Antimicrobial activity of gentamicin palmitate against high concentrations of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

The reduction of implant related infections plays a pivotal role in orthopaedic surgery as an increasing number of people require implants (up to 200,000 per year in the United States (source: Joint Implant Surgery & Research Foundation 2010)). The aim of the current study is to prevent and thus decrease the number of bacterial infections. Both pre and post operative systemic antibiotic treatment and gentamicin containing bone cements (polymethylmethacrylate, PMMA) are commonly used strategies to overcome infections. In this study, the antimicrobial efficacy of gentamicin sulfate loaded bone cement was compared with titan discs coated with a new form of gentamicin, gentamicin palmitate. Adherence prevention, killing rates and killing kinetics were compared in an in vitro model, using Staphylococcus aureus (S. aureus), which together with Staphylococcus epidermidis (S. epidermidis) represents 60% of bacteria found responsible for hip implant infections (An and Friedman, 1996, J Hosp Infect 33(2):93–108). In our experiments gentamicin, which was applied as gentamicin palmitate on the surface of the implants, showed a high efficacy in eliminating bacteria. In contrast to gentamicin sulfate containing bone cements, gentamicin palmitate is released over a shorter period of time thus not inducing antibiotic resistance. Another benefit for clinical application is that it achieves high local levels of active ingredient which fight early infections and minimize toxic side effects. Furthermore, the short term hydrophobic effect of gentamicin palmitate can successfully impede biofilm formation. Thus, the use of self-adhesive antibiotic fatty acid complexes like gentamicin palmitate represents a new option for the anti-infective coating of cementless titan implants.     

Lack of Contribution of p66shc to Pressure Overload-Induced Right Heart Hypertrophy

The leading cause of death in pulmonary arterial hypertension (PAH) is right ventricular (RV) failure (RVF). Reactive oxygen species (ROS) have been suggested to play a role in the development of RV hypertrophy (RVH) and the transition to RVF. The hydrogen peroxide-generating protein p66shc has been associated with left ventricular (LV) hypertrophy but its role in RVH is unclear. The purpose of this study was to determine whether genetic deletion of p66shc affects the development and/or progression of RVH and RVF in the pulmonary artery banding (PAB) model of RV pressure overload. The impact of p66shc on mitochondrial ROS formation, RV cardiomyocyte function, as well as on RV morphology and function were studied three weeks after PAB or sham operation. PAB in wild type mice did not affect mitochondrial ROS production or RV cardiomyocyte function, but induced RVH and impaired cardiac function. Genetic deletion of p66shc did also not alter basal mitochondrial ROS production or RV cardiomyocyte function, but impaired RV cardiomyocyte shortening was observed following PAB. The development of RVH and RVF following PAB was not affected by p66shc deletion. Thus, our data suggest that p66shc-derived ROS are not involved in the development and progression of RVH or RVF in PAH.     

Zustandsformen von Verbundnetzen

A set of state equations, needed for stability analysis of interconnected electric power systems, is difficult to determine for large grids. These equations can be set up by calculating the state equations for every individual transmission system and joining them to the interconnected system afterwards. This algorithm avoids privacy problems, which can result from data exchange with other transmission system operators in the free electricity market. No competition-relevant data, which would allow conclusions to be drawn regarding the individual grid structure, are passed on.     

TiH2粉末烧结研究进展

目的 研究烧结温度、升温速率、压制压力分别对TiH2粉末压坯脱氢相演变过程以及显微组织的影响规律.方法 采用氢化钛(TiH2)粉末为原料,经过压制和真空烧结制备粉末冶金Ti材料,结合原位中子粉末衍射、差示扫描量热法等技术,表征TiH2粉末压坯在烧结过程中的显微形貌及相变过程.结果 在真空烧结条件下,TiH2粉末压坯的脱...     

Selektiv S-geschützte Cysteinpeptide. Zur Synthese von Cysteinpeptiden unter Verwendung der S-Äthylmercapto-Schutzgruppe

Selectively S-Protected Cysteine Peptides. Synthesis of Cysteine Peptides Using the S-Ethylthio Protecting Group Studying the problems of the selective sulphur protection in cysteine peptides, a model heptapeptide from the sheep insulin A-chain was prepared by conventional and solid phase synthesis using the S-ethylthio and the S-diphenylmethyl group. The conventional synthesis of the heptapeptide N-tert.-butyloxycarbonyl-S-ethylthiocysteinyl-S-diphenylmethylcysteinyl-alanyl-glycyl-valyl-S-ethylthiocysteinyl-alanine 1 was carried out with the fragments N-tert.-butyloxycarbonyl-S-ethylthiocysteinyl-S-diphenylmethyleysteinyl-alanyl-glycine 2 and valyl-S-ethyl-thiocysteinyl-alanine 3 by means of the hydroxysuccinimide ester of 2 . Because of the small stability of S-ethylthio-protected cysteine peptides against alkali, 2 was synthesized without carbonyl protecting group by hydroxysuccinimide ester couplings from the carboxyterminal end, whereas 3 was obtained using the 2-p-toluenesulphonyl ethyl ester carboxyl protecting group, which can be saponified selectively at pH 10 preserving the S-protecting group. The S-ethylthio group exhibits only a small acid stability and was not completely stable during the deprotection of the N^α-Boc-group. Therefore neither 3 nor 1 could be obtained in a pure state by solid phase technique.     

Proprotein Convertase Subtilisin Kexin Type 9 (PCSK9) Deletion but Not Inhibition of Extracellular PCSK9 Reduces Infarct Sizes Ex Vivo but Not In Vivo

Hypoxia upregulates PCSK9 expression in the heart, and PCSK9 affects the function of myocytes. This study aimed to investigate the impact of PCSK9 on reperfusion injury in rats and mice fed normal or high-fat diets. Either the genetic knockout of PCSK9 (mice) or the antagonism of circulating PCSK9 via Pep2-8 (mice and rats) was used. Isolated perfused hearts were exposed to 45 min of ischemia followed by 120 min of reperfusion. In vivo, mice were fed normal or high-fat diets (2% cholesterol) for eight weeks prior to coronary artery occlusion (45 min of ischemia) and reperfusion (120 min). Ischemia/reperfusion upregulates PCSK9 expression (rats and mice) and releases it into the perfusate. The inhibition of extracellular PCSK9 does not affect infarct sizes or functional recovery. However, genetic deletion largely reduces infarct size and improves post-ischemic recovery in mice ex vivo but not in vivo. A high-fat diet reduced the survival rate during ischemia and reperfusion, but in a PCSK9-independent manner that was associated with increased plasma matrix metalloproteinase (MMP)9 activity. PCSK9 deletion, but not the inhibition of extracellular PCSK9, reduces infarct sizes in ex vivo hearts, but this effect is overridden in vivo by factors such as MMP9.     

Non-invasive mobile monitoring of meat quality

Detailed investigations into the time-dependent changes of pork meat quality and composition have been carried out using standard analytical techniques and Raman and fluorescence spectroscopy. Characteristic changes in soluble protein content, microbial load and biogenic amine content have been measured in the time period from slaughter up to 20 to 30 days post mortem on samples of porcine musculus longissimus dorsi. Characteristic behaviour indicative of a deterioration of meat quality and an increase in microorganism population on the meat surface has been observed. Fluorescence and Raman optical signals have been identified which change over this time period, correlating with the standard measurements and these can be used as indicators of meat properties. These signals can be measured rapidly and without the destruction of the meat sample allowing non-invasive testing. The combination of these two powerful measurement techniques provides a pathway to comprehensive meat quality monitoring. Furthermore we have developed a hardware concept for carrying out these spectroscopic measurements using a compact and light handheld device and we present concepts for the use of such a device in the logistic chain in combination with a transponder chip and integrated sensors which provide product identification and information about storage conditions along the entire logistic chain to the supermarket shelf. Received: September 16, 2008; accepted: October 5, 2008     

Uncertainty budgeting for range calibration

The Guide to the Expression of Uncertainty in Measurement (GUM) established a general procedure to evaluate measurement uncertainty. The Guide covers only the evaluation of a single result or a set of individual results. Modern measuring instruments and procedures operate over a wide range of values. Therefore in practice a calibration procedure is needed that is valid for this range. The procedure should include an evaluation of uncertainty associated with the calibration results and for the subsequent measurements performed with the calibrated instrument. Traditionally regression analysis is used for this purpose. In this paper we will discuss some weaknesses of the regression approach and suggest an alternative. We show that for instruments with a linear response function the regression can be replaced by 2-point calibration. We introduce a limit of the deviation from linearity to address observed deviations from a linear response function of the instrument. To improve an existing instrument with a non-linear response function a combination of the instrument and a correction function can be treated as a virtual linear measuring device and a 2-point calibration can be applied. As an example we use the calibration of a pressure sensor to illustrate the procedure. The approach can be used for instruments and measurement procedures with a linear or non-linear response function.     

Highly sulfonated poly(phenylene sulfones): optimization of the polymerization conditions

The preparation of highly sulfonated poly(phenylene sulfone) (ion exchange capacity = 4.45 meq g⁻¹) by polycondensation of sulfonated difluorodiphenyl sulfone with metal sulfide and subsequent oxidation with hydrogen peroxide is optimized. The monomer/metal sulfide ratio, polymerization time and temperature, and type of metal sulfide have been varied. For the best conditions high molecular weights of up to 300 kg mol⁻¹ are obtained reproducibly. This high molecular weight polyelectrolyte is meant to be used as main constituent of heterogeneous membrane structures such as interpenetrating networks, polymer blends, or simple physical mixtures with other polymers, e.g., for application in PEM fuel cells.