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Biomedical subjects

V A Stepanov

Publications and source records attributed to V A Stepanov.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Haplotypes of two diallelic Y chromosome loci in the indigenous and migrant populations of Siberia].

Two diallelic Y-chromosome markers, the Y Alu polymorphism (YAP) and the T-C transition (Tat), were analyzed in the indigenous (Tuvinian, Buryat, Northern Altaic, and Tatar) and migrant (Slavic) populations of Siberia. A high frequency of the allele C was revealed in several indigenous populations (25-55%) and in Russians (20.8%). The YAP+ allele occurred at a surprisingly high frequency (31.4%) and was completely linked with the C allele in Buryats. The YAP+ chromosome was also found in the Tuvinian population (1.5%). The two diallelic loci showed a marked linkage disequilibrium (D = 92.4%) in the total sample. The YAP-/T and YAP-/C haplotypes prevailed in both indigenous and migrant populations: their respective frequencies were 80.4 and 19.6% in the Slavic population and 71.8 and 19.9%, respectively, in the indigenous one. The YAP+/C (7.8%) and YAP+/T (0.5%) haplotypes were found only in the indigenous population. An appreciable heterogeneity in haplotype frequency distribution between regional subpopulations was revealed in Russians, Tuvinians, and Buryats. The origin and evolution of Y-chromosome lines in Northern Asia are considered.

Alleles↗
PubMed2000

[Analysis of allele frequency of seven microsatellite loci of Y chromosome in three Tuva populations].

The allele frequency distribution of seven microsatellite loci of the nonrecombining region of the Y chromosome (Y-STRs) was analyzed in three geographically distant indigenous populations of the Tuva Republic. The populations did not differ in allele frequency distribution of the seven Y-STRs. The Y-chromosome microsatellite loci in Tuvinians showed a high diversity (H = 0.575) that was nearly identical in all three populations. The genetic distance Ddm between the three populations was low, suggesting no subdivision of the modern male population of Tuva. Estimates of the period of linear changes in Ddm showed that Y-chromosome microsatellites can be used to reconstruct evolutionary events dating back no more than 40,000-50,000 years. The problems of human population phylogeny are discussed on the basis of data on Y-chromosome STRs.

Alleles↗
PubMed2000

[Microsatellite haplotypes of the Y-chromosome demonstrate the absence of subdivisions and presence of several components in the Tuvinian male gene pool].

The haplotype analysis of seven Y-chromosome microsatellites in three regional populations of Tuvinians revealed high intrapopulation variation in the male gene pool of the modern population of the Tuva Republic. In total, 49 haplotypes were found in 111 individuals; only four haplotypes occurred at a frequency higher than 5%. High genetic diversity (H = 0.935) suggested a high power of discrimination for the Y-chromosome haplotypes. The analysis of molecular variance (AMOVA) and other data did not reveal subdivision of the Tuvinian population with respect to Y-chromosome haplotypes. Most haplotypes found in Tuvinians formed two lines. Line A included approximately 64% of the haplotypes found, line B, approximately 24%. A putative ancestral haplotype of line B was similar to a haplotype most common in modern Caucasoids (Md = 3), whereas a putative ancestral haplotype of line A proved to be distant from the ancestral haplotype of line A and haplotypes common for Caucasoids and Mongoloids. Estimates of the age of the Y-chromosome lines showed that the male gene pool of modern Tuvinians originated in the late Paleolithic or Neolithic period. With two methods, the age of line A was estimated at 3500 or 18,000 years and the age of line B was approximately at 5500 or 15,000 years. Considering the less conservative estimates to be more reliable, line B was assumed to originate from the ancient Caucasoid population of the Tuva region. The more widespread and evolutionarily younger line A was associated with the peopling region by ancient Mongoloid tribes of the Turkic language group in the Hun-Sarmatian period.

Asian People↗
PubMed2000

[Relationship between polymorphism C677T of the methylene tetrahydrofolate reductase gene with clinical symptoms of coronary atherosclerosis].

Association of the methylenetetrahydrofolate reductase gene (MTHFR) C677T missense mutation (substitution of cytosine by thymine at position 677) with coronary artery disease (CAD), as well as with blood levels of various lipoprotein fractions, systolic pressure (SP), diastolic arterial blood pressures (DP), and body mass index (BMI) in patients with angiographically verified CAD and in a control group. The affected and control subjects did not differ substantially with respect to genotypic and allelic frequencies. The MTHFR gene polymorphism was not associated with variation in either total cholesterol (TC), very-low-density-lipoprotein cholesterol (VLDLC), low-density-lipoprotein cholesterol (LDLC), high-density-lipoprotein cholesterol (HDLC), or triglyceride (TG) levels. SP and DP in subjects with different MTHFR genotypes did not differ significantly. BMI tended to correlate with the C677T polymorphism of the MTHFR gene (0.05 < P < 0.1). C677T mutation frequencies in western Siberia were determined for the first time; they are about the same as in most European populations.

Blood Pressure↗
PubMed1999

[Analysis of the Alu insertion polymorphism in urban and rural populations of Siberia].

Polymorphic Alu-repeat loci of human genome are commonly used as effective genetic markers in population and evolution studies. In this work, the data on genetic structure of two Russian populations from Siberia obtained via analysis of five polymorphic Alu repeats are presented. The urban population was characterized by a slightly higher level of genetic diversity compared to the rural population. The value of genetic differentiation coefficient for the populations studied was 0.57%, pointing to the absence of genetic subdivision within the urban and rural populations. Phylogenetic analysis of these populations, together with literature data, shows that, with respect to the markers examined, the gene pool structure of Russian population is similar to that of other Caucasoid populations.

Alu Elements↗
PubMed1998

[Polymorphism of angiotensin-converting enzyme and endothelial nitric oxide synthase genes in people with arterial hypertension, left ventricular hypertrophy, and hypertrophic cardiomyopathy].

Data on polymorphism of the angiotensin-converting enzyme (ACE) and endothelial cell nitric oxide synthase (NOS3) genes in patients having arterial hypertension (AH) with or without left ventricular hypertrophy (LVH) and those with hypertrophic cardiomyopathy (HCM) are presented. An association between polymorphism for the ACE and NOS3 loci and the LVH index among AH patients with LVH and HCM was shown. In AH patients, an association between the NOS3 locus polymorphism and some parameters of blood pressure was revealed. Possible relationships between the ACE and NOS3 polymorphisms and the clinical manifestation of the LVH and AH are discussed.

Alleles↗
PubMed1998

Genetic markers in coronary artery disease in a Russian population.

The association of genetic markers at the apolipoprotein B gene (APOB) (XbaI, MspI, and EcoRI polymorphisms) and the lipoprotein lipase gene (LPL) (PvuII polymorphism) with coronary artery disease (CAD) and with variation in plasma lipid levels (total cholesterol, high-density lipoprotein cholesterol, and total triglycerides) was studied in 94 male patients with CAD diagnosed by angiography and in 122 unrelated men of Russian descent free of clinical signs of CAD. The frequent allele (M+) of the APOB MspI RFLP was seen more frequently in CAD patients than in control subjects (0.963 vs. 0.898, p < 0.025). No significant differences in allele frequencies were observed for the APOB XbaI and EcoRI polymorphisms or for the LPL PvuII polymorphism. In patients, carriers of the rare allele (E-) of the EcoRI RFLP had higher mean triglyceride levels than homozygotes for E+ (p < 0.05). No significant differences in lipid variables were determined for the other three polymorphisms studied. Analysis of intragenotype variances and the multivariate measure of mean values of lipid concentrations showed that genetic variability within the APOB locus may contribute to a certain extent to the level and variability of serum lipid levels in this Russian population.

Analysis of Variance↗
PubMed1998

[Genomic studies of hereditary cardiomyopathies].

Cardiomyopathies (CMP) clinically and genetically belong to the heterogeneous group of myocardial diseases. Among them, three major clinical forms (hypertrophic, dilated, and restricted) are distinguished. Genetic factors play a substantial role in the etiology of dilated and hypertrophic CMP; family cases constitute more than 20% of these forms. Most familial cases of CMP are inherited as an autosomal dominant character. Autosomal recessive and X-linked forms are rare. Genetic basis for rare familial forms of restricted CMP is unclear. There are forms with strict maternal inheritance, which suggests the involvement of the mitochondrial genome. The nature of several CMP forms was determined and a number of genetic loci for this disease was revealed by modern methods of genetic mapping. In familial hypertrophic cardiomyopathy (FHC), four genes have been identified (those of beta-myosin heavy chain, alpha-tropomyosin, cardiac troponin T, and myosin-binding protein C), all of which encode sarcomeric proteins. Maternally inherited forms of FHC are associated with mutations in the mitochondrial tRNA genes. Linkage analysis in familial dilated CMP revealed at least five genetic loci on chromosomes 1, 3, 9, and X. X-linked forms of dilated CMP are caused by mutations in dystrophin gene, but the nature of autosomal forms is unclear. A recently recognized form of dilated CMP, arrhythmogenic CMP/right ventricular dysplasia (ARVD) is linked to two actinin gene loci on chromosomes 1 and 14. Genomic studies of CMP provided a basis for a new stage of "genetic cardiology", genetic mapping, which at present includes the quest of candidate genes for many other human cardiovascular diseases.

Cardiomegaly↗
PubMed1998

[Role of apolipoprotein B and lipoprotein lipase gene polymorphism in variability of serum lipid levels].

The serum lipid level is determined by the complex interaction of genetic and environmental factors. The genetic component of this system includes apolipoprotein B (apoB) and lipoprotein lipase (LPL) genes. Three RFLP markers (XbaI, MspI, EcoRI) in the apoB gene and PvuII-RFLP in the LPL gene were genotypes and five lipid traits (fasting plasma levels of total cholesterol, triglycerides, HDL-, LDL-, and VLDL- cholesterol) were measured in 122 unrelated individuals without clinical signs of cardiovascular disease. Several alleles and genotypes which were associated with significant effects on cholesterol, triglycerides, and LDL-cholesterol levels were identified. Analysis of intragenotypic variance and multivariate measures of the mean values of lipid concentrations indicate that apoB gene variation may contribute both to the level and variability of plasma lipids.

Adult↗
PubMed1997

[Restriction polymorphism of the APOB locus in residents of the city of Tomsk].

Restriction fragment length polymorphism (RFLP) of the apolipoprotein B locus was investigated in the population of Tomsk. The frequencies of alleles and haplotypes of polymorphic restriction sites XbaI, MspI, and EcoRI were determined. The parameters of linkage disequilibrium and polymorphism information content (PIC) were estimated. Comparative data on various regions of the world are shown.

Alleles↗
PubMed1995

[Interrelationship between structural variants of the apolipoprotein B and ischemic heart disease and plasma lipid levels].

Xba I and EcoR I polymorphism of the apolipoprotein B (APOB) gene was studied by PCR. A significant increase in the frequency of allele X+ and haplotype H+E+ was demonstrated in patients with coronarographically documented coronary heart disease (CHD) over that of the general population. Association of allele E- with increased levels of serum triglycerides was found. The results provide evidence about the contribution of structural variants of the APOB gene to determining CHD.

Adult↗
PubMed1994

Apolipoprotein B gene polymorphism in a Russian population.

The XbaI and EcoRI restriction fragment length polymorphisms at the apolipoprotein B gene locus were studied using the polymerase chain reaction. The allele, genotype, and haplotype frequencies in Russians from west Siberia were determined. Linkage disequilibrium between the XbaI and EcoRI loci was detected.

Alleles↗
PubMed1993

[The effect of adaptation to repeated stresses on the recovery of cardiac function and creatine phosphate after total ischemia (a 31P-NMR study)].

Adaptation to stress was produced by eight immobilizations of rats for 1 hour every other day. The effects of 25-min ischemia and subsequent 50-min reperfusion on the heart contractile function and energy metabolism were studied. In the adapted rats, the velocities of contraction and relaxation as well as the developed pressure restored during reperfusion much faster than in the controls. The NMR-study showed that a drastic fall of creatine phosphate (CP) and ATP during ischemia was followed by a rapid CP restoration, a Pi drop and a slow ATP restoration during reperfusion. In the adapted animals, the CP restoration was twice as rapid as in the controls. It is obvious that in adaptation to stress the heart function and the system of CP resynthesis appear to be significantly more resistant to ischemia stroke and this is why they restore their activity faster than in the controls.

Adaptation, Physiological↗
PubMed1991

Cardiac contractile function, oxygen consumption rate and cytosolic phosphates during inhibition of electron flux by amytal--a 31P-NMR study.

In order to investigate the potential role of cytosolic phosphates ([ATP], [ADP] and [Pi]) in the integration of mitochondrial respiration and mechanical function in the perfused heart, inhibition of the substrate end of the respiratory chain by amytal has been employed. A stepwise increase in amytal concentration (from 0.2 to 1.2 mM) resulted in the progressive abolition of the cardiac oxygen consumption, rate (VO2) in hearts oxidizing pyruvate (5 mM). The inhibition curve for VO2 was S-shaped, with K0.5 = 1.1 mM, and independent of the initial VO2 values varied by coronary flow and isoproterenol (Iso) addition. ADP-stimulated respiration of isolated mitochondria (malate + pyruvate) was twice as sensitive to amytal inhibition, whereas state 2 respiration (before ADP addition) had the same sensitivity as cardiac VO2. Decrease in VO2 was followed by a decline in phosphocreatine (PCr) content and augmentation of Pi at nearly constant ATP level and intracellular pH as assessed by the 31P-NMR method. These changes were associated with an elevation of cytosolic free [ADP] and a reduction of the [ATP]/[ADP] ratio and ATP affinity calculated from creatine kinase equilibrium. Concomitantly, pressure-rate product (PRP), maximal rates of contraction and relaxation fell down and the end diastolic pressure (EDP) rose at all initial loads. Amytal-inhibited hearts retained the capability to respond to Iso stimulation (0.1 microM, about 50% enhancement of PRP) even at 1 mM amytal, but their response to elevation of coronary flow was greatly diminished. Alterations in the PRP value induced by the inhibitor at a fixed coronary flow correlated negatively with cytosolic [ADP] and [Pi], and positively with [ATP]/[ADP] and A(ATP). In contrast, EDP correlated with all these parameters in the opposite manner. However, when PRP was varied by coronary flow in the absence of the inhibitor or at its fixed concentrations, such correlations were absent. These data imply that cytosolic phosphates can serve as a feedback between energy production and utilization when the control point(s) is (are) at the mitochondria. In contrast, other regulatory mechanisms should be involved when control is distributed among different steps located both in energy producing and utilizing systems.

Adenosine Triphosphate↗
PubMed1991

[Membranotropic effect of phosphocreatine and its structural analogs].

The effects of phosphocreatine (PCr) and its analogues (creatine, phosphocreatinine, phosphoarginine and inorganic phosphate) on liposomal and erythrocyte membranes and on the sarcolemmal membrane of cardiomyocytes were studied. The ESR spectrum of the spin-labeled probe, 5-doxyl-stearate, incorporated into the membrane were recorded for analysis of the structural order of the phospholipid bilayer of these membranes. PCr and its analogues had no effect on the structure of the phospholipid bilayer in liposomes; this effect was temperature-independent. However, in erythrocyte and sarcolemmal membranes the rigidity of the membranes was increased by these compounds (except for creatine) at temperatures above 38-40 degrees C. Analysis of these and literary data revealed that cardiac cell membranes may be the site of protective action of PCr on the ischemic myocardium. The lack of effect on liposomes may suggest that the membrane-stabilizing effect of PCr depends on the presence of membrane proteins. The compounds under study may influence the lipid-protein interactions by increasing the rigidity of membrane phospholipids. These membranotropic effects may be due to the interaction of charged molecules of the compounds with polar heads of phospholipids and/or polar groups of proteins in the membrane interphase which, in turn, may influence the packing of hydrophobic fatty acid chains.

Animals↗
PubMed1989

[Diagnosis and treatment of gastric campylobacteriosis in patients with peptic ulcer and chronic gastritis].

The endoscopic picture of peptic ulcer was studied in 104 patients; the gastric mucosa of 30 per cent of the patients was infected with Campylobacter pyloridis (CP) and had acute erosions in the pyloroduodenal zone. Erosions in uninfected patients were found in 3 per cent of the cases. The predominant lymphoid infiltration of the mucous coat of the stomach was revealed in 60 ulcer patients irrespective of the CP infection. Mucous infiltration with polymorphonuclear leukocytes was found in 13 chronic gastritis patients (in 6 of them gastritis was combined with CP infection). The urease test was positive during the first hour in 82 per cent of the cases in the presence of a large number of CP in histological specimens. Treatment of 31 patients with gastric campylobacteriosis using various antibacterial agents or their combination revealed that continuous 2 months bismuth subnitrate medication was more effective for gastric mucosa disinfection. In addition, favourable results were often obtained when a combination of two antimicrobial agents was used.

Adult↗