Translocation of radioactivity from substrate to macromycetes in the Crucea (Romania) uranium mining area

The present study follows the extent of translocation radioactivity from the substrates of the Crucea uranium mining area to the macromycetes spontaneously occurred during June–October 2008. To this end, radioactivity measurements (gross α + β and ¹³⁷Cs) on both macromycetes and their substrates were made. The resultants obtained were confirmed by FT-IR spectroscopy, evidencing the presence of characteristic bands around of 910 cm⁻¹, corresponding to the asymmetric stretching vibration of the uranyl unit and to the interaction between the UO₂ ²⁺ ions and the group belonging to various cellular components.     

Current trends in lead discovery: are we looking for the appropriate properties?

The new drug discovery paradigm is based on high-throughput technologies, both with respect to synthesis and screening. The progression HTS hits lead series candidate drug marketed drug appears to indicate that the probability of reaching launched status is one in a million. This has shifted the focus from good quality candidate drugs to good quality leads. We examined the current trends in lead discovery by comparing MW (molecular weight), LogP (octanol/water partition coefficient, estimated by Kowwin [17]) and LogSw (intrinsic water solubility, estimated by Wskowwin [18]) for the following categories: 62 leads and 75 drugs [11]; compounds in the development phase (I, II, III and launched), as indexed in MDDR; and compounds indexed in medicinal chemistry journals [ref. 20], categorized according to their biological activity. Comparing the distribution of the above properties, the 62 lead structures show the lowest median with respect to MW (smaller) and LogP (less hydrophobic), and the highest median with respect to LogSw (more soluble). By contrast, over 50% of the medicinal chemistry compounds with activities above 1 nanomolar have MW > 425, LogP > 4.25 and LogSw < -4.75, indicating that the reported active compounds are larger, more hydrophobic and less soluble when compared to time-tested quality leads. In the MDDR set, a progressive constraint to reduce MW and LogP, and to increase LogSw, can be observed when examining trends in the developmental sequence: phase I, II, III and launched drugs. These trends indicate that other properties besides binding affinity, e.g., solubility and hydrophobicity, need to be considered when choosing the appropriate leads.     

HT-7装置电子回旋辐射系统接收天线改进

为了提高HT-7装置上等离子体电子回旋辐射(ECE)超外差诊断系统的极向分辨率,根据高斯光学原理,分析了诊断系统天线的改进方案。优化了天线的圆形角锥喇叭尺寸和凸透镜参数以及在装置上的相对位置,使天线接收到的等离子体ECE异常模二次谐波辐射的高斯光束束半径只有30mm左右,能量的高斯光学性质损失不大于13%。     

Synthesis,characterization, and biological activity of some complex combinations of nickel with α-ketoglutaric acid and 1-(o-tolyl)biguanide

The four divalent nickel complexes having α-ketoglutaric acid (H₂A) and 1-(o-tolyl)biguanide (TB) ligands have been synthesized, characterized, and tested for antibacterial and antitumor activity.The proposed formulas for these complexes are [Ni(TB)(HA)(H₂O)₂]Cl (C1), [Ni(TB)(HA)(H₂O)₂]Br (C2), [Ni(TB)(HA)]NO₃·H₂O (C3), and [Ni(TB)(HA)]CH₃COO (C4), where HA represents deprotonated H₂A.For the four complexes and for the ligands used in the synthesis, the antibacterial activity against Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 and antitumor activity in HeLa tumor cells were tested. A moderate cytotoxic effect of C3 and C4 complexes has been observed on the development and metabolic activity of HeLa cells, whereas C1 and C2 ligands have a very low effect on them.The synthesized complexes (obtained) inhibit adherence to the inert substrate of bacterial strains S. aureus and P. aeruginosa; therefore, they may be candidates for (potential) therapeutic applications.     

Preparation and characterization of strontium targets for nuclear astrophysics experiments

Journal of Radioanalytical and Nuclear Chemistry - The present paper describes preparation and characterization of strontium targets for nuclear astrophysical experiments with alpha particles...     

Higher Lefschetz Traces and Spherical Euler Characteristics

Higher analogs of the Euler characteristic and Lefschetz number are introduced. It is shown that they possess a variety of properties generalizing known features of those classical invariants. Applications are then given. In particular, it is shown that the higher Euler characteristics are obstructions to homotopy properties such as the TNCZ condition, and to a manifold being homologically Kähler.

     

MTD-PLS: a PLS variant of the minimal topologic difference method. III. Mapping interactions between estradiol derivatives and the alpha estrogenic receptor

A homogeneous collection of 45 estrogen agonist derivatives with relative binding affinities measured to the estrogen receptor from Ratus norvegicus was used. The quantitative structure-activity relationships were derived using an improved minimal topologic difference (MTD) method in a partial least-squares (PLS) variant. The spatially assigned analysis of fragment properties can provide receptor site maps, within the limits of the existing series. A steric misfit was found for the steroidal position 2; benefic hydrophobic and van der Waals (enhanced by high polarizability) interactions were found for the 17alpha-CH=CH-X group. MTD-PLS mapping results are confirmed by the experimentally derived estradiol-estrogen receptor binding site contacts (based on X-ray crystallography). Our results suggest that this MTD-PLS method can yield useful results for interactions with receptors of unknown 3D structure and, generally, for the steric rigidity of receptor sites.     

ENERGY TRANSFER FROM CAROTENOIDS TO CHLOROPHYLL a IN BLACK LIPID MEMBRANES

Abstract— Black lipid membranes (BLM) were prepared from extracts of Chlorella and spinach chloroplasts. Excitation spectra of the 730 nm fluorescence of chlorophyll a in the BLM contained peaks identified as due to carotenoids and which therefore indicate sensitization of the chlorophyll fluorescence by them. The efficiency of this energy transfer was evaluated by comparison of the actual excitation spectra with those corresponding to 0 and 100 per cent transfer efficiency. Efficiencies were of the order of 40–50 per cent in BLM, but only 10 per cent in pigment solutions, when the mean distance between pigment molecules was 23 Å in both systems. The fluorescence quantum yield of chlorophyll a in such solutions was only 2 per cent of that found in BLM. Enhancement of energy transfer in BLM is considered to be mainly due to suppression of competing deactivation processes of excited carotenoid states, such as diffusional quenching by ground-state molecules and internal conversion. Favorable orientation of pigment molecules in the BLM constitutes a further enhancement factor.     

WHOLE-CELL CLAMP STUDY OF XENOPUS EMBRYONIC CHOLINERGIC NEURONS

Whole-cell clamped myoballs are placed into direct visible contact with the growth cones of isolated neurons in embryonic Xenopus culture to serve as probe of acetylchollne (AcCHo) release in order to determine whether these neurons are cholinergic or not. Using a GQ-seal, whole-cell recording method, the electrophysiological properties of these identified cholinergic neurons are studied. It is found that these embryonic neurons, like adult frog motor neurons, exhibit repetitive firings in a certain embryonic developing stage. A development of repetitive firings is observed simultaneously. Tracing the development of one neuron, we find that the development of repetitive firing is completed at the 48th h after fertilization. Tetrodotoxin (TTX) which blocks Na~+ channels can abolish all firings; and tetraethyl ammonium chloride (TEA), the blocker of K~+ channels, reverses this development, i. e. it makes the repetitive firings disappear again. These data show that the nature of the development of repetiti