The Effect of Single Mismatches on Primer Extension

BACKGROUND Allele-specific PCR is an important diagnostic tool that identifies single-nucleotide variants by preferential amplification of a particular allele, using primers that are mismatched to all but one allele variant. METHODS We applied a fluorescent stopped-flow polymerase assay to measure extension rates from oligonucleotide hairpins to simulate primer–template pairs. Under PCR-applicable conditions, reaction rates were recorded in nucleotides per second per polymerase (nt/s/poly). The effects of temperature, potassium chloride, mismatch type, and position were studied with primarily a deletion mutant of Thermus aquaticus (Taq) DNA polymerase and 135 oligonucleotide sequences. RESULTS Rates at 65 °C were between 205 ± 11 and 177 ± 8 nt/s/poly for matched templates and between 4.55 ± 0.21 and 0.008 ± 0.005 nt/s/poly for 3′-mismatched templates. Although extension rates progressively increased with mismatches further away from the 3′ end, rates were still reduced by as much as 84% with a C · C mismatch 6 bases from the 3′ end. The optimal extension temperature for matched sequences was 70 °C, shifting to 55–60 °C for 3′ mismatches. KCl inhibited mismatch extension. The Michaelis constant (Km) was increased and the apparent unimolecular rate constant (kcat) decreased for 3′ mismatches relative to matched templates. CONCLUSIONS Although primer extension of mismatches depends on mismatch type and position, variation also depends on local sequence, KCl concentration, and the type of polymerase. Introduction of 3′ mismatches reduces the optimal temperature for extension, suggesting higher annealing temperatures for better allele discrimination. Quantitative descriptions of expected specificity in allele-specific PCR provide additional design direction and suggest when other methods (e.g., high-resolution melting analysis) may be a better choice.

PROVISION OF EMPLOYEES’ HEALTH - A NECESSARY ELEMENT OF CORPORATE SOCIAL RESPONSIBILITY IN RUSSIA

The paper studies some opportunities of corporate social responsibility implementation that may improve Russian population’s health. The study shows such employees’ health support problems as ecological, organizational and social problems as well as economic, financial and informational issues. The analysis of the companies’ CSR including employees’ health increase measures has been given in the article. The paper also provides a way of employees’ health support measure extension by modern and traditional therapeutic techniques. The article explains the necessity to add CSR units that will provide employees not only with treatment but ill-health prevention, healthy lifestyle promotion and independent researches on the therapeutic measure influence on health condition, production and working efficiency rates. These studies are offered to be carried out by labor economics specialists.

Classification Proposal to measure extension defects of endodontically treated anterior teeth

Summary: A classification of the extension defects ofendodontically anterior teeth is presented. This classification is based on the amount of remanentcoronal tooth after an essential treatment has been done, such as: root canal therapy, removal ofcarious tissue, periodontal surgery whenever needed and tooth preparation either for the placementof a direct restoration material such as composite or a post and core and full crown restoration.This classification is based on 3 specific variables: supragingival remaining coronal toothstructure or core height, diameter and root canal depth. Key words: Post and core. Root canaltreatment. Diagnostic.

A note on measure extension problem of ℓ-group-valued measures

For an Abelian, Archimedean Dedekind complete lattice-ordered, weakly σ-distributive group G and an algebra Ƒ of subsets of a set X, every positive measure μ: Ƒ→G has a unique countably additive (in order convergence) extension to σ-algebra generated by Ƒ.