[Simple methods of enzymatic amplification of DNA for clinical practice]. / Prostye metody énzimaticheskoi amplifikatsii DNK dlia klinicheskoi praktiki.

The methods for enzymatic DNA amplification in vitro that allow to avoid the step of preliminary DNA extraction and purification are proposed. Lysates of blood cells in the solution or immobilized on the nylon membrane filters and dried blood spots on the filter paper blotters were used directly in amplification permitting one to solve the problems of adapting the method of polymerase chain reaction in clinical practice, for instance, in massive screening of genome mutations, viral infections etc.

[Identification of a nature of mutation in the 12th exon of phenylalanine hydroxylase gene in patients with phenylketonuria]. / Opredelenie prirody mutatsionnogo povrezhdeniia v 12-om ékzone fenilalaningidroksilaznogo gena u bol'nykh fenilketonuriei.

Upon amplification in vitro of the 12th exon area of the human phenylalanine hydroxylase gene followed by allele-specific hybridisation of the amplification product with synthetic probes and its sequencing by the Maxam-Gilbert method, a C----T transition causing phenylketonuria has been identified in Latvian patients.

[Disorders of phenylalanine and tyrosine metabolism in Down's syndrome]. / Narushenie obmena fenilalanina i tirozina pri bolezni Dauna.

Content of phenylalanine and tyrosine was increased in blood serum in mongolism. When 4 patients with mongolism and 10 healthy persons were loaded with 1-phenylalanine, content of the amino acid in blood serum of patients exceeded 1.5--2-fold that found in healthy persons within 4 and 6 hrs after the treatment. The hydroxylation rate of phenylalanine was lower in mongolism as compared to normal state; it corresponded to the rate of phenylalanine hydroxylation in atypical homo- and heterozygote patients bearing "phenylketonuria" gene and in patients with viral hepatitis. Concentration of tyrosine was distinctly higher in the impaired patients within 2--6 hrs after the loading as compared with the healthy persons. But content of tyrosine was increased only slightly in patients with mongolism during the loading and excretion of homogentisinic acid with urine was decreased. These data suggest that activity of phenylalanine hydroxylase system is impaired in liver tissue in mongolism. Excretion of phenylpyruvic acid with urine was not observed in the patients and healthy persons both before and during the amino acid loading. The data obtained suggest that impairment of phenylalanine and tyrosine turnover in mongolism appears to be one of the factors responsible for disturbance of neurotransmitter synthesis and to be related to development of mental retardation.