Noninvasive assessment of hepatobiliary and renal elimination of cysteinyl leukotrienes by positron emission tomography

N-Acetyl-leukotriene E4 has been identified as an endogenous, biologically less active cysteinyl leukotriene metabolite in rodents and humans. To evaluate the ratio of hepatobiliary to renal elimination of leukotrienes noninvasively by positron emission tomography (PET), we synthesized N-[11C]acetyl-leukotriene E4 by chemical N-acetylation of leukotriene E4. After the intravenous injection of N-[11C]acetyl-leukotriene E4 in normal rats and monkey, uptake by the liver and subsequent excretion into bile were largely responsible for its rapid elimination from blood. In the Cynomolgus monkey, renal excretion of the leukotriene into urine was of additional quantitative importance. Kinetic modeling indicated a mean transit time through the liver of 17 minutes and 34 minutes in rat and monkey, respectively; the corresponding hepatic excretion half-times amounted to 8.5 minutes and 16 minutes. In a mutant rat strain deficient in the hepatobiliary excretion of cysteinyl leukotrienes across the canalicular membrane, the apparent mean liver transit time was 54 minutes, and the hepatic excretion half-time was 29 minutes, indicating prolonged organ storage and metabolism. After transport from the liver back into the circulating blood of omega-oxidized and beta-oxidized metabolites of N-[11C]acetyl-leukotriene E4, renal excretion compensated for the impairment of hepatobiliary elimination in the transport mutant. Metabolite analyses in urine after intravenous injection of N-[3H]acetyl-leukotriene E4 indicated the extensive inactivation of N-acetyl-leukotriene E4 by beta-oxidation from the omega-end in the mutants. A similar shift from hepatobiliary to renal cysteinyl leukotriene elimination was monitored in rats with cholestasis due to bile duct obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolism of anabolic androgenic steroids

Anabolic androgenic steroids (AAS) are misused to a high extent in sports by athletes to improve their physical performance. Sports federations consider the use of these drugs in sports as doping. The misuse of AAS is controlled by detection of the parent AAS (when excreted into urine) and (or) their metabolites in urine of athletes. I present a review of the metabolism of AAS. Testosterone is the principal androgenic steroid and its metabolism is compared with that of AAS. The review is divided into two parts: the general metabolism of AAS, which is separated into phase I and phase II metabolism and includes a systematic discussion of metabolic changes in the steroid molecule according to the regions (A-D rings), and the specific metabolism of AAS, which presents the metabolism of 26 AAS in humans.     

Oligomerization of phenyl glycidyl ether in the presence of ZnCl2

Summary In the presence of ZnCl₂ phenyl glycidyl ether reacts to different products owing to the ring-opening reaction of the oxirane and the cleavage of the ether bond. Using HPLC and offline mass spectrometry most of the reaction products could be identified.A reaction scheme and the supposed reaction mechanism were described involving the formation of chlorine — containing oligomers and low molecular weight by — products resulting from the cleavage of the ether bond of the monomer. Conclusions were drawn for original polyfunctional epoxy resin systems.     

SWOF - an open framework for shared workspaces to support different cooperation tasks

Computer supported collaborative work (CSCW) allows people to cooperate by computers from different places and at different times. To enable an easier integration of such collaborative components into web-based communities and portals, a Shared Workspace Open Framework (SWOF) was developed. This framework provides the basic features of shared workspaces and can be customized to different cooperation cases. High usability is an important aspect of the implementation. To achieve these aims SWOF focuses on an information space with more task-suited item-types that can help to pre-structure the information. Thus, on the one hand the system can help the users to write down the needed information in a consistent way and, on the other, could reduce the arguments between the group members on how to structure their workspace. As a use case for SWOF the development of a Web-based portal for the community of man-machine interaction was chosen. In the project MMI-Interaktiv, a portal is built with a SWOF-based shared workspace component. An evaluation for this use case is presented.     

Computer-assisted evaluation of mammography images. Initial clinical experiences

Preceding studies have shown that a second independent reviewer of conventional mammographies increases the detection rate of features typical for malignancy by up to 15%. METHODS: In order to test a computer-aided diagnostic (CAD) system (ImageChecker, R2 Technology, USA) for the detection of pathologic criteria in conventional mammography, 96 mammographies were retrospectively evaluated using ImageChecker. Thirty-five of these mammographies had been diagnosed as not showing pathologies, and 61 had depicted histologically confirmed malignancy. RESULTS: Detecting 41 of 61 breast malignancies, ImageChecker showed a diagnostic sensitivity of 70.5%. All malignancies accompanied by microcalcifications were identified by ImageChecker, whereas 18 cases characterized by parenchymal opacity without microcalcifications were not marked. On the average, 1.95 markers per image were set, giving a total of 187 markers in this study. 63% of all markers showed normal tissue and were thus false positive. CONCLUSIONS: Pathologic parenchymal opacities in mammography are a well-known problem for all CAD systems in use. Despite this major drawback, even now ImageChecker can provide tremendous support in routine interpretation of conventional mammographies.     

Bücherschau

Ohne Zusammenfassung VDI     

Beer enemy number one: genetic diversity,physiology and biofilm formation of Lactobacillus brevis

Lactobacillus brevis is the most significant beer spoilage bacteria worldwide. It is found as a contaminant at all stages of brewing, including during primary and secondary fermentation, storage, filtration and the packaging process. In production with flash pasteurisation and subsequent hygienic filling, avoiding and tracing secondary contaminations is the key to a microbiologically stable product. However, L. brevis strains vary in their spoilage potential and can grow in many different beer types. This study presents a physiological test scheme for growth potential and biofilm formation in various media. It was determined that a large number of L. brevis strains can form biofilms as a first coloniser. The identification of the species alone is therefore not enough to be sure of the spoilage risk, which shows the need for a more in depth differentiation. DNA fingerprint techniques are crucial to differentiate isolates of this species at strain level. The rep‐PCR fingerprint system (GTG)₅ was used to differentiate a selected collection of 20 isolates, which were characterised in growth and biofilm formation in various media. The data showed a high variation within the selected isolates. As second step, generated fingerprint clusters of L. brevis were traced back to contamination sources in a German brewery, revealing a high number of isolates with potentially varying growth, spoilage and biofilm potential. L. brevis being the demonstrator species, the PCR system used is a powerful and compatible tracing and troubleshooting tool for all kinds of spoilage bacteria in the brewing industry. © 2019 The Institute of Brewing & Distilling     

Morphological impact of zinc oxide layers on the device performance in thin-film transistors

Zinc oxide thin-films are prepared either by spin coating of an ethanolic dispersion of nanoparticles (NP, diameter 5 nm) or by spray pyrolysis of a zinc acetate dihydrate precursor. High-resolution electron microscopy studies reveal a monolayer of particles for the low temperature spin coating approach and larger crystalline domains of more than 30 nm for the spray pyrolysis technique. Thin-film transistor devices (TFTs) based on spray pyrolysis films exhibit higher electron mobilities of up to 24 cm2 V(-1) s(-1) compared to 0.6 cm2 V(-1) s(-1) for NP based TFTs. These observations were dedicated to a reduced number of grain boundaries within the transistor channel.