Sigma- and pi- electron structure of aza-azoles

The reasons behind changes of aromaticity in 10 unsubstituted aza-azoles were analysed by employing the natural bond orbital (NBO) approach at the MP2/6-311+G(d,p) level of theory. Sum of occupations of p _z orbitals at atoms in the ring correlates well with the magnetism based aromaticity index NICS as well as with the number of nitrogen atoms in the ring. Changes of NICS depend strongly in a linear way on the number of NN bonds. Classification of azoles based on the number of pyridine-type nitrogen atoms vicinal to NH is supported by plotting the relative occupation of π orbitals (π_occ) against the relative occupation of σ orbitals (σ_occ) for all individual atoms in rings.     

Alterations in the expression of the Atp7a gene in the early postnatal development of the mosaic mutant mice (Atp7amo-ms) – An animal model for Menkes disease

Copper is a trace element that is essential for the normal growth and development of all living organisms. In mammals, the ATP7A Cu-transporting ATPase is a key protein that is required for the maintenance of copper homeostasis. In both humans and mice, the ATP7A protein is coded by the X-linked ATP7A/Atp7a gene. Disturbances in copper metabolism caused by mutations in the ATP7A/Atp7a gene lead to severe metabolic syndromes Menkes disease in humans and the lethal mottled phenotype in mice. Mosaic is one of numerous mottled mutations and may serve as a model for a severe Menkes disease variant. In Menkes patients, mutations in the ATP7A gene often result in a decreased level of the normal ATP7A protein. The aim of this study was to analyse the expression of the Atp7a gene in mosaic mutants in early postnatal development, a critical period for starting copper supplementation therapy in both Menkes patients and mutant mice. Using real-time quantitative RT-PCR, we analysed the expression of the Atp7a gene in the brain, kidney and liver of newborn (P0.5) and suckling (P14) mice. Our results indicate that in mosaic P0.5 mutants, the Atp7a mRNA level is decreased in all analysed organs in comparison with wild-type animals. In two week-old mutants, a significant decrease was observed only in the kidney. In contrast, their hepatic level of Atp7a tended to be higher than in wild-type mice. We speculate that disturbance in the expression of the Atp7a gene and, consequently, change in the copper concentration of the organs, may contribute to the early fatal outcome of mosaic males.     

Selenium and glutathione peroxidases in blood of patients with different stages of chronic renal failure

In patients with chronic renal failure (CRF) Se concentration in blood components is usually lower as compared with healthy controls. One of the five known forms of Se-dependent glutathione peroxidases (GSH-Px), the plasma GSH-Px, is synthesized primarily in the kidney. In CRF patients, plasma GSH-Px activity is reduced and the reduction increases with the progress of the disease.

The Se concentration in blood components was measured spectrofluorometrically with 2,3-diaminonaphthalene as complexing reagent. Activities of GSH-Px in red cells and in plasma were assayed by the coupled method with t-butyl hydroperoxide as substrate. The study group consisted of 150 patients in different stages of CRF. The results were compared with the values for 30 healthy subjects.

Se concentrations in whole blood and plasma of the entire group of patients were significantly lower (p < 0.01) as compared with the healthy subjects. In the incipient stage, however, the Se levels in all blood components were non-significantly lower. In whole blood and plasma the Se levels gradually decreased, reaching in the end stage values that were lower by 29 to 32% (p < 0.0001) as compared with the control group. Total protein and albumin levels in plasma of patients were significantly lower (p < 0.0001) as compared with healthy subjects and they decreased linearly with the progress of the disease. Positive and highly significant correlations were noted between total plasma protein and plasma Se concentrations (p < 0.0001) as well as between plasma albumin and plasma Se concentrations (p < 0.0001).

Red cell GSH-Px activity in the entire group of patients was lower (p < 0.05) than in the control group and did not change significantly with the progress of the disease. In plasma, however, GSH-Px activity of the entire group was lower by 33% (p < 0.0001) as compared with healthy subjects and decreased gradually with increasing renal failure. Highly significant, inverse correlations were seen between creatinine levels and plasma GSH-Px activities (p < 0.0001) as well as between urea nitrogen levels and plasma GSH-Px activities (p < 0.0001) when all stages of the disease were included.

In conclusion, patients with CRF exhibit lower Se levels in blood components as compared with healthy subjects. In whole blood and plasma these levels decrease with the progress of the disease. Plasma GSH-Px activity in patients was extremely reduced and it dramatically decreased with the progress of the illness.     

Probabilistic discounting in “certain gain-uncertain loss” and “certain loss-uncertain gain” conditions

Studies on probabilistic discounting typically involve choosing between two outcomes of the same sign (i.e., positive or negative). Commonly, participants are given a choice between a smaller, certain gain and a larger, but uncertain gain, or (less commonly) the options may be a certain, smaller loss and an uncertain, but larger loss. In contrast, participants in this study had to make yes/no decisions as to whether they would accept a financial offer involving a combination of both a gain and a loss. This offer could be either a certain gain which, when accepted, could bring an uncertain larger loss, or a certain loss which, when accepted, could bring an uncertain larger gain. Despite the substantial differences between the alternatives posed in the present study and those in typical discounting studies, the same hyperboloid discounting function that describes the choice between certain and uncertain gains also accurately described choice in the situations presented in the present study. In addition, steeper discounting was observed with a larger uncertain gain than with a smaller uncertain gain. No amount effect was revealed with uncertain losses.     

Factors that Affect the Content of Cadmium,Nickel, Copper and Zinc in Tissues of the Knee Joint

Osteoarthritis causes the degradation of the articular cartilage and periarticular bones. Trace elements influence the growth, development and condition of the bone tissue. Changes to the mineral composition of the bone tissue can cause degenerative changes and fractures. The aim of the research was to determine the content of cadmium (Cd), nickel (Ni), copper (Cu) and zinc (Zn) in the tibia, the femur and the meniscus in men and women who underwent a knee replacement surgery. Samples were collected from 50 patients, including 36 women and 14 men. The determination of trace elements content were performed by ICP-AES method, using Varian 710-ES. Average concentration in the tissues of the knee joint teeth amounted for cadmium 0.015, nickel 0.60, copper 0.89 and zinc 80.81 mg/kg wet weight. There were statistically significant differences in the content of cadmium, copper and zinc in different parts of the knee joint. There were no statistically significant differences in the content of cadmium, nickel, copper and zinc in women and men in the examined parts of the knee joint. Among the elements tested, copper and nickel showed a high content in the connective tissue (the meniscus) compared to the bone tissue (the tibia and the femur).     

Comparison of dose distribution in IMRT and RapidArc technique in prostate radiotherapy

AimThe aim was to provide a dosimetric comparison between IMRT and RapidArc treatment plans with RPI index with simultaneous comparison of the treatment delivery time.BackgroundIMRT and RapidArc provide highly conformal dose distribution with good sparing of normal tissues. However, a complex spatial dosimetry of IMRT and RapidArc plans hampers the evaluation and comparison between plans calculated for the two modalities. RPI was used in this paper for treatment plan comparisons. The duration of the therapeutic session in RapidArc is reported to be shorter in comparison to therapeutic time of the other dynamic techniques. For this reasons, total treatment delivery time in both techniques was compared and discussed.Materials and methods15 patients with prostate carcinoma were randomly selected for the analysis. Two competitive treatment plans using respectively the IMRT and RapidArc techniques were computed for each patient in Eclipse planning system v. 8.6.15. RPIwin^® application was used for RPI calculations for each treatment plan.Additionally, total treatment time was compared between IMRT and RapidArc plans. Total treatment time was a sum of monitor units (MU) for each treated field.ResultsThe mean values of the RPI indices were insignificantly higher for IMRT plans in comparison to rotational therapy. Comparison of the mean numbers of monitor units confirmed that the use of rotational technique instead of conventional static field IMRT can significantly reduce the treatment time.ConclusionAnalysis presented in this paper, demonstrated that RapidArc can compete with the IMRT technique in the field of treatment plan dosimetry reducing the time required for dose delivery.     

Alfalfa Nuclei Contain Cold-Responsive Phosphoproteins and Accumulate Heat-Stable Proteins during Cold Treatment of Seedlings

We have examined whether low temperature, as a pervasive thermodynamicstimulus, is sensed independently in different parts of thecell by studying low temperature responses of phosphoproteinsin isolated nuclei. The isolated alfalfa (Medicago saliva) nucleirespond to cold by rapid and reversible changes in phosphorylationlevel of their proteins. The population of such cold-regulatedphosphoproteins and the cold-stimulation of their phosphorylationare greater in a freezing-tolerant cultivar Apica than in asensitive cultivar Trek. With a 4-day cold treatment of theseedlings, additional proteins showing cold-stimulated phosphorylationappear in the nucleus of Apica while there is little changein the case of Trek. Furthermore, nuclei from cold-treated seedlingsof Apica, but not of Trek, show a large accumulation of heat-stableproteins. These results support the view that the low temperaturesensing and acclimation occur in all vital parts of the celland that accumulation of heat-stable nuclear proteins may berelated to freezing tolerance. (Received October 14, 1996; Accepted November 11, 1996)     

Estimation of binding parameters for the protein–protein interaction using a site-directed spin labeling and EPR spectroscopy

Sensitivity of the electron paramagnetic resonance (CW EPR) to molecular tumbling provides potential means for studying processes of molecular association. It uses spin-labeled macromolecules, whose CW EPR spectra may change upon binding to other macromolecules. When a spin-labeled molecule is mixed with its liganding partner, the EPR spectrum constitutes a linear combination of spectra of the bound and unbound ligand (as seen in our example of spin-labeled cytochrome c ₂ interacting with cytochrome bc ₁ complex). In principle, the fraction of each state can be extracted by the numerical decomposition of the spectrum; however, the accuracy of such decomposition may often be compromised by the lack of the spectrum of the fully bound ligand, imposed by the equilibrium nature of molecular association. To understand how this may affect the final estimation of the binding parameters, such as stoichiometry and affinity of the binding, a series of virtual titration experiments was conducted. Our non-linear regression analysis considered a case in which only a single class of binding sites exists, and a case in which classes of both specific and non-specific binding sites co-exist. The results indicate that in both models, the error due to the unknown admixture of the unbound ligand component in the EPR spectrum causes an overestimation of the bound fraction leading to the bias in the dissociation constant. At the same time, the stoichiometry of the binding remains relatively unaffected, which overall makes the decomposition of the EPR spectrum an attractive method for studying protein–protein interactions in equilibrium. Our theoretical treatment appears to be valid for any spectroscopic techniques dealing with overlapping spectra of free and bound component.