Publications by authors named "Irina Demina"

19 Publications

  • Page 1 of 1

Additional flow cytometric studies for differential diagnosis between Burkitt lymphoma/leukemia and B-cell precursor acute lymphoblastic leukemia.

Leuk Res 2021 01 8;100:106491. Epub 2020 Dec 8.

National Medical Research Center of Pediatric Hematology, Oncology and Immunology, 1 Samory Mashela St., 117998, Moscow, Russia. Electronic address:

The differentiation between Burkitt lymphoma/leukemia (BL) and B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is sometimes complicated. Laboratory findings that favor BL (e.g., surface expression of μ heavy chain and/or one of the light chains of immunoglobulin, FAB L3 morphology of blasts, MYC gene rearrangements) are not always present simultaneously. Our previous work demonstrated that BL differed from Ig(+) BCP-ALL by expression of Ig and other surface markers. In the current study, we have evaluated additional flow cytometric markers for reliable differentiation between BL and BCP-ALL. Among three studied surface antigens (CD44, CD38, CD58), only CD58 demonstrated significantly higher expression in BL as compared to BCP-ALL. Moreover, BL cases were associated with an increased level of Ki-67 and a higher percentage of cells in the S-phase of cell cycle. These two features reflect an aggressive proliferative potential of BL. Thus, when BL is suspected and results of surface Ig evaluation are controversial, the flow cytometric analysis of CD58, Ki-67 and cell cycle could assist in the differential diagnosis.
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http://dx.doi.org/10.1016/j.leukres.2020.106491DOI Listing
January 2021

Accumulation of and Response to Auxins in Roots and Nodules of the Actinorhizal Plant Compared to the Model Legume .

Front Plant Sci 2019 24;10:1085. Epub 2019 Sep 24.

Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden.

Actinorhizal nodules are structurally different from legume nodules and show a greater similarity to lateral roots. Because of the important role of auxins in lateral root and nodule formation, auxin profiles were examined in roots and nodules of the actinorhizal species and the model legume . The auxin response in roots and nodules of both species was analyzed in transgenic root systems expressing a beta-glucuronidase gene under control of the synthetic auxin-responsive promoter . The effects of two different auxin on root development were compared for both species. The auxin present in nodules at the highest levels was phenylacetic acid (PAA). No differences were found between the concentrations of active auxins of roots nodules, while levels of the auxin conjugate indole-3-acetic acid-alanine were increased in nodules compared to roots of both species. Because auxins typically act in concert with cytokinins, cytokinins were also quantified. Concentrations of -zeatin and some glycosylated cytokinins were dramatically increased in nodules compared to roots of , but not of . The ratio of active auxins to cytokinins remained similar in nodules compared to roots in both species. The auxin response, as shown by the activation of the promoter, seemed significantly reduced in nodules compared to roots of both species, suggesting the accumulation of auxins in cell types that do not express the signal transduction pathway leading to activation. Effects on root development were analyzed for the synthetic auxin naphthaleneacetic acid (NAA) and PAA, the dominant auxin in nodules. Both auxins had similar effects, except that the sensitivity of roots to PAA was lower than to NAA. However, while the effects of both auxins on primary root growth were similar for both species, effects on root branching were different: both auxins had the classical positive effect on root branching in , but a negative effect in . Such a negative effect of exogenous auxin on root branching has previously been found for a cucurbit that forms lateral root primordia in the meristem of the parental root; however, root branching in does not follow that pattern.
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http://dx.doi.org/10.3389/fpls.2019.01085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6773980PMC
September 2019

Heterogeneity of childhood acute leukemia with mature B-cell immunophenotype.

J Cancer Res Clin Oncol 2019 Nov 28;145(11):2803-2811. Epub 2019 Aug 28.

Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, 1 Samory Mashela St., GSP-7, Moscow, 117997, Russia.

Background: Flow cytometry (FCM) plays a crucial role in the differential diagnosis of Burkitt lymphoma/leukemia (BL) and B-cell precursor acute lymphoblastic leukemia (BCP-ALL). The presence of surface IgM (sIgM) alone or with light chain restriction indicates a mature blast phenotype (BIV by EGIL) and is usually observed in BL. However, sIgM expression could also be detected in transitional BCP-ALL cases. These similarities in immunophenotype and ambiguous correspondence with other laboratory findings may challenge the correct BL diagnostics.

Methods: We retrospectively reviewed the available data from immunophenotypic, morphological, cytogenetic, and molecular genetic studies of 146 children (85 boys and 61 girls) with a median age of 10 years (range 0-18 years) who were diagnosed with BL and BCP-ALL. The blasts' immunophenotype was studied by multicolor FCM. The conventional cytogenetic analysis included G-banded karyotyping and fluorescence in situ hybridization (FISH).

Results: In 54 children classified as BIV-ALL according to the EGIL, it was demonstrated that sIgM in a minority of cases can be associated with various types of BCP-ALL. Analysis of the antigen expression profile of 105 patients with verified BL (n = 21) and BCP-ALL (n = 84) showed significant differences in BL and the sIgM(+) vs BCP-ALL immunophenotype. Thus, even in cases of ambiguous sIgM expression, these two diseases could be reliably discriminated by complex immunophenotyping. Moreover, 10 patients (7 boys and 3 girls) with BL leukemic cells did not express sIgM, and they were diagnosed with BL on the basis of other laboratory and clinical signs.

Conclusions: In conclusion, our study shows that BIV subtype is heterogeneous group of leukemia including not only the BL, but also BCP-ALL. In ambiguous cases, only a combination of multiple immunophenotypic, cytomorphologic, and genetic diagnostic technologies can allow the precise discrimination of BL and BCP-ALL and selection of the appropriate treatment scheme.
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http://dx.doi.org/10.1007/s00432-019-03010-1DOI Listing
November 2019

Bleeding tendency and platelet function during treatment with romiplostim in children with severe immune thrombocytopenic purpura.

Int J Hematol 2017 Jun 7;105(6):841-848. Epub 2017 Mar 7.

National Scientific and Practical Center of Pediatric Hematology, Oncology and Immunology, 117198, Moscow, Russia.

It has been suggested that platelet function in chronic immune thrombocytopenic purpura (ITP) may be abnormal. Thrombopoietin mimetics used for treatment can affect it, but the data remain limited. We investigated platelet function of 20 children diagnosed with severe ITP (aged 1-16 years, 12 females and eight males). Platelet functional activity in whole blood was characterized by flow cytometry before and after stimulation with SFLLRN plus collagen-related peptide. Levels of CD42b, PAC1, and CD62P, but not CD61 or annexin V, were significantly increased (P < 0.05) in resting platelets of patients before treatment compared with healthy donors. On average, PAC1 and CD62P in patients after activation were also significantly elevated, although some patients failed to activate integrins. Romiplostim (1-15 μg/kg/week s.c.) was prescribed to seven patients, with clinical improvement in six. Interestingly, one patient had clinical improvement without platelet count increase. Eltrombopag (25-75 mg/day p.o.) was given to four patients, with positive response in one. Others switched to romiplostim, with one stable positive response, one unstable positive response, and one non-responding. Platelet quality improved with romiplostim treatment, and their parameters approached the normal values. Our results suggest that platelets in children with severe ITP are pre-activated and abnormal, but improve with treatment.
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http://dx.doi.org/10.1007/s12185-017-2207-3DOI Listing
June 2017

Hysteresis-like binding of coagulation factors X/Xa to procoagulant activated platelets and phospholipids results from multistep association and membrane-dependent multimerization.

Biochim Biophys Acta 2016 Jun 10;1858(6):1216-27. Epub 2016 Feb 10.

Federal Research and Clinical Centre of Pediatric Hematology, Oncology and Immunology, Moscow 117198, Russia; Laboratory of Molecular Mechanisms of Hemostasis, Center for Theoretical Problems of Physicochemical Pharmacology, Moscow 119991, Russia; Faculty of Physics, Moscow State University, Moscow 119992, Russia; Faculty of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia. Electronic address:

Binding of coagulation factors X (fX) and Xa (fXa) to activated platelets is required for the formation of membrane-dependent enzymatic complexes of intrinsic tenase and prothrombinase. We carried out an in-depth characterization of fX/fXa binding to phospholipids and gel-filtered, thrombin-activated platelets. Flow cytometry, surface plasmon resonance, and computational modeling were used to investigate interactions of fX/fXa with the membranes. Confocal microscopy was employed to study fXa binding to platelet thrombi formed in flowing whole blood under arterial conditions. Binding of fX/fXa to either vesicles or procoagulant platelets did not follow a traditional one-step reversible binding model. Their dissociation was a two-step process resulting in a plateau that was up to 10-fold greater than the saturation value observed in the association experiments. Computational modeling and experimental evidence suggested that this was caused by a combination of two-step association (mainly for fX) and multimerization on the membrane (mainly for fXa). Importantly, fX formed multimers with fXa, thereby improving its retention. The same binding/dissociation hysteresis was observed for annexin V known to form trimers on the membranes. Experiments with platelets from gray syndrome patients showed that alpha-granular factor Va provided an additional high-affinity binding site for fXa that did not affect the hysteresis. Confocal microscopy observation of fXa binding to platelet thrombi in a flow chamber and its wash-out confirmed that this phenomenon persisted under physiologically relevant conditions. This suggests its possible role of "locking" coagulation factors on the membrane and preventing their inhibition in plasma and removal from thrombi by flow.
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http://dx.doi.org/10.1016/j.bbamem.2016.02.008DOI Listing
June 2016

Candidatus Frankia Datiscae Dg1, the Actinobacterial Microsymbiont of Datisca glomerata, Expresses the Canonical nod Genes nodABC in Symbiosis with Its Host Plant.

PLoS One 2015 28;10(5):e0127630. Epub 2015 May 28.

Department of Plant Sciences, University of California Davis, Davis, California, 95616, United States of America.

Frankia strains are nitrogen-fixing soil actinobacteria that can form root symbioses with actinorhizal plants. Phylogenetically, symbiotic frankiae can be divided into three clusters, and this division also corresponds to host specificity groups. The strains of cluster II which form symbioses with actinorhizal Rosales and Cucurbitales, thus displaying a broad host range, show suprisingly low genetic diversity and to date can not be cultured. The genome of the first representative of this cluster, Candidatus Frankia datiscae Dg1 (Dg1), a microsymbiont of Datisca glomerata, was recently sequenced. A phylogenetic analysis of 50 different housekeeping genes of Dg1 and three published Frankia genomes showed that cluster II is basal among the symbiotic Frankia clusters. Detailed analysis showed that nodules of D. glomerata, independent of the origin of the inoculum, contain several closely related cluster II Frankia operational taxonomic units. Actinorhizal plants and legumes both belong to the nitrogen-fixing plant clade, and bacterial signaling in both groups involves the common symbiotic pathway also used by arbuscular mycorrhizal fungi. However, so far, no molecules resembling rhizobial Nod factors could be isolated from Frankia cultures. Alone among Frankia genomes available to date, the genome of Dg1 contains the canonical nod genes nodA, nodB and nodC known from rhizobia, and these genes are arranged in two operons which are expressed in D. glomerata nodules. Furthermore, Frankia Dg1 nodC was able to partially complement a Rhizobium leguminosarum A34 nodC::Tn5 mutant. Phylogenetic analysis showed that Dg1 Nod proteins are positioned at the root of both α- and β-rhizobial NodABC proteins. NodA-like acyl transferases were found across the phylum Actinobacteria, but among Proteobacteria only in nodulators. Taken together, our evidence indicates an Actinobacterial origin of rhizobial Nod factors.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0127630PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4447401PMC
April 2016

Platelet surface-associated activation and secretion-mediated inhibition of coagulation factor XII.

PLoS One 2015 17;10(2):e0116665. Epub 2015 Feb 17.

National Research Center for Hematology, Moscow, Russia; Center for Theoretical Problems of Physicochemical Pharmacology, Moscow, Russia; Federal Research and Clinical Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia; Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia; Faculty of Biological and Medical Physics, Moscow Institute of Physics and Technology, Dolgoprudny, Russia.

Coagulation factor XII (fXII) is important for arterial thrombosis, but its physiological activation mechanisms are unclear. In this study, we elucidated the role of platelets and platelet-derived material in fXII activation. FXII activation was only observed upon potent platelet stimulation (with thrombin, collagen-related peptide, or calcium ionophore, but not ADP) accompanied by phosphatidylserine exposure and was localised to the platelet surface. Platelets from three patients with grey platelet syndrome did not activate fXII, which suggests that platelet-associated fXII-activating material might be released from α-granules. FXII was preferentially bound by phosphotidylserine-positive platelets and annexin V abrogated platelet-dependent fXII activation; however, artificial phosphotidylserine/phosphatidylcholine microvesicles did not support fXII activation under the conditions herein. Confocal microscopy using DAPI as a poly-phosphate marker did not reveal poly-phosphates associated with an activated platelet surface. Experimental data for fXII activation indicates an auto-inhibition mechanism (ki/ka = 180 molecules/platelet). Unlike surface-associated fXII activation, platelet secretion inhibited activated fXII (fXIIa), particularly due to a released C1-inhibitor. Platelet surface-associated fXIIa formation triggered contact pathway-dependent clotting in recalcified plasma. Computer modelling suggests that fXIIa inactivation was greatly decreased in thrombi under high blood flow due to inhibitor washout. Combined, the surface-associated fXII activation and its inhibition in solution herein may be regarded as a flow-sensitive regulator that can shift the balance between surface-associated clotting and plasma-dependent inhibition, which may explain the role of fXII at high shear and why fXII is important for thrombosis but negligible in haemostasis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0116665PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4331558PMC
December 2015

Comparison of the nodule vs. root transcriptome of the actinorhizal plant Datisca glomerata: actinorhizal nodules contain a specific class of defensins.

PLoS One 2013 29;8(8):e72442. Epub 2013 Aug 29.

Department of Botany, Stockholm University, Stockholm, Sweden.

Actinorhizal root nodule symbioses are very diverse, and the symbiosis of Datisca glomerata has previously been shown to have many unusual aspects. In order to gain molecular information on the infection mechanism, nodule development and nodule metabolism, we compared the transcriptomes of D. glomerata roots and nodules. Root and nodule libraries representing the 3'-ends of cDNAs were subjected to high-throughput parallel 454 sequencing. To identify the corresponding genes and to improve the assembly, Illumina sequencing of the nodule transcriptome was performed as well. The evaluation revealed 406 differentially regulated genes, 295 of which (72.7%) could be assigned a function based on homology. Analysis of the nodule transcriptome showed that genes encoding components of the common symbiosis signaling pathway were present in nodules of D. glomerata, which in combination with the previously established function of SymRK in D. glomerata nodulation suggests that this pathway is also active in actinorhizal Cucurbitales. Furthermore, comparison of the D. glomerata nodule transcriptome with nodule transcriptomes from actinorhizal Fagales revealed a new subgroup of nodule-specific defensins that might play a role specific to actinorhizal symbioses. The D. glomerata members of this defensin subgroup contain an acidic C-terminal domain that was never found in plant defensins before.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0072442PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3756986PMC
April 2014

A nascent proteome study combining click chemistry with 2DE.

Proteomics 2013 Jan 15;13(1):17-21. Epub 2012 Dec 15.

Department of Chemistry, A.N. Belozersky Institute for Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.

To investigate the dynamic cellular response to a condition change, selective labeling of the nascent proteome is necessary. Here, we report a method combining click chemistry protein labeling with 2D DIGE. To test the relevance of the method, we compared nascent proteomes of actively growing bacterial cells with that of cells exposed to protein synthesis inhibitor, erythromycin. Cells were incubated with methionine analog, homopropargyl glycin, and their nascent proteome was selectively labeled with monosulfonated neutral Cy3 and Cy5 azides specially synthesized for this purpose. Following fluorescent labeling, the protein samples were mixed and subjected to standard 2D DIGE separation. The method allowed us to reveal a dramatic reduction of newly synthesized proteins upon erythromycin treatment, while the total proteome was not significantly affected. Additionally, several proteins, whose synthesis was resistant to erythromycin, were identified.
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http://dx.doi.org/10.1002/pmic.201200393DOI Listing
January 2013

Non-stressful death of 23S rRNA mutant G2061C defective in puromycin reaction.

J Mol Biol 2012 Mar 10;416(5):656-67. Epub 2012 Jan 10.

Department of Chemistry and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia.

Catalysis of peptide bond formation in the peptidyl transferase center is a major enzymatic activity of the ribosome. Mutations limiting peptidyl transferase activity are mostly lethal. However, cellular processes triggered by peptidyl transferase deficiency in the bacterial cell are largely unknown. Here we report a study of the lethal G2061C mutant of Escherichia coli 23S ribosomal RNA (rRNA). The G2061C mutation completely impaired the puromycin reaction and abolished formation of the active firefly luciferase in an in vitro translation system, while poly(U)- and short synthetic mRNA-directed peptidyl transferase reaction with aminoacylated tRNAs in vitro was seemingly unaffected. Study of the cellular proteome upon expression of the 23S rRNA gene carrying the G2061C mutation compared to cells expressing wild-type 23S rRNA gene revealed substantial differences. Most of the observed effects in the mutant were associated with reduced expression of stress response proteins and particularly proteins associated with the ppGpp-mediated stringent response.
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http://dx.doi.org/10.1016/j.jmb.2012.01.005DOI Listing
March 2012

Application of Spiroplasma melliferum proteogenomic profiling for the discovery of virulence factors and pathogenicity mechanisms in host-associated spiroplasmas.

J Proteome Res 2012 Jan 16;11(1):224-36. Epub 2011 Dec 16.

Russian Institute of Physico-Chemical Medicine, Malaya Pirogovskaya 1a, Moscow, Russian Federation.

To date, no genome of any of the species from the genus Spiroplasma has been completely sequenced. Long repetitive sequences similar to mobile units present a major obstacle for current genome sequencing technologies. Here, we report the assembly of the Spiroplasma melliferum KC3 genome into 4 contigs, followed by proteogenomic annotation and metabolic reconstruction based on the discovery of 521 expressed proteins and comprehensive metabolomic profiling. A systems approach allowed us to elucidate putative pathogenicity mechanisms and to discover major virulence factors, such as Chitinase utilization enzymes and toxins never before reported for insect pathogenic spiroplasmas.
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http://dx.doi.org/10.1021/pr2008626DOI Listing
January 2012

Core proteome of the minimal cell: comparative proteomics of three mollicute species.

PLoS One 2011 19;6(7):e21964. Epub 2011 Jul 19.

Scientific Research Institute of Physical-Chemical Medicine, Federal Bio-Medical Agency of Russia, Moscow, Russia.

Mollicutes (mycoplasmas) have been recognized as highly evolved prokaryotes with an extremely small genome size and very limited coding capacity. Thus, they may serve as a model of a 'minimal cell': a cell with the lowest possible number of genes yet capable of autonomous self-replication. We present the results of a comparative analysis of proteomes of three mycoplasma species: A. laidlawii, M. gallisepticum, and M. mobile. The core proteome components found in the three mycoplasma species are involved in fundamental cellular processes which are necessary for the free living of cells. They include replication, transcription, translation, and minimal metabolism. The members of the proteome core seem to be tightly interconnected with a number of interactions forming core interactome whether or not additional species-specific proteins are located on the periphery. We also obtained a genome core of the respective organisms and compared it with the proteome core. It was found that the genome core encodes 73 more proteins than the proteome core. Apart of proteins which may not be identified due to technical limitations, there are 24 proteins that seem to not be expressed under the optimal conditions.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0021964PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3139596PMC
December 2011

The acylation state of surface lipoproteins of mollicute Acholeplasma laidlawii.

J Biol Chem 2011 Jul 3;286(26):22769-76. Epub 2011 May 3.

Institute of Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow 119992, Russia.

Acylation of the N-terminal Cys residue is an essential, ubiquitous, and uniquely bacterial posttranslational modification that allows anchoring of proteins to the lipid membrane. In gram-negative bacteria, acylation proceeds through three sequential steps requiring lipoprotein diacylglyceryltransferase, lipoprotein signal peptidase, and finally lipoprotein N-acyltransferase. The apparent lack of genes coding for recognizable homologs of lipoprotein N-acyltransferase in gram-positive bacteria and Mollicutes suggests that the final step of the protein acylation process may be absent in these organisms. In this work, we monitored the acylation state of eight major lipoproteins of the mollicute Acholeplasma laidlawii using a combination of standard two-dimensional gel electrophoresis protein separation, blotting to nitrocellulose membranes, and MALDI-MS identification of modified N-terminal tryptic peptides. We show that for each A. laidlawii lipoprotein studied a third fatty acid in an amide linkage on the N-terminal Cys residue is present, whereas diacylated species were not detected. The result thus proves that A. laidlawii encodes a lipoprotein N-acyltransferase activity. We hypothesize that N-acyltransferases encoded by genes non-homologous to N-acyltransferases of gram-negative bacteria are also present in other mollicutes and gram-positive bacteria.
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http://dx.doi.org/10.1074/jbc.M111.231316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3123044PMC
July 2011

The role of intracellular glutathione in the progression of Chlamydia trachomatis infection.

Free Radic Biol Med 2010 Dec 29;49(12):1947-55. Epub 2010 Sep 29.

Research Institute for Physico-Chemical Medicine, Moscow, Russia.

The productive internalization in the host cell of Chlamydia trachomatis elementary bodies and their infectivity depends on the degree of reduction of disulfide bonds in the outer envelope of the elementary body. We have hypothesized that the reducing agent may be intracellular glutathione (GSH). Three approaches were used to modulate the intracellular GSH concentration: (1) treatment of cells with buthionine sulfoximine, which causes irreversible inhibition of GSH biosynthesis; (2) hydrogen peroxide-induced oxidation of GSH by intracellular glutathione peroxidases; and (3) treatment of cells with N-acetyl-l-cysteine (NAC), a precursor of glutathione. In the first two cases, we observed a four- to sixfold inhibition of C. trachomatis infection, whereas in NAC-treated cells we detected an increase in the size of chlamydial inclusions. Using a proteomics approach, we showed that the inhibition of chlamydial infection does not combine with alterations in protein expression patterns after cell treatment. These results suggest that GSH plays a key role in the reduction of disulfide bonds in the C. trachomatis outer envelope at an initial stage of the infection.
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http://dx.doi.org/10.1016/j.freeradbiomed.2010.09.024DOI Listing
December 2010

Functional divergence of Helicobacter pylori related to early gastric cancer.

J Proteome Res 2010 Jan;9(1):254-67

Research Institute for Physico-Chemical Medicine, Moscow, Russia.

Helicobacter pylori is an extra macro- and microdiverse bacterial species, but where and when diversity arises is not well-understood. To test whether a new environment accelerates H. pylori genetic changes for quick adaptation, we have examined the genetic and phenotypic changes in H. pylori obtained from different locations of the stomach from patients with early gastric cancer (ECG) or chronic gastritis (CG). Macroarray analysis did not detect differences in genetic content among all of the isolates obtained from different locations within the same stomach of patients with EGC or CG. The extent and types of functional diversity of H. pylori isolates were characterized by 2-D difference gel electrophoresis (2D DIGE). Our analysis revealed 32 differentially expressed proteins in H. pylori related to EGC and 14 differentially expressed proteins in H. pylori related to CG. Most of the differentially expressed proteins belong to the antioxidant protein group (SodB, KatA, AphC/TsaA, TrxA, Pfr), tricarbon acid cycle proteins (Idh, FrdA, FrdB, FldA, AcnB) and heat shock proteins (GroEL and ClpB). We conclude that H. pylori protein expression variability is mostly associated with microorganism adaptation to morphologically different parts of the stomach, which has histological features and morphological changes due to pathological processes; gene loss or acquisition is not involved in the adaptation process.
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http://dx.doi.org/10.1021/pr900586wDOI Listing
January 2010

The yfiC gene of E. coli encodes an adenine-N6 methyltransferase that specifically modifies A37 of tRNA1Val(cmo5UAC).

RNA 2009 Jun 21;15(6):1134-41. Epub 2009 Apr 21.

Department of Chemistry, Moscow State University, Moscow 119992, Russia.

Transfer RNA is highly modified. Nucleotide 37 of the anticodon loop is represented by various modified nucleotides. In Escherichia coli, the valine-specific tRNA (cmo(5)UAC) contains a unique modification, N(6)-methyladenosine, at position 37; however, the enzyme responsible for this modification is unknown. Here we demonstrate that the yfiC gene of E. coli encodes an enzyme responsible for the methylation of A37 in tRNA(1)(Val). Inactivation of yfiC gene abolishes m(6)A formation in tRNA(1)(Val), while expression of the yfiC gene from a plasmid restores the modification. Additionally, unmodified tRNA(1)(Val) can be methylated by recombinant YfiC protein in vitro. Although the methylation of m(6)A in tRNA(1)(Val) by YfiC has little influence on the cell growth under standard conditions, the yfiC gene confers a growth advantage under conditions of osmotic and oxidative stress.
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http://dx.doi.org/10.1261/rna.1494409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2685529PMC
June 2009

Importance of Protocol Immunization in Epitope Selectivity of Monoclonal Antibodies Interacting with Binding Subunit of Viscumin.

Russ J Immunol 2000 Dec;5(4):375-384

M.V. Lomonosov Moscow State University, Moscow, Russia.

The application of two immunization protocols and two screening systems has allowed to produce five hybridomas mlb5, mlb6, mlb7, mlb9 and Mbch1, secreting mAbs against different sites of viscumin B-subunit. On the base of mlb9 and Mbch1 hybridomas, the test-system has been developed, able to detect up to 5 ng/ml of viscumin and up to 1 ng/ml of its B-chain. Produced hybridomas and monoclonal antibodies will be used for the studies of intracellular transport of plant toxins. Monoclonal antibody mlb7 will be used for the studies of viscumin interactions with immune system of mammals.
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December 2000
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