RESUMO
Taking advantage of point mutations between DNA sequences of closely related microbial strains, PCR primers modified with respect to the target sequence at positions 2-5 near the 3' end were designed to obtain a fragment harbouring an artificial restriction site specific for a given strain. The modified forward primer coupled with a specific reverse primer allows for the amplification of DNA fragments which can be digested with the specific endonuclease only in those strains where the restriction site is inserted by the DNA polymerase. The effectiveness of the method, named restriction site insertion-PCR (RSI-PCR), was tested on isolates of the 'Bacillus cereus group' for the rapid typing and discrimination of these closely related strains.
Assuntos
Técnicas de Tipagem Bacteriana , Reação em Cadeia da Polimerase/métodos , Bacillus cereus/classificação , Bacillus cereus/genética , Primers do DNA/genética , DNA Bacteriano/genética , DNA Ribossômico/genética , Estudos de Viabilidade , Mutação Puntual , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , RNA Ribossômico 23S/genética , Especificidade da EspécieRESUMO
The internal transcribed spacers between the 16S and the 23S ribosomal RNA genes were used to discriminate species of the 16S rRNA group I of the genus Bacillus by PCR. The spacer-PCR fingerprints clearly discriminated the different species, except those closely related like the members of the 'B. cereus group' (B. cereus, B. thuringiensis and B. mycoides) and the species of the 'B. subtilis group' (B. amyloliquefaciens and B. licheniformis). Examining in more detail the shortest internal transcribed spacers, B. subtilis group species were distinguished by single-strand conformation polymorphism analysis, whereas B. mycoides was differentiated from B. cereus/B. thuringiensis by restriction analysis.
Assuntos
Bacillus/classificação , Bacillus/genética , DNA Ribossômico/química , RNA Ribossômico 16S/genética , Animais , Impressões Digitais de DNA , DNA Bacteriano/análise , DNA Ribossômico/genética , Marcadores Genéticos , Humanos , Reação em Cadeia da Polimerase/métodos , Polimorfismo Conformacional de Fita Simples , RNA Ribossômico 23S/genética , Mapeamento por RestriçãoRESUMO
Taking into account the toxicology of soluble barium salts, the authors treated 32 hypertensive subjects who were confirned to bed in two old people's homes with Baryta carbonica 15 CH versus placebo in a randomized double-blind study. Seventeen patients were given Baryta carbonica and 15 placebo. Taking the groups as a whole, no statistically significant differences were found between the effects of placebo and active drug on the blood pressure. But the four subjects who had been prospectively considered sensitive and were treated with Baryta carbonica gave strongly positive results. Some interesting conclusions were arrived at both from the general medical and the homoeopathic point of view
