Structural, chemical, and magnetic investigation of a graphene/cobalt/platinum multilayer system on silicon carbide

We investigate the magnetic interlayer coupling and domain structure of ultra-thin ferromagnetic (FM) cobalt (Co) layers embedded between a graphene (G) layer and a platinum (Pt) layer on a silicon carbide (SiC) substrate (G/Co/Pt on SiC). Experimentally, a combination of x-ray photoemission electron microscopy with x-ray magnetic circular dichroism has been carried out at the Co L-edge. Furthermore, structural and chemical properties of the system have been investigated using low energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS).In situLEED patterns revealed the crystalline structure of each layer within the system. Moreover, XPS confirmed the presence of quasi-freestanding graphene, the absence of cobalt silicide, and the appearance of two silicon carbide surface components due to Pt intercalation. Thus, the Pt-layer effectively functions as a diffusion barrier. The magnetic structure of the system was unaffected by the substrate's step structure. Furthermore, numerous vortices and anti-vortices were found in all samples, distributed all over the surfaces, indicating Dzyaloshinskii-Moriya interaction. Only regions with a locally increased Co-layer thickness showed no vortices. Moreover, unlike in similar systems, the magnetization was predominantly in-plane, so no perpendicular magnetic anisotropy was found.

MO161: Comparison of Therapeutic Plasma Exchange with Centrifugation and Filter Technique with a Focus on Efficacy, Safety, Platelet Loss and Patients' Comfort

BACKGROUND AND AIMS

Therapeutic plasma exchange (TPE) is an established therapy in the treatment of various immunologic kidney and neurological diseases. Humoral factors as antibodies, complement factors, cytokines and immune complexes, which all are assumed to play a role in demyelinating or inflammatory disorders as multiple sclerosis, can be eliminated. TPE has been implemented into therapeutic guidelines of a broad spectrum of neurological diseases [1–3]. Centrifugal (cTPE) and membrane-based (mTPE) are the methods of choice for TPE. Head to head studies comparing both methods are scarce and patients’ comfort has not yet been investigated [4–7].

Our aim was to compare cTPE (Spectra Optia™, TerumoBCT) with mTPE (multiFiltrate™, Fresenius Medical Care) with a focus not only on safety and efficacy parameters but also on patients’ comfort with the present monocentric, prospective and randomized crossover study. This is, to the best of our knowledge, the first study addressing patients’ comfort comparing both systems.

METHODS

The study was conducted as an open-label prospective trial with a cross-over design comparing cTPE using the Spectra Optia™ (Terumo BCT, Lakewood, CO, USA), and mTPE using the multiFiltrate™ with the plasmafilter plasmaFluxP2dry™ (Fresenius Medical Care, Bad Homburg, Germany). The first two treatments were performed within the study for each patient: one with the Spectra Optia and one with the multiFiltrate. Duration of set-up and priming of the devices, total procedure time, blood flow, total plasma volume exchanged, volume of the removal bag, volume of the anticoagulant and the type of vascular access were documented. Laboratory parameters such as IgG, IgA, IgM, fibrinogen, white blood cell, red blood count and thrombocytes were documented before and after treatment. Data from the first two treatments were documented. The differences of the parameters were compared using the Wilcoxon matched-pairs signed-rank or Mann-Whitney (U) test.

RESULTS

A total of 26 patients (17 women /9 mem) were included in the study and 52 treatments were documented. A median of 3000 mL of plasma was treated; the median duration of the procedure was 117 min (cTPE) versus 154 min (mTPE) (P = .03). Despite removal of fibrinogen (P = .04), no significant differences were found for the removal IgG (P = .09), IgM (P = .18) and IgA (P = .57). Both methods were equally effective. Erythrocyte loss was higher with mTPE (P = .003), platelet loss tended to be higher with mTPE, but without reaching a level of significance (P = .22; Table 1). The results of the patient questionnaire are shown in Figure 1.

CONCLUSION

Both procedures can be performed safely with comparable results regarding parameters of quality as fibrinogen, IgG, IgM and IgA with a trend to better elimination with cTPE. Comparing the duration of the procedure, cTPE was significantly superior to mTPE. An advantage regarding cell loss (RBC) was seen for cTPE, platelet loss tended to be higher with mTPA, but without statistical significance. Finally, as a result of shorter duration, patients’ comfort was significantly higher with cTPE.

Healthcare avoidance: a qualitative study of dental care avoidance in Germany in terms of emergent behaviours and characteristics

Background

The treatment of acute pain is part of everyday dental practice. Often, these symptoms result from years of patients' inadequate or missing dental routines and lead to a reduction in the quality of life or health of the patients and to high costs for the health care system. Despite the enormous advantages of modern dentistry, many patients avoid going to the dentist. Therefore, the study aimed to determine the reasons and behaviours that cause patients to avoid visits to the dentist.

Methods

We conducted semi-structured interviews with patients who had an above-average DMFT index and had been going to the dentist only irregularly for years. The sample participants were recruited from the northern German region of Mecklenburg-Western Pomerania. 20 individual interviews were recorded, transcribed verbatim and coded. We used a qualitative framework approach to code the transcripts in order to establish a consensus among the researchers. Ultimately, through discussions and reviews of the attributes and meaning of the topics, a typology could be established.

Results

A typology of patients who avoid the dentist was developed. Four independent characteristic patterns of dentist avoidance could be developed: avoiding the dentist due to "distance" (type A; includes subtype A1 "avoiding the dentist due to negligence" and subtype A2 "dental avoidance due to neutralization"), "disappointment" (type B), "shame" (type C), and "fear" (type D). Using the typology as a generalised tool to determine the minimum and maximum contrasts, it was possible to capture the diversity and multidimensionality of the reasons and behaviours for avoidance. All patients had negative dental experiences, which had led to different avoidance patterns and strategies.

Conclusions

The identified avoidance characteristics represent a spectrum of patients from Northern Germany who avoid going to the dentist. This is the first comprehensive study in Germany representing avoidance behaviour of dentist patients in the form of a typology. The results suggest that dentistry also needs qualitative research to better understand patient characteristics and provide direct access to patients who avoid regular dental visits. Thus, the results make a potentially fundamental contribution to the improvement of dental care and enrich its understanding.

Comparison of changes in albumin binding capacity during hemodiafiltration or hemodialysis with middle cut off membranes

BACKGROUND

Albumin is important for the transport of protein-bound substances (PBS). Albumin binding capacity (ABiC) is reduced in dialysis patients. This can contribute to worsening of uremic symptoms. It is presumed that open-porous middle cut off filters that is, HDx (Baxter-Theranova) remove high molecular substances more efficiently than conventional treatment. To evaluate HDx for the improvement of ABiC and removal of PBS, HDx was compared to hemodiafiltration (Fresenius-FX80, HDF).

METHODS

We included 32 chronic patients on HDF. After inclusion patients were treated with HDx for 14 days. Blood samples were drawn before/after treatments at study entry, first HDx and sixth HDx, to determine ABiC and other study parameters.

RESULTS

ABiC improved in HDx (68.4% vs 72.4%) and HDF (69.9% vs 72.4%) without differences between both therapies. No reduction of albumin concentration during HDx treatment was observed.

CONCLUSION

HDx is accepted as a safe and equally efficient therapy for removing albumin bound uremic toxins compared to HDF with high flux dialyzers.

Development of Robust 17(R),18(S)-Epoxyeicosatetraenoic Acid (17,18-EEQ) Analogues as Potential Clinical Antiarrhythmic Agents

17(R),18(S)-Epoxyeicosatetraenoic acid (EEQ) is a cytochrome P450 metabolite of eicosapentaenoic acid (EPA) and a powerful negative chronotrope with low nanomolar activity in a neonatal rat cardiomyocyte (NRCM) arrhythmia model. Prior studies identified oxamide 2b as a soluble epoxide hydrolase (sEH) stable replacement but unsuitable for in vivo applications due to limited oral bioavailability and metabolic stability. These ADME limitations have been addressed in an improved generation of negative chronotropes, e.g., 4 and 16, which were evaluated as potential clinical candidates.

Structural, chemical, and magnetic properties of cobalt intercalated graphene on silicon carbide

We report on a study of the Co intercalation process underneath the [Formula: see text] R30° reconstructed 6H-SiC(0001) surface for Co film-thicknesses in a range of 0.4-12 nm using a combination of surface sensitive imaging, diffractive, and spectroscopic methods. In situ photoemission electron microscopy reveals a dependence of the intercalation temperature on the Co film-thickness. Using low energy electron diffraction and photoemission spectroscopy (XPS), we find that the SiC surface reconstruction is partially lifted and transformed. We show that the [Formula: see text] R30° reconstruction does not prevent silicide formation for Co film-thicknesses  ≥0.4 nm according to XPS and x-ray absorption spectra. Our results indicate that the silicide formation is self-limited to a thin interface region and is followed by Co intercalation between graphene and silicide. Furthermore, we analyze the magnetic properties using x-ray magnetic circular dichroism at the Co L-edge. In-plane magnetization is observed for all analyzed film-thicknesses. For ultra-thin Co films, self-assembled magnetic wires with a width of the order of 100 nm form at the step-edges.

Is the Rise in the Prevalence of Renal Replacement Therapy at Older Ages the Price for Living Longer?

Background

Renal replacement therapy (RRT) is one of the most expensive in renal medicine. Cross-sectional studies suggest that life expectancy increases in the general population are associated with a higher burden of RRT. This study tests this hypothesis in a prospective setting among people aged 75+ living in Western Europe.

Methods

We gathered sex-specific data for 11 Western European countries in 2005-2014. RRT prevalence on country level was extracted from the ERA-EDTA registry, while data on population size and life expectancy for the 75+ age group came from the Eurostat database. GDP per capita was extracted from the OECD database. To measure the association between RRT prevalence and life expectancy, we performed Poisson regression models separately for each country and for all countries combined. To adjust for confounding, GDP per capita as well as time and country-fixed effects were included.

Results

Our analysis revealed that living longer coincides with rising RRT prevalence at ages 75+ in Western Europe between 2005 and 2014. On average, a 1-year increase in life expectancy was associated with a roughly 20% increase in RRT prevalence [(95% CI) 21-23% in men and 19-22% in women]. However, after adjustments for confounding were made, the association became insignificant among women and became weaker among men, falling to a level of 11% [(95% CI) 6-17%].

Conclusion

Living longer was not necessarily associated with a higher burden of RRT in Western European countries.

On the present State of our Knowledge regarding General Paralysis of the Insane

Medical Psychologists have long been familiar with a peculiar form of disease which is characterised by a combination of disorders of the intellectual and motor faculties. The French physicians, to whom is due the honour of having first minutely described it, have given to it various names, according to the views then generally held and the special opinions of the individual observers: General incomplete paralysis (Delaye); general paralysis of the insane (Calmeil); general progressive paralysis (Requin, Sandras); paralytic insanity (Parchappe), &c. In Germany the terms general paralysis, paralysis of the insane, and most recently paralytic dementia have been generally employed. Familiar though this disease has become to medical psychologists, and though much discussion has taken place regarding it, within a narrow sphere, still slight has been the interest hitherto taken in extending that sphere. These poor patients, whose treatment either cannot or can only with great difficulty be pursued in the ordinary relations of life, who from henceforth appear hopeless, are gladly handed over to physicians to the insane, and with the entrance of the patient into the asylum all interest in the disease ceases. The time is, I believe, at hand when in regard to this, as well as to many other matters, the veil of the asylum will be removed, when once for all the barriers will be thrown down which divide mental pathology, as we must still call it, from that of the remainder of the nervous system. Each has a series of facts to oppose to the other, and it is certainly surprising how many points of connection there are between them. The question is merely one of comprehension: mental pathology often manifests itself in a manner which outwardly is not easily understood, though it must be admitted sufficient pains have not always been taken to understand these manifestations.

Healthy Migrants? Health Selection of Internal Migrants in Germany

In Germany, internal migration streams have shaped the population structure quite notably during the past two decades. As selective migration can have a substantial impact on the geographical distribution of health, this paper examines whether internal migrants in Germany are selected regarding their health status. To capture health selection, one measure-i.e. self-rated contentment with health-and two established risk factors for poor health-i.e. smoking and BMI-were included. Applying event history analysis, the health status of migrants was compared to non-migrants, controlling for other individual characteristics. The analyses were based on the German Socio-Economic Panel, a retrospective data set representative of the German population. Results for self-rated health and smoking were inconclusive. While self-rated health was only related to migration in men, smoking was only linked to migration in women. However, there was a clear association between BMI and migration, i.e. the propensity to migrate decreased significantly with increasing weight. The results suggest that BMI is an important indicator of increased susceptibility to ill health, which prevent people from migration. Leaving behind a population who has a greater susceptibility to chronic conditions, selective migration is likely to reinforce the consequences of population ageing and healthcare demand, in particular in regions characterized by outmigration.

Reduction of apoptosis and preservation of mitochondrial integrity under ischemia/reperfusion injury is mediated by estrogen receptor β

Background

Estrogen improves cardiac recovery after ischemia/reperfusion (I/R) by yet incompletely understood mechanisms. Mitochondria play a crucial role in I/R injury through cytochrome c-dependent apoptosis activation. We tested the hypothesis that 17β-estradiol (E2) as well as a specific ERβ agonist improve cardiac recovery through estrogen receptor (ER)β-mediated mechanisms by reducing mitochondria-induced apoptosis and preserving mitochondrial integrity.

Methods

We randomized ovariectomized C57BL/6N mice 24h before I/R to pre-treatment with E2 or a specific ERβ agonist (ERβA). Isolated hearts were perfused for 20min prior to 30min global ischemia followed by 40min reperfusion.

Results

Compared with controls, ERβA and E2 treated groups showed a significant improvement in cardiac recovery, i.e. an increase in left ventricular developed pressure, dP/dtmax and dP/dtmin. ERβA and E2 pre-treatment led to a significant reduction in apoptosis with decreased cytochrome c release from the mitochondria and increased mitochondrial levels of anti-apoptotic Bcl2 and ACAA2. Protein levels of mitochondrial translocase inner membrane (TIM23) and mitochondrial complex I of respiratory chain were increased by ERβA and E2 pre-treatment. Furthermore, we found a significant increase of myosin light chain 2 (MLC2) phosphorylation together with ERK1/2 activation in E2, but not in ERβA treated groups.

Conclusions

Activation of ERβ is essential for the improvement of cardiac recovery after I/R through the inhibition of apoptosis and preservation of mitochondrial integrity and can be a achieved by a specific ERβ agonist. Furthermore, E2 modulates MLC2 activation after I/R independent of ERβ.

Electronic supplementary material

The online version of this article (doi:10.1186/s13293-016-0104-8) contains supplementary material, which is available to authorized users.

Abstract 89: 17beta-Estradiol-activated Estrogen Receptors Attenuate Cardiac Fibrosis Through Inhibition of Collagen I and III Expression in Female Hearts

Objectives: Female pressure-overloaded hearts show less fibrosis compared with males. 17β-Estradiol (E2) attenuates cardiac fibrosis in female mice. Whether this is mediated by direct E2-effects on collagen synthesis is still unknown. Therefore, we investigated the role of E2 and estrogen receptors (ER) on collagen I and III expression and analyzed involved mechanisms.

Methods: Female C57BL/6J mice (7 weeks) underwent sham operation, ovariectomy (OVX), OVX with E2-supplementation (390mg E2-containing pellets) or placebo. After 2 weeks, animals underwent transverse aortic constriction (TAC) or sham surgery. Mice were sacrificed after 9 weeks. Collagen amount, collagen I and III protein in left ventricular tissue were detected by Sirius Red and antibody staining, respectively. Gene and protein expression were determined by quantitative Real-Time PCR and Western blot. Adult female rat cardiac fibroblasts were treated with E2 (10 -8 M), vehicle, ERα- and β-agonists (10 -7 M) for 24h or pre-treated with PD98059 for 1h. ER binding to the collagen I and III promoter was analyzed by chromatin immunoprecipitation assays.

Findings: In female OVX mice, undergoing TAC surgery, E2-supplementation significantly reduced collagen deposition, collagen I and III mRNA and protein levels in comparison with mice without E2. In female rat cardiac fibroblasts, E2 significantly down-regulated collagen I and III mRNA and protein level. Specific ER-agonist-treatment showed that E2-mediated regulation of collagen I and III expression was mediated via activation of ERα, but not ERβ. Further, upon E2-treatment, ERα was phosphorylated at Ser118, which occurred by E2-induced activation of ERK1/2 signaling. Furthermore, we could show that ERα and ERβ bind to two putative half-palindromic estrogen response elements within the collagen I and III promoter in female cardiac fibroblasts.

Conclusion: E2 inhibits cardiac collagen I and III mRNA and protein in female mice under pressure overload. Data from rat female cardiac fibroblasts suggest that this is mediated via E2-activated ERK1/2 signaling and ERα, which binds with ERβ to the collagen I and III promoter. Understanding of how E2/ER attenuate collagen I and III expression in pathological hypertrophy may improve therapy.

Cytochrome p450 enzymes in the bioactivation of polyunsaturated Fatty acids and their role in cardiovascular disease

Various members of the cytochrome P450 (CYP) superfamily have the capacity of metabolizing omega-6 and omega-3 polyunsaturated fatty acids (n-6 and n-3 PUFAs). In most mammalian tissues, CYP2C and CYP2J enzymes are the major PUFA epoxygenases, whereas CYP4A and CYP4F subfamily members function as PUFA hydroxylases. The individual CYP enzymes differ in their substrate specificities as well as regio- and stereoselectivities and thus produce distinct sets of epoxy and/or hydroxy metabolites, collectively termed CYP eicosanoids. Nutrition has a major impact on the endogenous CYP-eicosanoid profile. "Western diets" rich in n-6 PUFAs result in a predominance of arachidonic acid-derived metabolites, whereas marine foodstuffs rich in n-3 PUFAs shift the profile to eicosapentaenoic and docosahexaenoic acid-derived metabolites. In general, CYP eicosanoids are formed as second messengers of numerous hormones, growth factors and cytokines regulating cardiovascular and renal function, and a variety of other physiological processes. Imbalances in the formation of individual CYP eicosanoids are linked to the development of hypertension, myocardial infarction, maladaptive cardiac hypertrophy, acute kidney injury, stroke and inflammatory disorders. The underlying mechanisms are increasingly understood and may provide novel targets for the prevention and treatment of these disease states. Suitable pharmacological agents are under development and first proofs of concept have been obtained in animal models.

Projections of trends in overweight in the elderly population in Germany until 2030 and international comparison

BACKGROUND/AIMS

To project the numbers of pre-obese (BMI 25-29.99 kg/m²) and obese (BMI > 30 kg/m²) men and women aged 50+ in Germany until 2030 and to compare our estimates with actual figures from four European countries and the USA. Estimates are based on six scenarios encompassing improvements as well as worsenings of current trends.

METHODS

We used pooled data from 1999 to 2009 of the German Microcensus (n = 1,472,547). Using multinomial logistic regression models we estimated age-specific probabilities of pre-obesity and obesity and applied them to the 12th population projection of the Federal Statistical Office.

RESULTS

We project overall increases in absolute numbers of pre-obesity ranging between 14.2 and 18.2 million. However, the prevalence of pre-obesity is likely to decrease slightly. In contrast, absolute and relative numbers of obesity are projected to increase, ranging between 7.2 and 15.8 million. The international comparison revealed that pre-obesity prevalences will remain among the highest in Germany, while obesity is projected to fall below current levels of the UK or the USA.

CONCLUSION

Pre-obesity and, particularly, obesity are likely to become a more prominent health issue in Germany in the near future which could have large repercussions for the public health system.

Sex- and estrogen-dependent regulation of a miRNA network in the healthy and hypertrophied heart

BACKGROUND

In pressure overload, profibrotic gene expression and cardiac fibrosis are more pronounced in males than in females. Sex-specific and estrogen-dependent regulation of microRNAs (miRNAs), such as miR-21, may be a potential mechanism leading to sex differences in fibrosis.

OBJECTIVES

To analyze the influence of sex, estrogen, and estrogen receptor beta (ERβ) on the expression of miR-21 and to identify additional miRNAs potentially involved in sex-specific pressure overload-induced cardiac remodeling.

METHODS

The sex-specific regulation of fibrosis-related miRNAs was analyzed in male and female wild type and ERβ-deficient mice after transverse aortic constriction (TAC), in rat fibroblasts, and in a cardiomyocyte-like cell line.

RESULTS

We report the sex-specific expression of functionally-related miR-21, -24, -27a, -27b, 106a, -106b and the regulation of their expression by estrogen in a sex-specific manner. These effects were abolished in ERβ-deficient mice. We demonstrate the presence of common functional target sites for these miRNAs on three repressors of the mitogen-activated protein kinase signaling pathway, i.e. Rasa1, Rasa2 and Spry1, which may all lead to cardiac fibrosis. As expected, transfection with miRNA mimics targeting these repressors induced ERK1/2 phosphorylation.

CONCLUSIONS

Estrogen regulates a network of miRNAs in a sex-specific manner via ERβ. Our data suggest that the sex-specific expression of these miRNAs may be related to sex differences in fibrosis after pressure overload.

CYP2J2 overexpression protects against arrhythmia susceptibility in cardiac hypertrophy

Maladaptive cardiac hypertrophy predisposes one to arrhythmia and sudden death. Cytochrome P450 (CYP)-derived epoxyeicosatrienoic acids (EETs) promote anti-inflammatory and antiapoptotic mechanisms, and are involved in the regulation of cardiac Ca(2+)-, K(+)- and Na(+)-channels. To test the hypothesis that enhanced cardiac EET biosynthesis counteracts hypertrophy-induced electrical remodeling, male transgenic mice with cardiomyocyte-specific overexpression of the human epoxygenase CYP2J2 (CYP2J2-TG) and wildtype littermates (WT) were subjected to chronic pressure overload (transverse aortic constriction, TAC) or β-adrenergic stimulation (isoproterenol infusion, ISO). TAC caused progressive mortality that was higher in WT (42% over 8 weeks after TAC), compared to CYP2J2-TG mice (6%). In vivo electrophysiological studies, 4 weeks after TAC, revealed high ventricular tachyarrhythmia inducibility in WT (47% of the stimulation protocols), but not in CYP2J2-TG mice (0%). CYP2J2 overexpression also enhanced ventricular refractoriness and protected against TAC-induced QRS prolongation and delocalization of left ventricular connexin-43. ISO for 14 days induced high vulnerability for atrial fibrillation in WT mice (54%) that was reduced in CYP-TG mice (17%). CYP2J2 overexpression also protected against ISO-induced reduction of atrial refractoriness and development of atrial fibrosis. In contrast to these profound effects on electrical remodeling, CYP2J2 overexpression only moderately reduced TAC-induced cardiac hypertrophy and did not affect the hypertrophic response to β-adrenergic stimulation. These results demonstrate that enhanced cardiac EET biosynthesis protects against electrical remodeling, ventricular tachyarrhythmia, and atrial fibrillation susceptibility during maladaptive cardiac hypertrophy.

Effects of estrogen, an ERα agonist and raloxifene on pressure overload induced cardiac hypertrophy

The aim of this study was to investigate the effects of 17β-estradiol (E2), the selective ERα agonist 16α-LE2, and the selective estrogen receptor modulator (SERM) raloxifene on remodeling processes during the development of myocardial hypertrophy (MH) in a mouse model of pressure overload. Myocardial hypertrophy in ovariectomized female C57Bl/6J mice was induced by transverse aortic constriction (TAC). Two weeks after TAC, placebo treated mice developed left ventricular hypertrophy and mild systolic dysfunction. Estrogen treatment, but not 16α-LE2 or raloxifene reduced TAC induced MH compared to placebo. E2, 16α-LE2 and raloxifene supported maintenance of cardiac function in comparison with placebo. Nine weeks after induction of pressure overload, MH was present in all TAC groups, most pronounced in the raloxifene treated group. Ejection fraction (EF) was decreased in all animals. However, 16α-LE2 treated animals showed a smaller reduction of EF than animals treated with placebo. E2 and 16α-LE2, but not raloxifene diminished the development of fibrosis and reduced the TGFβ and CTGF gene expression. Treatment with E2 or 16α-LE2 but not with raloxifene reduced survival rate after TAC significantly in comparison with placebo treatment. In conclusion, E2 and 16α-LE2 slowed down the progression of MH and reduced systolic dysfunction after nine weeks of pressure overload. Raloxifene did not reduce MH but improved cardiac function two weeks after TAC. However, raloxifene was not able to maintain EF in the long term period.

Abstract 607: Antiarrhythmic Effects Of Omega-3 Fatty Acids And Cyp-eicosanoids In A Murine Atrial Fibrillation Model

Atrial fibrillation (AF) is the most common arrhythmia in man. Small animal models of AF are rare, limiting the opportunities of mechanistic studies and of evaluating novel treatment strategies. We found that mice can be rendered susceptible to AF by chronic ß-adrenergic stimulation and used this model to test the hypothesis that dietary n-3 polyunsaturated fatty acids (n-3 PUFAs) and endogenously produced cytochrome P450 (CYP)-dependent epoxyeicosanoids protect against AF. Our study included male wild type C57BL/6 mice given either normal chow (WT-n6-group) or a diet supplemented with n-3 PUFAs (2.5% EPA/DHA added to normal chow; WT-n3-group), as well as transgenic littermates with cardiomyocyte-specific overexpression of the human epoxygenase CYP2J2 (CYP-n6 group). All animal groups received 40mg/kg/d of isoproterenol (ISO) or vehicle over 14 days via osmotic mini-pumps. AF induction was tested in vivo by programmed electrical stimulation (PES) and reached 48% (13 of 27 protocols) in ISO-treated WT-n6, compared to 9% (2 of 22) in the vehicle group. ISO-treated WT-n6 mice also featured increased atrial fibrosis, decreased atrial connexin-40 expression, and significantly reduced atrial refractoriness (AERP: 13.1±0.5 vs. 21.7±0.9 ms in vehicle-infused controls). Ventricular refractoriness remained unchanged and ventricular arrhythmias were not inducible. EPA/DHA-supplementation as well as CYP2J2 overexpression significantly reduced ISO-stimulated AF inducibility to 17% (5 of 30 in WT-n3, and 4 of 24 in CYP-n6), decreased atrial fibrosis, and partially prevented connexin-40 down-regulation and AERP reduction (16,1±0,9 in WT-n3 and 17.5±0.5 ms in CYP-n6). Finally, we tested the antiarrhythmic potential of a synthetic analog of 17,18-epoxyeicosatetraenoic acid (17,18-EEQ), an EPA metabolite predominantly produced by CYP2J2 and other epoxygenases. Acute i.v. injection of the 17,18-EEQ compound decreased AF inducibility in ISO-stimulated WT-n6 mice from 67% (14 of 21 in vehicle control) to 33% (10 of 30) and also the mean duration of AF episodes. These results show that ISO-infusion allows establishing a suitable mouse model of AF and indicate an important role of CYP-dependent n-3 PUFA metabolites in preventing AF.

Abstract 631: Cardiomyocyte-specific Cyp4a12a Overexpression Aggravates Maladaptive Cardiac Hypertrophy

Alterations in cytochrome P450 (CYP)-dependent formation of 20-hydroxyeicosatetraenoic acid (20-HETE) are associated with hypertension and end-organ damage. The cause-and-effect relationships are only partially understood and difficult to dissect due to the multiple and partially opposing roles of 20-HETE in different tissues. We established a Cre/loxP-system for tissue-specific overexpression of Cyp4a12a, a murine 20-HETE producing isoform. We used this system to test the hypothesis that enhanced formation of 20-HETE plays a detrimental role in cardiac hypertrophy. Floxed Cyp4a12a mice were crossed with alpha-MHC-Cre mice to generate animals with cardiomyocyte-specific Cyp4a12a overexpression (CYP) and wildtype littermates (WT). RT-PCR and immunohistochemistry confirmed Cyp4a12a overexpression in CYP compared to WT hearts. The animals (n=10-12 per group) were subjected to transverse aortic constriction (TAC). Eight weeks after TAC, the left ventricular mass-to-tibia length ratio (mg/mm) increased to 14.6±2.3 in male WT and to 12.6±2.3 in male CYP mice. Hypertrophy was lower in WT females (11.2±1.4) but not in CYP females (12.3±2.1), compared to their male counterparts. ANP and βMHC expression levels were higher in CYP than WT mice (2.6- and 2.2-fold in males, and 1.9- and 1.8-fold in females). The ejection fraction (%) was more severely impaired in the CYP than WT groups (male WT: 22.3±4.7 vs. CYP: 9.5±3.4; female WT: 21.8±11.7 vs. CYP: 15.5±4.8). Cyp4a12a overexpression also worsened TAC-induced end-diastolic posterior wall thinning (male WT: 1.05±0.17 vs. CYP: 0.80±0.12; female WT: 0.93±0.12 vs. CYP: 0.85±0.11mm), and dilation (male WT: 5.21±0.53 vs. TG: 5.83±0.53; female WT: 4.82±0.56 vs. CYP: 5.39±0.43mm). Moreover, the interventricular septal thickness was clearly reduced in male CYP compared to WT hearts after TAC. The lung weight was markedly higher in male CYP than WT mice (WT: 201.4±90.9 vs. CYP: 485.3±50.7 mg), but not different in female groups. These results demonstrate that cardiomyocyte-specific overexpression of Cyp4a12a/20-HETE aggravates pressure overload-induced maladaptive hypertrophy and promotes the development of dilated cardiomyopathy. The effects were more pronounced in males compared to females.

CYP-eicosanoids--a new link between omega-3 fatty acids and cardiac disease?

Fish oil omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) protect against arrhythmia and sudden cardiac death by largely unknown mechanisms. Recent in vitro and in vivo studies demonstrate that arachidonic acid (AA) metabolizing cytochrome P450-(CYP) enzymes accept EPA and DHA as efficient alternative substrates. Dietary EPA/DHA supplementation causes a profound shift of the cardiac CYP-eicosanoid profile from AA- to EPA- and DHA-derived epoxy- and hydroxy-metabolites. CYP2J2 and other CYP epoxygenases preferentially epoxidize the ω-3 double bond of EPA and DHA. The corresponding metabolites, 17,18-epoxy-EPA and 19,20-epoxy-DHA, dominate the CYP-eicosanoid profile of the rat heart after EPA/DHA supplementation. The (ω-3)-epoxyeicosanoids show highly potent antiarrhythmic properties in neonatal cardiomyocytes, suggesting that these metabolites may specifically contribute to the cardioprotective effects of omega-3 fatty acids. This hypothesis is discussed in the context of recent findings that revealed CYP-eicosanoid mediated mechanisms in cardiac ischemia-reperfusion injury and maladaptive cardiac hypertrophy.

Establishment of a cross-European field site network in the ALARM project for assessing large-scale changes in biodiversity

The field site network (FSN) plays a central role in conducting joint research within all Assessing Large-scale Risks for biodiversity with tested Methods (ALARM) modules and provides a mechanism for integrating research on different topics in ALARM on the same site for measuring multiple impacts on biodiversity. The network covers most European climates and biogeographic regions, from Mediterranean through central European and boreal to subarctic. The project links databases with the European-wide field site network FSN, including geographic information system (GIS)-based information to characterise the test location for ALARM researchers for joint on-site research. Maps are provided in a standardised way and merged with other site-specific information. The application of GIS for these field sites and the information management promotes the use of the FSN for research and to disseminate the results. We conclude that ALARM FSN sites together with other research sites in Europe jointly could be used as a future backbone for research proposals.

The mammalian mid-pachytene checkpoint: meiotic arrest in spermatocytes with a mutation in Atm alone or in combination with a Trp53 (p53) or Cdkn1a (p21/cip1) mutation

ATM, the protein product of the gene mutated in the human autosomal recessive disorder ataxia telangiectasia, is involved in detection of double strand breaks (DSBs) and is a key component of the damage surveillance network of cell cycle proteins. In somatic cells ATM phosphorylates many other proteins including p53, an important regulator of cell cycle control. Mice deficient for Atm are male sterile with arrest and apoptosis occurring at testis epithelial stage IV, which in normal spermatocytes corresponds to mid-pachynema. Unlike the situation in somatic cells, we find no evidence that disruption of the Trp53 (p53) gene, or its down-stream target Cdkn1a (p21/Cip1) results in even a partial rescue of the Atm defect.

Structural analysis of the SiO2/Si100 interface by means of photoelectron diffraction

The local environment of Si atoms at the interface between a thermally grown SiO2 film and Si(100) was studied by angle-scanned photoelectron diffraction. Experimental photoelectron diffraction patterns for each Si oxidation state were obtained from the results of least squares fitting on Si 2p core-level spectra. A comparison of the diffraction patterns with multiple-scattering calculations including an R-factor analysis was performed. An excellent agreement between experimental and simulated data was achieved within the proposed bridge-bonded interface model [Phys. Rev. Lett. 84, 4393 (2000)]].

Local atomic environment of Si suboxides at the SiO2/Si(111) interface determined by angle-scanned photoelectron diffraction

Local environments of Si suboxides at the interface between a thermally grown SiO2 film and Si(111) were studied by angle-scanned photoelectron diffraction. Si 2p core-level spectra containing chemically shifted components were recorded. The components were deconvoluted by least squares fitting and assigned to different Si oxidation states. The obtained diffraction patterns of the various suboxides exhibit different features. Comparison of these patterns with multiple scattering calculations including a multipole R-factor analysis shows that a simple chemical abrupt interface model describes well the environment of the suboxides and indicates ordered SiO2 close to the interface.

Characterization of a novel plasmid-encoded HsdS subunit, S.LlaW12I, from Lactococcus lactis W12

A novel type I restriction-modification specificity subunit, S. LlaW12I, has been identified on the naturally occurring 8.0-kb plasmid pAW122 in the lactic acid bacterium Lactococcus lactis subsp. cremoris W12. Presence of the HsdS protein together with a complete type I restriction-modification system conferred increased phage restriction to the host, indicating exchange of specificity subunits. Sequence analysis showed that the S.LlaW12I subunit is most probably of type IC. Presumably, the hsdS gene is organized together with the repB gene on one transcriptional unit.

Newly found selenium-containing proteins in the tissues of the rat

The Se-containing proteins in 27 tissues of the rat were investigated by in vivo labeling with 75Se-selenite, separation of the tissue homogenate proteins by SDS-polyacrylamide gel electrophoresis, and determination of the labeled proteins by autoradiography. By using Se-depleted rats and a 75Se-tracer with a high specific activity, Se compounds present at only very low concentrations could be detected. Besides the 13 Se-containing proteins previously described, for which apparent molecular masses of 12, 15, 18, 20, 22, 25, 28, 34, 56, 60, 65, 70, and 75 kD have been found here, a further 15 75Se-labeled bands, with apparent molecular masses of 8, 10, 15.5, 16.5, 24, 32, 34.5, 38, 40, 41, 44, 45, 46.5, 53 and 116 kD could be distinguished. Two-dimensional separation of the kidney homogenate proteins showed that some of the Se-containing bands could be resolved into several labeled spots. Most of the newly found compounds were present in various tissues, but with some the enrichment in certain tissues suggested specific sites of action.

Studies on the distribution and characteristics of new mammalian selenium-containing proteins

It has now been established that the essential effects of selenium in mammals are owing to the presence of several biologically active selenium compounds. Seleno-enzymes identified so far include several glutathione peroxidases and the type 1 iodothyronine de-iodinase. Some other selenoproteins have been sequenced and characterized. After in vivo labelling of rats with 75Se and protein separation using gel electrophoretic methods, more than 25 selenium-containing proteins or protein sub-units were detected. Some of the results of the investigations on these compounds are summarized and discussed here. By determining the pattern in a large number of tissues information on the distribution of the selenium-containing proteins was obtained. Their biological significance is not yet known but several findings indicate that some of these proteins may have important functions, especially in the brain and the endocrine and reproductive organs. More detailed information is already available on a 34 kDa-protein found in the testis and spermatozoa. Studies on the effects of dosage and chemical form of dietary selenium indicated that the tissue levels of the seleno-enzymes are homeostatically controlled and cannot be increased by additional supply. The increase in the tissue selenium observed with high selenium intake was found to be mainly caused by the non-specific incorporation of the element into a large number or proteins. The formation of most of the other selenium-containing proteins has priority over that of the cytosolic and plasma glutathione peroxidases. Thus the selenium requirement, which was calculated for optimum plasma glutathione peroxidase activity, also covers the amounts needed for normal levels of the other biologically important selenium compounds.

Application of nuclear analytical methods in the investigation and identification of new selenoproteins

Nuclear methods have been applied in the investigation of selenium-containing proteins in rat tissues. Selenium was determined in tissues, cells, and cellular compartments by instrumental neutron activation analysis via 77mSe or 75Se. For tracer studies, the selenium compounds were labeled in vivo by administering 75Se with a high specific activity to rats. Quantitative determination of very small amounts of the element in protein fractions was achieved by measurement of the tracer after replenishment of selenium-depleted animals with the labeled element. The application of the nuclear methods in the detection, characterization, and identification of new selenium-containing proteins is shown with the help of some examples.

Integrin VLA-3: ultrastructural localization at cell-cell contact sites of human cell cultures

The integrin VLA-3 is a cell surface receptor, which binds to fibronectin, laminin, collagen type I and VI (Takada, Y., E. A. Wayner, W. G. Carter, and M. E. Hemler. 1988. J. Cell. Biochem. 37:385-393) and is highly expressed in substrate adherent cultures of almost all human cell types. The ligand specificity of VLA-3 and the inhibition of cell adhesion by anti-VLA-3 monoclonal antibodies suggest its involvement in cell-substrate interaction. In normal tissues, VLA-3 is restricted to few cell types, notably the kidney glomeruli and basal cells of the epidermis. In the epidermis, VLA-3 is generally strongly expressed on the entire plasma membrane of basal cells and is not polarized towards the basement membrane (Klein, C. E., C. Cardon-Cardo, R. Soehnchen, R. J. Cote, H. F. Oettgen, M. Eisinger, and L. J. Old. 1987. J. Invest. Dermatol. 89:500-507). Based on this finding we speculated that, in addition to a role of VLA-3 for adhesion of cells to substrate, it could also be relevant for cell-cell interaction. To investigate this, we ultrastructurally localized VLA-3 on the surface of cultured cells by immunoelectron microscopy. In accordance with our concept, we found VLA-3 strongly associated with intercellular contact sites. Interestingly, very little immunoreactivity was detected at the under-surface of cells which had been cultured for 18-32 h. This observation was unexpected but is consistent with previous findings (Kantor, R. R. S., M. J. Mattes, K. D. Lloyd, L. J. Old, and A. P. Albino. 1987. J. Biol. Chem. 262:15158-15165) which suggest that the association of VLA-3 with the basal surface of substrate adherent tumor cells is a late event occurring after days of culture under confluent conditions. However, we cannot formally rule out VLA-3 expression at the undersurface of cells under our experimental conditions, since VLA-3 molecules at this location could be inaccessible for in situ labeling of unfixed cells because of spatial interferences. In conclusion, our results demonstrate the expression of VLA-3 at intercellular contact sites of cultured cells supporting the concept that it may be relevant for intercellular interactions also.

Melamine resins and their application in electron microscopy

Melamine resins are derived from the heterocyclic compound triaminotriazine, C3H6N6. Similar to proteins in structure and reactivity, water-soluble melamine resins can be used as water-embedding media for electron microscopy (Bachhuber and Frösch, 1983). The idea behind this approach was to study some of the artefacts of traditional embedding techniques and to work out conditions to eliminate as far as possible denaturing of proteins and extraction of lipids. Sectioned cells and tissues processed in the melamine resin Nanoplast show remarkable preservation of ultrastructure. Because they can be sectioned extremely thinly, melamine resins are particularly suitable for dark-field and electron spectroscopic imaging of unstained molecular suspensions providing in this way an unusually clear reproduction of ultrastructural detail such as the helical structure of isolated unstained double-strand DNA molecules (Frösch et al., 1987b). In 1988, the melamine resin Nanostrat was introduced as an EM-compatible prolific substrate foil for cell culture (Westphal et al., 1988). Cells or bacteria cultivated on this material can be processed for various kinds of follow-up techniques like TEM, SEM, vertical sectioning and immunocytochemistry.

A new method for cell culture on an electron-transparent melamine foil suitable for successive LM, TEM and SEM studies of whole cells

A new cell culture technique is described which is based on the observation that foils cast from the melamine resin hexamethylol-melamine-ether are suitable for the cultivation of beating heart muscle cells and fibroblasts of the rat. This foil can be flamed for sterilization, is about 80 nm in thickness, homogeneous and smooth, withstands dehydration and critical point-drying, can be removed from glass and permits the imaging of whole cells successively by light microscopy, transmission and scanning electron microscopy. The method is capable of narrowing the gap between light and electron microscopy, yielding excellent whole cell preparations in various kinds of microscopic studies to be performed on one and the same cell.