PubMed Health⌕ Search

Biomedical subjects

F A Amosenko

Publications and source records attributed to F A Amosenko.

18 recordsLinked to original sources
PubMed2003

[Analysis of mutations in the RET proto-oncogene in patients with medullary thyroid tumor].

The spectrum of mutations of the RET protooncogene was analyzed in Russian patients with inherited or sporadic medullary thyroid carcinoma (MTC). Four RET exons (11, 13, 15, and 16) were subjected to molecular analysis, and mutations were revealed and identified in 47.4% (9/19) patients with sporadic MTC. In total, six mutations (including three new ones) were observed. The most common mutation affected codon 918 to cause substitution of methionine with threonine and accounted for 31.6% alleles. Analysis of exons 11 and 16 revealed four mutations in patients with inherited multiple endocrine neoplasia type 2 (MEN 2). Mutations were found in each patient. Thyroidectomy was performed in four asymptomatic carriers of RET mutations from three MET 2A families (in two families, affected relatives had bilateral pheochromocytoma). In two patients, analysis of the surgery material revealed MTC microfoci in both lobes of the thyroid gland. The results provide the ground for constructing a bank of genetic information on Russian MTC patients with the clinically verified diagnosis.

Adolescent↗
PubMed2001

Three novel mutations in the RET proto-oncogene.

Medullary thyroid carcinoma (MTC) occurs as a sporadic tumor or in connection with inherited cancer syndromes of multiple endocrine neoplasia type 2 and familial MTC. Missense RET proto-oncogene mutations and small in-frame deletions are found in most of the cases. In a significant amount of sporadic MTC cases somatic mutation at codon 918 (exon 16), or at codons 609, 611, 618, 620 (exon 10), or codons 630, 634 (exon 11) appear. We report here on three new somatic cell missense mutations of the RET proto-oncogene associated with sporadic MTC. In one tumor mutation at codon 922 TCC(Ser)-->TTC(Phe) in exon 16 was found. In another tumor two mutations at codons 639 GCA(Ala)-->GGA(Gly) and 641 GCT(Ala)-->CGT(Arg) in the exon 11 were observed. Allele-specific PCR followed by sequencing demonstrated the presence of both mutations at the same allele.

Base Sequence↗
PubMed2001

[Molecular diagnosis of multiple type 2 endocrine neoplasia].

The paper reviews the data on the molecular structure of the protooncogene RET encoding for receptor-type protein kinase, on the mechanism of transformation of the normal protooncogene RET to a dominant transforming oncogene, and on RET mutations detected in patients with the MEN-2 syndrome. Moreover, it presents the authors' own findings. The familial medullary thyroid carcinoma burdened genealogy shows a new point mutation TCG(Ser)-->GCG(Ala) in codon 891, in the exon 15 of the protooncogene RET. This mutation was not detected in the chromosomes of healthy individuals. Analyzing the linkage with two known and two new polymorphic markers showed that there was a cisaggregation of informative polymorphic markers, phenotypic manifestation of the disease, and mutations in the genealogy in question. In the protooncogene RET, there were two new polymorphisms: G/A at position 24 in intron 14 and C/T in codon 836 (exon 14). The rate of the polymorphism encountered in codon 836 proved to be similar for the Russians and the Germans (0.96%), which was also seen for two earlier described polymorphisms in codon 691 (0.80 and 0.81, respectively) and in codon 904 (0.21 and 0.22). At the same time, there were statistically significant differences in the rates of intron 14 polymorphism (0.87 and 0.77, respectively). In a family having MEN 2, a proband displayed TGC-->CGC mutation in codon 634 of the gene RET in the heterozygous state. The mutation results in substitution of cysteine amino acid residue in the cysteine-rich extracellular domain of protein kinase encoded by the gene RET for arginine. The results of molecular analysis were used to confirm its clinical diagnosis and to indicate that effective care should be delivered in MEN 2a.

Alleles↗
PubMed1998

[A new inherited RET proto-oncogene mutation associated with familial medullary thyroid carcinoma and polymorphisms in adjacent regions].

A new point mutation, TCG(Ser)-->GCG(Ala) in codon 891, exon 15 of the RET protooncogene was revealed in two patients from a pedigree with familial medullary thyroid carcinoma (FMTC), but not in healthy persons. A linkage analysis with two well-known and two new intragene polymorphisms showed that informative polymorphic markers, the phenotypic expression of the disease, and the mutation are cosegregated in the studied pedigree. Two new polymorphisms, G/A at position-24 of intron 14 and C/T in codon 836 of exon 14, were found in the RET protooncogene. The frequencies of allele 1 of the polymorphic site in codon 836 were the same (0.96) in the Russian and German populations. This was also characteristic of two polymorphisms revealed earlier, namely, the sites in codons 691 (0.80 and 0.81, respectively) and 904 (0.21 and 0.22). However, the frequency of allele 1 of the polymorphisms in intron 14 differed significantly (0.87 and 0.77, respectively).

Carcinoma, Medullary↗
PubMed1997

[TUB9 polymorphism in the CFTR gene of cystic fibrosis patients, carriers, and healthy donors from the Moscow region. SSCP and restriction analyses].

Data on the screening of 266 non-delta F508 chromosomes (42 cystic fibrosis patients, 43 carriers, and 48 healthy donors from the Moscow region) for the presence of structural abnormalities within the tenth exon of the CFTR gene conducted by means of the single-stranded conformation polymorphism (SSCP) technique in nonisotope modification are presented. The method used made it possible to detect three SSCP variants, one of which was present in cystic fibrosis patients (23.8%) and carriers (9.3%), but not in healthy donors. Sequencing of the 5 amplified DNA fragments carrying this SSCP variant revealed an A-->G substitution in the 1525-61 position, which indicated the presence of TUB9 polymorphism with allele 1 in the homozygous state in all cases tested. The three SSCP variants described corresponded to the three allelic variants of TUB9 polymorphism as judged by MnlI restriction analysis of the amplified tenth exon sequence. The modified SSCP technique is also suitable for routine screening for the G542X, G55ID, and W1282X point mutations within the CFTR gene. The frequency distribution of polymorphic TUB9 marker alleles across the non-delta F508 chromosomes in the three studied groups were estimated. Homozygotes for the TUB9 allele 1 were shown to have identical GATT-TUB9-M470V haplotypes.

Case-Control Studies↗
PubMed1997

[Molecular genetic analysis of TUB18 and TUB20 intragenic polymorphism and various mutations of the CFTR gene in the Moscow region].

Allelic frequencies of two intron polymorphisms in the cystic fibrosis transmembrane regulator (CFTR) gene, TUB18 and TUB20, were estimated on chromosomes of 67 cystic fibrosis patients and on that of 37 healthy donors from Moscow and the Moscow oblast. Allele 2 of the TUB 18, and allele 1 of the TUB20 were 2.1 and 1.5 times more frequent on the non-delta F508 chromosomes of the cystic fibrosis patients than on chromosomes of healthy donors, i.e. these alleles were in linkage disequilibrium with the CFTR gene. Allele 1 of the TUB18 marker and allele 2 of the TUB20 marker demonstrated absolute linkage disequilibrium with the delta F508 mutation of the CFTR gene. The degree of association between the TUB18 and TUB20 intron polymorphisms and the GATT and T854T intragenic polymorphisms was analyzed. Of all 62 delta F508 chromosomes tested, 98.3% shared the 2-1-1-2 GATT- T854T-TUB18-TUB20 haplotype. Eight major (more frequent) GATT-T854T-TUB18-TUB20 haplotypes were found in 89.5% of normal, and in 97.9% of non-delta F508 chromosomes of cystic fibrosis patients from the Moscow region. Three of these major haplotypes, 2-1-1-2, 1-2-2-1, and 2-2-1-2, were respectively 2.5, 2, and 1.5 times more frequent on non-delta F508 cystic fibrosis chromosomes than on normal chromosomes. Data on screening for the G542X, N1303K, and 394delTT mutations of the CFTR gene, carried out on 134 chromosomes of cystic fibrosis patients from the Moscow region are presented. The frequencies of the G542X and 394delTT mutations were estimated as 1.5%, while the frequency of the N1303K mutation was 2.2%.

Alleles↗
PubMed1995

[Analysis of various polymorphic markers of the CFTR gene in cystic fibrosis patients and healthy donors from the Moscow region].

Allelic frequencies at three polymorphic markers in the CFTR gene were detected on chromosomes derived from cystic fibrosis (CF) patients and healthy donors from Moscow and the Moscow region. These polymorphic markers are tetranucleotide tandem repeats GATT in intron 6B, M470V in exon 10, and T854T in exon 14 (fragment A). Frequencies at allele 1 of the M470V marker, along with allele 2 of GATT and T854T, are two times higher for CF patients without delta F508 mutation than for healthy donors, and there is linkage disequilibrium of these alleles of the polymorphic markers analyzed with the CF gene. Allele 1 of M470V and T854T markers, as well as allele 2 of the GATT marker (six repeats), are absolutely linked to mutation F508 of the CFTR gene. Using the polymorphic markers studied, family analysis of CF was carried out in two families.

Alleles↗
PubMed1991

Use of protamine sulphate for elimination of substrate DNA in poliovaccines produced on continuous cell lines.

Cell substrate DNA was shown to be an abundant contaminant in the clarified preparations of the Sabin type 1, 2 and 3 poliovaccines produced on a continuous cell line (4647). The size of the DNA, as evaluated for the Sabin type 1 poliovaccine, was highly heterogeneous, ranging from 100 to 20,000 base pairs. In view of potential oncogenicity of this DNA a simple and efficient procedure for its elimination is proposed. The method is based on use of protamine sulphate which at the concentration of 2.0 mg ml-1 precipitated cell DNA almost completely without affecting the virus titres.

Animals↗
PubMed1984

[Deletions of plasmid pRP3.1ts12 derived from RP1 leading to the suppression of the thermosensitive ts12 mutation and mucoid phenotype induction in Escherichia coli K-12].

Properties of a temperature-sensitive in replication mutant pRP3.1ts12 derived from the broad host range RP1 plasmid have been studied. pRP3.1ts12 is a shortened variant of the temperature-sensitive RP1ts12 mutant carrying a deletion in a region from 2.3 to 7.6 MD. In contrast to RP1ts12, the plasmid pRP3.1ts12 is a leaky ts mutant and is characterized by an elevated frequency of reversions to the temperature-independent phenotype. Temperature-independent derivatives of pRP3.1ts12 were studied. Approx. 15% of these were found to induce mucoid growth of the host cells. As revealed from restriction endonuclease analysis, most of the latter derivatives contain deletions of small DNA segments in the region 0.56 to 2.3 MD of the RP1 map. The possible nature of the gene(s), whose deletions suppress the temperature-sensitive ts12 mutation and results in superproduction of Escherichia coli capsular poly-saccharide is discussed.

Chromosome Deletion↗
PubMed1983

[Integration of plasmid RP1 with the chromosome of Escherichia coli K-12 recA. 2 classes of Hfr strains].

Integration of broad host range RP1 plasmid into the chromosome of Escherichia coli K-12 recA- cells has been studied. Using temperature-sensitive for replication plasmids pVD1 and pVD3, the derivatives of RP1, it has been shown that integration of RP1 into the bacterial chromosome results in formation of two classes of Hfr strains. Properties of these Hfrs have been examined. From the data obtained, it has been concluded that the plasmid integration and formation of one of the Hfrs classes appear to be mediated by transposon Tn1 residing on RP1. The other class of Hfr strains is formed due to a stable integration of RP1. In the course of analysis of R+ transconjugants arising at low frequency in crosses between stable Hfrs and E. coli rec+ recipients, it has been found that the significant part of them contain plasmid-chromosome hybrids (R-prim plasmids). On the basis of the latter results, a new simple method for R' plasmids selection has been proposed. Using restriction endonuclease analysis, the structure of plasmids that were excised from chromosomes of the stable Hfr strains and were comparable in their size to RP1, has been investigated. Probable mechanisms of the stable Hfr strains formation are discussed.

Chromosomes, Bacterial↗
PubMed1980

[Restriction and electron microscopic analyses of deletion derivatives thermosensitive with respect to maintaining plasmid pEG1].

Temperature-independent deletion mutants of temperature-sensitive in self-maintenance plasmid pEG-1, derived from R-factor RP4, are mapped using the restriction endonucleases PstI, SmaI, EcoRI, BamHI and the heteroduplex analysis. The pEG1 derivatives under study are found to have deletions in the area of ampicillin transposon Tn1 and nearby genes. The left and the right ends of these deletions boundaries are localized between 37.5 MD and 7.6 MD in the RP4 map. Thus far, the area of plasmid RP4 (37.5-7.6 MD) with Tn1 and, presumably, inc gene(s) in it does not have any genes needed for stable maintenance of R-factor. A conclusion is made that the gene RP4, which carries the mutation determining thermosensitive character of pEG1 maintenance and of inhibition of the cell growth, is localized between the EcoRI site and transposon Tn1 at a distance less than 1.0 MD from the latter.

DNA Restriction Enzymes↗
PubMed1978

[RP4 factor integration with E. coli chromosome].

Integration of R-factor RP4 with the chromosome of E. coli was studied with the use of replication thermosensitive mutant pEG1 of this factor. It was found that the frequency of integration of factor pEG1 containing the ampicillin transposone Tn1 with the chromosome of bacteria JC411 carrying transposone Tn1 previously inserted into it was very high and markedly exceeded that of its insertion into the same chromosome but not carrying this transposone. The frequency of factor pEG1 insertion into the chromosome of bacteria JC 1553 rec A defective with respect to genetic recombination was less than 2.10(-5) and did not depend on the presence of transposone Tn1 in it. Probably, insertion of factor RP4 into the bacterial chromosome may be realized through the rec A-dependent process of recombination between transposone Tn1 previously translocated into the chromosome and the same transposone contained in R-factor.

Ampicillin↗
PubMedDate not supplied

[The purification of tick-borne encephalitis virus preparations of cellular DNA].

According to the WHO requirements, the concentration of cellular DNA in vaccine preparations produced by pooling virus from continuous cell lines is limited to 100 ng/dose. In this study, different methods were used for purification of tick-borne encephalitis virus suspensions grown in continuous cultures of cell line 4647 from cellular DNA. Two approaches are proposed based on treatment with DNAse and promamin sulfate which allow one to reduce cellular DNA concentration in the virus preparation to the acceptable level. Prospects of their use in vaccine production are discussed.

Animals↗
PubMedDate not supplied

[Thermosensitive vector derived from RP1 plasmid for detection of transposable elements].

The involvement of the transposable DNA element of E. coli K12 chromosome in integrative recombination of RP1 plasmid was studied. Using temperature sensitive for replication plasmid RP1ts12--the derivative of RP1 which contains mutated transposon Tnl, it was shown that integration of RP1 into host chromosome and Hfr formation may occur according to a mechanism mediated by chromosome IS-elements. Plasmids that are desintegrated from the chromosome of these Hfrs contain discrete DNA segments (IS-elements) and possess elevated frequency of integration into chromosome of rec+ cells. The latter was used for selection of RP1ts12 recombinants carrying chromosome IS. For identification of IS involved in RP1 integration the number of independent RP1ts 12 recombinants was subjected to restriction and heteroduplex analysis. By analysing recombinants integrated into bacterial chromosome with frequency 5 X 10(-3), a new IS-element of E. coli K12 designated IS111 was discovered. IS111-element is about 1500bp of length, contains Smal, Pst1 and BamH1 restriction endonuclease sites and was found in the same position on the plasmid RP1 in two different orientations. IS-elements that have been revealed in a number of other RP1ts12 recombinants were preliminary identified as IS1-like elements. One recombinants plasmid was found to have an IS5-like elements. The activity of IS-elements inserted into RP1ts12 in recA-dependent integrative recombination was estimated. From the data of absolute and relative RP1ts12 integration frequencies mediated by IS111, IS1- and IS5-like elements a conclusion was made about the absence of E. coli K12 chromosome IS-elements in RP1 plasmid. The Hfr-formation and chromosomal gene transfer by recombinant plasmids RP1ts12: IS111 were studied. The possibility to use insertion RP1ts12 derivatives for the estimation of copies number, mapping and definition of orientation of IS-elements in bacterial chromosome and the possibilities for detection of transposable DNA elements using RP1ts12 in a wide range of gram-negative bacteria are discussed.

Bacterial Proteins↗
PubMedDate not supplied

[Presence of genomes of phage PBV-1 in the mycelia of the fungus Penicillium brevi-compactum].

The rate of reassociation of 3H-DNA of phage PBV-1 was increased in the presence of 100-fold excess of unlabeled DNA of Penicillium brevi-compactum. On this basis it was calculated that DNA isolated from Penicillium brevi-compactum contained 27--38 phage genomes per haploid cell genome, DNA of PBV-3 virus does not influence the rate of reassociation of PBV-1 virus DNA indicating the lack of homology between DNAs of PBV-1 and PBV-3 phages.

Bacteriophages↗