[Antisense oligonucleotides containing 1-(beta-D-2'-deoxy-threo-pentofuranosyl)thymine at the 3'- and 5'-end]. / Antisensovye oligonukleotidy, soderzhashchie po 3'- i 5'-kontsam 1-(beta-D'-dezoksi-treo-pentofuranozil)timin.

Oligonucleotides with 3'- and 5'-terminal 1-(beta-D-2'-deoxy-threo-pentafuranosyl)thymin residues (inversion at C3'-atom) were obtained by the automatic phosphoramidite synthesis. The modifications protect oligonucleotides from the nuclease degradation and do not affect the stability of nucleic acid duplexes.

[Chemical reactions in double-helical nucleic acids. XV. The effect of local DNA structure on the efficacy of chemical ligation]. / Khimicheskie reaktsii v dvuspiral'nykh nukleinovykh kislotakh. XV. Vliianie lokal'noi struktury DNK na éffektivnost' khimicheskogo ligirovaniia.

A series of model DNA-duplexes with a single break in one of the chains were studied. The efficiency of the new internucleotide bond formation by means of chemical ligation was shown to depend on the DNA structure in the nick site, decreasing in the following order: pyrimidine-pyrimidine > purine-pyrimidine > pyrimidine-purine > > purine-purine. This relationship is the most pronounced in duplexes with 5'-hydroxyl group as 3'-phosphate acceptor. For duplexes, containing non-complementary base pairs in the reaction centre, the yield of ligation products also depends on the nature of the interacting nucleotides.

[Chemical reactions in double-helical nucleic acids. XIV. Effectiveness of forming phosphodiester bonds between various nucleotide units]. / Khimicheskie reaktsii v dvuspiral'nykh nukleinovykh kislotakh. XIV. Effektivnost' obrazovaniia fosfodiéfirnykh sviazei mezhdu razlichnymi nukleotidnymi zven'iami.

Efficiency of the template-directed condensation of oligonucleotides depends on the nature of the nucleotide units to be joined. Fourteen out of sixteen dinucleotide combinations in double-stranded DNA were examined. Alterations of the reaction efficiency are identical for cyanogen bromide and 1-ethyl-3-(3'-dimethylaminopropyl)carbodiimide coupling reagents. Dependence of the chemical ligation efficiency on the DNA sequence-specific local conformation is discussed.

[Significance of catecholamine levels in the diagnosis and prognosis of dysadaptation of preterm newborn infants]. / Znachenie pokazatelei katekholaminov dlia diagnostiki i prognoza dizadaptatsii u nedonoshennykh novorozhdennykh.

Analysis of the clinical status of preterm newborns and the results of histochemical studies of the red cell catecholamine depositing function has led the authors to a conclusion that the Apgar score is reliable only in case of the newborn's critical condition. In slight and medium-severity asphyxia high red cell satiation with catecholamine granules was associated with a favorable outcome for the newborns. The authors claim that analysis of red cell catecholamine-depositing function is a sufficiently reliable diagnostic and prognostic criterion for the assessment of a preterm newborn's status.

Chemical ligation of DNA: the first non-enzymatic assembly of a biologically active gene.

An artificial gene comprising 183 base pairs has been assembled by template-directed condensation of 35- to 53-membered oligodeoxyribo nucleotides with cyanogen bromide as a condensing agent. The reaction is complete within several minutes at 0 degrees C in buffer. The resulting mini-gene was cloned and expressed in vivo and in vitro. We have also found that the polymerase inhibition technique (toe-printing) is a good way to ascertain that translation initiation complexes form in the case of single-stranded DNAs as well. Thus, along with the fully chemical assembly of synthetic genes, a rapid and sufficiently reliable method for determining their ribosome-binding properties was developed.

The use of BrCN for assembling modified DNA duplexes and DNA-RNA hybrids; comparison with water-soluble carbodiimide.

Both cyanogen bromide (BrCN) and 1-ethyl-3-(3'-dimethylaminopropyl) carbodiimide may be used as coupling reagents for the template-directed assembly of DNA duplexes containing the sugar-phosphate backbone modification. Both reagents show similar ligation site structure-specific trend. Practical recommendations are given for selection of the condensing reagent depending on the properties of the duplex. Based on 31P NMR spectroscopy data, a scheme is suggested for BrCN activation of the nucleotide phosphomonoester group. Using both condensing reagents, we studied the condensation of oligonucleotides containing ribo-segments (from mononucleotide residue to full sequence) on the DNA template. Efficiency of the chemical ligation of RNA oligomers was shown to be much lower than that of DNA analogues. The coupling yield depends on the position of the RNA segment in the hybrid duplexes and on the position of the phosphate group in the nick.

[Changes in the content of beta-endorphin in maternal and fetal blood during transcutaneous electric neurostimulation in premature labor]. / Izmenenie soderzhaniia beta-éndorfina v krovi materi i ploda v usloviiakh primeneniia chreskozhnoi élektroneirostimuliatsii pri prezhdevremennykh rodakh.

The effect of various parameters of transcutaneous electrical neurostimulation (TENS) on changes in B-endorphin (BE) blood plasma level has been studied in the mother and fetus during premature labour. A dependence of changes in BE plasma level on the frequency regimen of the impulse current has been established. The data, on the one hand, demonstrate the regulating effect of high- and low- frequency TENS on BE blood level and, on the other hand, indicate the involvement of endogenous opioid fetus system, which enables it to endure labour-induced stress.

[Effect of reflex regulation of premature labor on the status of the cholinergic system in the mother and newborn infant]. / Vliianie reflektornoi reguliatsii prezhdevremennykh rodov na sostoianie kholinergicheskoi sistemy materi i novorozhden- nogo.

The cholinergic system (CS) has been assessed in 60 women with a premature onset of labor and their newborns. Labor was regulated using transcutaneous electroneurostimulation (TENS) in 40 of them. High-frequency TENS (100-120 Hz) was used for uterine contractility stimulation and low-frequency (30 Hz) was used for relaxation. A pattern of contractile uterine activity was elucidated which indicated beneficial effects of TENS on abnormal conditions in premature labor. A correlation was found out between the maternal and neonatal SC status.

[Reflex correction of the tocolytic activity in premature labor]. / Reflektornaia korrektsiia rodovoi deiatel'nosti pri prezhdevremen- nykh rodakh.

Reflex relaxation using transcutaneous electroneurostimulation (TENS) has been employed in premature labor. Low-frequency TENS proved helpful in the prevention and therapy of un-coordinated uterine contractions and thus in the reduction of perinatal mortality.

[The prostaglandin E content of the blood serum in mother and fetus during the reflex regulation of premature labor]. / Soderzhanie prostaglandina E v syvorotke krovi materi i ploda pri reflektornoi reguliatsii prezhdevremennykh rodov.

Prostaglandin (PG) biosynthesis is promoted by enzyme activation induced by neurohormonal regulation, an important determinant of labor. However, contribution of PG to premature labor is largely uncertain. Maternal and fetal blood PGE levels have been determined during the reflex regulation of premature labor in 39 women and in 20 patients with spontaneous labor. The reflex regulation was performed as transcutaneous suprapubic and sacral electric stimulation. Comparison of PGE levels in the women and their newborns led to the conclusion that the reflex regulation of premature labour has modulating effects on PGE biosynthesis both in the mother and fetus, thereby modifying progress of labor.

[Reflex labor induction in premature labor complicated by premature rupture of fetal membranes]. / Reflektornoe rodovozbuzhdenie pri prezhdevremennykh rodakh, oslozhnennykh prezhdevremennym izlitiem okoloplodnykh vod.

Labor induction in impending premature delivery complicated by premature rupture of the membranes is controversial. Problems arise both with choice of a mode of delivery and induction manoeuvres to be used in biologically premature delivery. The paper addresses the results with a reflex method of labor induction based on transcutaneous electroneurostimulation (TENS). An appropriate TENS regimen was found to be a highly efficient method of labor induction allowing one to reduce the incidence of perinatal complications.

[Changes in various parameters of humoral immunity and the sympathetico-adrenal system in newborn infants after transcutaneous electric nerve stimulation in premature labor]. / Izmenenie nekotorykh parametrov gumoral'nogo immuniteta i simpatiko-adrenalovoi sistemy u novorozhdennykh pri chreskozhnoi élektroneirostimuliatsii prezhdevremennykh rodov.

Transcutaneous electric neurostimulation (TENS) as a mode of reflex therapy acts on the hypothalamic-pituitary control via the neuromediator system to modulate the activity of endocrine glands, metabolism and the immune status. Immunoglobulin and catecholamine levels and the activity of tumor necrosis factor have been assayed in umbilical blood sera of 25 preterm newborns who were delivered using TENS (n = 10) and spontaneously (n = 15). Comparison of clinical data and the findings of catecholamine and immune factor assays suggested that TENS in premature delivery improved fetal and neonatal adaptations to perinatal stresses and infection.

Total chemical assembly of genes.

An artificial gene comprising 183 base pairs has been assembled by template-directed condensation of 35- to 53-membered oligodeoxyribonucleotides with cyanogen bromide as a condensing agent. The reaction is complete within several minutes at 0 degree C in buffer. The resulting gene was cloned into M13mp11 and sequenced using the Sanger sequencing procedure.

[Chemical reactions in double-helical nucleic acids. VIII. Assembly of hybrid RNA-DNA-duplexes using water soluble condensing agents]. / Khimicheskie reaktsii v dvukhspiral'nykh nukleinovykh kislotakh. VIII. Sborka gibridnykh RNK-DNK dupleksov s ispol'zovaniem vodorasvorimykh kondensiruiushchikh agentov.

Condensation of oligonucleotides containing ribonucleotide segments (from mononucleotide to full sequence) on DNA-template was studied, with cyanogen bromide and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as condensing agents. Efficiency of the chemical ligation of RNA oligomers was much lower than that of DNA analogues. The yield of chemical ligation products was found to depend on the position of RNA segment in the hybrid duplexes and on the position of the phosphate group in the nick. The oligoribonucleotide's length does not affect the yield of condensation products. A nick in 5S RNA loop was repaired by means of the chemical ligation method.

Chemical reactions within DNA duplexes. Cyanogen bromide as an effective oligodeoxyribonucleotide coupling agent.

Cyanogen bromide was found to condense oligodeoxyribonucleotides on a complementary template in aqueous solution. Optimum conditions for this vigorous and effective reaction were developed. CNBr proved to be useful for incorporation of phosphoramidate or pyrophosphate internucleotide bonds in DNA duplexes.

Site-directed modification of DNA duplexes by chemical ligation.

The efficiency of chemical ligation method have been demonstrated by assembling a number of DNA duplexes with modified sugar phosphate backbone. Condensation on a tetradecanucleotide template of hexa(penta)- and undecanucleotides differing only in the terminal nucleoside residue have been performed using water-soluble carbodiimide as a condensing agent. As was shown by comparing the efficiency of chemical ligation of single-strand breaks in those duplexes, the reaction rate rises 70 or 45 times if the 3'-OH group is substituted with an amino or phosphate group (the yield of products with a phosphoramidate or pyrophosphate bond is 96-100% in 6 d). Changes in the conformation of reacting groups caused by mismatched base pairs (A.A, A.C) as well as the hybrid rU.dA pair or an unpaired base make the template-directed condensation less effective. The thermal stability of DNA duplexes was assayed before and after the chemical ligation. Among all of the modified duplexes, only the duplex containing 3'-rU in the nick was found to be a substrate of T4 DNA ligase.

[Chemical reactions in double-stranded nucleic acids. IV. Cyanogen bromide--a highly effective reagent in the condensation of oligodeoxyribonucleotides]. / Khimicheskie reaktsii v dvuspiral'nykh nukleinovykh kislotakh. IV. Bromtsian--vysokoéffektivnyi reagent pri kondensatsii oligodezoksiribonukleotidov.

Cyanogen bromide was found to induce a smooth and highly efficient condensation of oligonucleotide blocks within DNA duplexes. This template-directed reaction proceeds in the aqueous solution at 0 degree C for 1-2 min. Cyanogen bromide catalyzes the formation not only of phosphodiester, but also of unnatural phosphoramide and pyrophosphate interoligomer bonds.