings may be of essential interest for devising new strategies aiming to prevent the progression of high-fat diet induced pathologies.

BACKGROUND: The effect of dietary fats on human health and disease are likely mediated by changes in gene expression. Several transcription factors have been shown to respond to fatty acids, including SREBP-1c, NF-kappaB, RXRs, LXRs, FXR, HNF4alpha, and PPARs. However, it is unclear to what extent these transcription factors play a role in gene regulation by dietary fatty acids in vivo. METHODOLOGY/PRINCIPAL FINDINGS: Here, we take advantage of a unique experimental design using synthetic triglycerides composed of one single fatty acid in combination with gene expression profiling to examine the effects of various individual dietary fatty acids on hepatic gene expression in mice. We observed that the number of significantly changed genes and the fold-induction of genes increased with increasing fatty acid chain length and degree of unsaturation. Importantly, almost every single gene regulated by dietary unsaturated fatty acids remained unaltered in mice lacking PPARalpha. In addition, the majority of genes regulated by unsaturated fatty acids, especially docosahexaenoic acid, were also regulated by the specific PPARalpha agonist WY14643. Excellent agreement was found between the effects of unsaturated fatty acids on mouse liver versus cultured rat hepatoma cells. Interestingly, using Nuclear Receptor PamChip(R) Arrays, fatty acid- and WY14643-induced interactions between PPARalpha and coregulators were found to be highly similar, although several PPARalpha-coactivator interactions specific for WY14643 were identified. CONCLUSIONS/SIGNIFICANCE: We conclude that the effects of dietary unsaturated fatty acids on hepatic gene expression are almost entirely mediated by PPARalpha and mimic those of synthetic PPARalpha agonists in terms of regulation of target genes and molecular mechanism. Use of synthetic dietary triglycerides may provide a novel paradigm for nutrigenomics research.