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Biomedical subjects

I A Kozlov

Publications and source records attributed to I A Kozlov.

At least 19 recordsLinked to original sources
PubMed2003

[Pancreatoduodenal resection with preservation of the pylorus].

Experience with 106 pancreatoduodenal resections (PDR) with pylorus savage for tumors and benign diseases of pancreatic head and periampullar zone is analyzed. Features of mobilization of pancreatoduodenal complex in PDR are shown. They permit to reduce the rate of complications (gastrostasis). Necessity of differential approach to choice of creation of biliodigestive anastomosis is demonstrated. Risk of postoperative pancreatitis is highest in non-dilated pancreatic duct and small-changed pancreatic parenchyma. In these cases terminolateral pancreatojejunostomy with external drainage of pancreatic duct (12 patients) and pancreatogastrostomy (21) are preferable. PDR with pylorus savage permitted to use wider pancreato-, bilio- and duodenoenteroejunoanastomosis on one loop of the jejunum. Gastrostasis was seen in 50% patients after PDR with pylorus savage. Technical features of surgery and also postoperative complications leading to gastrostasis are demonstrated.

Humans↗
PubMed2001

Synthesis of solid-supported mirror-image sugars: a novel method for selecting receptors for cellular-surface carbohydrates.

We introduced a novel method, through mirror-image phage display, for the identification of high-affinity D-peptides to target specific cell-surface carbohydrates. Both 3-deoxy-alpha-L-manno-2-octulosonic acid (L-KDO) and L-sialic acid and an L-sialo-disaccharide have been synthesized and attached to a solid support for selection of high-affinity peptide binders displayed on phages. Our initial studies in this effort produce single-chain Fab sequences and dodecapeptides that bind to sialic acid and KDO with nanomolar and high micromolar affinity.

Amino Acid Sequence↗
PubMed2000

Nonenzymatic template-directed reactions on altritol oligomers, preorganized analogues of oligonucleotides.

Altritol nucleic acids (ANAs) are RNA analogues with a phosphorylated D-altritol backbone. The nucleobase is attached at the 2-(S)-position of the carbohydrate moiety. We report that ANA oligomers are superior to the corresponding DNA, RNA, and HNA (hexitol nucleic acid) in supporting efficient nonenzymatic template-directed synthesis of complementary RNAs from nucleoside-5'-phosphoro-2-methyl imidazolides. Activated ANA and HNA monomers do not oligomerize efficiently on DNA, RNA, HNA, or ANA templates.

Chemistry↗
PubMed1999

Nonenzymatic synthesis of RNA and DNA oligomers on hexitol nucleic acid templates: the importance of the A structure.

Hexitol nucleic acid (HNA) is an analogue of DNA containing the standard nucleoside bases, but with a phosphorylated 1,5-anhydrohexitol backbone. HNA oligomers form duplexes having the nucleic acid A structure with complementary DNA or RNA oligomers. The HNA decacytidylate oligomer is an efficient template for the oligomerization of the 5'-phosphoroimidazolides of guanosine or deoxyguanosine. Comparison of the oligomerization efficiencies on HNA, RNA, and DNA decacytidylate templates under various conditions suggests strongly that only nucleic acid double helices with the A structure support efficient template-directed synthesis when 5'-phosphoroimidazolides of nucleosides are used as substrates.

Catalysis↗
PubMed1999

Nonenzymatic oligomerization reactions on templates containing inosinic acid or diaminopurine nucleotide residues.

The template-directed oligomerization of nucleoside-5'-phosphoro-2-methyl imidazolides on standard oligonucleotide templates has been studied extensively. Here, we describe experiments with templates in which inosinic acid (I) is substituted for guanylic acid, or 2,6-diaminopurine nucleotide (D) for adenylic acid. We find that the substitution of I for G in a template is strongly inhibitory and prevents any incorporation of C into internal positions in the oligomeric products of the reaction. The substitution of D for A, on the contrary, leads to increased incorporation of U into the products. We found no evidence for the template-directed facilitation of oligomerization of A or I through A-I base pairing. The significance of these results for prebiotic chemistry is discussed.

2-Aminopurine↗
PubMed1999

Efficient transfer of information from hexitol nucleic acids to RNA during nonenzymatic oligomerization.

Hexitol nucleic acids (HNAs) are DNA analogues that contain the standard nucleoside bases attached to a phosphorylated 1,5-anhydrohexitol backbone. We find that HNAs support efficient information transfer in nonensymatic template-directed reactions. HNA heterosequences appeared to be superior to the corresponding DNA heterosequences in facilitating synthesis of complementary oligonucleotides from nucleoside-5'-phosphoro-2-methyl imidazolides.

Chromatography, High Pressure Liquid↗
PubMed1999

Oligomerization of deoxyguanosine 5'-phosphoro-2-methylimidazolide on a polycytidylate template.

The oligomerization of deoxyguanosine 5'-phosphoro-2-methylimidazolide on a polycytidylate template is much less efficient than the oligomerization of the corresponding activated ribonucleotide. Nonetheless oligomers containing up to eight nucleotide residues are detected. The products are 3'-5'-linked oligodeoxyribonucleotides capped at the 5'-terminus with a pyrophosphate-linked monomer.

Chromatography, High Pressure Liquid↗
PubMed1998

Oligomerization of activated D- and L-guanosine mononucleotides on templates containing D- and L-deoxycytidylate residues.

The oligomerization of activated D- and L- and racemic guanosine-5'-phosphoro-2-methylimidazole on short templates containing D- and L-deoxycytidylate has been studied. Results obtained with D-oligo(dC)s as templates are similar to those previously reported for experiments with a poly(C) template. When one L-dC or two consecutive L-dCs are introduced into a D-template, regiospecific synthesis of 3'-5' oligo(G)s proceeds to the end of the template, but three consecutive L-dCs block synthesis. Alternating D-,L-oligomers do not facilitate oligomerization of the D-, L-, and racemic 2-guanosine-5'-phosphoro-2-methylimidazole. We suggest that once a "predominately D-metabolism" existed, occasional L-residues in a template would not have led to the termination of self-replication.

Dimerization↗
PubMed1997

Design of new reagents on the base of DNA duplexes for irreversible inhibition of transcription factor NF-kappa B.

The main purpose of the present work is to search for the optimal design of a DNA duplex containing an active group for crosslinking and irreversible inhibition of the transcription factor NF-kappa B. Modified DNA duplexes with an identical nucleotide sequence but different internucleotide phosphates replaced by the trisubstituted pyrophosphate internucleotide group were synthesized. Crosslinking of the human NF-kappa B p50 subunit with the modified DNA duplexes was carried out. It was shown that only four modified duplexes crosslinked with the NF-kappa B p50 subunit. The specificity of these reactions was confirmed. A position of the phosphate in the NF-kappa B recognition site was found where replacement on the active trisubstituted pyrophosphate group resulted in a 50% yield of crosslinking. The fact that DNA duplexes containing the trisubstituted pyrophosphate group specifically react with the NF-kappa B p50 subunit in the Escherichia coli total lysate supports the idea that such modified DNA can be used as high specific inhibitors for DNA-recognizing proteins.

Animals↗
PubMed1997

[Surgical treatment of postbulbar duodenal ulcers].

The results of the surgery in 121 patients with post-bulbar duodenal peptic ulcers (8.5% of all cases of duodenal ulcer) are analysed. In 72.7% the ulcer was complicated with the duodenal stenosis, in 41.3%--with the penetration, in 5.8%--choledochoduodenal fistulas. In 41.3% of the patients the course of ulcer was complicated with bleeding and in 8.3% with perforation. In 18 (14.9%) patients gastric resection was performed with total removal of the ulcer (8) or its remaining pait (10). There were no cases of mortality. In 5 cases there was postoperative pancreonecrosis. Long-term follow up results were evaluated with the use of the Visick' method. Satisfactory results were achieved in 12 patients, unsatisfactory results--in 2 patients. There were no cases of excellent and good results. Selective proximal vagotomy (SPV) was performed in 34 patients, SPV and draining operation--in 28 patients, SPV and duodenoplasty-in 41 patients. There were no mortality and serious complications. Better results were achieved with the use of SPV and duodenoplasty.

Duodenal Ulcer↗
PubMed1995

[A new approach to the problem of immobilizing oligonucleotides on carboxyl-containing nylon membranes for nucleic acid hybridization].

A simple and efficient method of the covalent immobilization of oligonucleotides on carboxyl-containing nylon membranes was proposed. The method is based on the reaction between a postsynthetically introduced aminoalkyl group of an oligonucleotide and membrane carboxyl catalyzed by a water soluble N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide. Judging from the mechanism of carboxyl group activation by the carbodiimide, optimal conditions of the immobilization were selected, which made it possible to increase the immobilization efficiency and carrier capacity as compared with those described previously. Using a 23-unit membrane-immobilized oligonucleotide as an example, the oligonucleotides immobilized were shown to be capable of hybridizing with complementary sequences.

Base Sequence↗