Merging gold plasmonic nanoparticles and L-proline inside a MOF for plasmon-induced visible light chiral organocatalysis at low temperature.

Light-driven asymmetric photocatalysis represents a straightforward approach in modern organic chemistry. In comparison to the homogeneous one, heterogeneous asymmetric photocatalysis has the advantages of easy catalyst separation, recovery, and reuse, thus being cost- and time-effective. Here, we demonstrate how plasmon-active centers (gold nanoparticles - AuNPs) allow visible light triggering of chiral catalyst (proline) in model aldol reaction between acetone and benzaldehyde. The metal-organic framework UiO-66-NH2 was used as an advanced host platform for the loading of proline and AuNPs and their stabilization in spatial proximity. Aldol reactions were carried out at a low temperature (-20 °C) under light illumination which resulted in 91% ee with a closed-to-quantitative yield, 4.5 times higher than that without light (i.e. in the absence of plasmon triggering). A set of control experiments and quantum chemical modeling revealed that the plasmon assistance proceeds through hot electron excitation followed by an interaction with an enamine with the formation of anion radical species. We also demonstrated the high stability of the proposed system in multiple catalytic cycles without leaching metal ions, which makes our approach especially promising for heterogeneous asymmetric photocatalysis.

Comparative analysis of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase expression in colorectal cancer and surrounding normal tissue.

Thymidylate synthase [TS], thymidine phosphorylase [TP] and dihydropyrimidine dehydrogenase [DPD] play the essential role in the activation and catabolism of the fluoropyrimidines used in cancer therapy. Its expression may influence the antitumor activity or toxicity of these drugs. We studied the expression levels of selected enzymes in colorectal tumors and adjacent normal mucosa. The analysis of TS, TP and DPD gene expression was performed using quantitative Real time PCR technique (Roche) in 15 (TS), 64 (TP) and 12 (DPD) of 64 colorectal cancer patients. The mean gene expression of TS, TP and DPD was found to be 3.29; 3.79 and 8.24 in tumors and 1.88; 3.80 and 19.69 in normal mucosa. The corresponding median gene expression was 1.87; 2.32 and 4.50 for tumors and 2.14; 2.63 and 11.64 for normal tissue. We did not find any significant differences in TS, TP and DPD gene expression between colorectal tumor and surrounding mucosa.

[Cellular and tissue hypoxia--role of the von Hippel Lindau gene and hypoxia-inducible factor-1]. / Bunecná a tkánová hypoxie--úloha von Hippel Lindau genu a hypoxií indukovaného faktoru-1.

Hypoxia results in increased expression of some genes. This can compensate effects of hypoxia on the organism, and adapt cells and tissues to the environment with low oxygen tension. Mechanisms of cell and tissue responses to hypoxia have been extensively studied last years. The first identified mediator of cell response to hypoxia was hypoxia-inducible factor (HIF-1), which is being up regulated during hypoxic conditions. It binds to regulatory regions of sensitive genes and increases their transcription rate. Other key elements of cell response to hypoxia have been described recently--von Hippel-Lindau protein and prolyl hydroxylases, that allow degradation of alpha-subunit of HIF-1 during normal oxygen tension. This can ensure low level of HIF-1 in cells under physiological oxygen tension thus the expression of target genes is maintained on basal level. These new findings are starting points for further research and possible therapeutic use.

Cytokine gene expression in regenerating haematopoietic tissues of mice after cyclophosphamide treatment.

The goal of the study was to investigate changes in expression of selected growth factors tentatively involved in regeneration of haematopoietic tissues (bone marrow and spleen) following cyclophosphamide (CY) damage in the mouse. The bone marrow (BM) and spleen were examined separately, since the regenerating pattern for haematopoietic progenitor cells (HPC) markedly differs in these two haematopoietically active organs after CY. Cytokines assumed to have a stimulatory effect on HPC - stem cell factor (SCF), fetal liver tyrosine kinase 3-ligand (flt3-ligand), thrombopoietin (TPO), stromal cell-derived factor 1 (SDF-1), oncostatin M (OSM) -, a suppressive effect on HPC proliferation - macrophage inflammatory protein-1alpha (MIP-1alpha), transforming growth factor-beta1 (TGFbeta1), tumour necrosis factor-alpha (TNFalpha) - and to be involved in migration of HPC (SCF, flt3-ligand, MIP1alpha, SDF-1) were examined at the level of mRNA expression by means of real-time RT-PCR. The expression of a particular cytokine appears to be similar in both BM and spleen of untreated mice. CY administration changed the expression pattern of the studied genes in BM and spleen. In BM, the levels of mRNAs for SCF and SDF-1 were increased and that for TGFbeta1 decreased at time intervals at which HPC are known to proliferate intensively during BM regeneration. In contrast, stimulated proliferation of HPC in spleen was accompanied by increased expression of flt3-ligand and oncostatin M. Upon mobilization of HPC from BM into blood after CY, the expression of SCF, TPO, SDF-1 and TGFbeta1 tends to decrease in BM. Accumulation of HPC in spleen is accompanied by increased mRNA for flt3-ligand and OSM. Our findings demonstrate that different cytokines may be involved in the proliferation and mobilization/homing of HPC during recovery after CY damage in BM and spleen.

Biodegradability of ethylenediamine-based complexing agents and related compounds.

The biological degradability (Zahn-Wellens test) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Mixed bacterial culture (activated sludge) was used as inoculum (non-adapted sludge and sludge adapted at different mean biomass retention time, the so-called sludge age). Biodegradability of ethylene(propylene)di(tri)amine-based complexing agents depends on the character and number of substituents and nitrogen atoms in the molecule. Tetra(penta)substituted derivatives with two or more tertiary nitrogen atoms and carboxymethyl or 2-hydroxyethyl groups in the molecule (EDTA, DTPA, PDTA, HEDTA) are very stable from an environmental point of view. On the contrary, disubstituted derivatives with two secondary nitrogen atoms in the molecule (e.g., EDDA) are potentially degradable.

Biodegradability of ethylenediamine-based complexing agents.

Biological degradability of ethylenediamine derivatives depends on the type and number of substituents. The susceptibility to biodegradation decreases in the sequence of substituents -COCH3, -CH3, -C2H5, -CH2CH2OH, -CH2COOH and with polysubstitution. The biodegradability depends also on the kind and number of nitrogen atoms. Complexing agents with a single-nitrogen atom in the molecule (e.g. NTA) succumb relatively readily to biodegradation whereas, compounds with two or more tertiary amino groups are biologically highly stable and do not undergo biodegradation even in experiments with activated sludge adapted at an age of up to 30 days (EDTA, DTPA, PDTA, HEDTA). A lowering of the degree of substitution brings about an increased susceptibility to biodegradation. This holds, e.g., for replacement of tertiary amino groups with secondary ones; thus the symmetrically disubstituted ethylenediamine-N,N'-diacetic acid (EDDA) possesses still sufficient complexing ability while belonging already to the group of potentially degradable substances.

Hairlessness does not influence growth retardation in nude mice. Computer image analysis study.

Ossification in 4-week-old nu/nu and nu/+ BALB/c and BFU mice was studied by X-ray analysis and by measurement of the thickness of the proximal tibial growth cartilage using CUE 4 Olympus computer image analysis. Not only altered architecture but also a significantly thinner proximal tibial growth plate was observed in athymic nu/nu as opposed to nu/+ and BFU mice. On the other hand, no significant differences were found between nu/+ and BFU littermates. Higher X-ray density of tail vertebrae was observed in nu/+ and BFU than in nu/nu mice. This comparison between athymic nu/nu and hairless euthymic BFU mice indicates that altered postnatal ossification in nude mice is not caused by hairlessness, but is due to other (immunological or endocrinological) differences.

Development of the cellular response in the mouse omentum after intraperitoneal immunization.

Using computer image analysis we studied the development of dense cellular and dense lymphoid areas ("milky spots") and of pendant lymphatic nodules in mouse omenta after intraperitoneal immunization with sheep red blood cells. In both euthymic (BALB/c and hairless BFU) and athymic hairless nu/nu BALB/c mice the proportion of newly developing activated omental areas (AOA) was biphasic, with distinct peaks on days 3-4 and 8-12 after immunization, and a trough on days 5 and 14. There was a small difference between athymic and euthymic BALB/c mice. In comparison with the nu/nu BALB/c mouse, the BFU mutant had a lower proportion of AOA on days 4 and 10. The athymic state is not thought to have a great influence on the AOA development; this depends on a basic macrophage defence, which is well developed in the athymic model, and is self-regulated and shaped by a sequence of cell immigration, settling, differentiation and emigration.

[Influence of feed mixtures supplemented with animal fat on milk yield and milk composition]. / Der Einfluss von Futtermischungen mit Zusatz von tierischem Fett auf die Menge und Zusammensetzung der Milch

Animal fat was administered in fat-supplemented mixtures of concentrates in amounts varying from 0%, 5%, to 10%. The trials were carried out on 12 dairy cows. The best results were obtained with mixed concentrates containing 5% of animal fat. Animals on these food rations produced 6.75% more milk (expressed in units of fat-corrected milk (FCM) and 9.87% more milk fat. Additions of animal fat affected the composition of milk fat in such a way that the milk contained smaller portions of short-chain fatty acids and higher proportions of stearic and oleic acid.