Stability and DNA binding ability of the DNA binding domains of interferon regulatory factors 1 and 3

The thermodynamic properties and DNA binding ability of the N-terminal DNA binding domains of interferon regulatory factors IRF-1 (DBD1) and IRF-3 (DBD3) were studied using microcalorimetric and optical methods. DBD3 is significantly more stable than DBD1: at 20 degrees C the Gibbs energy of unfolding of DBD3 is -28.6 kJ/mol, which is 2 times larger than that of DBD1, -14.9 kJ/mol. Fluorescence anisotropy titration experiments showed that at this temperature the association constants with the PRDI binding site are 1.1 x 10(6) M(-)(1) for DBD1 and 3.6 x 10(6) M(-)(1) for DBD3, corresponding to Gibbs energies of association of -34 and -37 kJ/mol, respectively. However, the larger binding energy of DBD3 is due to its larger electrostatic component, while its nonelectrostatic component is smaller than that of DBD1. Therefore, DBD1 appears to have more sequence specificity than DBD3. Binding of DBD1 to target DNA is characterized by a substantially larger negative enthalpy than binding of DBD3, implying that the more flexible structure of DBD1 forms tighter contacts with DNA than the more rigid structure of DBD3. Thus, the strength of the DBDs' specific association with DNA is inversely related to the stability of the free DBDs.     

Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating

Using electrostatic calculations, we have examined the dependence of the protonation state of cytochrome c oxidase from bovine heart on its redox state. Based on these calculations, we propose a possible scheme of redox-linked proton pumping. The scheme involves His291 - one of the ligands of the Cu(B) redox center - which plays the role of the proton loading site (PLS) of the pump. The mechanism of pumping is based on ET reaction between two hemes of the enzyme, which is coupled to a transfer of two protons. Upon ET, the first proton (fast reaction) is transferred to the PLS (His291), while subsequent transfer of the second "chemical" proton to the binuclear center (slow reaction) is accompanied by the ejection of the first (pumped) proton. Within the proposed model, we discuss the catalytic cycle of the enzyme.     

Phylogeography of Y-chromosome haplogroup I reveals distinct domains of prehistoric gene flow in europe

To investigate which aspects of contemporary human Y-chromosome variation in Europe are characteristic of primary colonization, late-glacial expansions from refuge areas, Neolithic dispersals, or more recent events of gene flow, we have analyzed, in detail, haplogroup I (Hg I), the only major clade of the Y phylogeny that is widespread over Europe but virtually absent elsewhere. The analysis of 1,104 Hg I Y chromosomes, which were identified in the survey of 7,574 males from 60 population samples, revealed several subclades with distinct geographic distributions. Subclade I1a accounts for most of Hg I in Scandinavia, with a rapidly decreasing frequency toward both the East European Plain and the Atlantic fringe, but microsatellite diversity reveals that France could be the source region of the early spread of both I1a and the less common I1c. Also, I1b*, which extends from the eastern Adriatic to eastern Europe and declines noticeably toward the southern Balkans and abruptly toward the periphery of northern Italy, probably diffused after the Last Glacial Maximum from a homeland in eastern Europe or the Balkans. In contrast, I1b2 most likely arose in southern France/Iberia. Similarly to the other subclades, it underwent a postglacial expansion and marked the human colonization of Sardinia ~9,000 years ago.     

Coupled electron and proton transfer reactions during the O→E transition in bovine cytochrome c oxidase

A combined DFT/electrostatic approach is employed to study the coupling of proton and electron transfer reactions in cytochrome c oxidase (CcO) and its proton pumping mechanism. The coupling of the chemical proton to the internal electron transfer within the binuclear center is examined for the O→E transition. The novel features of the His291 pumping model are proposed, which involve timely well-synchronized sequence of the proton-coupled electron transfer reactions. The obtained pK(a)s and E(m)s of the key ionizable and redox-active groups at the different stages of the O→E transition are consistent with available experimental data. The PT step from E242 to H291 is examined in detail for various redox states of the hemes and various conformations of E242 side-chain. Redox potential calculations of the successive steps in the reaction cycle during the O→E transition are able to explain a cascade of equilibria between the different intermediate states and electron redistribution between the metal centers during the course of the catalytic activity. All four electrometric phases are discussed in the light of the obtained results, providing a robust support for the His291 model of proton pumping in CcO.     

B-type natriuretic peptide predicts new-onset atrial fibrillation in patients with ST-segment elevation myocardial infarction treated by primary percutaneous coronary intervention

The predictive value of B-type natriuretic peptide (BNP) with respect to the occurrence of new-onset atrial fibrillation (AF) in patients with ST-segment elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (PCI) is unknown. The aim of this study was to evaluate whether BNP has a predictive value for the occurrence of new-onset AF in patients with STEMI treated by primary PCI. In 180 patients with STEMI treated by primary PCI, BNP concentrations were measured 24h after chest pain onset. The Receiver Operating Characteristic analysis was performed to identify the most useful BNP cut-off level for the prediction of AF. The patients were divided into the two groups according to calculated cut-off level: high BNP group (BNP≥720 pg/mL, n=33) and low BNP group (BNP<720 pg/mL, n=147). The incidence of AF was 5.0%, and occurred more frequently in high BNP group (7/33, 21.2%) than in low BNP group (2/147, 1.4%), (p<0.001). Patients with high BNP were older (p=0.017), had more often anterior wall infarction (p=0.015), higher Killip class on admission (p=0.038), higher peak troponin I (p=0.002), lower left ventricular ejection fraction (p=0.029) than patients with low BNP. After multivariate adjustment, BNP was an independent predictor of AF (OR 3.70, 95% CI 1.40-9.77, p=0.008). BNP independently predicts the occurrence of new-onset AF in STEMI patients treated by primary PCI.     

Ultra-fast pg/ml anthrax toxin (protective antigen) detection assay based on microwave-accelerated metal-enhanced fluorescence

Rapid presymptomatic diagnosis of Bacillus anthracis at early stages of infection plays a crucial role in prompt medical intervention to prevent rapid disease progression and accumulation of lethal levels of toxin. To detect low levels of the anthrax protective antigen (PA) exotoxin in biological fluids, we have developed a metal-enhanced fluorescence (MEF)-PA assay using a combination of the MEF effect and microwave-accelerated PA protein surface absorption. The assay is based on a modified version of our "rapid catch and signal" (RCS) technology previously designed for the ultra-fast and sensitive analysis of genomic DNA sequences. Technologically, the proposed MEF-PA assay uses standard 96-well plastic plates modified with silver island films (SiFs) grown within the wells. It is shown that the fluorescent probe, covalently attached to the secondary antibody, plays a crucial role of indicating complex formation (i.e., shows a strong MEF response to the recognition event). Microwave irradiation rapidly accelerates PA deposition onto the surface ("rapid catch"), significantly speeding up the MEF-PA assay and resulting in a total assay run time of less than 40 min with an analytical sensitivity of less than 1 pg/ml PA.     

Apatite formation on nanomaterial calcium phosphate/poly-DL-lactide-co-glycolide in simulated body fluid

Simulated body fluid (SBF) is an artificial fluid which has ionic composition and ionic concentration similar to human blood plasma. Purpose: This paper compares the interaction between the nanomaterial containing calcium phosphate/poly-dl-lactide-co-glycolide (N-CP/PLGA) and SBF, in order to investigate whether and to what extent inorganic ionic composition of human blood plasma leads to the aforementioned changes in the material. Methods: N-CP/PLGA was incubated for 1, 2, 3, and 5 weeks in SBF. The surface of the material was analyzed on SEM-EDS and FTIR spectrometer, while SBF was subjected to pH and electrical conductivity measurement. Results: Our results indicate that dissolution of the polymer component of the material N-CP/PLGA and precipitation of the material similar to hydroxyapatite on its surface are based on the morphologic changes seen in this material. Conclusions: The mechanism of the apatite formation on the bioceramic surface was intensively studied and was considered crucial in designing the new biomaterials. The results obtained in this work indicate that N-CP/PLGA may be a good candidate for application to bone regeneration.     

Isometric force development of some muscle groups in athletes

In a large sample of both male and female athletes, subdivided by age and sex, a development curve of isometric muscule force (F) was analyzed for hand flexors, upper-body flexors and extensors, and knee extensors (PDS). A sample of 1,857 male and 1,009 female athletes, aged 8-30 years, subdivided by their age and sex, was used to measure the mean values of isometric muscle force of certain muscle groups by way of 5 topologically defined tests. Based on the results, isometric muscle force (F) development curves are shown and analyzed for the right-hand and left-hand (PLS) flexors, upper-body flexors (PTR), upper-body extensors (OTR), and knee extensors (ONO). The application of certain statistical programs gave rise to equations of the relationship between isometric force and age. The maximum mean value of PLS was chosen as the reference value or "the gold standard," with which PTR, OTR, and ONO were subsequently compared. The relationships were 1:1:1:2.8:5.9 (for male athletes), and 1:1:1.3:3.2:5.2 (for female athletes). The newly derived relationship was recognized as "the canon." The results may have practical application in athletes' fitness and conditioning. Every topologically defined muscle force has its own patterns and rules that should be closely followed in the training process, because any generalization may lead to false conclusions.