PubMed Health⌕ Search

Biomedical subjects

A S Mironov

Publications and source records attributed to A S Mironov.

At least 19 recordsLinked to original sources
PubMed2006

[Diagnosis and treatment of sterile pancreonecrosis].

The experience in the treatment of 77 patients with sterile pancreonecrosis is analyzed. The importance of USE as an effective method of screening-diagnosis is emphasized. Computed tomography provides a more accurate diagnosis of pancreonecrosis and complications of it. Lethality in pancreonecrosis correlates with necrosis severity. More than 50% necrosis-affected parenchyma in combination with three and more systemic complications is an unfavorable prognostic factor. Hemofiltration and early management with carbapenem antibiotics arrest progression of multiorgan failure and pyoseptic complications in 75% of cases. Laparoscopic sanation of the abdominal cavity is necessary only for patients with peritonitis. This procedure may be supplemented with laparoscopic cholecystectomy and endoscopic papillosphincterotomy with lithoextraction directly during sanation.

Adult↗
PubMed2006

[Diagnostic algorithm in severe acute pancreatitis].

Efficacy of diagnostic algorithm in 164 patients with severe acute pancreatitis based on complex results of ultrasonic examination, esophagogastroduodenoscopy, computed tomography, magnetic resonance pancreatocholangiography and retrograde pancreatocholangiography is analyzed. The results show that this algorithm is highly effective and provides optimal treatment policy, better treatment results and lower lethality in severe acute pancreatitis. Balthazar's score system with calculation of CTSI index in combination with Ranson and Apache II scales raise accuracy of the disease prognosis.

Acute Disease↗
PubMed2005

[Diagnosis and differential treatment of acute pancreatitis of biliary etiology].

The experience in examination and treatment of 208 patients with acute pancreatitis of biliary etiology was analyzed. Complex endoscopic treatment was carried out in 88% patients. If there are indications, it is reasonable to perform retrograde pancreatocholangiography (RPCG) and endoscopic papillosphincterotomy (EPST) during surgery in patients with concomitant enzymatic ascites-peritonitis. In the others patients RPCG and EPST must be regarded as the first stage of treatment. Surgical procedure of choice at the second stage of treatment is laparoscopic cholecystectomy.

Acute Disease↗
PubMed2004

[Structural-functional analysis of the promoter region of Escherichia coli udp gene].

Effect of mutations in the -10 and -35 regions of the udp gene promoter on the nature of its regulation by CytR and CRP proteins was studied. In studies of expression of mutant promoters, competition between RNA polymerase and the CytR repressor for the promoter region of the udp gene was shown. In the presence of the improved -10 region, the introduction of a substitution 15C-->T (that is the presence of the elongated Pribnow block) resulted in the CRP-independent transcription of the udp gene promoter. The binding site CRP2 was shown to be indispensable for the maximum promoter activation by the transcription-activating cAMP-CRP complex. Both positive (cAMP-CRP complex) and negative (CytR) regulation of the promoter was virtually fully abolished after the introduction of mutations leading to the creation of canonical sequences in -10 and -35 promoter regions.

Base Sequence↗
PubMed2004

[Study of the mechanism for regulating ribR gene activity in Bacillus subtilis].

Analysis of the phenotypic manifestation of inactivation of several genes from the ytlI-ytnM operon containing the ribR gene and results of Northern hybridization showed that the ribR gene does not have the self promoter and is transcribed from the main promoter of the ytlI-ytnM operon. Two sites of single nucleotide substitutions leading to derepresson of ribR gene were identified between the putative main promoter and transcription start of the ytlI-ytnM operon regulatory region.

Bacillus subtilis↗
PubMed2004

[Involvement of sigma S and sigma 70 subunits of RNA polymerase and the CRP protein in the regulation of microcin C51 operon expression].

Expression of the microcin C51 operon in Escherichia coli cells is activated during cell entry into the stationary growth phase and depends on the sigmaS subunit of RNA polymerase (RpoS). The null rpoS mutations retained the residual expression level of the transcriptional P(mcc)-lac fusion, which indicates that other sigma subunit can participate in the regulation of transcription of the microcin C51 operon. Data presented in this work show that the overproduction of sigma70 in rpoS- cells diminished the level of P(mcc)-lac expression, as in wild-type cells, which seems to be the consequence of competition between sigma factors for a limited number of core RNA polymerase molecules. In the presence of the rpoD800 mutation that renders sigma70 temperature-sensitive, expression of P(mcc)-lac was not induced in the phase of delayed culture growth at nonpermissive temperature, which indicates that sigma70 is indispensable for microcin operon expression. Point substitutions in the -10 P(mcc) region, leading to the formation of 5'-TGaTATAAT-3' site, enhanced promoter activity but did not affect the relationship between P(mcc)-lac transcription and growth phase, sigmaS, and the activator protein CRP. The activator protein CRP was shown to bind a DNA fragment containing the TGTGA(AATGAA)TCTAT site in the -59.5 bp position relative to the start site of transcription. Mutation in the ssrI gene encoding 6S RNA did not disturb P9mcc)-lac expression; these results indicate that 6S RNA does not participate in the regulation of microcin C51 operon expression.

Bacteriocins↗
PubMed2004

[Undeveloped high intestinal fistulas as an urgent problem of modern surgery].

Eighty-two cases of un formed high intestinal fistulas are analyzed. Degree of non-formation and volume of chymus loss are the main criteria determining treatment policy. Early surgery (one or two-sided switching of fistulas zone) is indicated in intestinal loss more then 600-700 ml per day or in complete fistula. Mezonnes surgery was un effective in the majority of cases. Special policy including trunk vagotomy, antrumectomy and plastic repair of the duodenal bulb permitted in the last years to avoid duodenal fistulas in the treatment of ulcer disease.

Adolescent↗
PubMed2003

[Determination of functional role of nucleotide composition in the transcription start region of the Escherichia coli udp gene].

The promoter of the Escherichia coli udp gene contains the poly-T (5'-TTTTT-3') motif in the transcription start region located at the distance of 3 nucleotides with respect to the Pribnow box. By means of site-directed mutagenesis, mutations in the +1, -1, and +3 positions of this region were isolated and their functional role in transcription initiation was determined. It was shown that in addition to the thymine nucleotide earlier identified at position 4 (with respect to the 5' end of the poly-T motif), the third thymine nucleotide may serve as an efficient transcription site. The functional significance of the presence of the poly-T motif in the transcription initiation region is discussed. Analysis of the isolated mutant promoters revealed the ability of the guanine nucleotide at the +3 position to stabilize the formation of a productive transcription complex and to serve as an additional transcription start.

Base Composition↗
PubMed2002

[Formation of an additional promotor in the regulatory region of the Escherichia coli udp gene and its structural and functional characterization].

Structural and functional organization of the mutant udpP18 promoter generated after the spontaneous deletion of the G base in the -79 position relative to the start site of transcription from the main (P1) promoter within the regulatory region of the udp gene was studied. In this mutant, a new, functionally active promoter (P2) with the start site of transcription in the -64 position that contained the typical motif 5'-TG-3' located in front of the Pribnow sequence was formed. The data presented suggest that the expression of the P2 promoter, unlike that of P1, is not subjected to regulation with participation of the CytR protein and the cAMP-CRP complex. Results of mutational analysis of the P2 promoter showed that substitutions of the nucleotide G in the -14 position and nucleotide T in the -15 position significantly diminish the level of transcription from the P2 promoter. On the basis of these data, it is concluded that the P2 promoter could be assigned with respect to its characteristics to a group of promoters with an extended -10 region. The synergistic effect of P1 and P2 promoters on total expression of the udp gene in the mutant udpP18 was detected.

Base Sequence↗
PubMed2002

[Functional interrelationship between elements of the Escherichia coli udp gene promotor responsible for binding regulatory proteins CytR, CRP, and RNA polymerase].

Site-directed mutagenesis was conducted in the regulatory region of the Escherichia coli udp gene at promoter sites responsible for binding regulatory proteins CRP and CytR as well as RNA polymerase (the core-promoter containing the--10 sequence). In mutants with an "improved"--10 region, a partial relief from the control of the cAMP-CRP transcription activation complex occurred, and the negative CytR repressor regulation was reduced. In contrast, mutant promoters with a weak Pribnow block or with a deletion that completely eliminates the core-promoter exhibited an increased ability to titrate the CytR protein in vivo. On the other hand, the affinity of CytR for DNA in mutants with an altered--10 region was the same as in the wild-type udp promoter. After introduction of mutations affecting binding sites for CRP (CRP1 and CRP2), the negative effect of the CytR protein on promoter transcription was fully abolished. The CRP1 binding site was shown to play the main role in the activation of the promoter by the cAMP-CRP complex, whereas the CRP2 site participates in the formation of the repressor complex. Mutations in the main and additional CytR binding sites were isolated and characterized. On the basis of these data, it is concluded that the modification of each structural element of the udp regulatory region (binding sites for CytR, CRP, or RNA polymerase) caused changes in the overall pattern of the promoter regulation.

Base Sequence↗
PubMed2000

[Choice of cholecystolithiasis treatment].

Since January 1996 to December 1998 in the surgical department of Central Clinical Hospital (CCH) 594 cholecystectomies were performed. Laparoscopic cholecystectomies were made in 516 (86.8%) patients. Intraoperative complications occurred in 8 patients, without lethal outcomes. In the gastroenterological department of CCH 146 patients had cholelithic therapy with mechanical lithotripsy. It was possible to completely eliminate fragments of stones in 45 patients. The rest (101 patients) have undergone cholecystectomy. Cholelithic therapy with mechanical lithotripsy is indicated only in young patients it they reject cholecystectomy.

Adult↗
PubMed1999

Dissection of a surface-exposed portion of the cAMP-CRP complex that mediates transcription activation and repression.

The Escherichia coli cAMP receptor protein (CRP) is essential for the activation and repression of transcription initiation at promoters in the CytR regulon. CRP performs these activities by making direct protein-protein interactions to the alpha-subunits of RNA polymerase and to the CytR regulator. Strikingly, it has been shown that amino acids of CRP that are critical for communication with the two partner proteins are located in close proximity on the surface of CRP. Here, we have dissected this surface in order to pinpoint the 'repression region' of CRP and to assess whether it overlaps with the characterized 'activating region'. Our results established that residues 12, 13, 17, 105, 108 and 110 are essential for the interaction with CytR and confirmed that 'activating region' 2 of CRP is made up of residues 19, 21 and 101. In the crystallographic structure of the CRP-DNA complex, the two sets of determinants are located immediately adjacent to each other forming a consecutive surface-exposed patch. The 'repression region' is chemically complementary to the characterized region on CytR that is essential for protein-protein communication to CRP. Moreover, the results provide insight into the mechanism by which CytR might prevent CRP-mediated transcription.

Alanine↗
PubMed1998

Isolation and initial characterization of the uridine phosphorylase from Salmonella typhimurium.

The structural udp gene encoding uridine phosphorylase (UPase) was cloned from the Salmonella typhimurium chromosome and overexpressed in E. coli cells. The S. typhimurium UPase was purified to an apparently homogeneous state, and some physicochemical characteristics of the enzyme were studied. The molecular weight of one subunit of UPase is 27.5 kD, and the optimal pH for its activity is 7.2--7.4. The native S. typhimurium UPase consists of six identical subunits, and its molecular weight is about 165 kD. According to these parameters, the S. typhimurium UPase is similar to the E. coli UPase. However, these enzymes differ substantially from one another by the substrate sensitivity and sensitivity to polarity of the medium. The S. typhimurium UPase has much higher phosphorylation activity toward thymidine, deoxyuridine, and 5;-bromide- or 5;-fluoride-containing analogs of nucleosides than that of E. coli UPase.

Cloning, Molecular↗
PubMed1998

[Role of additional binding sites for the CytR protein in the regulation of Escherichia coli udp gene expression].

The nucleotide sequence of a 1000-bp fragment of the Escherichia coli chromosome located between genes metE and udp and including the promoter region of the udp gene was determined. Multiple binding sites for the CytR and CRP proteins were identified outside the canonical udp gene promoter. A set of deletion variants with the truncated regulatory region of the udp gene was isolated based on plasmids pSKII and pJEL250. The level of CytR regulation of the udp gene was shown to depend on the size of the regulatory region relative to the transcription initiation site. On the basis of these data, it is concluded that additional binding sites for the CytR protein located in the regulatory region are functionally active in the regulation of udp gene expression. This conclusion has been confirmed by properties of the udp264 promoter mutant, which contains a deletion covering the main CytR binding site within the canonical promoter. Irrespective of the deletion, the expression of the udp gene in mutant udpP264 retains the dependence on the allelic state of the cytR gene. The CytR protein was shown to act as a transcription repressor or activator, depending on the configuration of the promoter and on the relative location and quantity of binding sites for CytR and CRP proteins.

Bacterial Proteins↗
PubMed1996

[Physical mapping of Escherichia coli genome rearrangements using pulsed-field gel electrophoresis and the PCR method].

Physical mapping of Tn10-induced chromosomal rearrangements in Escherichia coli was carried out by means of pulse-field electrophoresis, Southern hybridization, and PCR analysis. Mutants with chromosomal rearrangements were obtained by a method of selection of strains with constitutive udp-gene expression elaborated earlier. Screenings were performed in two E. coli strains that had a udp gene orientation diametrical to oriC and carried in metE :: Tn10- insertion and mutation in the dam gene encoding DNA-methylase. Selection of mutants with constitutive uridine phosphorylase synthesis was aimed at placing the udp-gene under the control of a novel, strong promoter via genome rearrangements. Physical mapping indicated that chromosomal rearrangements, in all cases studied, involved regions of operons encoding ribosomal RNA synthesis and placed the udp gene under the control of an rrn promoter. The majority of rearrangements are inversions of the chromosomal segment between the IS10-element, located in the metE gene, and various sites in different rrn operons. It is shown that the involvement of a particular operon in inversion depends on the direction of rrn operon and udp gene transcription. The rearrangement frequency increases 8-10 times in the presence of dam mutation.

Base Sequence↗