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E Therman

Publications and source records attributed to E Therman.

At least 37 records · Page 2Linked to original sources
PubMed1984

The phenotypic effects of small, distal Xq deletions.

The effects of small, distal Xq deletions (Xq26----qter) have been reviewed in light of three cases of our own and five from the literature. The symptoms caused by such deletions range from apparently none through irregular menstruation to secondary amenorrhea (or premature menopause) to primary amenorrhea. That the abnormal chromosome has any effects when it is inactivated may best be explained by one or by a combination of the following hypotheses. (1) the Xq-chromosome might exert an effect during development when cells in which it is active compete with cells in which it is inactivated, assuming that the inactivation of the two X chromosomes is originally random. (2) a more probable hypothesis is that there is a position effect when a break has occurred in the critical region Xq13----q27 which apparently must be intact in both X chromosomes to allow normal development of the ovaries. (3) this position effect might, in turn, affect the oocytes (and thus the ovary) after the inactive X chromosome is reactivated before meiosis or the deletion as such might have a direct effect on the ovaries.

Amenorrhea↗
PubMed1984

Mitotic modifications and aberrations in human cervical cancer.

Mitotic modifications and aberrations characteristic of human malignant tumors have been analyzed and illustrated in cervical cancer. Most of them can be explained by assuming that the coordination of the centrosomal and chromosomal mechanisms, typical of normal mitosis, is disturbed. When the spindle mechanism is ahead of the chromosomes, the prophase is relatively shortened. This expresses itself in an increase of the ratio of metaphases to prophases (M/P), which in normal tissues is around 1. With M/P values of 4-6, the first tripolar metaphases are formed, and with higher ratios, divisions having more and more poles appear. The spindle and the chromosomes are out of step in the opposite direction in endocycles, in which the spindle is slowed down or absent. The most common of the endocycles is endoreduplication, followed by endomitosis, which is found in more than half of the cervical cancers. Mitotic abnormalities include lagging chromosomes in metaphase and anaphase and bridges in anaphase, which, when numerous, may lead to restitution. More sporadically occurring are C-mitosis and other abnormalities, including cell and nuclear fusions. There is a wide range of variation in the occurrence and frequency of chromocenters within a tumor, and an even greater variation between tumors. About one-fifth of cervical cancers lack X chromatin bodies. The abnormal chromosome constitutions in cancer are the result of various mitotic modifications and aberrations, as well as chromosome rearrangements. New chromosome combinations are constantly created and selection promotes the fastest dividing ones, which, in turn, become new stem lines of the tumor.

Chromatin↗
PubMed1983

Endomitosis: a reappraisal.

The concept and role of endomitosis is reevaluated in the light of observations on three organisms. Endomitosis which morphologically agrees with Geitler's (1939) classical definition is compared in tapetal cells of the liliaceous plant Eremurus, in the septal cells of the testicular follicles of the grasshopper Melanoplus, and in human cells from normal and molar trophoblasts and cervical cancer. These observations, together with those of Kidnadze and Istomina (1980), show that functionally at least two fundamentally different types of endomitosis exist, although morphologically the stages resemble each other in the three organisms. In the first type, exemplified by Eremurus, each endomitosis leads to a chromosome constitution which represents one level higher ploidy, a course that has been assumed to be characteristic of endomitosis in general. The second type, observed in its most characteristic form in the grasshopper, seems to be stationary: no DNA synthesis occurs, but an intensive RNA synthesis takes place. Presumably such cells have reached a final state in their development and are specialized in manufacturing one or more gene products. Endomitosis in normal placenta comes near this type, although DNA synthesis takes place in occasional cells. However, similar endomitotic nuclei in the hydatiform moles are in the process of DNA synthesis. When endomitosis is analyzed in different organisms and tissues, the observation that this process is not one entity should be kept in mind.

Animals↗
PubMed1983

The structure and origin of giant nuclei in human cancer cells.

The structure and origin of giant nuclei in human cancer cells were studied in two cases of squamous cell carcinoma of the cervix. Feulgen-squash preparations of untreated biopsies showed the following types of nuclei: fairly evenly stained nuclei, nuclei with distinct chromocenters from which individual chromosomes sometimes seemed to radiate, and nuclei with banded structures which we tentatively interpret as some type of "polytene" chromosomes possibly showing prophase chromomeres. In neither tumor did either the small or large nuclei display any X chromatin bodies. The main processes giving rise to the different types of nuclei are endoreduplication, true endomitosis, and a kind of polytenization. The multichromosome chromocenters that fell apart possibly represent polytene chromosomes separating into individual chromosomes.

Biopsy↗
PubMed1982

Origin of symmetrical triradial chromosomes in human cells.

We have collected 23 sporadic symmetrical triradial chromosomes (plus one D with duplicate satellites), 22 from cultured lymphocytes and one from a bone marrow cell. Fifteen triradials were from patients with Bloom's syndrome, and two from a Fanconi's anemia patient. The following chromosomes and chromosome groups were involved: 1, 2, 3, 4, 5, C(11 identified), D, and 17. The branchpoints were localized nonrandomly. Regions in or near centric heterochromatin were often involved. Some of the branchpoints are regions which also contain a high number of mitotic chiasmata. When the present sporadic triradials combined with those from the literature were compared with triradials with branchpoints in the "fragile regions", the localized branchpoints were different in these two groups. Our conclusion that most -- possibly all -- symmetrical triradials are caused by partial endoreduplication is based on the following observations: the shape of the triradials which shows that the extra segments are paired with their intact sister chromatids and not with each other; the failure of X-rays in G2 to increase the incidence of symmetrical triradials; the fact that in some cases the end of the extra segment is joined to its intact sister chromatid; and the occurrence of duplicate satellites.

Amenorrhea↗
PubMed1982

Endomitosis in human trophoblast.

Endopolyploidy, which arises through the duplication of DNA without accompanying nuclear division, occurs in large numbers of lower and higher plants and animals, including the best known, the salivary gland nuclei of Drosophila. Endomitosis is one of the processes leading to endopolyploidy, in which the stages of mitosis (prophase, metaphase, anaphase) take place inside the nuclear membrane and without spindle formation. In mammals, endomitosis has been observed in the trophoblast of the placenta of the mouse, rat and rabbit. This is the first report of endomitosis in a normal human tissue, the trophoblast of first trimester human placenta.

Cell Nucleus↗
PubMed1982

Spontaneous cell fusion and PCC formation in Bloom's syndrome.

Corresponding to 4,633 diploid lymphocytes 64 tetraploid or near-tetraploid (including one octoploid) metaphases were found in two sibs with Bloom's syndrome. Eight of the polyploid cells had resulted from cell fusion with half the chromosomes representing PCC. One similar fibroblast was also observed. In 13,584 untreated cells from persons without a chromosome-breakage syndrome no such cells were encountered (P = 0.0000176). This seems to be the first description of spontaneous fusion of nonmalignant cells. The extended segments in the G2 type PCC which correspond to the Q-bright, late-replicating chromosome parts are less tightly spiralized than other chromosome regions which renders the chromosomes similar to those which have incorporated BrdU late in the S period. Obviously the chromosome segments which replicate last also are the last to spiralize.

Bloom Syndrome↗
PubMed1981

The origin of telocentric chromosomes in man: a girl with tel(Xq).

A mentally retarded girl with several Turner symptoms had the chromosome constitution 46,Xtel(Xq). The abnormal X chromosome appeared to be completely telocentric and stable. It was late-replicating and formed a smaller than normal Barr body. The origin of telocentric chromosomes is discussed.

Child, Preschool↗
PubMed1981

Partial 11q trisomy syndrome.

The syndrome caused by partial trisomy for 11q is reviewed on the basis of a patient of our own and 20 cases (including a stillbirth) from the literature. The main symptoms are presented in Tables 1 and 2. The syndrome can be suspected when, in addition to mental retardation, the following characteristics are present: short nose, long philtrum, micrognathia, retracted lower lip, and micropenis in males. In 15 families, the mother was a balanced translocation carrier and in four the father. The translocation had arisen de novo in two patients. The chromosome number was 46 in 13 affected individuals (including the stillbirth) and 47 in eight. In seven of the latter patients the other translocation chromosome was 22, and in one, chromosome 9. The breakpoints on 11q ranged from 11q121 to 11q232 (Fig. 5). There is no apparent correlation between the length of the trisomic segment and the number or severity of the symptoms (Table 2). This could be explained by assuming that most, if not all, symptoms are caused by trisomy for the Q-dark region distal to 11q232, whereas trisomy for the rest of the 11q up to q121 has few phenotypic effects. These observations support the idea that Q-dark segments, and especially certain hot spots, have a high gene density in contrast with Q-brighter regions.

Abnormalities, Multiple↗
PubMed1981

Mitotic recombination and segregation of satellites in Bloom's syndrome.

Mitotic recombination in satellite stalks--a phenomenon often difficult to distinguish from satellite association--was studied in a sister and a brother with Bloom's syndrome. Segregation after recombination was analyzed in the lymphocytes of the sister who had Q-bright satellites. Her cells varied greatly both in regard to the acrocentrics which displayed Q-bright satellites and the number of such satellites per cell. In 58 cells a total of 31 different patterns were seen. In 83 cells of 6 controls who also had Q-bright satellites on at least one acrocentric chromosome, not one cell was found in which the pattern differed from that characteristic of the person. Obviously exchanges between satellite stalks in patients with Bloom's syndrome are fairly frequent (estimated lower limit 6/1000) and very rare in persons who do not have this syndrome (estimated 0.1/1000).

Chromosome Aberrations↗
PubMed1981

The behavior of allocyclic chromosomes in Bloom's syndrome.

The behavior of individual allocyclic chromosomes has been analyzed in lymphocytes of a sister and a brother with Bloom's syndrome. Of 4,633 46 diploid cells, 115 showed allocyclic chromosomes, and 74 of these had 44, 45 or 46 normal metaphase chromosomes accompanied by one or two allocyclic chromosomes. Of 56 tetraploid cells, 9 contained such chromosomes. The allocyclic chromosomes appeared "pulverized" or extended corresponding to S or G2 PCC. We have proposed the hypothesis that individual allocyclic chromosomes do not, as a rule, come from micronuclei, as has often been assumed, but have been left behind in their cycle. This would be caused by a mutation or deletion of a hypothetical coiling center situated near the centromere of each chromosome arm. The following observations agree with our explanation but less well or not at all with the idea of micronuclei: (1) In only 9.6% of the cells does the allocyclic chromosome lie at the edge of the metaphase plate. (2) In 24 cells a part of a chromosome is "pulverized" while the rest is in metaphase. (3) Both a "pulverized" and an extended chromosome were present in the same cell. (4) A "pulverized" acrocentric is often nose-to-nose with a normal D or G chromosome. (5) No allocyclic chromosomes corresponding to G1 PCC have been found in our material. (6) When a ring is replaced by an allocyclic chromosome, it is usually a member of a 46-chromosome complement. Furthermore, the occurrence of allocyclic chromosomes is correlated with that of other chromosome anomalies which do not follow a Poisson distribution. Allocyclic chromosomes are also more frequent (16%) in tetraploid than in diploid cells (2%).

Bloom Syndrome↗
PubMed1980

Replication and inactivation of a dicentric X formed by telomeric fusion.

A woman complaining of secondary amenorrhea and infertility was found to have, in addition to a normal X chromosome, a long compound chromosome that consisted of two X chromosomes attached by telomeric fusion of the short arms without any apparent loss of genetic material, 46,X,dic(X)(pter), hereafter referred to as t(X;X). The t(X;X) chromosome was late replicating; the inactivation pattern was analyzed. It formed Barr bodies that were larger than normal, of which the majority were bipartite. Analysis of the X-chromatin masses supports our hypotheses that there is a region next to the centromere on the short arm of the inactive X chromosome that remains active and that there is an inactivation center located on Xq, a short distance from the centromere, around which the X chromatin condenses.

Adult↗
PubMed1980

A boy with congenital malformations and chromosome breakage.

A patient with increased chromosome breakage and multiple congenital malformations is described. The lack of any apparent quantitative or qualitative disturbance in hemopoiesis and adequate number of myeloid and erythroid progenitor cells and the absence of certain clinical features such as webbed neck and absence of dark pigmentation in the patient did not support the diagnosis of the Fanconi pancytopenia syndrome. The cytogenetic studies revealed increased chromosome breakage at G1 phase, a finding which is also at variance with that observed in patients with the Fanconi pancytopenia syndrome.

Abnormalities, Multiple↗
PubMed1980

X chromosome constitution and the human female phenotype.

The correlations of abnormal X chromosome constitutions and the resulting phenotypes in the human female are reviewed. The following hypotheses put forward to explain these correlations are discussed in detail: (1) The damage is done before X inactivation; (2) An effect is exerted between reactivation of the X chromosome(s) and meiosis in oocytes; (3) A recessive gene(s) in hemizygous condition might be expressed in the cases in which the same X is active in all cells; (4) A change in the number of presumed active regions on the inactive X chromosomes might have an effect; (5) A position effect, in that the region Xq13-q27 has to be intact in both X chromosomes to allow normal development, may be responsible; (6) An effect during the period when cells with different inactivation patterns compete is a probability; (7) The original X inactivation may be neither regular nor random. The conclusion reached is that the phenotypic effects of a specific X chromosome aberration may be simultaneously exerted through different pathways (Tables 1 and 2). Hypotheses (2), (4), (5), and (6) are considered probable. Hypothesis (3) has been discarded, and there is very little evidence for hypotheses (1) and (7).

Adolescent↗
PubMed1979

Chromosome breakage and rejoining of sister chromatids in Bloom's syndrome.

The occurrence of chromosome breaks and reunion of sister chromatids in lymphocytes of two patients with Bloom's syndrome has been compared with those found in X-rayed and control cells. The distribution of breaks in BS is non-random both between and within chromosomes, the centric regions of certain chromosomes being preferentially involved. The following working hypotheses are put forward: When chromosome breaks in human lymphocytes occur in G0-G1, practically no sister chromatid reunion (SCR) takes place, whereas ends created by an S-G2 break show a considerable tendency to SCR. We propose further that chromosome aberrations in BS mainly result from breaks in S-G2, including possible U-type rejoining of sister chromatid exchanges. Fragments extra to an intact chromosome complement result from a chromatid break or an asymmetrical chromatid translocation in a previous mitosis.

Cells, Cultured↗
PubMed1979

Position of the human X inactivation center on Xq.

In three women with a 46,XXq- chromosome constitution, the length of the deletion was expressed as the ratio of the remaining part of Xq to Xp c' over a + b. In one of them (KH) this ratio was 0.33, in another (GE) 0.59, and in the third (AP) the ratio fell between these values. The break in KH is more or less on the border of the Q-dark proximal region. A comparison with relevant X-autosomal translocations indicates that the X inactivation center lies near, but not at the border of, the Q-dark and the adjoining bright region (c and d).

Adult↗