The Role of Repin1 in Adipose Tissue

Since 1980 worldwide obesity has doubled in incidence to 52 % of people being overweight or obese. Obesity causes various comorbidities such as cardiovascular diseases, type II diabetes, dyslipidemia and several cancer types, making it one of the biggest challenges in worldwide health care systems. It is well known that obesity is highly heritable by either monogenetic causes or multifactorial interactions of different genes that superimpose on environmental factors and behavior. To answer questions in understanding mechanisms of obesity and/or associated metabolic pathways, mouse models have been a powerful tool. Several approaches in characterizing genes involved in obesity development through mouse engineering have been implemented, with the Cre/loxP system emerging as one of the most informative and widespread techniques. Using this approach, promoter-dependent temporal and tissue-specific regulated recombination can be achieved by Tamoxifen administration. To investigate effects of Tamoxifen on adipocyte biology in vivo, we characterized 12 weeks old male C57BL/6NTac mice after Tamoxifen treatment. We found that Tamoxifen treatment caused transient body composition changes, increased HbA1c, triglyceride and free fatty acid serum concentrations as well as smaller adipocytes in combination with browning of subcutaneous adipose tissue. Therefore, we suggest considering these effects when using Tamoxifen as a tool to induce conditional transgenic mouse models and to treat control mice in parallel. Another methodology used to identify genes involved in obesity related traits is QTL mapping in combination with congenic and subcongenic strains of mice or rats. One candidate gene that was previously identified on rat chromosome 4 is replication initiator 1 (Repin1 ). This gene was first described as a 60 kDa zinc finger protein involved in replication activation of the Chinese hamster dihydrofolate reductase (dhfr ) gene. Moreover, a triplet repeat (TTT) in the 3’UTR is associated with facets of the metabolic syndrome, including body weight, serum insulin, cholesterol and triglyceride levels. In vitro studies in 3T3-L1 cells revealed that Repin1 regulates adipocyte size, glucose transport and lipid metabolism. In this thesis functional analyses of Repin1 were performed using different Repin1 deficient mouse models. In the first study we generated a whole body Repin1 deficient db/db double knockout mouse (Rep1−/−x db/db) and systematically characterized the consequences of Repin1 deficiency. Our study provided evidence that loss of Repin1 in db/db mice improves insulin sensitivity and reduces chronic hyperglycemia most likely by reducing fat mass and adipose tissue inflammation. We next generated a liver-specific Repin1 knockout mouse (LRep1−/−) and could show that loss of Repin1 in liver leads to reduced body weight gain in combination with lower fat mass. Liver specific Repin1 deficient mice also show lower triglyceride content in the liver, improved insulin sensitivity and altered gene expression of genes involved in lipid and glucose metabolism. Finally, we inactivated the Repin1 gene in adipose tissue (iARep−/−) at an age of four weeks using Tamoxifen-inducible gene targeting strategies on a background of C57BL/6NTac mice. Mice lacking Repin1 in adipose tissue showed reduced body weight gain, decreased fat mass with smaller adipocytes, improved insulin sensitivity, lower LDL-, HDL- and total cholesterol serum concentrations and reduced expression of genes involved in lipid metabolism (Cd36 and Lcn2 ). In conclusion, the thesis presented here provides novel insights into Repin1 function. Moreover, the data clearly indicate that Repin1 plays a role in insulin sensitivity and lipid metabolism by regulating key genes involved in those pathways

The effect of titanium on the expression and activity of Matrix metalloproteinase 7 in differentially activated macrophages

Implant material is widely used in medical fields such as orthopedics, odontology or cardiology. Due to its excellent properties regarding corrosion resistance and biocompatibility, titanium has been used successfully for decades. However, in the orthopedic field, studies report failure rates between 3,4-9%. One of the main reasons for implant failure is aseptic implant loosening which has been reported to be responsible for 80% of revision surgeries. Matrix metalloproteinase and especially MMP-7 play a significant role in the pathology of implant failure. MMP-7 has, due to the lack of its hemopexin domain, one of the broadest substrate spectrums among all MMPs. It can degrade the extracellular matrix as well as activate a large number of cytokines. These cytokines, in turn, can cause numerous pathologies (e.g., fibrosis or chronic inflammation). Macrophages are the principal cell type involved in the orchestration of the foreign body response. In order to analyze the foreign body response to titanium, which is one of the most used materials for implants in humans, the aim of this work was to examine the effect of human primary macrophage exposure to titanium on the MMP-7 production. Using Affymetrix microarray assays it was previously identified in our laboratory, that titanium induces MMP-7 gene expression in macrophages (82). The specific aims of the current project included 1) quantification of titanium induced changes in gene expression and secretion of MMP-7 in human primary M0, M1 and M2 macrophages; 2) comparative analysis of titanium induced MMP-7 production on 3 different levels (mRNA, protein secretion, activity); and 3) analysis of TIMP-3 and CD151, regulators of MMP-7 activity, in response to titanium stimulation. Analysis of differential effects of porous and polished titanium on MMP-7 production by M0, M1, and M2 was performed in the model system established in our laboratory where human primary M0, M1, and M2 macrophages are differentiated out of peripheral blood monocytes cultured on titanium disks was used. RT-PCR analysis revealed that both polished and porous titanium up-regulate MMP-7 mRNA in M0 and M2 macrophages. Additionally, polished titanium was able to induce MMP-7 in M1 macrophages. Protein analysis by ELISA confirmed that secretion of MMP-7 correlates with the up-regulated levels of mRNA in M0 and M2. Analysis of active MMP-7 demonstrated that titanium induced release in M0 and M2 in some donors, however without statistical significance. The inducing effect of titanium on MMP7 production was differential on each level of regulation with a principal induction on mRNA and protein level. It was shown that MMP-7 increased by the time of incubation both under titanium stimulation as well as without titanium. The maximum MMP-7 levels were detected on day 6 of incubation. Exposure of macrophages to titanium resulted in changes of expression of the MMP-7 regulators TIMP3 and CD151 in some donors, however without statistical significance, suggesting that there are also other mechanisms responsible for the post-translational regulation of MMP-7. Collectively, the results demonstrate that MMP-7 is statistically significant induced in human primary macrophages by titanium on mRNA and protein levels, and in part of donors on the levels of released active MMP-7. MMP-7 production was induced in macrophages by both porous and polished titanium, while the strongest effect was found in M2 macrophages. As the up-regulation of MMP-7 may be essential for the success of the integration of a titanium implant, a macrophage-based model system is suggested as a predictive tool for implant failure enabling a personalized therapeutic approach

Methoden zur applikationsspezifischen Verlustleitungsoptimierung für eingebettete Prozessoren

Dieser Beitrag beschreibt eine Methodik zur Verlustleistungsmodellierung von eingebetteten Prozessoren im Entwurfsstadium auf Basis der Hardwarebeschreibung. Die Methodik wurde exemplarisch auf einen typischen RISC-Prozessor angewendet. Die gewonnenen Verlustleistungsmodelle zeigen eine geringe Abweichung hinsichtlich der mittleren Verlustleistungsaufnahme von unter 5% und eine hohe Güte bezüglich des zeitlichen Verlaufes der Verlustleistungsaufnahme im Vergleich zur sehr zeitaufwendigen Simulation der Gatter-Netzliste. Zudem lassen sich die Modelle zusammen mit der funktionalen Emulation des Prozessors auf einem FPGA abbilden. Die hohe Ausführungsgeschwindigkeit der Emulation erlaubt sowohl eine umfassende, verlustleistungsorientierte Optimierung der Anwendungen durch den Applikationsentwickler als auch eine anwendungsorientierte Optimierung der Prozessorarchitektur durch den Hardwareentwickler

Perspectives of people living with HIV on access to healthcare in Canada: a systematic review and framework analysis

The infection with HIV requires continuous healthcare. Some people living with HIV / AIDS (PLHA) in Canada enter the healthcare system only sporadically which has a negative effect on health outcomes for this population. To analyse patients’ perspectives on access to healthcare, a systematic review with data synthesis and framework analysis was chosen to review Canadian literature. The “5 A’s” on access to healthcare were used for synthesis and modified to fit our research question. Domains and Concepts on access to healthcare were developed, analyzed, and categorized into enablers, barriers, and suggestions from PLHA. From 26,190 articles, 334 met the inclusion criteria, leaving 11 relevant articles. The modified framework contained of 91 concepts in 7 domains: Acceptability, Availability, Accessibility, Affordability, Accommodation, Communication, and Others. Our findings highlight research opportunities and can be used by decision makers and healthcare providers to improve access to healthcare for PLHA in the future

Evaluation of the consistency of fiber reinforced cementitious composites

The rheological properties of fresh concrete, mortar or cement paste are among the most important parameters when cementitious building materials are placed. New material designs, like high or ultrahigh performance concretes, include the addition of a high volume of fibers to the fresh mix influencing its workability properties. However, the analysis of the rheological properties of fiber reinforced cementitious composites is difficult. Conventional methods mostly do not apply, especially when a high fiber content and relatively stiff mixtures are used. For this reason, a new method was developed to evaluate the workability of fiber reinforced composites. This method was applied to carbon and PVA fiber reinforced high performance composites and was used to optimize the rheological properties of these composites for an application in a centrifugation casting proces

Continuously variable W-band phase shifters based on MEMS-actuated conductive fingers

This paper presents four continuously variable W-band phase shifters in terms of design, fabrication, and radiofrequency (RF) characterization. They are based on low-loss ridge waveguide resonators tuned by electrostatically actuated highly conductive rigid fingers with measured variable deflection between 0.3° and 8.25° (at a control voltage of 0-27.5 V). A transmission-type phase shifter based on a tunable highly coupled resonator has been manufactured and measured. It shows a maximum figure of merit (FOM) of 19.5°/dB and a transmission phase variation of 70° at 98.4GHz. The FOM and the transmission phase shift are increased to 55°/dB and 134°, respectively, by the effective coupling of two tunable resonances at the same device with a single tuning element. The FOM can be further improved for a tunable reflective-type phase shifter, consisting of a transmission-type phase shifter in series with a passive resonator and a waveguide short. Such a reflective-type phase shifter has been built and tested. It shows a maximum FOM of 101°/dB at 107.4GHz. Here, the maximum phase shift varied between 0° and 377° for fingers deflections between 0.3° and 8.25

Comparison of electromagnetic field solvers for the 3D analysis of plasmonic nano antennas

Plasmonic nano antennas are highly attractive at optical frequencies due to their strong resonances - even when their size is smaller than the wavelength - and because of their potential of extreme field enhancement. Such antennas may be applied for sensing of biological nano particles as well as for single molecule detection. Because of considerable material losses and strong dispersion of metals at optical frequencies, the numerical analysis of plasmonic antennas is very demanding. An additional difficulty is caused when very narrow gaps between nano particles are utilized for increasing the field enhancement. In this paper we discuss the main difficulties of time domain solvers, namely FDTD and FVTD and we compare various frequency domain solvers, namely the commercial FEM packages JCMsuite, Comsol, HFSS,and Microwave Studio with the semi-analytic MMP code that may be used as a reference due to its fast convergence and high accuracy.Comment: 12 pages, SPIE conference, Errata added on last pag