Structural, bonding, and electronic properties of the hexagonal ferroelectric and paraelectric phases of LuMnO3 compound: a density functional theory study.

We have investigated the structural, bonding, and electronic properties of both ferroelectric (FE) and paraelectric (PE) phases of the hexagonal LuMnO3 compound using calculations based on density functional theory. The structural properties have been determined by employing the generalized gradient approximation with Perdew-Burke-Ernzerhof and Wu-Cohen parameterization. The bonding and electronic properties have been treated by recently developed modified Becke-Johnson exchange potential, which succeeded to open a band gap for both PE and FE phases, in agreement with experimental predictions. The Bader's topological analysis of electronic density showed that the character of the Lu-O axial bonds changes when the crystal exhibits the PE → FE structural transition. This fact is in agreement with experimental findings. The covalent character of the Lu-O bond significantly increases due to orbital hybridization between the Lu 5dz(2) and O 2pz-states. This bonding mechanism causes the ferroelectricity in the hexagonal LuMnO3 compound.

First-principles study of the BiMO4 antisite defect in the Bi12MO20 (M=Si, Ge, Ti) sillenite compounds.

Structural, electronic and optical properties of the antisite BiMO4 defect in Bi12MO20 sillenites (BMO, M=Si, Ge, Ti) were investigated using density functional theory. The defect is studied in neutral, positively and negatively charged states. It is demonstrated that within the neutral defect the Bi 6s(2) lone pair is broken and the valence state of the Bi is 4+ (6s(1)). Within the charged defects, the Bi 6s orbital is found to be either full (Bi(3+): 6s(2)) or empty (Bi(5+): 6s(0)). All three charged states introduce energy bands within the BMO gap. By analyzing possible transitions between them we deduced a simple model of functioning of the BiMO4 defect that is able to explain the photochromic and photorefractive effect in sillenites and that reproduces almost all known experimental facts.

Does oral health counseling effectively improve oral hygiene of orthodontic patients?

AIM: The aim of this study was to compare the effectiveness of oral health counseling sessions with traditional oral hygiene education in orthodontic patients with fixed appliances. STUDY DESIGN: randomised control trial with experimental and control group. A group of 99 adolescents with fixed orthodontic appliances were randomly assigned to oral health counseling (experimental) or traditional health education (control) group. Subjects in the control group received verbal instructions and a demonstration of the modified Bass brushing technique on a model. The experimental group also received the verbal information with demonstration on the model and in addition a personalised 40-minutes counseling session on oral hygiene. Plaque Index (PI) and gingivitis (G) were recorded before, 1 and 6 months after the counseling session/traditional education. RESULTS: Oral health counseling and traditional education improved the oral hygiene of orthodontic patients. PI values were significantly lower after 6 months compared to the baseline in both groups, but the prevalence of gingival inflammation remained significantly lower only in the experimental group. CONCLUSION: Oral health counseling increased plaque removal efficacy and control of gingival inflammation. The efficiency of counseling and traditional education was similar. Counseling is a promising approach that warrants further attention in a variety of dental contexts.

Th1 cells specific for a secreted protein of Listeria monocytogenes are protective in vivo.

In the present study we have investigated the role of the secreted p60 protein from Listeria monocytogenes as an Ag for CD4 T cells. The p60 protein is an abundant extracellular protein that is highly conserved within the members of the genus Listeria. Our results show that L. monocytogenes infection induces a potent p60-specific Th1 immune response. Remarkably, we found that p60-specific Th1 clones mediate significant protection against L. monocytogenes infection. For one p60-specific clone, the peptide epitope was defined. This clone recognized p60 301-312 (EAAKPAPAPSTN) in the context of the H-2Ad molecule. Despite the fact that acquired immunity against L. monocytogenes is primarily mediated by cytotoxic CD8 T lymphocytes, our data clearly demonstrate that secreted bacterial proteins are important CD4 T cell Ags and that Th1 clones specific for a secreted bacterial protein can contribute to the protection against an intracellular pathogen such as L. monocytogenes.

Nonhemolytic strains of Listeria monocytogenes detected in milk products using VIDAS immunoassay kit.

In December 1995 detection of Listeria monocytogenes Sv 1/2a in milk products that were routinely sampled for investigation at the Austrian Federal Food Inspection Laboratory (Vienna) led the food manufacturer in question to withdraw his product from the market. While one of seven Listeria strains isolated from this food product using "VIDAS L. monocytogenes kit" was undoubtedly L. monocyotogenes, six strains were nonhemolytic. In classical bacteriology haemolysin is used as an important phenotypic property to differentiate L. monocytogenes from the apathogenic L. innocua species. Species identification by PCR and by Western blotting confirmed that all nonhemolytic strains were indeed L. monocytogenes. Our confirmation of nonhemolytic isolates as true L. monocytogenes strains underlines the considerable potential of the VIDAS system as a specific immunological easy-to-use and automated test kit for detection of L. monocytogenes in food products. Whether or not the presence of non-hemolytic Listeria monocytogenes in food products justifies legal actions should be addressed by the proper authorities.

Postprandial response of serum cationic trypsin-like immunoreactivity in insulin-dependent diabetes mellitus.

Conflicting reports exist on the postprandial response of serum cationic trypsin like immunoreactivity (SCTLI). The purpose of the current study was to examine the postprandial response of SCTLI in healthy persons and in insulin dependent diabetes mellitus (IDDM) patients and relate this to C-peptide secretion. The study was performed on six healthy males 25-40 years old and in nine male IDDM patients 25-38 years old. To all the patients after an overnight fast was given a standardized breakfast. Blood samples were obtained through a butterfly needle inserted into the antecubital vein at 0, 30, 60 and 120 minutes. Radioimmunoassays were performed using commercially available kits: for SCTLI CIS-SORIN and for C-peptide BIODATA. In healthy persons there was a significant rise of SCTLI concentration at 30 minutes, and C-peptide at 30 and 60 minutes. IDDM patients showed lower basal levels of SCTLI and C-peptide, without any significant changes of SCTLI and C-peptide during the test. We concluded that trypsin appearance in serum closely correlates with endocrine pancreatic function.