The Human Induced Pluripotent Stem Cell Test as an Alternative Method for Embryotoxicity Testing

The evaluation of substances for their potency to induce embryotoxicity is controlled by safety regulations. Test guidelines for reproductive and developmental toxicity rely mainly on animal studies, which make up the majority of animal usage in regulatory toxicology. Therefore, there is an urgent need for alternative in vitro methods to follow the 3R principles. To improve human safety, cell models based on human cells are of great interest to overcome species differences. Here, human induced pluripotent stem cells (hiPSCs) are an ideal cell source as they largely recapitulate embryonic stem cells without bearing ethical concerns and they are able to differentiate into most cell types of the human body. Here, we set up and characterized a fetal bovine serum (FBS)-free hiPSC-based in vitro test method, called the human induced pluripotent stem cell test (hiPS Test), to evaluate the embryotoxic potential of substances. After 10 days in culture, hiPSCs develop into beating cardiomyocytes. As terminal endpoint evaluations, cell viability, qPCR analyses as well as beating frequency and area of beating cardiomyocytes by video analyses are measured. The embryotoxic positive and non-embryotoxic negative controls, 5-Fluorouracil (5-FU) and Penicillin G (PenG), respectively, were correctly assessed in the hiPS Test. More compounds need to be screened in the future for defining the assay’s applicability domain, which will inform us of the suitability of the hiPS Test for detecting adverse effects of substances on embryonic development.     

Impact of novel methodologies on the analysis of conjugated linoleic acid (CLA). Implications of CLA feeding studies

Interest in conjugated linoleic acid (CLA) has increased in the past decade as a result of reports of several health benefits related to its consumption. Naturally occurring CLA isomers are found in milk, dairy, and meat products from ruminants. Detailed isomeric composition of CLA in different chemical and biological matrices had been hindered by the lack of adequate analytical techniques. New methodologies were developed and used to determine the distribution of major and minor geometric and positional CLA isomers in cheese, beef, cow milk, human adipose, and human milk. Base-catalyzed methylation was used. A novel silver ion high-performance liquid chromatographic procedure was developed, which successfully resolved up to 16 isomers. The double bond configuration and position for CLA isomers were confirmed by gas chromatography (GC)-direct deposition-Fourier transform infrared spectroscopy and GC-electron ionization mass spectrometry, respectively: The incorporation of CLA isomers in tissues of animals fed CLA diets was also determined. Currently available analytical data suggest the need to re-evaluate prior CLA studies and their nutritional and biological implications.     

Conjugated linoleic acid (CLA) isomers: formation,analysis, amounts in foods,and dietary intake

The analysis, content, and daily intake of conjugated linoleic acid isomers (CLA) are presented in the following review. Modern analytical techniques such as capillary gas chromatography (GC), silverion high performance liquid chromatography (Ag⁺-HPLC) combined with different detection methods (flame ionisation, mass spectroscopic, ultra violet) are mandatory for the unequivocal determination of geometric and positional CLA isomers. An overview is given on the CLA contents in 139 German foods, e. g. milk/dairy products, meat/meat products, edible oils, margarines, fish, and deep fried products. The dietary intake for men and women is estimated using consumption data.     

Morphology and properties of blends with different thermoplastic polyurethanes and polyolefines

Unmodified blends of two thermoplastic polyurethanes (TPU) and six polyolefines were used to study the influence of the component viscosities on the blend morphology and mechanical properties. Blends were produced by melt mixing using a twin screw extruder. Interactions between the blend components could not be detected by DSC, DMA, selective extraction, and SEM micrographs of cryofractures. The variation in tensile strength with blend composition produce a U-shaped curve with the minimum between 40 and 60 wt % of polyolefine. At similar viscosity ratios (η_d/η_m), blends with polyether based TPU (TPU-eth) have a finer morphology than blends with polyester based TPU (TPU-est). This is due to the lower surface free energy of the polyether soft segments compared to the polyester soft segments. Different morphologies also lead to changes in mechanical behavior. Blends with TPU-eth show a lower decrease in tensile strength with blend composition than blends with TPU-est. The viscosity ratio between TPU and polyolefines can be directly correlated to the blend morphology obtained under similar blending conditions. TPU/PE blends show a lower dispersity than TPU/PP blends, due to the higher viscosity ratios of TPU/PE blends. This results in a greater reduction in tensile strength with the disperse phase content. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 749–762, 1997     

Influence of sampling on steroid hormone patterns of beef from bulls and steers

Three different muscles (Longissimus dorsi, Semitendinosus, Extensor carpi ulnaris) of bulls and steers, which represent different parts of the carcass and which have differing properties (function, proportions of fat and connective tissue), were analysed with GC-MS for their contents of testosterone, cortisol, cortisone, pregnenolone, dehydroepiandrosterone, progesterone, hydroxyprogesterone, androstenedione, dihydrotestosterone, epitestosterone and androsterone. No difference in the hormone patterns could be detected between the three muscles. However, the enrichment of beef samples with inter- and intramuscular fat decreased the levels of the polar corticosteroids, whereas the levels of lipophilic steroids were increased. The patterns of the lipophilic sex steroids, their precursors and metabolites, which can be used to determine the sexual origin of beef and which might prove useful in evaluating residues of administered steroid hormones, seem to be less affected by the beef sample's fat content, however.     

Origin of Band-like and Atom-like Features of the Valence Band Auger Emission from Transition Metals

The occurrence of both band-like and atom-like Auger spectra involving valence band electron of d-transition metals is discussed based on the two-step model of the Auger electron emission, i.e. an initial core-hole is first generated and the Auger transition occurs between the core-hole and the valence states. The occupied valence states relax to screen the core-hole which results in a redistribution of the valence electrons. The electronic states concerned by the Auger transition are calculated by the FLAPW method. There is a clear relation between band-like and atom-like features of the spectra and the different responses of these metals to the existence of a core-hole.     

Application of standard addition to eliminate conjugated linoleic acid and other interferences in the determination of total Trans fatty acids in selected food products by infrared spectroscopy

A novel and rapid (5 min) attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic method AOCS Cd 14d-99 for the determination of total isolated trans fatty afids, which absorb at 966 cm^‐, was recently developed, collaboratively studied, and applied to food products containing 1–50% rans fat (as percentage of total fat). Attempts to apply the ATR-FTIR method to biological matrices of low trans fat and/or low total fat content, and to dairy and other products were not satisfactory due to interfering IR absorptions in the trans region. One group of interfering compounds with absorption bands near 985 and 948 cm⁻¹ was the cis/trans positional isomes of conjugated linoleic acid (CLA) found in dairy and meat products from ruminants at levels of <1% (as percentage of total fat). In the present study, we modified the ATR-FTIR method to overcome matrix interferences. This modification, which consisted of applying the standard addition technique to the ATR-FTIR determination, was also applied to several food products, namely, dairy products, infant formula and salad oil dressing, which successfully eliminated interfering absorbances that impacted on accuracy. The presence of <1% CLA in two butter and two cheese products containing 6.8, 7.5, 8.5, and 10.4% trans fatty acids (as a percentage of total fat) would have led to errors of −11.6, 10.4, 17.6 and 34.6%, respectively, in trans fat measurements had the standard addition technique not been used. The applicability of ATR-FTIR to the quantitation of food products is discussed.     

Greenhouse gas balances and mitigation costs of 70 modern Germany-focused and 4 traditional biomass pathways including land-use change effects

With Germany as the point of energy end-use, 70 current and future modern pathways plus 4 traditional biomass pathways for heat, power and transport have been compiled and examined in one single greenhouse gas (GHG) balancing assessment. This is needed to broaden the narrow focus on biofuels for transport and identify the role of bioenergy in GHG mitigation. Sensitivity analysis for land-use changes and fossil reference systems are included. Co-firing of woody biomass and fermentation of waste biomass are the most cost-efficient and effective biomass applications for GHG emission reduction in modern pathways. Replacing traditional biomass with modern biomass applications offers an underestimated economic potential of GHG emission reduction. The range of maximum CO₂ equivalent GHG reduction potential of bioenergy is identified in a range of 2.5-16 Gt a⁻¹ in 2050 (5-33% of today’s global GHG emissions), and has an economic bioenergy potential of 150 EJ a⁻¹.     

Crystal structure of L-arginine:inosamine-phosphate amidinotransferase StrB1 from Streptomyces griseus: an enzyme involved in streptomycin biosynthesis

Inosamine-phosphate amidinotransferases catalyze two nonconsecutive transamidination reactions in the biosynthesis of the streptomycin family of antibiotics. L-Arginine:inosamine-phosphate amidinotransferase StrB1 from Streptomyces griseus (StrB1) was cloned as an N-terminal hexa-histidine fusion protein, purified by affinity chromatography, and crystallized, and its crystal structure was solved by Patterson search methods at 3.1 A resolution. The structure is composed of five betabeta alphabeta-modules which are arranged circularly into a pseudo-5-fold symmetric particle. The three-dimensional structure is closely related to the structure of human L-arginine:glycine amidinotransferase (AT), but five loops (the 40-, 170-, 220-, 250-, and 270-loop) are organized very differently. The major changes are found in loops around the active site which open the narrow active site channel of AT to form an open and solvent-exposed cavity. In particular, module II of StrB1 is AT-like but lacks a 10-residue alpha-helix in the 170-loop. The concomitant reorganization of neighboring surface loops that surround the active site, i.e., the 40-loop and the 270-loop, results in an arrangement of loops which allows an unrestricted access of substrates to the cavity. However, the residues which are involved in substrate binding and catalysis are conserved in AT and StrB1 and are at equivalent topological positions, suggesting a similar reaction mechanism among amidinotransferases. The binding site for L-arginine had been deduced from its complex with AT. Molecular modeling revealed a possible binding mode for the second substrate scyllo-inosamine 4-phosphate.