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Biomedical subjects

A I Miroshnikov

Publications and source records attributed to A I Miroshnikov.

At least 19 recordsLinked to original sources
PubMed2005

Galectins as markers of aggressiveness of mouse mammary carcinoma: towards a lectin target therapy of human breast cancer.

Galectins, beta-galactoside binding proteins, expressed selectively in human breast carcinoma are attractive targets to employ lectin-aimed therapeutics. We examined beta-galactoside binding potency of neoplastic cells using fluorescein-labelled synthetic glycoconjugates as probes for flow cytometry. As a result, surface beta-galactoside binding proteins/galectins were discovered on mouse mammary carcinoma cells in vitro and in vivo unlike non-malignant cells from the several tissues; and asialo-GM1 ganglioside carbohydrate part--containing probe was the most specific one. However, in liver and lung metastatic cells galectins seem to be expressed within cytoplasm and/or nuclei. Galectin expression correlated directly with aggressive tumour potential in the A/Sn transplantable model similar to findings in several human breast carcinoma cell lines. However, galectin expression was reduced during tumour progression in more aggressive forms of spontaneous BLRB mammary carcinomas like it was shown for human breast carcinoma specimens. Analysis of the histopathological data led, however, to the conclusion that galectin expression hardly might be a suitable marker of aggressiveness of heterogeneous mammary carcinomas as the observed level of galectin expression is influenced by the amount of the stroma in a tumour sample and/or probably, galectin expression inversely correlates with tumour aggressiveness during the initial and advanced steps of mammary tumour progression. We conclude that surface beta-galactoside binding proteins/galectins that are selectively expressed during mouse mammary carcinoma progression, similarly to human breast carcinomas, seem to be proper targets for asialo-GM1-vectored cytotoxics and our mouse model system might be a relevant instrument to further test novel modes of anti-breast cancer therapy.

Animals↗
PubMed2002

Wheat germ cell-free translation system as a tool for in vitro selection of functional proteins.

We have demonstrated that mRNA, ribosome and resulting protein form complexes (ternary complexes) in wheat germ cell-free translation system and these complexes are stable for at least several hours. The protein folds into a proper conformation capable of specific binding with the inhibitor of its enzymatic activity. The removal of the stop codon from mRNA does not affect translation and mRNA-ribosome-protein complex stability. We have used these results to develop a method of isolation of mouse dihydrofolate reductase (mDHFR) encoding mRNA from native pool of mouse liver mRNA. The native pool of mouse liver mRNA was translated in vitro in a wheat germ cell-free translation system (WG-CFS), and enzyme-specific ternary complexes were affinity selected on a methotrexate-BSA coated 96-well microtiter plate (methotrexate, MTX, is an inhibitor of DHFR enzymatic activity). Bounded ternary complexes were eluted by MTX treatment. mRNA from eluates was amplified by template-switch RT-PCR and products of RT-PCR analyzed by gel electrophoresis. The cDNA was amplified by one-step reverse transcription-PCR and used for transcription, followed by translation and determination of the DHFR enzymatic activity in translation mixtures. This method is suitable for direct cDNA cloning from mRNA or cDNA libraries and for investigation of protein-protein interactions.

Animals↗
PubMed2002

[Mutation of a 5,10-methylenetetrahydrofolate reductase gene in systemic lupus erythematosis and antiphospholipid syndrome].

AIM: To study prevalence of mutation C677T in gene 5.10-MTHFR in systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) as well as in persons free of symptoms of systemic diseases of the connective tissue. MATERIAL AND METHODS: 85 patients participating in the study were divided into three groups: those with SLE (n = 17), with SLE + APS (n = 42), with primary APS (n = 26). The control group consisted of 30 persons without SLE or APS. 55% of the examinees had thrombotic complications of different location. The diagnosis of the mutation was made using DNA isolated from the peripheral blood with standard methods and polymerase chain reaction. Allele (homozygous or heterozygous) condition of the mutation was confirmed by means of allele-specific primers. RESULTS: Mutation C677T in MTHFR gene was found in 40 of 85 patients (47%); 11(27.5%) had a homozygous variant, 29(72.5%)--heterozygous. C677T mutation occurred in 5 of 17 SLE patients (29%), it was in all the cases heterozygous. In primary and secondary APS mutation was detected in 51.5% (35 of 68 patients). Recurrent thrombosis occurred more frequently in patients with mutation MTHFR. Three and more episodes of thrombosis were registered in 17 of 40 patients with mutation C677T against 9 of 44 patients without the mutations (p = 0.04). CONCLUSION: Relationship between elevated blood levels of APL and MTHFR mutation points to the fact that this genetic marker is an additional thrombogenic factor in APS. Mutation C677T in MTHFR gene in APS patients correlates with recurrent thrombosis.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed2001

Monitoring of recombinant human insulin production by narrow-bore reversed-phase high-performance liquid chromatography, high-performance capillary electrophoresis and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry.

An analytical scheme for monitoring recombinant human insulin (rhI) production is suggested. The scheme includes high-performance separation micro-techniques (narrow-bore RP-HPLC, HPCE) based on different separation mechanisms and matrix-assisted laser desorption ionisation time-of-flight MS, and allows one to obtain unambiguous information about purity and primary structure of all intermediates of the rhI production. The use of this scheme at all production steps provided optimisation of certain technological parameters [conditions for a fusion protein (FP) refolding, temperature and duration of the FP cleavage with trypsin, conditions for carboxypeptidase B digestion of di-ArgB31-B32-insulin] and achievement of a high purity of the end-product. The proposed scheme may be used for solving various problems in monitoring production of other recombinant proteins.

Chromatography, High Pressure Liquid↗
PubMed2000

[Analytical biotechnology of recombinant peptides and proteins. I. Analysis of the purity, composition and structure of human, porcine and bovine insulins].

A method for analysis of the type, purity, and possible structural modifications of insulins of bovine, porcine, and human origin was proposed. It is based on a combination of narrow-bore reversed-phase HPLC and mass spectrometry. The hydrolysis of insulins with highly specific Glu-protease V8 from Staphylococcus aureus followed by peptide mapping of the hydrolysis products and mass spectrometry of the isolated fragments helps rapidly and reliably localize and identify substitutions of amino acid residues in insulin structure by using insulin samples of less than 1 nmol.

Animals↗
PubMed2000

[Hydrolysis of primary amide groups in Asn/Gln-containing peptides].

Peptides Boc-Ala-Asn/Gln-OH and Boc-Asn/Gln-Ala-OH were saponified with barium hydroxide to corresponding Asp/Glu-containing peptides. Under the conditions of saponification, Boc-Asn-Ala-OH additionally afforded Boc-Asp-OH, isopeptide Boc-Asp(Ala)-OH, and Boc-NHSuc > Ala-OH, with the third being the key intermediate in these transformations. Boc-Asp(OMe)-Ala-OMe underwent similar transformations under treatment with diazomethane or triethylamine. Saponification with barium hydroxide was accompanied by a high epimerization of N-terminal amino acid residues, whereas the products of the diazomethane treatment of Boc-Asp(OMe)-Ala-OMe had a low degree of epimerization.

Amides↗
PubMed2000

[Analytical biotechnology of recombinant peptides and proteins. II. Primary structure of the fusion protein containing human proinsulin and optimization of its proteolysis by trypsin].

The kinetics of trypsin proteolysis of the fusion protein (FP) containing human proinsulin was studied by a set of analytical micromethods. These were the microcolumn reversed-phase HPLC and the qualitative identification by MALDI-TOF mass spectrometry and amino acid sequencing. The first stage of the proteolysis was shown to be the cleavage of FP into the leader fragment and proinsulin. The subsequent splitting off of C-peptide from proinsulin results in the formation of ArgB31-ArgB32-insulin. The effect of temperature on the formation of de-ThrB30-insulin, a by-product, was also studied. The structure of FP was confirmed by the peptide mapping technique, and the leader fragment was shown to contain no N-terminal Met residue.

Amino Acid Sequence↗
PubMed2000

[MALD-MS in the quantitative analysis of peptides and proteins].

A modified method of isotope dilution was applied to the quantitative determination of peptides and proteins by MALDI MS at subpicomolar level. The essence of the method consists in the quantitative analysis of the enzymic hydrolysis products rather than the starting compounds. This allows the measurements to be performed at a higher resolution and makes the method independent of the molecular mass of oligopeptides and proteins examined. Fragments obtained by hydrolysis of the same oligopeptide or protein in a known concentration by the same enzyme and labeled with the stable 18O isotope are used as internal standards. The label is introduced by carrying out the hydrolysis in H(2)18O, and the oligopeptide concentration is calculated from the isotope distribution between the labeled and unlabeled hydrolysis products in the mass spectrum. This method was tested in the determination of concentrations of the angiotensinogen (1-14) fragment (oligopeptide), extracellular RNAase from Bacillus amyloliquefaciens (protein) and its protein inhibitor, barstar M. Usefulness of this method in kinetic studies was also demonstrated.

Amino Acid Substitution↗
PubMed2000

[Leiden, G20210A mutations in prothrombin gene and antiphospholipid antibodies in systemic lupus erythematosus and antiphospholipid syndrome].

AIM: To estimate incidence rate of Leiden mutation in factor V gene, prothrombin gene mutation responsible for replacement of G for A in position 20210 (G20210A) of its 3'-end noncoding part in patients with systemic lupus erytheamtosus (SLE) and antiphospholipid syndrome (APS) and their relationships with antiphospholipid antibodies (aPL): lupus anticoagulant (LA) and anticardiolipin antibodies (aCL). MATERIALS AND METHODS: The trial included 33 patients (2 males and 31 females) aged 20-62 years (mean age 32.7 +/- 9.8 years). 29 patients suffered from SLE, 17 of them had also APS (criteria by G. R. V Hudhes). 3 patients had primary APS, 1 female had hemorrhagic vasculitis. IgG and IgM-aCL were detected by enzyme immunoassay. In revealing mutation, DNA was used isolated from peripheral blood by standard methods based on polymerase chain reaction (PCR). Primary screening of Leiden mutation was made according to Bertina et al. with Mnl I restrictase. The mutation was confirmed by an original technique with allele-specific primers. G20210A mutation in the prothrombin gene was determined with restrictase Taq I after introduction of artificial restriction site in PCR product. The patients were divided into 2 groups. Group 1 incorporated 12 patients with SLE without APS. Group 2--21 patients with APS (17 with SLE + APS, 3 with primary APS and 1 with hemorrhagic vasculitis). RESULTS: Patients of group 1 had neither thrombotic complications nor Leiden mutation. Two patients of group 2 had heterozygous Leiden mutation. Both females were aPL-positive and had previously recurrent thrombophlebitis. One of them had also recurrent disorders of cerebral circulation. None of the examinees had any G20210A mutations in the prothrombin gene. CONCLUSION: Detection of genetic defects in APS provide arguments in the dispute about the necessity, duration and choice of anticoagulant therapy. If patients with APL syndrome appeared to have besides aPL also genetic defects in coagulation, this will enable identification of patients at high risk of thrombosis which need permanent administration of anticoagulants among which only low-molecular ones or glycosaminoglycanes are indicated. Mutation in gene of factor V is absolute contraindication to phenilin and quamarines.

Adult↗
PubMed2000

[Synthesis isomeric 4-prolylamines and 4,4'-diprolylamines].

Starting from the previously described tert-butyl esters of 4-epimeric N-benzyloxycarbonyl-4-hydroxyprolines and N-benzyloxycarbonyl-4-trans- and 4-cis-trifluoroacetamidoproline tert-butyl esters, the corresponding un-protected 4-aminoprolines and a number of their partially protected derivatives were synthesized via the intermediate 4-O-mesyl and 4-azide derivatives. The reductive amination of N-benzyloxycarbonyl-4-oxoproline tert-butyl ester with ammonium acetate led to N-benzyloxycarbonyl-4-cis-4'-cis- and 4-cis-4'-trans-diprolinylamines. The 1H NMR and CD spectra of the synthesized compounds are described.

Circular Dichroism↗
PubMed1999

Mutation S543N in the thumb subdomain of the Taq DNA polymerase large fragment suppresses pausing associated with the template structure.

Substitution of Asn for the conserved Ser543 in the thumb subdomain of the Taq DNA polymerase large fragment (Klentaq DNA polymerase) prevents pausing during DNA synthesis and allows the enzyme to circumvent template regions with a complex structure. The mutant enzyme (KlentaqN DNA polymerase) provides specific PCR amplification and sequencing of difficult templates, e.g. those with a high GC% content or strong secondary structure.

Asparagine↗
PubMed1998

New DNA diagnostic system for detection of factor V Leiden.

Use was made of allele-specific PCR to develop a highly effective DNA diagnostic system for detection of the factor V Leiden mutation in exon 10 of human factor V gene. The allele-specific primers contain a 3'-OH end nucleotide, which matches a mutant or wild-type nucleotide of the template DNA (A-allele and G-allele, respectively) and also one mismatched nucleotide near the 3'-end. The universal primers have an internal mismatch with the mutant nucleotide of the template DNA and another mismatched nucleotide at 3'-OH end. The A-allele-specific primer enables the preferential amplification of both the homozygous and heterozygous mutant alleles. The extension of the G-allele-specific primer or the universal one is inhibited in the presence of the homozygous factor V Leiden. The developed assay system allowed us to detect five patients, who are heterozygous for factor V Leiden among the 48 patients with deep venous thrombosis and pulmonary thromboembolism.

Alleles↗
PubMed1998

[Isolation of trypsin PC from the Kamchatka crab Paralithodes camtschatica and its properties].

Trypsin PC from the hepatopancreas of the king crab Paralithodes camtschatica was isolated and purified to apparent homogeneity by ion-exchange chromatography on Aminosilochrom and DEAE-Sephadex and affinity chromatography on arginine-agarose. The yield of the enzyme was 37.7%, and the purification degree was 21. Trypsin PC has a molecular mass of 29 kDa and pI < 2.5. It hydrolysis N-benzoyl-L-arginine p-nitroanilide at the optimum pH of 7.5-8.0 and at the temperature optimum of 55 degrees C (K(m) = 0.05 mM). Trypsin PC retained its activity within the pH range of 5.8-9.0 in the presence of Ca2+. The enzyme was inhibited by the specific inhibitors of serine proteases diisopropyl fluorophoshate and phenylmethylsulfonyl fluoride, by the trypsin inhibitor N-tosyl-L-lysylchloromethylketone, and by the trypsin inhibitors from soybean and potato. Trypsin PC was found to hydrolyze amide bonds formed by carboxylic groups of lysine and arginine in peptide substrates. The N-terminal sequence of this enzyme is IVGGTEVTPG.

Amino Acid Sequence↗
PubMed1998

[New DNA diagnostic system for determination and identification of homo- and heterozygote point mutations].

A straightforward and effective PCR-based assay system is devised that allows one to reveal and identify homozygous and heterozygous point mutations. The system uses two sets of allele-specific primers. In one set, the 3'-nucleotide matches the allele under study so that the primer functions effectively only if the DNA contains the corresponding allele. To increase primer specificity, template-noncomplementary nucleotides are introduced near its 3'-end. The primers from another set invariably bear a 3'-terminal mismatch, and, in addition, the mutant nucleotides of the alleles under study form mismatches with the internal nucleotides of the primers. In such combination, the primer activity is suppressed if the DNA contains a homozygous mutation. The assay system devised was utilized to reveal the Leiden mutation in the gene for factor V of the human blood clotting system in patients with thrombophilia.

Alleles↗
PubMed1997

[Proteolysis of human proinsulin catalysed by native, modified, and immobilized trypsin].

Proteolysis of recombinant human proinsulin by the native trypsin, by trypsin modified with a copolymer of vinylpyrrolidone and acrolein, and by the same modified trypsin immobilized on Silochrom 1.5 was studied by RP HPLC and mass spectrometry. Rate constants of the main stages of proinsulin hydrolysis by the native trypsin were estimated. The values of rate constants of the digestions of the most easily hydrolyzable bonds (those formed by the pairs of the basic amino acid residues) in proinsulin were found to be of the same order as those formed by the separate lysine residues (Lys7) and those formed by the four basic amino acid residues of the C-terminal cluster of melittin. It was established that covalent trypsin binding to the copolymer did not change the ratio of the rate constants of the individual stages of proinsulin hydrolysis, whereas after the immobilization of modified trypsin on the Silochrome, the formation of diarginyl insulin-ArgArg, intermediate forms of hydrolyzed insulin, and desThr-insulin proceeds with comparable rates.

Amino Acid Sequence↗