Biomedical subjects

A N Smirnov

Publications and source records attributed to A N Smirnov.

At least 19 recordsLinked to original sources

PubMed2006

[Urgent laparoscopic surgeries in children of the first year of life].

One hundred and ninety-two urgent laparoscopic operations in 179 infants (including 31 newborn infants) were performed. Indications for surgery were intestinal obstruction (108 children), acute diseases of abdominal organs (61), and gynecological diseases (10). The rate of conversion in 3 groups was 10.9, 4.6% and 0, respectively. In all the cases conversion was performed due to technical difficulties, there were no intrasurgical complications, diagnostic value of the method reached 100%. Combined laparoscopic surgeries were performed in 25.1% cases. Intestinal invagination was the most frequent cause of laparoscopy. Comparative analysis of open (28) and laparoscopic (85) desinvagination demonstrated the advantages of the latter one both during and after surgery. Laparoscopy is the useful method for diagnosis and treatment of acute abdominal disease requiring urgent surgery in infants.

Abdomen, Acute↗

PubMed2005

[Membrane localization of the nuclear receptor: a paradox with important consequences].

Lipophilic signal compounds can exert regulatory effects in a cell at the level of gene expression via interactions with cognate nuclear receptors that function as transcriptional factors, and also by rapid regulation of activities of proteins participating in intracellular transduction of extracellular signals. This nongenomic way can be mediated by translocation of a subset of nuclear receptors to cell membrane. By the example of estrogen receptors, mechanisms of such translocation and ligand-induced coupling between receptors and effector proteins of cell membrane are reviewed. Both immediate physiological reactions and delayed effects which are secondary, at the transcriptional level can be the consequences of such nongenomic action. The revealing of nuclear receptors in cell membrane adds to understanding of mechanisms of various regulatory stimuli integration by a cell, and is an important step towards design of selective hormonal analogs.

Animals↗

PubMed2004

Neutron flow exposure as a test for survival of Artemia salina spores.

Live and heat-inactivated Artemia salina spores (samples with the same mass and filling density) were exposed to a flow of thermal neutrons from a (252)Cf radioactive source at an equivalent dose power of about 1 microSv/h. Irradiation led to a 4-fold acceleration of nauplius development and to modification of the element profiles of live spores. The difference between absorption/diffusion of thermal neutrons by live and dead spores was revealed.

Animals↗

PubMed2004

[Videolaparoscopic nephrectomy and nephrouretherectomy in children].

The experience with 72 laparoscopic nephrectomies and nephrouretherectomies in children aged from 13 days to 14 years is reviewed. 51 children were under 3 years of age, 2 patients - under 1 month of life. Pathological changes of the kidneys with complete loss of function were indications for endoscopic surgery. Complex of examinations in the preoperative period included repeated USE, cystography, urography, scintigraphy, angiography. Time of surgery was 30-150 min (45 min, on the average). Blood loss during surgery was less than 50-60 ml and didn't require hemotransfusion. There were no complications during surgery. Fast recovery of physical activity after surgery, a decrease of hospital stay were seen. There were no postoperative complications and lethality. Laparoscopic nephrectomy and nephrouretherectomy are low-traumatic, safe and effective surgeries in children of any age in different diseases of the kidneys.

Adolescent↗

PubMed2003

DNA slows dissociation of progesterone receptor-steroid ligand complexes.

Steroid ligands are known to affect the interactions of their respective receptors with DNA. In the present study, the possibility of DNA interference in progesterone receptor-ligand interactions was investigated. An oligonucleotide containing a hormone response element (HRE) was shown to decrease the dissociation rate of complexes of [3H]progesterone or [3H]16alpha,17alpha-cycloalkanoprogesterones with PRs from rabbit and rat uterine cytosol. The extent to which the oligonucleotide affected the dissociation constant varied from about 4- to 1.5-fold depending on the ligand structure and was ranked in the following order: progesterone>16alpha,17alpha-cyclopropanoprogesterone approximately 16alpha,17alpha-cyclopentanoprogesterone>/=16alpha,17alpha-cyclohex-2'-enoprogesterone approximately 6alpha-methyl-16alpha,17alpha-cyclohexanoprogesterone>/=16alpha,17alpha-cyclohexanoprogesterone. The control oligonucleotide lacking HRE had a weak effect, if any, on the dissociation kinetics. No influence of the HRE-containing oligonucleotide on the equilibrium binding of ligands to PR was observed. The results suggest that the DNA partner affects binding of PR to its ligand.

Animals↗

PubMed2003

Localization of a site for interaction with hepatic male-specific proteins in two rat estrogen sulfotransferase genes.

Using electromobility shift assay the interaction of fragments of two paralogous rat estrogen sulfotransferase (Ste) genes with proteins of nuclear extracts from male and female rat liver was studied. Male-specific DNA-protein complexes were revealed with labeled oligonucleotides corresponding to fragments +1150/+1449, +1358/+1449, +1397/+1449, and +1417/+1449 of intron 1 of the Ste1 gene. The removal of a 20 bp region corresponding to the sequence +1430/+1449, or even either 5;- or 3;-terminal 5 bp of this region abolished the selective interaction of the oligonucleotides with the male-specific protein(s). According to the results of the experiments on mutual competition of the oligonucleotides, the fragment of the Ste2 gene corresponding to the sequence +1397/+1449 of the Ste1 gene formed complexes with the same male-specific protein(s) as the fragment of the Ste1 gene did. The data suggest the mapped element to participate in gender differentiation of the expression of the Ste1 and Ste2 genes.

Animals↗

PubMed2003

[Preoperative care and surgical treatment of small-intestinal fistulas in children].

Experience in using complex treatment in 42 children with unformed small-intestinal fistulas, generalized defects of the anterior abdominal wall and severe disorders of alimentary status is presented. Their preoperative preparation included parenteral alimentation, enteral probe feeding with special elementary milk formulas, correction of metabolic disorders. Intestinoplication during surgery was carried out with the medicinal glue MK-7 to prevent intestinal obstruction and formation of interloop abscesses. The use of portions of the tendinous part of the musculus tensor fasciale late was one the simple and effective methods for plasty of anterior abdominal wall defects.

Adolescent↗

PubMed2003

[Laparoscopic surgery in children--current possibilities and perspectives].

Experience in use of different laparoscopic methods in 6046 children who needed urgent and elective surgeries are analyzed. Urgent surgeries were performed in 3292 children for acute appendicitis and it complications, acute adhesive intestinal obstruction, invagination, trauma of abdominal organs, pathological changes of Meckel diverticulum, urgent inflammatory and non-inflammatory gynecological diseases. In this group endosurgery was successful in 3120 (94.8%) patients, conversion to open surgery was necessary in 5.2% cases (172 patients). Laparoscopic cholecystectomy, splenectomy, nephrectomy, surgeries for cysts of parenchymatous organs, benign cysts and tumors of abdominal cavity and retroperitoneal space, varicocele, syndrome of unpalpable testes and abdominal cryptorchism were performed as elective surgeries in 2754 patients. Endosurgical methods to minimized number of complications (1.1% or 29 patients in the whole group), conversion to open surgery was necessary in 10 (0.4%) cases. Laparoscopic methods in many cases are the "gold standard" in elective and urgent surgery in children.

Adolescent↗

PubMed2003

[Laparoscopy in the treatment of intestinal invagination in children].

The experience with laparoscopy in diagnosis and treatment of intestinal invagination in 142 children aged from 2 months to 11 years (study group) is reviewed. Endoscopic desinvagination was performed when conservative (pneumoirrhigoscopy) treatment was ineffective or hospitalization of patients was late. The invaginate was straightened out under video-control with two atraumatic forceps-graspers introduced into abdominal cavity and simultaneous pumping of air into the large intestine. This method permitted to cure completely intestinal invagination in 126 (88.7%) patients without laparotomy. In the control group (50 children aged from 3 months to 2 years) traditional surgery (laparotomy) was performed. Mean time of laparoscopic desinvagination was 32.6 min, time of surgery in the control group - 65 min. Postoperative complications in the study group were 5 times more rare than in the control. Mean time of hospitalization in the study group was decreased 3 times compared with the control. There were no lethal outcomes in both groups. Laparoscopic desinvagination is safe and high-effective procedure in the treatment of intestinal invagination in children.

Child↗

PubMed2002

Pregna-D'-pentarane structure influences progesterone receptor affinity for DNA.

Electrophoretic mobility shift assay was used to determine whether pregna-D'-pentaranes allow progesterone receptor (PR) from rat uterine cytosol to bind hormone response element (HRE)-containing oligonucleotide duplexes and to measure the affinity of this interaction. The formation of DNA-protein complexes in low salt medium was progesterone-related ligand-, temperature-, and PR-dependent, and specific for HRE. The highest affinity of PR to DNA (equilibrium K(a) = 0.420 +/- 0.185 nM(-1)) was found in the presence of the partial agonist/antagonist RU486, while the lowest affinity (K(a) = 0.074 +/- 0.013 nM(-1)) was demonstrated with the full agonist 6alpha-methyl-16alpha,17alpha-cyclohexanoprogesterone. With the exception of the strong full agonist R5020, there was a tendency toward correlation between the induced lower affinity of PR for DNA in the context of tyrosine aminotransferase HRE and the full agonistic activity of tested compounds.

Animals↗

PubMed2002

Nuclear receptors: nomenclature, ligands, mechanisms of their effects on gene expression.

Nuclear receptors are DNA binding transcription factors possessing conservative domain organization. Their activity is regulated by lipophilic ligands, phosphorylation, and by interactions with other proteins. This review highlights the nomenclature of 1999 for human nuclear receptors and the ligand structure and domain organization of these receptors. The review also summarizes recent data on the structure of hormone response elements of specific genes, the structure-functional organization of receptor co-regulators (coactivators and corepressors). They mediate their effects on transcription via two main mechanisms: chromatin remodeling and the effect on the main transcriptional factors. Some attention is focused on specific features of signal transduction at negative hormone-response elements, regulation of receptor activity via phosphorylation, mechanisms of receptor cycle termination, and on physiological and biochemical properties of certain groups of receptors and processes that they regulate.

Animals↗

PubMed2002

[Diagnosis and treatment of abdominal trauma in children].

Treatment of 79 children with injuries of abdominal and retroabdominal organs was analyzed. Results of diagnosis and treatment were evaluated in 3 groups: group 1--29 children treated conservatively; group 2--20 patients in whom total hemostasis was achieved during laparoscopy; group 3--30 children who have undergone open operations. Non-invasive and minimally invasive diagnostic methods permitted to avoid surgery in 46.4% patients. Efficacy of polymeric knitted netted material and Surgicell) for hemostasis in parenchymatous organs was demonstrated experimentally in rats.

Abdominal Injuries↗

PubMed2002

[Laparoscopic splenectomy in congenital hemolytic anemia in children].

Experience of 48 laparoscopic splenectomies in children aged from 3 to 14 years with congenital hemolytic anemia is analyzed. The main stages of laparoscopic splenectomy were the following: isolation of the inferior pole of the spleen, transection of the gastro-splenic ligament, transection of the splenic vascular trunk (with endostapler or intracorporeal ligature), dissection of the splenic ligaments, removal of the organ (with endoscopic sac or morcellator). One-stage cholecystectomy for cholelithiasis was performed in 11 patients. Time of surgery was 110-115 minutes, on the average. One-stage cholecystectomy prolonged surgery by 30-40 minutes. There were no intraoperative and postoperative complications. Conversion to open surgery was necessary in 2 cases because of endostapler failure. Patients were discharged on the 5-8th day after surgery. Physical activity restored completely 10-14 days after surgery. There were no lethal outcomes. Excellent cosmetic results were achieved in all the patients. Laparoscopic splenectomy in congenital hemolytic anemia is safe, sparing and effective endoscopic surgery in childhood.

Adolescent↗

PubMed2001

Nuclear melatonin receptors.

Current opinions on the potential role of orphan nuclear retinoid receptors of the ROR/RZR subfamily in regulatory activities of the pineal gland hormone melatonin are reviewed. The mechanisms of receptor--DNA interactions and known coactivators, tissue peculiarities of the expression of different receptor isoforms, and its regulation are described. The spectrum of probable targets for regulation by the receptors, the most promoted of which in this aspect being the immune and central nervous systems, is traced. It is clear that for final "adoption" of the orphan ROR/RZR receptors, there is need for a full collaboration of endocrinologists for solution of the still debatable questions whether and under which situations melatonin does serve as a physiological modulator of the activities of these receptors.

Animals↗

PubMed2001

16alpha,17alpha-cycloalkane derivatives of progesterone intensively bind to a rat serum protein.

The interaction of 6alpha-methyl-[1,2-3H]16alpha,17alpha-cyclohexanoprogesterone with rat serum proteins has been studied. Specific binding of this ligand characterized by Kd = 0.36 +/- 0.10 microM and concentration of binding sites (Bmax) of about 1 microM (27.8 +/- 12.5 pmol/mg total protein) was found. According to competitive analysis, the affinity of the studied progestins to a protein that differs from transcortin was to some extent correlated with their hydrophobicity. The dissociation kinetics of 3H-ligand-protein complexes were biphasic, the binding sites forming stable and labile complexes with 3H-ligand being eluted in the same region during ion-exchange chromatography. In overall properties, the serum protein differs from the progesterone receptor and the pregna-D'-pentarane-specific protein from rat uterus. It is suggested that the revealed protein may provide high progestagenic activity of 6alpha-methyl-16alpha,17alpha-cyclohexanoprogesterone by prolonging its retention in the bloodstream.

Animals↗

PubMed2001

Bioactive 5-reduced 16 alpha,17 alpha-cyclohexanoprogesterone derivatives weakly interact with proteins of the soluble uterine fraction.

We studied competitive activities of 16 alpha,17 alpha-cyclohexano-5 alpha- and 5 beta-dihydroprogesterone in replacing(3)H-progesterone and(3)H-16 alpha,17 alpha-cyclohexano-6 alpha-methylprogesterone from protein complexes. Direct binding of(3)H-5-reduced derivatives with proteins of soluble fractions from rat and rabbit uteri was also assayed. C(d) values for 5-reduced derivatives were in the micro- or submicromolar range. The data suggest that biological effects of these analogues are not mediated via soluble uterine receptors.

Animals↗

PubMed2000

Expression of prolactin receptors in rat reproductive tissues during periovulatory prolactin imbalance.

Indirect immunoperoxidase technique in combination with cytophotometry showed that prolactin imbalance in the periovulatory period is characterized by considerable changes in the expression of prolactin receptors in uterine glands and endometrial stroma (but not in the myometrium) and in the pituitary gland and hypothalamus, while receptor compartmentalization pattern remains unchanged.

Animals↗

PubMed2000

The size and/or configuration of the cycloalkane D' ring in pentacyclic progesterone derivatives are crucial for their high-affinity binding to a protein in addition to progesterone receptor in rat uterine cytosol.

[(3)H]labeled progesterone and a number of its 16alpha, 17alpha-cycloalkano derivatives with an additional three to six-membered D' ring were investigated for mutual competition and equilibrium binding to proteins from rat uterine cytosol. The interaction of all studied [(3)H]ligands with proteins was characterized by comparable affinity (K(d) in nM region) and apparent homogeneity in terms of affinity. At the same time, the concentrations of binding sites for ligands bearing 16alpha,17alpha cyclopentano, cyclohexano, or cyclohexeno substituents were several-fold higher than those for progesterone or 16alpha, 17alpha-cyclopropanoprogesterone. In mutual competition experiments, when [(3)H]progesterone or [(3)H]16alpha, 17alpha-cyclopropanoprogesterone were used, the curves of 'bound radioactivity-log of competitor concentration' for all compounds studied were parallel and corresponded to a model of 'one protein-two ligands.' However, when [(3)H]ligands with bulky 16alpha, 17alpha-substituents (with the possible exception of cyclohexene derivative) were used, competitive curves for various ligands had different appearances and fell into two groups. Parallel curves for derivatives with 5 or 6 carbons in D' ring described by a model of 'one protein-two ligands' formed the 1st group. The 2nd group comprised curves for progesterone or 16alpha, 17alpha-cyclopropanoprogesterone that had lower slopes and could be described by a model of 'two proteins-two ligands.' Taken together, the results suggest the presence in rat uterine cytosol, of a protein in addition to progesterone receptor capable of discriminating between ligands with no or small 16alpha, 17alpha-cycloalkano substituents and ligands with more bulky substituents.

Alkanes↗