Nutritional Calcium Supply Dependent Calcium Balance,Bone Calcification and Calcium Isotope Ratios in Rats

Serum calcium isotopes (δ^44/42Ca) have been suggested as a non-invasive and sensitive Ca balance marker. Quantitative δ^44/42Ca changes associated with Ca flux across body compartment barriers relative to the dietary Ca and the correlation of δ^44/42Ca_Serum with bone histology are unknown. We analyzed Ca and δ^44/42Ca by mass-spectrometry in rats after two weeks of standard-Ca-diet (0.5%) and after four subsequent weeks of standard- and of low-Ca-diet (0.25%). In animals on a low-Ca-diet net Ca gain was 61 ± 3% and femur Ca content 68 ± 41% of standard-Ca-diet, bone mineralized area per section area was 68 ± 15% compared to standard-Ca-diet. δ^44/42Ca was similar in the diets, and decreased in feces and urine and increased in serum in animals on low-Ca-diet. δ^44/42Ca_Bone was higher in animals on low-Ca-diet, lower in the diaphysis than the metaphysis and epiphysis, and unaffected by gender. Independent of diet, δ^44/42Ca_Bone was similar in the femora and ribs. At the time of sacrifice, δ^44/42Ca_Serum inversely correlated with intestinal Ca uptake and histological bone mineralization markers, but not with Ca content and bone mineral density by µCT. In conclusion, δ^44/42Ca_Bone was bone site specific, but mechanical stress and gender independent. Low-Ca-diet induced marked changes in feces, serum and urine δ^44/42Ca in growing rats. δ^44/42Ca_Serum inversely correlated with markers of bone mineralization.     

Azoperoxide. VI. Selektive Spaltungen von β-Azo-acylperoxiden

Azoperoxides. VI. Selective Decomposition of β-Azoacylperoxides The selective decomposition of the O O-Groups in the azoperoxides 1 and 2 is possible by reaction with dimethylaniline at 35°C. Rate constants were measured and the decomposition products were analyzed. Intermediates are azoalkyl radicals. The radical yield of the amine induced decomposition of 2 in ethylbenzene is 8.2% at 35°C. UV irradiation of the azoperoxides 1 and 2 at 20°C in ethylbenzene results in a quantitative and selective decomposition of the azo groups. Intermediates are C-radicals with intact peroxide groups. The reaction of 1 and 2 with triethylstannane yields reduction products of the O O-groups and the NN-groups, respectively.     

Novel oxidative in vitro metabolites of the mycotoxins alternariol and alternariol methyl ether

The Alternaria toxins alternariol (AOH; 3,7,9-trihydroxy-1-methyl-6H-benzo[c]chromen-6-one) and alternariol methyl ether (AME, 3,7-dihydroxy-9-methoxy-1-methyl-6H-benzo[c]chromen-6-one) are common contaminants of food and feed, but their oxidative metabolism in mammals is as yet unknown. We have therefore incubated AME and AOH with microsomes from rat, human, and porcine liver and analyzed the microsomal metabolites with HPLC and GC-MS/MS. Seven oxidative metabolites of AME and five of AOH were detected. Their chemical structures were derived from their mass spectra using deuterated trimethylsilyl (TMS) derivatives, and from the information obtained from enzymatic methylation. Several of the metabolites were identified by comparison with synthetic reference compounds. AME as well as AOH were monohydroxylated at each of the four possible aromatic carbon atoms and also at the methyl group. In addition, AME was demethylated to AOH and dihydroxylated to a small extent. As the four metabolites arising through aromatic hydroxylation of AME and AOH are either catechols or hydroquinones, the oxidative metabolism of these mycotoxins may be of toxicological significance.     

Online variance minimization

We consider the following type of online variance minimization problem: In every trial t our algorithms get a covariance matrix C ^t and try to select a parameter vector w ^t−1 such that the total variance over a sequence of trials ?_t=1^T (w^t-1)^T C^tw^t-1\sum_{t=1}^{T} (\boldsymbol {w}^{t-1})^{\top} \boldsymbol {C}^{t}\boldsymbol {w}^{t-1} is not much larger than the total variance of the best parameter vector u chosen in hindsight. Two parameter spaces in ℝ ⁿ are considered—the probability simplex and the unit sphere. The first space is associated with the problem of minimizing risk in stock portfolios and the second space leads to an online calculation of the eigenvector with minimum eigenvalue of the total covariance matrix ?_t=1^T C^t\sum_{t=1}^{T} \boldsymbol {C}^{t}. For the first parameter space we apply the Exponentiated Gradient algorithm which is motivated with a relative entropy regularization. In the second case, the algorithm has to maintain uncertainty information over all unit directions u. For this purpose, directions are represented as dyads uu ^⊤ and the uncertainty over all directions as a mixture of dyads which is a density matrix. The motivating divergence for density matrices is the quantum version of the relative entropy and the resulting algorithm is a special case of the Matrix Exponentiated Gradient algorithm. In each of the two cases we prove bounds on the additional total variance incurred by the online algorithm over the best offline parameter.     

Enzymatic esterification of glycerol III. Lipase-catalyzed synthesis of regioisomerically pure 1,3-sn-diacylglycerols and 1 (3)-rac-monoacylglycerols derived from unsaturated fatty acids

Lipases that display high regioselectivities and broad substrate tolerance were used as catalysts for the efficient esterification of glycerol under the conditions of irreversible acyl transfer. A variety of unsaturated fatty acids, such as oleic, linoleic, erucic, ricinolic, hydroxystearic and coriolic acid, were used for this purpose in the form of their vinyl esters. Suitable biocatalysts were chosen on the basis of systematic screening experiments regarding their regioselectivities (RE) and substrate tolerances. Distinct differences were found and expressed in numerical RE values as a measure for differences of these biocatalysts as being specific, selective, and nonspecific. Based on these experiments, a variety of molecules were synthesized on a preparative scale (>150 mmol) in good yield (ca.85%) and with high regioisomerical purities (>95% RE).     

Atmospheric trace gas analysis with cavity ring-down spectroscopy

Cavity ring-down spectroscopy (CRDS) is a highly sensitive laser absorption method. It can be used for quantitative analysis of molecular species at the sub-ppb level. The absorption cell (cavity) is sealed by two high-reflective mirrors on each side, which results in an effective absorption path-length of some kilometers. Our experiments for atmospheric gas analysis have been carried out so far with an Excimer pumped dye laser in the UV-VIS and a CO overtone sideband laser in the wavelength region around 3 μm. Experiments with an all solid-state difference frequency laser system will follow. In the UV-VIS region, we measured trace gas molecules like SO₂, NO₂, and CH₂O. In the mid-infrared, around 3 μm, we measured hydrocarbons like CH₄, C₂H₆, and C₂H₄ with a detection limit of less than 1 ppb. The noise equivalent absorption coefficients in the MIR are in the order of 1.7·10⁻⁹ cm⁻¹. Due to the high data acquisition rate and the high sensitivity, CRDS enables real-time detection of trace gases in ambient air.     

The Role of Oncostatin M and Its Receptor Complexes in Cardiomyocyte Protection,Regeneration, and Failure

Oncostatin M (OSM), a member of the interleukin-6 family, functions as a major mediator of cardiomyocyte remodeling under pathological conditions. Its involvement in a variety of human cardiac diseases such as aortic stenosis, myocardial infarction, myocarditis, cardiac sarcoidosis, and various cardiomyopathies make the OSM receptor (OSMR) signaling cascades a promising therapeutic target. However, the development of pharmacological treatment strategies is highly challenging for many reasons. In mouse models of heart disease, OSM elicits opposing effects via activation of the type II receptor complex (OSMR/gp130). Short-term activation of OSMR/gp130 protects the heart after acute injury, whereas chronic activation promotes the development of heart failure. Furthermore, OSM has the ability to integrate signals from unrelated receptors that enhance fetal remodeling (dedifferentiation) of adult cardiomyocytes. Because OSM strongly stimulates the production and secretion of extracellular proteins, it is likely to exert systemic effects, which in turn, could influence cardiac remodeling. Compared with the mouse, the complexity of OSM signaling is even greater in humans because this cytokine also activates the type I leukemia inhibitory factor receptor complex (LIFR/gp130). In this article, we provide an overview of OSM-induced cardiomyocyte remodeling and discuss the consequences of OSMR/gp130 and LIFR/gp130 activation under acute and chronic conditions.     

Corner-Turning Distance and Retonation Radius

All high explosives, at least the ones used in military applications, have a specific minimum detonation radius, R_min with which the detonation can change its direction through 90° or 180°. It is to be emphasized that this applies not only to thc so-called insensitive high explosives, but the sensitive explosives of course have smaller radii than the insensitive ones. The corner-turning distance, As, determined in the radial test, also corresponds to the minimum radius, R_min for the detonation wave to invert its direction through 180°. The radial test is a simple method, with regard to both design and analysis, that is suitable for determining the 90°-distance, or the minimum detonation radius, R_min.     

Predicting and tuning physicochemical properties in lead optimization: amine basicities

This review describes simple and useful concepts for predicting and tuning the pK(a) values of basic amine centers, a crucial step in the optimization of physical and ADME properties of many lead structures in drug-discovery research. The article starts with a case study of tricyclic thrombin inhibitors featuring a tertiary amine center with pK(a) values that can be tuned over a wide range, from the usual value of around 10 to below 2 by (remote) neighboring functionalities commonly encountered in medicinal chemistry. Next, the changes in pK(a) of acyclic and cyclic amines upon substitution by fluorine, oxygen, nitrogen, and sulfur functionalities, as well as carbonyl and carboxyl derivatives are systematically analyzed, leading to the derivation of simple rules for pK(a) prediction. Electronic and stereoelectronic effects in cyclic amines are discussed, and the emerging computational methods for pK(a) predictions are briefly surveyed. The rules for tuning amine basicities should not only be of interest in drug-discovery research, but also to the development of new crop-protection agents, new amine ligands for organometallic complexes, and in particular, to the growing field of amine-based organocatalysis.     

The Critical Role of Passive Permeability in Designing Successful Drugs

Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients.