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Biomedical subjects

K G Gazarian

Publications and source records attributed to K G Gazarian.

At least 19 recordsLinked to original sources
PubMed2002

L-Homoserine: a novel excreted metabolic marker of hepatitis B abnormally produced in liver from methionine.

The hepatitis B infection leads to various profound pathological processes in liver metabolism. Some biochemical alterations detectable by blood analysis are currently used for a preliminary evaluation of the infection. Based on existing data we present here evidence that non-protein amino acid L-homoserine is a pathological, hepatitis B-induced metabolite that is formed and excreted into urine from methionine via splitting S-adenosylmethionine. The urine L-homoserine is proposed as a new marker in the pre-diagnosis examinations that is easier for the clinical analysis than currently used blood test, and is applicable to large-scale epidemiological surveys of the probability of hepatitis B.

Alkyl and Aryl Transferases↗
PubMed2001

Post-panning computer-aided analysis of phagotope collections selected with neurocysticercosis patient polyclonal antibodies: separation of disease-relevant and irrelevant peptide sequences.

The homology of peptide sequences selected from a 7mer phage display library with antibodies elicited by the multicelled parasite Taenia solium in cerebrospinal fluid and serum of neurocysticercosis (NCC) patients and by antibodies of uninfected control patients with similar neurological complications of other ethiology (non-NCC) were analyzed using a PILEUP-Tudos sequence alignments program. The analysis generated dendrograms bearing two types of sequence clusters, those containing (1) only NCC patients-derived peptides and (2) both NCC- and control non-CC -- patient derivatives. By using ELISA, peptides that were selected by the antibodies were identified predominantly in the NCC-derived clusters. In repeated analysis in which sequences were added or removed, the first type of clusters maintained their structure, while the second type of clusters were split into many separate homology units dispersed throughout the guide tree. These results are interpreted as the ability of the analysis to segregate NCC-specific peptide sequences from other sequences. Altogether, this study demonstrates the high potential of the PILEUP-Tudos computer program to analyze phagotope collections recovered through biopanning with polyclonal antibodies elicited in patients by complex and as yet unknown multiple pathogenic antigens and to separate all phagotopes that are disease-relevant on the basis of the sequence homology.

Amino Acid Sequence↗
PubMed2000

Epitope mapping on N-terminal region of taenia solium paramyosin.

Epitope mapping of the amino-terminal 20aa sequence from Taenia solium paramyosin (TPmy), an immunodominant protein involved in the complex host-parasite relationship in human and porcine cysticercosis is reported. A 12-mer random peptide phage display library was screened with antibodies raised against a synthetic peptide corresponding to the amino-terminal 20aa sequence of TPmy, its highly immunodominant region. In total, 57 clones isolated in two panning conditions were analyzed, of which a single group of 14 sequences found in 25 clones shared a consensus motif showing structural similarity with the antigen Arg10-Thr16 region.

Amino Acid Sequence↗
PubMed1994

[Determination of homoserine kinase activity by chromatographic separation and measurement of reaction products].

A highly specific procedure for quantitative assay of the homoserine kinase activity in an optimized enzymatic reaction using 14C-labelled homoserine or [gamma 33P]-ATP as substrates, and paper or thin-layer chromatography for separation of the formed o-phosphohomoserine, is described. The procedure is simple, sensitive and allows the assay for the activity of both purified and non-purified homoserine kinases.

Adenosine Triphosphate↗
PubMed1991

[Induction of unstable mutations in Drosophila melanogaster by microinjection of oncogenic virus DNA into the embryo polar plasma. Insertional nature of mutations].

We have demonstrated that mutations induced in Drosophila melanogaster by the microinjections of adenovirus Sa7 DNA in early embryos are of insertional nature. The role of insertional elements is played by the Drosophila transposons, but not by the virus DNA. The ability of oncoviral DNA to induce transpositions of mobile elements in recipient genome is the molecular basis of this system of genetic instability.

Adenoviridae↗
PubMed1991

[Induction of unstable mutations in Drosophila melanogaster by microinjections of oncogenic virus DNA into the embryo polar plasma. Prolonged genetic instability of mutations at the lobe locus].

Mutations Lobe induced by the microinjections of RSV cDNA into Drosophila melanogaster early embryos are characterized by permanent genetic instability; the level of this instability is being changed in time. Based on the results of genetic analyses of Lobe mutations and molecular analysis of white and ADH mutations induced at high frequency in this system of gene instability, we supposed that unstable mutations which arose under the influence of retroviral cDNA are of the insertional nature.

Animals↗
PubMed1991

[Biological effect of human erythropoietin in transgenic mice].

Transgenic mice were obtained inheriting the human erythropoietin gene under the control of viral regulatory elements. The reliable difference in haematocrit, the content of haemoglobin and percentage of reticulocytes in peripheral blood were not revealed. The level of serum erythropoietin in transgenic mice is several fold higher than in control mice. The increased pool of erythroid cells was observed in the bone marrow of transgenic mice, especially of normoblasts (3-fold) and reticulocytes (4,5-fold).

Animals↗
PubMed1991

[Localization of fragments binding nuclear proteins in the promotor region of the human alpha-1-antitrypsin gene].

Human and mice nuclear extracts from livers and mice spleen extract were analysed in an attempt to find any proteins capable of binding to the human alpha 1-antitrypsin gene promoter. The nuclei of all studied tissues contain such proteins. The proteins were partially purified on DEAE-trisacryl, heparin sepharose and phosphocellulose columns. The multiple sites for liver nuclear proteins binding to the human alpha 1-antitrypsin gene promoter were found by the DNAse I footprinting technique.

Animals↗
PubMed1991

[Design of a gene coding encoding a polypeptide, mixing the enzyme activity of Escherichia coli homoserine kinase and threonine synthetase].

The functioning of Escherichia coli threonine operon isolated genes thrB and thrC was studied by using the genetic complementation and enzymatic activity determination techniques. A new gene thrBC was obtained by the genes merging. The genes thrB and thrC were shown to function in Escherichia coli cells independent of the operon and the polipeptide encoded by the thrBC gene combined the functions to express the products of both genes in bacterial cell. At the same time the enzyme coded for by the merged genes demonstrates the level of activity compared with the ones of the isolated genes.

Amino Acid Sequence↗
PubMed1991

[Induction of unstable mutations in Drosophila melanogaster by microinjection of oncogenic virus DNA into polar embryonic plasm. Malignant effect of oncoviral DNA].

We have demonstrated that the ability to induce benign neoplasms We have dominant mode of inheritance in Drosophila melanogaster is the specific feature of oncoviral DNAs. It is supposed that development of this type of neoplasms in Drosophila is connected with the changes in expression of protooncogenes in mutant genome: firstly, the genetic factors directing the development of neoplasms and Drosophila protooncogenes which shared the homology with v-src are localised in the same regions; secondly, there are structural rearrangements in c-src/fps (29A) protooncogene in mutant stocks which display the ability for neoplastic growth.

Animals↗
PubMed1989

[Induction of unstable mutations in Drosophila melanogaster by microinjections of DNA from oncogene viruses into the embryonic polar plasm. Part IV. Malignantization of tissues of mutant larvae].

We have demonstrated that larval tissues of mutant stocks induced by injections of oncogene virus DNA (Sa7 and RSV) show the neoplastic mode of growth after transplantation into the body cavity of wild-type flies. Neoplasms tested were shown to be ordinary benign insect neoplasms, and at the same time they show the dominant mode of heredity typical of the neoplasms of vertebrates. Genetic factors responsible for the neoplastic growth are localised in the 3rd chromosome in the stocks obtained after injections of the adenoviral Sa7 DNA, and in the 2nd and 3rd chromosomes in the mutant stocks induced by the retroviral DNA.

Animals↗
PubMed1988

[Cloning of human erythropoietin gene].

The 17-mer oligonucleotide probe homologous to the fragment of the gene for human erythrocyte differentiation factor erythropoietin was used to screen the human genomic library for this gene. Restriction analysis and partial sequencing of one of the identified clones have confirmed that the clone does contain the human erythropoietin gene. We are planning to use the cloned human erythropoietin gene for developing a stably transfected mammalian cell line that should secrete erythropoietin.

Cloning, Molecular↗
PubMed1988

[Production of transgenic rabbits and mice carrying the gene for bovine growth hormone].

The results of experiments on the transfer of bovine gene for growth hormone into mice and rabbits are presented. The gene was transferred by the technique of microinjection into the zygote. In all cases transgene in rabbits occurred to be changed. In two transgenic mice the bovine growth hormone gene represented some tandem arranged copies. One of the mice had accelerated growth. This phenotypic changes is found to be inheritable.

Animals↗
PubMed1987

[Genetic transformation of somatic cells. XV. Production of transgenic mice containing the gene for the envelope protein of the human hepatitis B virus].

Transgenic mice containing in somatic (liver) cells a gene encoding hepatitis virus B surface antigen (HBsAg) were obtained and analysed. About 10(4)-10(5) copies of circular plasmid pSH21 with HBsAg gene under the control of the SV40 early promoter were microinjected into the cytoplasm (pronucleus region) of mouse zygotes. 10 of the 24 animals isolated after this treatment contained 1 to 5 copies of the HBsAg gene per genome of hepatocytes (7 males and 3 females). The Southern analysis of DNA from some of transgenic animals showed rearrangements of the HBsAg gene in most of them. In the liver of one female transcripts were found hybridizing with the probe on the HBsAg gene; progenies of this mouse expressed no HBsAg gene. Possible reasons for the high frequency HBsAg gene rearrangements in transgenic mice are discussed.

Animals↗