The prevalence of methicillin-resistant Staphylococcus aureus among nursing home residents for the elderly in Slovakia.

The objective of our study was to examine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) among residents of nursing homes for the elderly of selected institutions in two Slovak regions compared to non-institutionalized volunteers of the same age, as well as young volunteers (20-24 years old). Nasal swabs from all participants (n = 424) were processed using standard methods for the isolation and identification of S. aureus and MRSA. Statistically significant differences were found between nursing home residents and young volunteers (12% vs. 1.5%; OR 8.85; 95% CI 2.087-37.706; p = 0.0007), as well as between non-institutionalized seniors and young volunteers (11% vs. 1.5%; OR 8; 95% CI 1.888-33.901; p = 0.005) in the prevalence of MRSA. Our results suggest that nursing home residency and older age could be a risk factor for the occurrence of high-risk MRSA strains.

Applications of a powerful model organism Caenorhabditis elegans to study the neurotoxicity induced by heavy metals and pesticides.

The expansion of industry and the use of pesticides in agriculture represent one of the major causes of environmental contamination. Unfortunately, individuals and animals are exposed to these foreign and often toxic substances on a daily basis. Therefore, it is crucial to monitor the impact of such chemicals on human health. Several in vitro studies have addressed this issue, but it is difficult to explore the impact of these compounds on living organisms. A nematode Caenorhabditis elegans has become a useful alternative to animal models mainly because of its transparent body, fast growth, short life cycle, and easy cultivation. Furthermore, at the molecular level, there are significant similarities between humans and C. elegans. These unique features make it an excellent model to complement mammalian models in toxicology research. Heavy metals and pesticides, which are considered environmental contaminants, are known to have affected the locomotion, feeding behavior, brood size, growth, life span, and cell death of C. elegans. Today, there are increasing numbers of research articles dedicated to this topic, of which we summarized the most recent findings dedicated to the effect of heavy metals, heavy metal mixtures, and pesticides on the well-characterized nervous system of this nematode.

Expansion of bound-state energies in powers of m/M.

We describe a new approach to computing energy levels of a nonrelativistic bound state of two constituents with masses M and m, by a systematic expansion in powers of m/M. After discussing the method, we demonstrate its potential with an example of the radiative recoil corrections to the Lamb shift and hyperfine splitting relevant for the hydrogen, muonic hydrogen, and muonium. A discrepancy between two previous calculations of O(alpha(Zalpha)5m2/M) radiative recoil corrections to the Lamb shift is resolved and several new terms of O(alpha(Zalpha)5m4/M3) and higher are obtained.

O(alpha(3) lnalpha) corrections to muonium and positronium hyperfine splitting.

We compute O(alpha(3)lnalpha) relative corrections to the ground-state hyperfine splitting of a QED two-body bound state with different masses of constituents. The general result is then applied to muonium and positronium. In particular, a new value of the muon-to-electron mass ratio is derived from the muonium ground-state hyperfine splitting.

Three-loop slope of the dirac form factor and the 1S lamb shift in hydrogen

The last unknown contribution to hydrogen energy levels at order malpha(7), due to the slope of the Dirac form factor at three loops, is evaluated in a closed analytical form. The resulting shift of the hydrogen nS energy level is found to be 3.016/n(3) kHz. Using the QED calculations of the 1S Lamb shift, we extract a precise value of the proton charge radius r(p) = 0.883+/-0.014 fm.

Three-Loop Slope of the Dirac Form Factor and the 1S Lamb Shift in Hydrogen.

The last unknown contribution to hydrogen energy levels at order mα^{7}, due to the slope of the Dirac form factor at three loops, is evaluated in a closed analytical form. The resulting shift of the hydrogen nS energy level is found to be 3.016/n^{3} kHz. Using the QED calculations of the 1S Lamb shift, we extract a precise value of the proton charge radius r_{p}=0.883±0.014 fm.