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Biomedical subjects

A V Mikelsaar

Publications and source records attributed to A V Mikelsaar.

At least 19 recordsLinked to original sources
PubMed2001

The frequency of C282Y and H63D mutations in Hemochromatosis gene in native Estonians.

Four hundred and forty two adult individuals of Estonian nationality were examined in different regions of Estonia for the C282Y and H63D HFE mutations to determine the allele and genotype frequencies. The sample consisted only of those people whose at least four grandparents were born in Estonia, and have lived settled in the same region. The study was carried out using the PCR technique and restriction analysis for C282Y and H63D mutations respectively. For the C282Y mutation the frequency of heterozygotes was 6.6% and homozygotes 0.2%, giving allele frequency 0.035. The allele frequency for the H63D mutation was 0.136, and the frequency of homo- and hetero-zygotes 1.6% and 24.0% respectively.

Adolescent↗
PubMed2001

Geographical, linguistic, and cultural influences on genetic diversity: Y-chromosomal distribution in Northern European populations.

We analyzed 10 Y-chromosomal binary markers in 363 males from 8 populations in Northern Europe and 5 Y microsatellites in 346 of these individuals. These populations can be grouped according to cultural, linguistic, or geographical criteria, and the groupings are different in each case. We can therefore ask which criterion best corresponds to the distribution of genetic variation. In an AMOVA analysis using the binary markers, 13% of the Y variation was found between populations, indicating a high level of differentiation within this small area. No significant difference was seen between the traditionally nomadic Saami and the neighboring, historically farming, populations. When the populations were divided into Uralic speakers and Indo-European speakers, 8% of the variation was found between groups, but when they were divided according to geographical location, 14% of the variation was between groups. Geographical factors have thus been the most important in limiting gene flow between these populations, but linguistic differences have also been important in the east.

Analysis of Variance↗
PubMed2001

A novel mutation in the M1S1 gene responsible for gelatinous droplike corneal dystrophy.

PURPOSE: To identify the genetic defect in the M1S1 gene causing gelatinous droplike corneal dystrophy (GDLD) in an Estonian family. METHODS: DNA was extracted from members of a GDLD-affected family and control persons. Polymerase chain reaction followed by direct sequencing was used to detect mutations in the M1S1 gene. Sequencing results were confirmed with restriction analysis. RESULTS: Sequencing of the M1S1 gene revealed a novel mutation and a common polymorphism. All patients with GDLD were found to be homozygous for the insertion of nucleotide C in position 520 in M1S1. The mutation leads to formation of truncated protein. The mutation was excluded in 103 normal, unaffected individuals. Very close to the location where the mutation was identified in the M1S1 gene, a single-nucleotide polymorphism (518A/C) was found, changing aspartic acid to alanine at codon 173. CONCLUSIONS: The data indicate that mutation ins520C in the M1S1 gene is the primary cause of GDLD in the family studied.

Antigens, Neoplasm↗
PubMed2000

Y-chromosomal diversity in Europe is clinal and influenced primarily by geography, rather than by language.

Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Y-chromosomal biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and are more regionally restricted and are likely to reflect distinct population movements, including one from north of the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography, rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that the demographic history of Europe has been complex and influenced by other major population movements, as well as by linguistic and geographic heterogeneities and the effects of drift.

Africa, Northern↗
PubMed2000

Polymorphic glutathione S-transferase M1 is a risk factor of primary open-angle glaucoma among Estonians.

Primary open-angle glaucoma, the most common form of glaucoma is a slowly progressive atrophy of the optic nerve, characterized by loss of peripheral visual function and is usually associated with elevated intraocular pressure. The etiology and genetic risk factors of primary open-angle glaucoma are mostly unknown. The aim of this study was to find out whether the polymorphism at GSTM1, GSTM3, GSTT1 and GSTP1 loci is associated with increased susceptibility to glaucoma, because these polymorphic enzymes are susceptibility candidates for several diseases, including such eye disease as cataract. The phenotype of GSTM1 and GSTT1 was determined by ELISA and the genotype of GSTM3 and GSTP1 was detected by polymerase chain reaction. Four hundred and fifty two Estonians (250 glaucomas and 202 controls) participated in a case-control study. A significant association of the GSTM1 polymorphism with glaucoma was observed. The frequency of the GSTM1 positive individuals among the glaucoma group was significantly higher than in controls (60 vs. 45.0%) with odds ratio of 1.83 (95% CI 1.26-2.66;P = 0.002). The risk among the GSTM1 positive individuals of developing glaucoma was even higher in the case of smoking: 62.7% of smokers were GSTM1 positive in the glaucoma group while only 33.3% of smokers had GSTM1 positive phenotype in controls (OR = 3.36; 95% CI 1.49-7.56;P = 0.012). An association with a lower level of significance was also found with the GSTM3 gene. Four% of the 250 patients with POAG were identified as carriers of the GSTM3 BB genotype, a proportion which was slightly higher than the 1.0% for the controls (OR = 4.17; 95% CI 0. 90-19.24;P = 0.144). The frequencies of the GSTT1 and GSTP1 genotypes in both groups were not statistically different. The present study suggests that the GSTM1 polymorphism may be associated with increased risk of development of primary open-angle glaucoma.

Adult↗
PubMed2000

High frequency of the HIV-1 protective CCR5 delta32 deletion in native Estonians.

In previous studies, the highest frequencies (16%) of the CCR5 delta32 deletion have been found in populations of Finno-Ugric origin. We here report a high CCR5 delta32 frequency (15%) in another Finno-Ugric populations, the Estonians. The highest frequency (18%) was found on the geographically isolated Estonian island of Dagö. We examined 504 healthy unrelated individuals of Estonian nationality, whose grandparents were born in Estonia. The polymerase chain reaction assay was performed and the amplified products were digested with EcoRI.

Base Sequence↗
PubMed2000

Polymorphic glutathione S-transferases as genetic risk factors for senile cortical cataract in Estonians.

PURPOSE: To investigate the possible association between glutathione S-transferase GSTM1, GSTM3, GSTT1, and GSTP1 polymorphism and the occurrence of age-related cataracts in Estonian patients. METHODS: Patients with cortical (155), nuclear (77), posterior subcapsular (120), mixed type (151) of senile cataract and control individuals (202) were phenotyped for GSTM1 and GSTT1 by enzyme-linked immunosorbent assay and genotyped for GSTM3 and GSTP1 by polymerase chain reaction. RESULTS: The frequency of the GSTM1-positive phenotype was significantly higher in the cortical cataract group (60.6%) than in the controls (45.0%) with odds ratio of 1.88 (95% CI, 1.23-2.94; P = 0.004). The cortical cataract risk associated with the GSTM1-positive phenotype was increased in carriers of the combined GSTM1-positive/GSTT1-positive phenotype (OR = 1.99; 95% CI, 1.30-3.11; P = 0.002) and the GSTM1-positive/GSTM3 AA genotype (OR = 2.28; 95% CI, 1.51-3.73; P < 0.001). The highest risk of cortical cataract was observed in patients having all three susceptible genotypes (OR = 2.56; 95% CI, 1.59-4.11; P < 0.001). Also, a significant interaction between the presence of the GSTP1* A allele and cortical cataract was found with prevalence of the GSTP1* A allele among the cortical cataract cases compared with the controls. Ninety-five percent of subjects with cortical cataract had the GSTP1 (AA, AB, or AC) genotype, whereas in controls 87% of persons had a genotype with GSTP1*A allele (OR = 3.1; 95% CI, 1.31-7.35; P = 0.007). In contrast to the GSTP1*A allele, the presence of the GSTP1*B allele in one or two copies leads to decreased cortical cataract risk (OR = 0.09 for GSTP1 BB genotype). CONCLUSIONS. The GSTM1-positive phenotype as well as the presence of the GSTP1*A allele may be a genetic risk factor for development of cortical cataract.

Adult↗
PubMed1996

Purification, characterization and tissue distribution of human class theta glutathione S-transferase T1-1.

A high activity glutathione S-transferase T1-1 (GSTT1-1) towards dichloromethane was isolated from human liver cytosol and purified to homogenity in 18.5% yield with a purification factor of 4400-fold. The GSTT1-1 was also isolated from erythrocytes, but the enzyme activity decreased rapidly in the final stages of purification. The purified GSTT1-1-s were homo-dimeric enzymes with a subunit M1 value 25,300 and pI 6 64, as confirmed by SDS-PAGE, IEF and Western blot analysis. The N-terminal amino acid sequences of GSTT1-1 from liver and red blood cells, analyzed up to the 12th amino acid, were identical. Immunoblot analysis revealed that GSTT1-1 was also present in lung, kidney, brain, skeletal muscle, heart, small intestine and spleen, but not in lymphocytes.

Erythrocytes↗
PubMed1996

Production and characterization of monoclonal antibodies against class theta glutathione S-transferase T1-1.

The recently discovered human class theta glutathione S-transferase T1-1 (GSTT1-1) is responsible for the GSH-dependent detoxification of naturally occurring monohalomethanes. The detoxifying role of GSTT1-1 has not been investigated in cancer susceptibility and the polymorphism of the protein is unknown in different populations. The purpose of our work was to produce a panel of mouse monoclonal antibodies (MAbs) that could bind to different regions of the GSTT1-1 protein and would help us select suitable MAbs for Western blot analyses and immunohistochemistry, and develop an ELISA assay for detection of GSTT1-1 in whole blood. Six highly specific MAbs were generated against GSTT1-1. Out of six MAbs, one was able to recognize only the native form of the enzyme and possesses two binding sites on the dimeric GSTT1-1 molecule. The other five MAbs bind to both native and denatured GSTT1-1 enzyme in direct and antigen capture ELISA or Western blot. The antibodies recognize at least four different epitopes on the GSTT1-1 molecule. Using MAbs 4G1 and 2D8, a sensitive ELISA assay for determination of GSTT1-1 in whole blood was developed.

Animals↗
PubMed1996

Distribution of glutathione S-transferase T1 phenotypes in the Estonian population.

The distribution of glutathione S-transferase T1 (GSTT1) phenotypes was studied in a total sample of 673 Estonians whose four grandparents were born in Estonia, by an ELISA test able to differentiate between GSTT1 positive and GSTT1 negative phenotypes. 18% of the total sample did not present GSTT1-1 protein in whole blood. GSTT1-1 concentration was assayed in 519 out of the 552 GSTT1 positive subjects (i.e. 82% of the total sample) 49% percent of this subsample made up by 519 subjects was found to have GSTT1-1 in intermediate concentration and 33% in high concentration. The gene frequency of the GSTT1 deleted allele was estimated to be 0.423 as the square root of the frequency of the GSTT1 negative subjects (square root of 0.18 = 0.423) and that of the GSTT1 positive allele as (1-0.423) = 0.577. Statistically significant regional differences were found within the population with the lowest frequency of GSTT1 negative in western Estonia (9.5%) and the highest in the southeastern part of the country (24.5%).

Adolescent↗
PubMed1995

Creatine kinase isoenzyme BB concentrations in cerebrospinal fluid in asphyxiated preterm neonates.

Creatine kinase isoenzyme BB was determined in cerebrospinal fluid (CSF) in 79 preterm neonates using an original enzyme-linked immunosorbent assay. The criterion for inclusion was an Apgar score of 7 or less at 5 min of life. Neurological examination was performed on day 2 and day 5 of life. CSF was obtained on the same days. Lumbar puncture was performed on 41 of these babies on day 2 and in 39 on day 5 of life (one baby underwent lumbar puncture twice). All babies had clinical features of hypoxic-ischemic encephalopathy (HIF) which was classified according to Sarnat and Sarnat. The control group consisted of 90 asphyxiated term babies and 30 adults without CNS pathology. The concentration of CK-BB in cerebrospinal fluid (mean +/- SD) was significantly higher (p < 0.0005) in preterm (168.0 +/- 2) than in term babies (29.0 +/- 3.1) and healthy adults (5.3 +/- 1.2). Our results demonstrate the possibility of using the classification system of Sarnat and Sarnat for assessment of the severity of brain damage not only in term, but also in preterm babies. Neonates with HIE stages II and III showed markedly higher CK-BB values than those with HIE I on day 2 (p < 0.025) and day 5 (p < 0.05) of life. CK-BB values were markedly higher in preterm babies with none of some primitive responses (head turning, Babkin's reflex, palmar grasp). The mean concentration of CK-BB was higher in neonates with retarded psychomotor development compared with those with normal development (p < 0.05) on day 3, and after 6 and 9 months. At 12 months of age no significant difference in median CK-BB concentration was detected between neonates with normal and developmental disturbances.

Adult↗
PubMed1994

Allele-specific monoclonal antibodies against glutathione S-transferase Mu1-1.

IgG1 class mouse monoclonal antibodies (MAbs) were produced against human glutathione S-transferase Mu1-1 (GSTMu1-1). Eight MAbs of 16 are able to recognize only the native form of the enzyme; 4 MAbs bind to native and denaturated enzyme, and the remaining 4 can bind only to partially denatured antigen in direct ELISA or Western blot. The antibodies recognizing the native form of the enzyme bind to six different epitopes. Three overlapping epitopes are responsible for specific binding of MAbs to different allelic variants of GSTMu1-1. Three allele-specific antibodies, 2E1, 11F12, and 7D11, bind to GSTM1a monomer and the other two, 1H8 and 3H10, recognize GSTM1b monomer.

Adult↗
PubMed1992

Ovarian carcinomas express a sperm acrosomal antigen, defined by monoclonal antibody 9H8.

A new monoclonal antibody (MAb 9H8, IgM class) reactive with human ovarian carcinoma has been raised after immunizing C57BL/6 mice with bovine sperm. Immunohistological studies indicated that 20/21 serous ovarian adenocarcinomas expressed 9H8-defined antigen but it was absent in benign ovarian tumors (0/11). 1/11 of breast carcinomas and 5/5 of rectal carcinomas expressed this antigen, although to a considerably lesser degree. Tumors of lung, skin, brain and mesothelium were negative. The antigen was also expressed in embryonic skin, in renal collecting tubule cells and in saliva. In bovine, human and mouse sperm the antigen is confined to the acrosomal region. The molecular weight of this antigen was determined by Western blot analysis and gel filtration. In SDS-PAGE the antigen ran as a broad band barely entering the 7% gel, indicating an apparent molecular weight > 300 kDa. In the absence of detergents and reducing agents this glycoprotein forms larger complexes (> 1,500 kDa) as determined by gel filtration on Sephacryl S300. The epitope contains carbohydrate structures recognized by lectin PNA (peanut agglutinin).

Acrosome↗
PubMed1988

Rapid, simple and sensitive antigen capture ELISA for the quantitation of myoglobin using monoclonal antibodies.

A rapid ELISA method has been developed to quantitate myoglobin in serum. An antigen capture enzyme-linked immunoassay with IgG1 mouse monoclonal antibodies produced by cell clones MGB20-4A1.1 and MGB20-3C1.2 were used for myoglobin detection. These monoclonal antibodies are specific for different epitopes of the myoglobin molecule. Monoclonal antibodies from the hybridoma clone MGB20-4A1.1 were adsorbed to microtiter plate wells. The plates were washed with PBS containing 0.05% Tween 20 and then 20 microliter of standard serum or serum of patients and 200 microliter of peroxidase labeled monoclonal antibodies MGB20-3C1.2 were added to each well. Plates were incubated for 90 min at 37 degrees C and enzyme activity was determined using o-phenylenediamine as a substrate. The ELISA assay described is a rapid and sensitive procedure to assess the quantity of myoglobin within the range 2-1000 ng/ml serum. 120 samples can be tested in 3 h.

Animals↗
PubMed1987

C-band polymorphisms in lymphocytes of patients with ovarian or breast adenocarcinoma.

To establish the significance of the variability of human chromosome constitutive heterochromatin areas (C-band variants) in a risk of malignancy, C-banding pattern study has been performed in 33 female patients with ovarian or breast adenocarcinoma. The control group included 180 healthy women. The following characteristics of C-bands on chromosomes #1, #9, and #16 were studied: (a) size, (b) size heteromorphisms and (c) inversions, using quantitative and semiquantitative methods of analysis. Our data show no significant difference in the presence of C-band size and location variants in chromosomes #1, #9, and #16 between the patients with adenocarcinoma of the ovary or breast and healthy women. From that we conclude that there is no causal association between the presence of C-band variants on chromosomes #1, #9, and #16 and an elevated risk of ovarian and breast adenocarcinoma.

Adenocarcinoma↗
PubMed1985

Polymorphism of Ag-stained nucleolus organizer regions in lymphocytes of patients with ovarian or breast adenocarcinoma.

The Ag-stainability of nucleolus organizer regions (NORs) in the acrocentric chromosomes identified by Q-banding was studied in 45 female patients with adenocarcinoma of the ovary or breast and in 45 healthy females. Significantly higher frequencies of Ag(+)NORs per individual (8.8 and 8.3; P less than 0.05), in the G group chromosomes (3.6 and 3.2; P less than 0.05), and in chromosome 21 (1.9 and 1.7; P less than 0.02) were found in patients, compared with controls. Despite the lack of significant differences in NORs between the groups of patients with ovarian and breast adenocarcinoma, the main difference between the patients and controls was due to the patients with adenocarcinoma of the ovary, where a significantly higher frequency of Ag(+)NORs was found in chromosomes 21 (P less than 0.01) and 13 (P less than 0.05).

Adenocarcinoma↗