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A divergent route for the synthesis of new derivatives of 4,11-diaminoanthra[2,3-b]thiophene-5,10-dione was developed based on the introduction of cyclic amines to the terminal positions of 4,11-aminoalkyl groups. Modification of the side chains of anthra[2,3-b]-thiophene-5,10-dione increases the affinity of ligands to DNA duplex and decreases the affinity to G-quadruplexes. An analysis of the structure–activity relationship showed that 2-(piperidin-1-yl)ethylamine is the most promising side chain fragment for the development of new double-stranded DNA ligands. The ability of new ligands to bind to DNA duplex correlates with inhibition of tumor cell growth, which indicates the prospects for a further search for new antitumor compounds or chemical probes for duplex-forming nucleic acid sequences among 4,11-diaminoanthra[2,3-b]thiophene-5,10-diones.

Patients with sarcoidosis are usually young people with active lifestyle. On early stages of the disease, clinical symptoms are commonly absent, and its detection occurs by chance. The results of examining this group of patients at rest may not exceed the normal values, therefore it s necessary asses them at the peak of exercise. Undoubtedly, it is important not only to assess the extent of cardiorespiratory system lesion, but also to estimate physical reserve, physical activity level they can perform without harming their health and aggravating underlying disease. Cardiorespiratory stress-echocardiography allows to get complete information for patients with sarcoidosis.

Purpose Identification of subclinical dysfunction of the right ventricular (RV) using modern exercise stress echo. Methods The main group consists of 66 patients with I-II stage of histologically verified pulmonary sarcoidosis: 42 men (63.6%) and 24 women (36.4%); mean age 31.9±5.59 years. The control group included 33 healthy, non-smokers: 24 men (72.7%) and 9 women (27.3%); average age 30.18±5.3 years. Stress-echo was performed on US system Vivid E9 (GE, USA), on a GE “e-Bike” horizontal bicycle ergometer, according to the “50x25” protocol with an increase in load every 2 min. In addition to the standard protocols, the global longitudinal RV strain (GLS RV) and systolic pressure in the pulmonary artery (SPAP, mm Hg) were assessed at rest and at the peak of exercise. Results RV GLS values in patients with sarcoidosis at the peak of exercise didn't increase, but rather decreased from −22.8±3.4% to 21.2±4.7% (p=0.004), unlike increased in healthy volunteers: from −24.1±2.7% to −25.1±3% (p=0.002), the whole values were within the normal range. An important fact is the decrease in the level of GLS RV in patients with pulmonary sarcoidosis (7%, p=0.00001). The estimated rest SPAP in patients with sarcoidosis was slightly higher than in healthy people (28.5±8.3 and 24.8±5.21 mm Hg.; p=0.03), but these values also didn't accede norms. At the peak of exercise, it increased greater than in the control group (32.9±10.1 and 48.36±14.4 mm Hg; p=0.000001). It was additionally revealed that in patients with sarcoidosis, GLS RV decrease by −0.8% was accompanied by an increase in SPAP by 8 mm Hg. In the control group the lower quartile of SPAP was 29 mm Hg, at the peak of exercise – 38 mm Hg. In the main group the value of SPAP exceeded the upper quartile of the control group (38 mm Hg) in 79% of cases. So we confirmed the presence of subclinical pulmonary hypertension in asymptomatic patients at the early stages of pulmonary sarcoidosis. To cut he limits of pathology in the main group, threshold GLS RV values were obtained at the peak of exercise by the method of classification trees. Values less than −21.6% were correlated with the presence of subclinical RV dysfunction with 90% rang; in combination with increase in SPAP more than 39.5 mm Hg – 100% rang. 50 patients (75% of the main group) showed an increase in SPAP at the peak of exercise more than 39.5 mm Hg. 37 patients (56%) showed GLS RV decrease less than −21.6%. Combination of these two parameters was detected in 42% of cases. Conclusions Thus, in 42% of young patients with sarcoidosis, latent right ventricular dysfunction was revealed at the absence of symtoms and pathological changes in resting echocardiography. Therefore, GLS RV decrease at the peak of exercise less than −21.6% with an increase in SPAP more than 39.5 mm Hg may be a predictor of subclinical cardiac dysfunction in patients with pulmonary sarcoidosis. Funding Acknowledgement Type of funding source: None

The modern doctrine of treating ischemic heart disease (IHD) is aimed to choose a method, which maximizes the effectiveness and safety for patients. Currently there are three approaches for treatment of stable IHD: optimal medical therapy, percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). Each approach has own indications and contraindications, based on international recommendations. Separate controversial group of patients are the elderly and senile patients. Limited physical activity, comorbidities, high complications risk in post-PCI double antiplatelet therapy and after CABG, requires strongly individualized approach and proved treatment method. Surgery is possible only after myocardial ischemia is proved by noninvasive imaging methods, assessment of fractional flow reserve (FFR) or its alternative – instant wave-free ratio (iFR) during the coronary angiography. Determination of hemodynamically significant stenosis helps interventional cardiologists to avoid unreasonable revascularization and PCI-related complications.

Purpose To assess CPET data in young patients with pulmonary sarcoidosis (grade I-II) respectively corresponding parameters in healthy individuals. Methods 99 people aged 25–44 years were examined: 66 people with pulmonary sarcoidosis (PS) I-II grade formed the main group. The control group included 33 healthy, non-smoking people. In both groups the CPET was performed for assessment functional status of cardiorespiratory system. Results Vital capacity and FEV1 didn't differ in both groups (p=0.6 and 0.19). However, Tiffno's index was significantly higher in the control group (p=0.0002). There were no differences in RVOT1, RVOT2, RA volume index in both groups. A comparative analysis of the RV wall thickness revealed that the values in both groups did not exceed the normal limits, but in the main group it was significantly larger (p=0.01). The basal RV diameter at rest were also larger in patients with sarcoidosis (p=0.007). LV contractility at rest was within normal values in both groups, however, in patients with sarcoidosis EF were statistically less than in the control group. At the peak of exercise EF increased more significantly in the control group (p Thus, at the early stages of pulmonary sarcoidosis in young people there are no significant contractility abnormalities both at rest and at the peak of exercise, whereas the EF increase was lower than in healthy individuals. It is necessary to determine GLS RV, which may indicate RV dysfunction preceding the development of LV dysfunction. In patients with sarcoidosis, it's necessary to determine PAP at the peak of exercise, which increased in 79% of cases more than in healthy individuals. This may be due to secondary heart lesion at presence of pulmonary hypertension. The maximum oxygen consumption at the peak of exercise is higher in healthy individuals than in patients with sarcoidosis. So functional reserve was higher in the control group. Thus, the CPET today is an informative diagnostic tool which should be included in the diagnostic algorithms for patients with sarcoidosis.

Olivomycin A (OA) exerts its cytotoxic potency due to binding to the minor groove of the G/C-rich DNA and interfering with replication and transcription. Screening of the complete set of tetranucleotide G/C sites by electrophoretic mobility gel shift assay (EMSA) revealed that the sites containing central GC or GG dinucleotides were able to bind OA, whereas the sites with the central CG dinucleotide were not. However, studies of equilibrium OA binding in solution by fluorescence, circular dichroism and isothermal titration calorimetry failed to confirm the sequence preference of OA, indicating instead a similar type of complex and comparable affinity of OA to all G/C binding sites. This discrepancy was resolved by kinetics analysis of the drug&ndash, DNA interaction: the dissociation rate significantly differed between SGCS, SGGS and SCGS sites (S stands for G or C), thereby explaining the disintegration of the complexes during EMSA. The functional relevance of the revealed differential kinetics of OA&ndash, DNA interaction was demonstrated in an in vitro transcription assay. These findings emphasize the crucial role of kinetics in the mechanism of OA action and provide an important approach to the screening of new drug candidates.

Nowadays Building Informational Modeling (BIM-technologies) adoption into the design, construction and operation of capital construction projects is currently a national priority. Optimization of construction costs is also within the state interest. For these reasons, one of the most important functions of BIM-systems which are currently being developed and implemented is the assessment of construction costs at various stages of the full life cycle of different construction objects. At the moment, this function is not fully implemented in software programs used to create BIM-models of capital construction. This paper focuses upon a structure of construction cost development at different stages of the life cycle of an investment and construction project integrated into BIM-systems (as well as the levels of development of its BIM-model). The researchers also introduce a system of estimated standards and indices relevant for BIM-products which can be used to determine the cost of construction.

Novel generations of antitumor anthraquinones are expected to be advantageous over the conventional chemotherapeutic agents. Previous structure–activity relationship studies demonstrated an importance of the positively charged side chains conjugated to anthra[2,3-b]thiophene-5,10-dione scaffolds. Exploring a role of individual side chain moieties in binding to the duplex and G-quadruplex DNA, modulation of telomerase and topoisomerase I activities, intracellular accumulation and cytostatic potency, we herein analyzed a series of reported and newly synthesized guanidine-containing derivatives of anthra[2,3-b]thiophene-5,10-dione. We found that the number of cationic side chains (namely, two) is critical for a tight interaction with human telomeric G-quadruplex (TelQ). Along with a larger drug–TelQ association constant, the telomerase attenuation by anthrathiophenediones with two basic groups in the side chains was more pronounced than by the analogs bearing one basic group. For mono-guanidinated compounds the substituent with the amino group in the side chain provided better TelQ affinity than the methylamine residue. The intracellular uptake of the mono-guanidino derivative with two side chains was >2-fold higher than the respective value for the bis(guanidino) derivative. This difference can explain a lower antiproliferative potency of bis(guanidine) containing compounds. Thus, the modifications of side chains of anthra[2,3-b]thiophene-5,10-dione differently modulated drug–target interactions and cellular effects. Nevertheless, the selected compound 11-(3-aminopropylamino)-4-(2-guanidinoethylamino)anthra[2,3-b]thiophene-5,10-dione 13 demonstrated a high affinity to TelQ and the ability to stabilize the quadruplex structure. These properties were paralleled by reasonable potency of 13 as a telomerase/topoisomerase I inhibitor and an antiproliferative agent. These results indicate that the structural elements of anthra[2,3-b]thiophene-5,10-dione derivatives can be balanced to yield a candidate for further preclinical study.

The porphyrin-based photosensitizers capable of binding to DNA are perspective drug candidates. Here we report the interactions with calf thymus DNA of 5,10,15,20-tetrakis(N-carboxymethyl-4-pyridinium)porphyrin (P1) and its derivatives containing Zn(II) or Ni(II) in the coordination sphere. These interactions were studied with absorption and circular dichroism spectroscopy. NiP1 and ZnP1 formed different types of complexes with DNA. NiP1 intercalated into the double helix, whereas ZnP1 bound the DNA groove. Compound P1 displayed both binding modes. The ZnP1-DNA binding constant was approximately three times smaller than the respective values for P1-DNA and NiP1-DNA complexes. Light induced degradation of the reactive oxygen species (ROS) trap 1,3-diphenylisobenzofuran in the presence of P1 and its metal derivatives revealed that NiP1 was a weaker photooxidative agent, whereas P1 and ZnP1 generated ROS to similar extents. Nevertheless, the DNA photodamaging effect of ZnP1 was the most pronounced. Illumination of the supercoiled plasmid caused single-strand DNA photocleavage in the presence of P1 and ZnP1; double strand breaks were detectable with micromolar concentrations of ZnP1. The concentration of ZnP1 required for plasmid photonicking was two times smaller than that of P1 and ~20 times lower than that for NiP1. Thus, the modes of P1, NiP1 and ZnP1 binding to DNA determine the differential photodamaging potency of these porphyrins. A greater accessibility to the solvent of the groove binder ZnP1, compared to the shielded intercalator NiP1 and the intercalated P1 molecules, allows for an efficient local generation of ROS followed by DNA photocleavage.

Porphyrins are a chemical class that is widely used in drug design. Cationic porphyrins may bind to DNA guanine quadruplexes. We report the parameters of the binding of 5,10,15,20-tetrakis(N-carboxymethyl-4-pyridinium) porphyrin (P1) and 5,10,15,20-tetrakis(N-etoxycarbonylmethyl-4-pyridinium) porphyrin (P2) to antiparallel telomeric G-quadruplex formed by d(TTAGGG)4 sequence (TelQ). The binding constants (K i ) and the number of binding sites (N j ) were determined from absorption isotherms generated from the absorption spectra of complexes of P1 and P2 with TelQ. Compound P1 demonstrated a high affinity to TelQ (K i = (40 ± 6) × 106 M−1, N 1 = 1; K 2 = (5.4 ± 0.4) × 106 M−1, N 2 = 2). In contrast, the binding constants of P2-TelQ complexes (K 1 = (3.1 ± 0.2) × 106 M−1, N 1 = 1; K 2 = (1.2 ± 0.2) × 106 M−1, N 2 = 2) were one order of magnitude smaller than the corresponding values for P2-TelQ complexes. Measurements of the quantum yield and fluorescence lifetime of the drug’s TelQ complexes revealed two types of binding sites for P1 and P2 on the quadruplex oligonucleotide. We concluded that strong complexes can result from the interaction of the porphyrins with TTA loops whereas the weaker complexes are formed with G-quartets. The altered TelQ conformation detected by the circular dichroism spectra of P1-TelQ complexes can be explained by the disruption of the G-quartet. We conclude that peripheral carboxy groups contribute to the high affinity of P1 for the antiparallel telomeric G-quadruplex.

Earlier, a new class of compounds--amphiphilic derivatives of 1,3-diazaadamantanes, capable of facilitating the strand exchange in the system of short oligonucleotides was revealed. Longer hydrophobic side chains of 1,3-diazaadamantanes promoted stronger acceleration of the reaction. In this study, interaction with DNA of two 1,3-diazaadamantane derivatives containing different side chains was investigated by use of optical methods. Concentration of the investigated 1,3-diazaadamantans micelles formation were determined by the means of monitoring fluorescence intensity enhancement of 1-anilinonaphtalene-8-sulphonate probe; as well as the ranges of concentrations where the compounds/water mixtures existed as true solutions. 1,3-diazaadamantanes affinity to DNA was determined with Fluorescent Intercalator Displacement (FID) approach. Significant increase in hydrodynamic volume of short DNA hairpins in the complexes with 1,3-diazaadamantanes was revealed by estimation of the fluorescence polarization of ethidium bromide probe bound to the hairpins. Intermolecular association of DNA hairpins upon binding with 1,3-diazaadamantans was confirmed by Förster resonance energy transfer in system of an equimolar mixture of fluorescently labeled with Cy-3 and Cy-5 hairpins. In this study, the number of positive charges at 1,3-diazaadamantane derivatives containing side chains of different lengths was demonstrated to affect their affinity to DNA, whereas longer length of the hydrophobic side chains ensured more efficient interaction between the DNA duplexes that may facilitate, in particular, DNA strand exchange.

The homology of subunit primary sequence of 40 glutamate decarboxylases (GAD) of different origin was analyzed by multiple alignment. A phylogenetic tree was designed on the basis of the resulting data. The following groups are distinguished in the consensus tree: archeans, bacteria, plant eukaryotes, and animal eukaryotes. The latter are clearly divided into two branches according to two enzyme isoforms. Borders of PLP domains in each enzyme were detected. The consensus phylogenetic tree for PLP domains is structurally rather similar to that obtained for subunits. Twenty homologous motifs of from 15 to 87 amino acid residues were revealed in all GAD studied. The results revealed the division of all of the enzymes into groups with characteristic sets of motifs in each and a fixed order of their arrangement along the sequence. Thus, we can show the divergent evolution of the enzyme. The results of multiple alignments during structural analysis of the 40 GAD confirmed and extended our previous data on conserved residues that arrange the position of the coenzyme (PLP) in the enzyme active center. The following residues should be noted: lysine forming a Schiff base with the PLP aldehyde group, an adjacent histidine, and aspartic acid that establishes a link with nitrogen of the PLP pyridine ring. The homology of the primary sequence fragments was also found in the residues in contact with the PLP phosphate group. Comparison of the GAD amino acid sequence with that of another PLP enzyme, aspartate aminotransferase, revealed a binding site for carboxylic group of the substrate—glutamic acid. The structures carrying out a particular catalytic function of all GAD studied were detected, i.e., convergent evolution of the enzyme was revealed.

Amino acid sequences of E. coli glutamate decarboxylase (GADa) and those of 36 GAD of different origin were compared by pairwise alignment using computer program CLUSTAL. GADalpha and plant enzymes showed 59.8-67.8% subunit homology, GADalpha and other bacterial GAD--49.8-77.6%, whereas GADalpha and animal enzymes--13.9-58.8%. Two PLP domains exhibited higher homology comparing to that of the whole subunit in the case of GAD67, plant (68.4-73.9%), and bacterial (46.7-83.2%) enzymes. The alignment of PLP-domains of 37 GAD, three group II decarboxylases, and two pyridoxal enzymes with known 3D structures (bacterial ORD and mAAT from chicken heart) allowed us to reveal conserved residues of the active sites. Their functional role is discussed. Modelling of the PLP-binding sites in active centers for GADalpha and human brain GAD67 was done using the Swiss-PdbViewer homology modelling program. Although the homology between GADalpha and GAD67 is rather low, structural similarity of their active sites allows us to consider here a functional convergence. Thus, glutamate decarboxylation by GADalpha may be helpful for understanding general mechanism of this reaction.

Porphyrins comprise a chemical class widely used in drug design. Cationic porphyrins may bind to DNA guanine quadruplexes. We report the parameters of binding of 5,10,15,20-tetrakis(N-carboxymethyl-4-pyridinium)porphyrin (P1) and 5,10,15,20-tetrakis(N-etoxy-carbonylmethyl-4-pyridinium)porphyrin (P2) to antiparallel telomeric G-quadruplex formed by d(TTAGGG)4 sequence (TelQ). The binding constants (K(i)) and the number of binding sites (N(i)) were determined from absorption isotherms generated from absorption spectra of complexes of P1 and P2 with TelQ. Compound P1 demonstrated a high affinity to TelQ (K1 = (40 +/- 6) x 10(6) M(-1), N1 = 1; K2 = (5.4 +/- 0.4) x 10(6) M(-1), N = 2). In contrast, the binding constants of P2-TelQ complexes (K1 = (3.1 +/- 0.2) x 10(6) M(-1), N1 = 1; K2 = (1.2 +/- 0.2) x x 10(6) M(-1), N2 = 2) were one order of magnitude smaller than the respective values for P2-TelQ complexes. Measurements of quantum yield and fluorescence lifetime of drug-TelQ complexes revealed two types of binding sites for P1 and P2 on the quadruplex oligonucleotide. The 'strong' complexes can result from interaction of the porphyrinswith TTA loops whereas the weaker complexes are formed with G-quartets. The altered TelQ conformation detected by circular dichroism spectra of P1-TelQ complexes can be explained by a disruption of a G-quartet. We conclude that peripheral carboxy groups contribute tothe high affinity of P1 for the antiparallel telomeric G-quadruplex.

In this study, various proviral HIV-1 DNA forms were analyzed in a chronically infected culture of human monocytes. To elucidate the role of viral RT and cellular DNA polymerases in the formation of the circular forms, we used azidothymidine (AZT) as a specific terminator of viral RT. We previously developed a method for testing the circular proviral DNA forms by means of polymerase chain reaction (PCR) [5] and specific pairs of primers located at the 3' and 5' ends of the HIV-1 DNA (in the env and gag gene regions, respectively). The primers were so oriented that both one-LTR and two-LTR circular proviral DNAs could be determined simultaneously [5]. The total HIV-1 DNA concentration was measured to prepare diluted samples with an equal amount of proviral DNA, in which the relative content of circular nonintegrated forms of viral DNA was detected by means of PCR. The primers nov1‐nov2 were used. An additional amplification with primers V1‐V2 or nov3‐nov4 was performed in samples with low two-LTR circular DNA concentrations.

Equivalent conductivities of lysine cations and phenylalanine anions in ion-exchangers KU-2-8 and AV-17, respectively, are studied. The mobility of ions of amino acids in the ionites is lower than that of mineral ions (sodium and chloride). The obtained results are applied to predict the occurrence of electrochemical regeneration of ion-exchangers in the amino acid forms.

The lithiation of o-sulfonyltriphenylcarbinols proceeds in the ortho position relative to the sulfonyl group, as indicated by formation of the corresponding carboxylic acids upon the action of CO2. Unusual facility was found for the loss of the tert-butyl group in 2-(tert-butylsulfonyl)-3-diphenylhydroxymethyl-benzoic acid in acid media to give the corresponding sultine.

The paper presents results obtained in conformational analysis of homopolymeric four- stranded poly(dT) · poly(dA) · poly(dA) · poly(dT) DNA helices in which the pairs of strands with identical bases are parallel and have a two-fold symmetry axis. All possible models of base binding to yield a symmetric complex have been considered. The dihedral angles of sugar-phosphate backbones and helix parameters, which are consistent with the minima of conformational energy for four-stranded DNAs, have been determined using the results of optimization of conformational energy calculated at atom-atom approximation. Potential energy is shown to depend on the structure of base complexes and on the mutual orientation of unlike strands. Possible biological functions of four-stranded helices are discussed.

The dimetallation of phenyl thienyl sulfones was used to obtain derivatives of benzo[b]thieno[3,2-f]fura2ano[3,4-d]thiepine-1(3),7,7-trioxide, which is anew condensed system.

In spite of ample research about a high level of cholesterol in the blood of patients with colorectal cancer (CRC), the relationship between factors causing hypercholesterolemia and factors leading to CRC development is not fully investigated. The purpose of this article is to provide a review of the current research about the risk factors leading to the development of hypercholesterolemia and CRC, and to show the relationship between these factors, hypercholesterolemia and CRC with the implication for CRC preventive and treatment practices.A systematic search of MEDLINE and PUBMED databases between 1990 and 2005 was conducted to locate the studies that investigated the risk factors causing CRC and hypercholesterolemia. From among 255 studies found, 66 were selected that matched the following criteria for selection: (1) reported original research; (2) discussed at least one of the listed eight factors; (3) discussed hypercholesterolemia; and/or (4) discussed colon or rectum cancer.The studies were grouped according to four areas of research: (1) studies that explored the relationship between different factors and CRC incidences; (2) studies that investigated the relationship between different factors and CRC incidences and the role of mutations in causing CRC; (3) studies that looked at the factors causing hypercholesterolemia; and (4) studies that explored the relationship among the factors, hypercholesterolemia, and CRC development. A discussion of the studies is presented and the details related to the studies major aspects are summarized in 4 tables.The review has revealed a relationship between factors that can lead to the development of CRC and those that lead to hypercholesterolemia. Although the role of many individual risk factors is still controversial the analysis of their significance in combination might be important for diagnostic and development of the models for prediction of cancer occurrence.

The homology of subunit primary sequence of 40 glutamate decarboxylases (GAD) of different origin was analyzed by multiple alignment. A phylogenetic tree was designed on the basis of the resulting data. The following groups are distinguished in the consensus tree: archeans, bacteria, plant eukaryotes, and animal eukaryotes. The latter are clearly divided into two branches according to two enzyme isoforms. Borders of PLP domains in each enzyme were detected. The consensus phylogenetic tree for PLP domains is structurally rather similar to that obtained for subunits. Twenty homologous motifs of from 15 to 87 amino acid residues were revealed in all GAD studied. The results revealed the division of all of the enzymes into groups with characteristic sets of motifs in each and a fixed order of their arrangement along the sequence. Thus, we can show the divergent evolution of the enzyme. The results of multiple alignments during structural analysis of the 40 GAD confirmed and extended our previous data on conserved residues that arrange the position of the coenzyme (PLP) in the enzyme active center. The following residues should be noted: lysine forming a Schiff base with the PLP aldehyde group, an adjacent histidine, and aspartic acid that establishes a link with nitrogen of the PLP pyridine ring. The homology of the primary sequence fragments was also found in the residues in contact with the PLP phosphate group. Comparison of the GAD amino acid sequence with that of another PLP enzyme, aspartate aminotransferase, revealed a binding site for carboxylic group of the substrate--glutamic acid. The structures carrying out a particular catalytic function of all GAD studied were detected, i.e., convergent evolution of the enzyme was revealed.

Cell culture U937 chronically infected with HIV-1 is suggested as a model for adequate evaluation of antiviral activity of HIV inhibitors. Azidothimidine (AZT) notable decreased HIV-1 reproduction in chronically infected U937 cells to passages 15-18. Glycirrhizic acid (GA) effectively inhibited the virus production during the first four passages, while in subsequent passages (up to passage 20) decreased the virus production by only 60% in comparison with the control. If a combination of AZT and GA (1:1000) was used, p24 was not detected in the culture fluid by passage 20. Culturing of U937 cells with AZT led to a 10-fold decrease in the amount of DNA 2-LTR in comparison with the total content of proviral DNA, the content of HIV-1 DNA 1-LTR remaining virtually unchanged. Culturing of U937 with a combination of AZT and GA resulted in a notable decrease in the content of proviral DNA 2-LTR after passage 3, while after passage 9 this form of HIV-1 DNA was not detected at all.

The content of 1-LTR and 2-LTR circular forms of HIV-1 proviral DNA was determined by nested PCR. Outer and inner primers for the first and second stages of PCR were selected in the env and gag regions that allowed the authors to simultaneously test 1- and 2 LTR of DNA HIV-1 forms in the analyzed samples. The accumulation of circular species of HIV-1 DNA was shown to occur during HIV infection as well for acutely infected cell lines as chronically infected mononuclear cells. The cell cultures providing productive infection was characterized by higher levels of 2-LTR circular HIV-1 DNA. Analysing the clinical samples demonstrated greater differences in the accumulation of the circular forms of proviral DNA. It was detected in 16 tested clinical samples both of 1-LTR and 2-LTR circular DNA in 6 samples and 1-LTR in 11 samples of 2-LTR of HIV-1 DNA is a minor fraction in most clinical samples, but in some samples the relative content of 1-LTR/2-LTR DNA was shown to be 1:1.

Primary structure was determined for the recently cloned f1/BglII-fragment [19] containing 2102 b.p. of the human tissue plasminogen activator (tPA) gene 3' end and adjacent DNA region. Computer analysis has revealed an Alu-repeat 820 b.p. downstream the tPA gene; the sequence proved to have a considerable homology (86-88%) with the Alus from the 3'-untranslated regions (3'UTRs) of cytochrome P-450, lysozyme and p53 protein human mRNAs. The same homology was estimated for this Alu in reversed orientation and Alus from the 3'UTRs of some other human mRNAs. In contrast, the homology between this 3' end tPA gene flanking Alu-repeat and other Alus dispersed throughout the gene introns either direct or reversed, was less than 70%. The polyadenylation signal AATAAA downstream the Alu and two nearby signals CACAG and GTGTT resembling consensus sequences CACAG and YGTGTTYY, respectively, were also detected. The two latter motifs located close to the 3' ends in most mammalian genes are likely to regulate mature mRNA formation. The comparison of the sequenced spaser flank adjacent to the tPA gene with short homologous sequence from the same genomic region primary structure reported previously has revealed discrepancies (substitutions, deletions or insertions) in 21 nucleotide positions. The nucleotide sequence of E. coli uvrB gene fragment (980 b.p.) is also reported. This E. coli gene fragment was cloned accidentally within the f1/BglII-fragment being an artifact of the host-vector system used.

It was established that 5'-phosphonates of 3'-azido-2',3'-dideoxythymidine (AZT) inhibit HIV reproduction in the MT-4 cell line as well as AZT. However, the viability of HIV-infected MT-4 cells after treatment with phosphonates was considerable higher that after AZT treatment. Inhibitory activities of 5'-phosphonates of 3'-fluoro-2',3'-dideoxythymidine (FLT) on HIV-infected MT-4 cells were rather low. The mechanism of action of these derivatives and prospects for their application for suppressing HIV infection are discussed.

The temperature dependence of the UV- and CD-spectra of the oligonucleotides 3'-d(A)10-L-(T)10-5' [anti(AT)], 3'-d(A)10-L-d(T)10-3' [par(AT)] and 3'-d(A)10-L-(dT)10-L-(dT)10-5' [tripl(ATT)] (L = -PO(CH2CH2O) 3p-) in the phosphate buffer at pH 7 under different concentrations of NaCL and in the presence or absence of 0.01 M MgCl2 was studied. All registered structural changes are the result of intramolecular processes if the concentrations of the oligonucleotides is low (about 2.2.10(-5) M). Par(AT) and anti(AT) exist in the only two forms, transforming into each other: under low temperatures they exist as hairpins with the parallel or antiparallel orientation of chains accordingly which transform into unfolded chains when the temperature increased. In contrast trip(ATT) exists in the three different forms depending on the temperature and ion conditions. They are: the three- stranded clip, the two-stranded hairpin with a single stranded "tail" and completely unfolded chain. For the first time this work presents thermodynamic parameters of the triplex formation from deoxyoligonucleotides depending on NaCl concentration. We have registered the CD spectra to one-, two-, and three-stranded forms. Ethidium bromide binding to three-stranded "clip" was investigated, and it was established that molecules of the dye may intercalate into the "clip" with formation of stable complexes (the constant of association 10(6) M-1). It is maximum three molecules of ethidium bromid which may bound to one molecule of the three-stranded clip. It has been shown that the suggested synthetic model (three oligonucleotide blocks combined by hydroxyalkyl chains) is the most convenient for physico-chemical investigations of triplexes today.

We have performed a conformational analysis of DNA double helices with parallel directed backbone strands. The calculations were made for homopolymers poly(dG).poly(dC). All possible models of base binding were checked. By the potential energy optimization the dihedral angles and helices parameters of stable conformations of parallel double polynucleotides were calculated. The dependences of conformational energy on the base pair structure were studied. Possible structure of parallel helices with various nucleotide composition are discussed.

The ability of oligonucleotides 3'-d(GT)5pO(CH2)5Opd(GT)5-5' (anti[d(GT)]) and 3'-d(GT)5pO(CH2)6Opd(GT)5-3' (par[d(GT)]) to form hairpins and higher associates is studied. Optical methods of thermal denaturation and circular dichroism as well as the fluorescence of ethidium bromide and acridine orange bound to oligonucleotides were used. At room temperatures the formation of hairpin structure with parallel and antiparallel strands is possible. Thermodynamic parameters of par[d(GT)] and anti[d(GT)] are similar and equal to delta H = -15 kcal/mol, delta S = -50 cal/mol. deg. In the temperature range 3-10 degrees C par[d(GT)] and anti[d(GT)] form four-stranded structures with parallel chains, in which layers of four G-residues alternate with unpaired T-residues being bulged out easily. On comparison of occurrence of alternating (GT)n, (GC)n and (G)n sequences in genome it can be stated that (GT)n biological functions could be connected with conformational possibilities of the four-stranded parallel structures with unpaired T-residues.

Conformational analysis of four stranded DNA helices poly(dT).poly(dA).poly(dA).poly(dT) with parallel arrangement of the identical sugar-phosphate chains connected by twofold symmetry has been performed. All possible models of symmetrical base binding were checked. By the potential energy optimization the dihedral angles and helices parameters of stable conformations of four stranded polynucleotides were calculated. The dependences of conformational energy on the base complex structure and mutual orientation of the poly(dA).and poly(dT) chains were studied. Possible biological functions of four stranded helices are discussed.

The use of the o-orienting effect of the sulfonyl group during metallation with BuLi made possible the synthesis of o-sulfonylbenzaldehydes. Oxidation of their oximes with hypochlorite gave o-sulfonylbenzonitrile oxides, stable at 20°C, which are compounds not obtained previously. They form normal 1,3-dipolar cycloaddition products with styrene, and on heating, they dimerize into furoxanes. o-Sulfonyl-bisbenzonitrile oxide cyclizes into dibenzo[b,f]furazano[3,4-d]thiepin 1(3),8,8-trioxide. 2- and 2,2′-Bistrimethylsilyldiphenyl sulfones were also synthesized, and their metallation was investigated.

The use of the o-orienting effect of the sulfonyl group during metallation with BuLi made possible the synthesis of o-sulfonylbenzaldehydes. Oxidation of their oximes with hypochlorite gave o-sulfonylbenzonitrile oxides, stable at 20°C, which are compounds not obtained previously. They form normal 1,3-dipolar cycloaddition products with styrene, and on heating, they dimerize into furoxanes. o-Sulfonyl-bisbenzonitrile oxide cyclizes into dibenzo[b,f]furazano[3,4-d]thiepin 1(3),8,8-trioxide. 2- and 2,2′-Bistrimethylsilyldiphenyl sulfones were also synthesized, and their metallation was investigated.

The thermal denaturation of four oligonucleotides, viz. 3'-d(AT)5pO(CH2)6Opd(AT)5-3' (parAT), 3'-d(AT)5pO(CH2)5Opd(AT)5-5' (antiAT), 3'-d(A)10pO(CH2)6Op(T)10-3' (parA-T) and 3'd(A)10pOX X (CH2)6Opd(T)10-5' (antiA-T) in 0.01 M phosphate buffer at pH 7 in presence 0.1, 0.25, 0.5 and 1.0 M NaCl have been studied. It was shown that at lower temperature (0-20 degrees C) all oligomeres exist as complexes of two (canonic duplex) or four (eight) molecules of oligonucleotides, but at higher temperature (30-70 degrees C)- as hairpins with parallel (parAT and parA-T) of antiparallel (antiAT and antiA-T) orientation of chains. Thermodinamic parameters of separated strands-hairpins and hairpins--"low temperature complexes" transition were computated from the melting curves [A260 (T)] by nonlinear regression. AntiA-T was shown by ethidium bromide binding to exist at low strength (0.01 M phosphate buffer without NaCl) as four-stranded complex from two antiparallel double stranded helices parallely oriented and bonded by satisfy hydrogen-bond of groups not involved in WC-pairing. At higher ionic strength the two of such tetramers was conjugated by hydrophobic interaction into octamers. We speculate that four-stranded complexes serves to bring together, and zipper up two antiparallel double stranded helices at replication of DNA, cross-over of gomologues chromosomes and other biochemically important processes.

The interaction of pyridoxal, pyridoxal-5'-mono-, di- and triphosphate with certain enzymes of polynucleotide synthesis (DNA-dependent RNA polymerase, DNA-dependent DNA polymerase I and polynucleotide phosphorylase from Escherichia coli and terminal deoxyribonucleotide transferase from calf thymus) was studied. All compounds tested was found to be reversible and competitive inhibitors of these enzymes. The reduction of the enzyme-inhibitor complex with NaBH4 gives rise to the complete irreversible inhibition of the enzymes under study. The comparison of the inhibition constants for pyridoxal and its phosphorylated derivatives with those for mono-, di- and triphosphates of nucleosides was carried out for the enzymes. The results obtained suggest that the modified epsilon-amino-group of lysine residue should be localized at the catalytic site in the vicinity of the pyrophosphate binding area of an enzyme.

Radiosensitivity of chromosomes at S and G2 periods was studied by means of autoradiography technique in cells or regenerating liver of rats treated with X-rays at the doses of 150 and 300 r. The experiments were made so that the interval between irradiation and mitosis in S and G2 cells was equal. The results have shown that under the experimental conditions there are significant differences in the yield of chromosome aberrations between the labelled and intact cells. This withnesses for the existence of differences in radiosensitivity of chromosomes at different periods of mitotic cycle.