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Biomedical subjects

A V Mikelsaar

Publications and source records attributed to A V Mikelsaar.

At least 37 records · Page 2Linked to original sources
PubMed1980

Partial short arm deletion of the X chromosome 46,X,del(X)(qter = to p21:).

It is known from the literature that total loss of the short arm causes complete Turner's signs (Hoo, 1975; Therman and Patau, 1974). Partial deletions of the short arm of the X chromosome are in some cases compatible with fertility (Fraccaro et al., 1977; Hoo, 1979), but in other cases they cause a significant ovarial insufficiency with Turner's signs (Giraud et al., 1974) or gonadal dysgenesis (Petrinelli et al, 1978). A common sign for all the patients having the Xp - with the break point in the dark band (p113-p21) seems to be a short stature. The presence of other clinical signs is rather irregular. In this work, a 25-year-old female patient have a Xp deficiency in region p21 (46,X,del(X) (qter = to p21 :)) with short stature, primary amenorrhea, sterility, and clear Turner's is described.

Adult↗
PubMed1980

Q- and C-band polymorphisms in patients with ovarian or breast carcinoma.

To establish the significance of the Q- and C-band variants in risk for malignant disease, chromosome analysis was carried out in 37 women with carcinoma of the ovary or breast and in 40 controls. The frequencies of brilliant fluorescence in segments 3p11q11, 4p11q11, 13p11, 13p13, 14p11, 14p13, 15p11, 15p13, 21p11, 21p13, 22p11 and 22p13, the mean numbers of the brilliant fluorescent segments per cell per individual, and the frequency of inversions of the brilliant fluorescent centromeric area of chromosome 3 were established. The absolute and relative lengths of C bands in chromosomes 1,9, and 16 and the frequencies of C-band size heteromorphisms and inversions were determined. The results of the investigation indicate that the presence of Q and C variants is not associated with an elevated risk of ovarian and breast carcinoma.

Adult↗
PubMed1979

Populational polymorphisms in silver staining of nucleolus organizer regions (NORs) in human acrocentric chromosomes.

The Ag stainability of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q banding of cultured lymphocytes in 41 karyotypically normal persons (33 males and 8 females) originating from southeast Estonia. The data obtained are compared with those established earlier for a combined Vienna-Ulm population of 51 karyotypically normal persons (see Mikelsaar et al., 1977a). Significant differences between the two populations in the frequency and patterns of Ag-positive NORs were found. The following findings were most striking: the frequency of Ag-positive NORs in chromosome 14 and in the totals was significantly lower in the Estonian population than in the Vienna-Ulm population (P less than 0.01). The average modal number of Ag-positive NORs per individual was 7.8 in the Estonian population and 8.7 in the Vienna-Ulm sample (P less than 0.01). If the data of the two populations were combined the frequency of positive NORs was significantly (P less than 0.05) lower in chromosome 22 than in 13, 15, and 21, but not 14.

Cells, Cultured↗
PubMed1979

Satellite association frequency and number of nucleoli depend on cell cycle duration and NOR-activity. Studies on first, second, and third mitoses of lymphocyte cultures.

In human lymphocyte cultures the frequencies of satellite associations in first, second, and third mitoses were investigated using the BUDR-method. A marked decrease of the association frequency with increasing numbers of cell cycles was found. The number of nucleoli seen in interphase is correlated with the satellite association frequency in the respective metaphase. Satellite association is positively correlated to Ag-staining intensity of the NORs. Individual differences in satellite association are due to differences in NOR activity and in lymphocyte activation. BUDR diminishes somewhat the Ag-staining intensity of the NORs but has no effect on satellite association frequencies. The main reason for the decrease of satellite association frequency in second and third lymphocyte mitoses is presumably a certain dislocation of the original chromosome position during mitosis and a decreased possibility of association during the short interphases. The high association frequency in first mitosis resembles the chromosome position in the long interphase of G0-lymphocytes.

Adult↗
PubMed1978

Comparison of silver staining of nucleolus organizer regions in human lymphocytes and fibroblasts.

Ag-staining of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding in repeated lymphocyte and skin fibroblast cultures from three different individuals. A similar pattern of Ag-stainability of NORs was found in the two tissues in each individual. Small differences concerning, in each case, only one of the acrocentric chromosomes were found between repeated lymphocyte cultures, as well as between lymphocyte and fibroblast cultures of the same individual without indication of any prevalence of one tissue type in a certain direction. The possibility that these differences are caused by different stages of NOR activation is discussed.

Cell Nucleolus↗
PubMed1978

Variant chromosome 3 (inv3) in normal newborns and their parents, and in children with mental retardation.

The chromosomes of 102 normal newborn babies (51 boys and 51 girls) born at term, their parents, and 45 nonrelated children with mental retardation at the level of imbecility were investigated by fluorescence microscopy using propyl quinacrine mustard. In each of the 11 families, one of the parents had a variant chromosome 3 that was interpreted as resulting from a pericentric inversion of the brilliant band (or C band) only (inv3). In four cases inv3 was transmitted to the child. The frequency of inv3 in newborn boys and girls was 2 and 6% respectively, and in adult men and women 5 and 6% respectively. In children with mental retardation of unknown etiology the inv3 was detected in five cases (11.1%). This difference from normal persons was not significant.

Child↗
PubMed1978

The nature of the Ag-staining of nucleolus organizer regions. Electron- and light-microscopic studies on human cells in interphase, mitosis, and meiosis.

Electron micrographs reveal that the Ag-stainable substance is located on the outside of NOR's or around them but not in the chromosomes themselves. In association figures, the Ag-positive material lies between the acrocentric chromosomes. Light-microscopic studies show that the Ag stainability of the nucleolus in interphase is correlated with the function of the NOR, as seen from inactive and activated lymphocytes. Much more Ag-positive material is seen in prophase than in meta- and anaphase. It starts to increase again in late telophase. In male meiosis the NOR's remain Ag-positive until pachytene. First and second metaphase figures are negative. Experiments using RNase, TCA, and trypsin indicate that the Ag-stainable substance is an acidic protein. The precipitation of Ag granules in interphase nuclei seen in the electron microscope is greatest over the fibrillar component of the nucleolus. The most likely interpretation is that the Ag-stainable material is a component of ribonucleic protein accumulating around active NOR's. In mitosis some of this material remains at the NOR's. In first meiosis it is completely removed before diakinesis.

Animals↗
PubMed1977

Inheritance of Ag-stainability of nucleolus organizer regions. Investigations in 7 families with trisomy 21.

The Ag-stainability of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding in cultured lymphocytes from seven children with trisomy 21 and their parents. The observed Ag-NOR patterns were in accordance with chromosomal inheritance except for a slight intraindividual variation which might be explained mainly by technical causes. In two cases the meiotic nondisjunction could be attributed to one of the parents, once to the father, and once to the mother. It is concluded that the Ag-stainability of the NORs is in general a heritable characteristic of the acrocentric chromosomes in maximally activated cells as, e.g., cultured lymphocytes. It may reflect individual differences in the amount of rDNA as well as differences in the capacity for NOR activation.

Cell Nucleolus↗
PubMed1977

Frequency of Ag-stained nucleolus organizer regions in the acrocentric chromosomes of man.

The Ag-stainability of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding of cultured lymphocytes in 51 karyotypically normal persons (31 males and 20 females). A consistent pattern of Ag-positive NORs was found in each individual. Ninety percent of individuals have a model number of 8--10 Ag-positive NORs per cell. The frequency of Ag-positive NORs is similar in all five acrocentrics. A statistically nonsignificant lower frequency is found in chromosome 22. Ag-negative NORs on both homologues were found in four cases. The observed frequency distribution of individuals with homozygous NOR-positive, heterozygous, and homozygous negative acrocentric chromosomes was in accordance with the Hardy-Weinberg law in all five pairs of the acrocentric chromosomes as well as in total. No sex difference was observed on our material.

Cell Nucleolus↗
PubMed1977

DIPI and DAPI: fluorescence banding with only negliglible fading.

DIPI and DAPI produce distinct fluorescent bands in human chromosomes similar to quinacrine banding patterns. Additionally, the AT rich secondary constrictions in the chromosomes Nos. 1, 9 and 16 are brightly fluorescent. On the other hand the brilliantly fluorescent regions after staining with quinacrine mustard in the chromosomes Nos. 3 and 4, satellites and some other regions in the acrocentric chromosomes are less striking. The distal part of the Y, however, is clearly discernible. Thus DIPI and DAPI seem to be strictly AT specific fluorochromes like Hoechst 33258. In interphase nuclei the Y chromosome can be identified. However, quinacrines are superior for Y-body analysis in buccal, hair cell and sperm smears. BrdU labeled chromatids show reduced fluorescence intensity. The difference, however, is less apparent than after staining with Hoechst 33 258. DAPI and especially DIPI are highly resistant to UV-irradiation; there is almost no fading within 30 min when using DIPI. Moreover, fluorescence intensity is stronger than in quinicrines. When photographing, exposure times may be reduced to about one quarter compared to quinacrine mustard.

Amidines↗
PubMed1975

Human karyotype polymorphism. III. Routine ank fluorescence microscopic investigation of chromosomes in normal adults and mentally retarded children.

The results of a routine and fluorescence microscopic investigation of chromosomes are presented in 208 normal adults and 141 mentally retarded children (80 with diagnosis of "mental retardation of unknown etiology" and 61 with Down's syndrome). The occurence of both real chromosome aberrations and chromosome variants are presented, with special attention being paid to the chromosome variants. The data obtained show that in all groups studied there is considerable polymorphism of heterochromatic regions that appears to be dependent on sex and connected with the origin of some pathologic conditions.

Adolescent↗