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M V Petrova

Publications and source records attributed to M V Petrova.

16 recordsLinked to original sources
PubMed1998

A pseudosquare knot structure of DNA in solution.

We report a high-resolution NMR structure of a homodimer formed by a synthetic 25 residue DNA oligonucleotide GCTCCCATGGTTTTTGTGCACGAGC. This structure presents a novel structural motif for single-stranded nucleic acids, called a pseudosquare knot (PSQ). The oligonucleotide was originally designed to mimic a slipped-loop structure (SLS), another "unusual" DNA structure postulated as an alternative conformation for short direct repeats in double-stranded DNA. The design of the sequence is compatible with both SLS and PSQ structures, both of which possess identical sets of base-paired and unpaired nucleotides but different tertiary folds. We used deuteration of the H8 positions of purines to ascertain that the PSQ is actually formed under the conditions used. The PSQ structure was solved based on homonuclear proton nuclear Overhauser effect data using complete relaxation matrix methods. The structure essentially consists of two side-by-side helices connected by single-stranded loops. Each of the helices is well-defined; however, the relative orientation of the two remains undetermined by the NMR data. The sequences compatible with the PSQ formation are frequent in single-stranded genomes; this structure may play a role as a dimerization motif.

Base Composition↗
PubMed1998

Slipped loop structure of DNA: a specific nucleotide sequence forms only one unique conformer.

Earlier with some DNA sequences we were able to prove the existence of a new polynucleotide chain folding named slipped loop structure, or SLS [1,2]. However, the possibility of the presence of two SLS isomers in equilibrium was not excluded in the experiments. Here we are dealing with a specially designed structure formed by two short oligonucleotides intended for avoiding such a situation. To minimize the possibility of alternative structure formation and stabilize the conformation under investigation, the oligonucleotide sequences were designed in such a way that the bimolecular structure SLS31 would have two binding sites for antibiotic distamycin A. The sample was exposed to chemical probing both in the presence of distamycin A and without the ligand and the accessible nucleotides were mapped. The results do not suggest the presence in the solution of two isomers with different types of loop slippage without interloop interactions and strongly support the formation of a unique slipped loop conformation stabilized by an additional interloop helix, or slipped loop structure.

Base Sequence↗
PubMed1995

Experimental evidence for slipped loop DNA, a novel folding type for polynucleotide chain.

DNA regions with short direct repeats (5-7bp) with a spacer in between, when under super-helical stress, are known to become susceptible to single-strand specific nuclease S1. This is in accord with formation of two shifted loops protruding from the opposite chains. Such type of folding could have been additionally stabilized by base pairing between the complementary parts of the loops that explains existence of the protected from S1 moieties of the loops. To test this possibility we designed and synthesized an oligonucleotide of 56 bases, so that it forms a hairpin with a stem which fails to acquire a traditional helix due to a special sequence but may favor the formation of the proposed Slipped Loop Structure (SLS). The oligonucleotide folding was studied by a chemical modification method at one nucleotide level resolution. Three zones, protected from the used probes were found: the one that forms the stem, and the others that are located within the two by-loops in those moieties which have the base pairing potential. Proceeding from the data obtained and stereochemical analysis a 3-D scheme for the SLS form of DNA is suggested.

Base Composition↗
PubMed1990

[A comparative analysis of immunoenzyme methods of determining bradykinin].

Various modifications of enzyme immunoassay (EIA) for measuring kallikrein-kinin system components (bradykinin, kininogen, kallikrein) are considered. Bradykinin assays are analyzed in detail: double antibodies and competitive solid-phase EIA techniques with the use of various enzymic labels. Special attention is paid to the solid-phase variant in polymeric microplates, the simplest technique that holds good promise for clinical application. The authors have used this method for bradykinin measurements and tried to improve its sensitivity.

Bradykinin↗
PubMedDate not supplied

[Changes in mechanical properties of the lungs in thoracic surgery in cancer patients].

Mechanical characteristics of the lungs and time course of their changes at various stages of thoracal surgery were studied in 119 cancer patients. Lung compliance significantly decreased during transfer of the patients into lateral position. The ranges of normal values of lung compliance and aerodynamic resistance at the stage of one-lung ventilation were determined. The studies confirmed the necessity of intraoperative spirometry in the complex of thoracal operation monitoring.

Adult↗
PubMedDate not supplied

[Optimization of oxygen transport with perfluorane emulsion during surgery of lung cancer].

Perfluorane emulsion was included in infusion/transfusion therapy for optimization of oxygen transport. Central hemodynamics was analyzed during the intervention and immediate postoperative period in 80 patients operated on for lung cancer (pneumonectomy, lobectomy, bilobectomy) under conditions of one-lung ventilation. In the control group perfluorane (6 ml/kg) was infused during induction anesthesia. Increased oxygen delivery without increase of cardiac index was observed in the patients treated with perfluorane. Perfluorane had a positive impact on total peripheral resistance during and immediately after the intervention and virtually did not affect other central hemodynamic parameters. Addition of perfluorane to intraoperative infusion therapy improved oxygen budget of operated cancer patients with concomitant therapeutic diseases.

Aged↗
PubMedDate not supplied

[Antibiotic prophylaxis of postoperative complications in surgical treatment of pulmonary, tracheal and mediastinal tumors].

A protocol of antibiotic protection, developed and used at Russian Research Center of Roentgenoradiology, is presented. This protocol of perioperative treatment is intended for control of a spectrum of bacterial infections retrospectively detected in patients with lung, tracheal, and mediastinal cancer. The efficiency of perioperative antibiotic prevention is demonstrated as exemplified by 105 patients of different age with various concomitant diseases.

Amikacin↗
PubMedDate not supplied

[Use of pyelo-cystic anastomosis in ureteral obliteration after kidney transplantation].

Reconstruction of the urinary tract because of ureteral stricture after kidney transplantation is a serious problem. In development of obliteration of the recipient's ureter near anastomosis and in the absence of own ureters reconstruction is made by pyelocystoanastomosis. A case is reported of a successful use of this method in reconstruction of the urinary tract. Preoperative preparation includes transcutaneous nephrostomy. Sometimes Boary flap is used. The arising reflux had insignificant effect on the transplant's function.

Adult↗
PubMedDate not supplied

[Invasion-free respiratory monitoring in thoracal surgery of oncology patients].

The results of intraoperative monitoring in thoracal surgery of 375 oncology patients with lung cancer were analyzed. The dynamic parameters of ventilation and blood gas composition were investigated in patients with uncomplicated anesthetic management and with complicated adequate ventilation. The diagnostic value of the above parameters is defined for optimizing the respiratory support in surgery for lung cancer.

Adult↗