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Biomedical subjects

I Hansmann

Publications and source records attributed to I Hansmann.

At least 91 records · Page 5Linked to original sources
PubMed1985

A male with a monocentric Yq isochromosome and presence of a Yp-specific DNA sequence.

We describe clinical features and laboratory findings in a physically and mentally retarded male with underdeveloped testes, a seemingly monocentric isochromosome of Yq but the presence of a Yp-specific DNA sequence at a single dose of unknown genomic localisation, and the presence of H-Y antigen at normal male titer. Our data contribute to the fine mapping of the human Y chromosome by correlating phenotypic features with results from karyotypic, immunologic, and molecular hybridisation analyses.

Adolescent↗
PubMed1985

Preferential nondisjunction of specific bivalents in oocytes from Djungarian hamsters (Phodopus sungorus) following colchicine treatment.

In an attempt to study the mechanisms leading to nondisjunction during meiosis I, Djungarian hamster females were treated with colchicine (3 mg/kg), which binds specifically to tubulin. The number of ovulated oocytes per female was significantly reduced following colchicine treatment (8.2 +/- 5.3, compared to 10.6 +/- 5.9 in controls receiving saline solution only). Application of colchicine rather late during oocyte maturation (ie, 5.5 h after injection of human chorionic gonadotrophin) caused a significant increase in the number of ovulated diploid (34.5%) and hyperhaploid (11.7%) oocytes, compared to the frequencies observed in the saline-treated controls (0.8% and 3.5%, respectively). Specific bivalents (viz, the large meta- and submetacentric chromosomes of groups A, B, and C) were preferentially involved in colchicine-induced nondisjunction. The same pattern of chromosomal malsegregation was previously observed in oocytes from this hamster species following hypergonadotrophic stimulation. Preferential involvement of bivalents in the process of nondisjunction, whether induced by colchicine or hypergonadotrophic stimulation, is explained by an interference with microtubular function affecting those bivalents that are the last to segregate.

Animals↗
PubMed1984

Developmental pathogenesis of chromosome disorders: report on two newly recognized signs of Down syndrome.

Testing the hypothesis of amplified developmental instability in autosomal trisomies as proposed by Shapiro we predicted and found an increased frequency of symphalangies in the toes of patients with Down syndrome. In our X-ray study of the feet of 71 adults with trisomy 21 we also detected a greater than normal number of sesamoid bones. A corollary to Shapiro's hypothesis is a dependence on ethnic origin of the frequency of symptoms in Down syndrome. Compared to data from Europe, toe symphalangies are more prevalent in Japan. We predict this anomaly to occur even more often in Japanese patients with trisomy 21.

Adult↗
PubMed1984

Mean corpuscular hemoglobin is increased in Martin-Bell syndrome.

Studying the blood picture of 11 patients with Martin-Bell syndrome, we found the erythrocytes relatively hyperchromic when compared to the data from 171 matched controls living in the same institution. Because mean corpuscular hemoglobin is increased also in patients with folic acid deficiency states, we feel that our data provide further evidence that Martin-Bell syndrome is an inherited disease of folate metabolism.

Adult↗
PubMed1984

Control of meiosis by somatic cells in mice: inheritance of the meiosis I error 'diploidy' and nonexpression in sensitive NMRI/Han oocytes ovulated from chimeras.

NMRI mouse and Djungarian hamster females ovulate diploid and/or hyperploid oocytes with increased frequencies after gonadotrophin stimulation, suggesting that somatic cells are involved in the failures of endocrine control resulting in aneuploidy. To study the inheritance of gonadotrophin-induced aneuploidy as well as the fate of sensitive oocytes in a resistant somatic environment and vice versa, we analysed the frequency of diploid oocytes in NMRI/Han, C57BL/6J and their F1 hybrids (C57BL/6J X NMRI/Han), (NMRI/Han X C57BL/6J) as well as in NMRI/Han in equilibrium C57BL/6J chimeric females after gonadotrophin injections. Ovulated oocytes were analysed in all females for the appearance of diploidy, characterized as premature arrest of development at metaphase I. Our data suggest that the trait of induced diploidy is genetically determined and can be transmitted either maternally or paternally. A maternal effect modulated the expression of that trait. Several mechanisms acting on the feed-back control ovary-hypothalamus/pituitary, within the ovary or even within a chimeric follicle, may be responsible that 'sensitive' oocytes ovulated from chimeras are all normal haploid. These data suggest that not only oocyte maturation but also chromosome disjunction during meiosis I is controlled by somatic cells.

Aneuploidy↗
PubMed1983

Cytogenic investigation of 103 patients with primary or secondary amenorrhea.

Cytogenetic investigations were carried out on 103 women presenting with either primary (n = 88) or secondary (n = 15) amenorrhea. A sex chromosome anomaly was found in 26% and 33% of these patients, respectively. Other studies on women with primary amenorrhea have found a similar or even higher percentage of patients with an abnormal karyotype. It is therefore suggested that all women with absence of menstruation after the age of 16 years should be investigated cytogenetically. The surprisingly high percentage of pathological karyotypes among the secondary amenorrhea group does indicate that sex chromosome anomalies cannot be ruled out in women who have had apparently normal ovarian function for at least some time, and therefore more patients from this group should be selected for chromosome analysis.

Adolescent↗
PubMed1983

Chromosome anomalies in 136 couples with a history of recurrent abortions.

Cytogenetic studies were performed on 136 couples with a history of two or more abortions referred to us after gynaecological causes of the abortions had been excluded. Fifteen (11%) of the couples were found to have a chromosome anomaly, and when the couples were subdivided according to number of abortions, surprisingly 6 (10%) of the 59 couples with a history of only two abortions had a chromosome anomaly. An increased frequency of mosaicism for X-chromosome aneuploidy (2.2%) in the women from the 136 couples was also found. A review of the literature shows that translocations of some chromosomes (e.g. nos. 1, 7 or 22) preferentially lead to fetal wastage, while those involving, for example, chromosome nos. 5, 9, 14 or 21 are more likely to result in the birth of a handicapped child. Couples with a history of two abortions should be investigated cytogenetically. Other causes of miscarriages must, however, be excluded first.

Abortion, Habitual↗
PubMed1983

The genetic basis of non-disjunction: increased incidence of hyperploidy in oocytes from F1 hybrid mice.

Oocytes from parental mice strains NMRI/Han, C57/bl and Balb/c and from F1 hybrid lines were analysed for aneuploidy due to non-disjunction after gonadotropin-stimulated ovulation. No hyperploid oocytes were present in five of the strains studied. F1 hybrids from crosses of NMRI/HanxC57/bl did ovulate, however, a significantly increased number of hyperploid oocytes, although females from their parental strains show a rather low incidence of non-disjunction. The evidence for a genetic basis for non-disjunction is assessed and possible causative factors are discussed.

Animals↗
PubMed1983

The genetic significance of accessory bisatellited marker chromosomes.

Ten new cases of accessory bisatellited marker chromosomes examined in different laboratories are reported. As a basis for genetic counseling in the context of prenatal diagnosis a cytogenetic categorization of such marker chromosomes is proposed and an estimation of the genetic risk associated with each category is carried out. The results are as follows: There is no increased risk for offspring with abnormal phenotype born to a healthy carrier of an accessory bisatellited marker chromosome with either a single or two closely adjacent C-bands (Category AI or AII). The unbiased sample of cases with de novo accessory bisatellited marker chromosomes of categories AI and AII is too small to allow a satisfactory estimation of the actual risk that, in case of such a prenatal finding, the foetus may not show a normal phenotype as a consequence of the marker chromosome. There is, however, evidence that this risk may be lower than 10%. Accessory bisatellited marker chromosomes showing a discrete pattern of G- and R-bands situated between two distant C-bands (Category AIII) usually indicate a chromosomal imbalance giving rise to an abnormal phenotype. Mosaic carriers of such dicentric marker chromosomes may, however, present a normal phenotype.

Abortion, Spontaneous↗
PubMed1983

Low doses of X-rays decrease the risk of diploidy in mouse oocytes.

Females from the NMRI/Han mouse strain ovulate a high number of diploid oocytes (about 12%) after gonadotrophin-stimulated ovulation. These oocytes can be fertilized and develop into triploid embryos subsequently. The exposure of such gonadotrophin-primed females to X-ray doses of 0.05, 0.10, 0.20 or 0.40 Gy during the preovulatory period (2 h after the HCG dose) significantly decreased the percentage of diploid oocytes. After the highest dose used, i.e. 0.80 Gy, however, the incidence was on the level from unirradiated females, again. We suggest that the observed negative hump-shaped dose response of diploidy is not caused by secondary modifications induced by irradiation, such as a selective killing of diploid oocytes before ovulation, or a (compensatory) super-ovulation of only normal oocytes, but rather is caused by a direct radiobiological interference of low doses in protecting from gonadotrophin-induced aneuploidy.

Aneuploidy↗
PubMed1983

X-ray induced reciprocal translocations and dicentrics in human G0 lymphocytes.

We have reinvestigated the question whether the assumed ratio 1:1 between the frequencies of symmetrical (translocations) and asymmetrical (dicentric) aberrations can be observed in human G0-lymphocytes. We have evaluated G-banded chromosomes in cells irradiated with doses of 1 and 2 Gy of 150 kV X-rays. The experimentally determined ratio of 1 . 04:1 is in agreement with the theoretically predicted value.

Chromosome Aberrations↗
PubMed1983

Partial trisomy 7q in two siblings.

Trisomy for 7q32 leads to 7qter and monosomy for 9p24 leads to 9pter is observed in a sister and a brother, due to a balanced reciprocal translocation between the long arm of the chromosome 7 and the short arm of the chromosome 9 in the mother. The siblings are retarded mentally as well as in statomotoric development. This paper discusses the correlation between chromosomal states and certain deformities in patients with trisomies of different segments of 7q.

Abnormalities, Multiple↗
PubMed1982

Nondisjunction and chromosome breakage in mouse oocytes after various x-ray doses.

The effect of varying X-ray doses (0.05-0.80 Gy) on preovulatory mouse oocytes was studied by measuring nondisjunction during the first meiotic division, as well as structural chromosome anomalies in ovulated oocytes at metaphase stage II. The incidence of nondisjunction (0.1% hyperploid oocytes) found in oocytes from nonirradiated NMRI-Han female mice was in accordance with the results previously obtained with the same strain. Significantly (P less than 0.05) more hyperploid oocytes (0.9%) were ovulated following irradiation with 0.8 Gy. There was no statistically significant increase of nondisjunction after low doses. Structural chromosome anomalies occurred, however, even after an irradiation dose as low as 0.05 Gy. The dose response for structural chromosome anomalies is altogether different from that of radiation-induced hyperploidy. We consider that irradiation of mature oocytes might well be less hazardous with regard to its potency for increasing nondisjunction during the first meiotic division when compared with the effect of chemical mutagens.

Animals↗
PubMed1982

Biochemical and therapeutical studies in a case of atrophia gyrata.

A thirty-six years old man from an inbred family with the typical clinical picture of Atrophia gyrata chorioideae et retinae was found to have hyperornithinemia and a partial deficiency of ornithin-ketoacid-transaminase activity. The residual activity was stimulated in vitro by high concentrations of pyridoxal phosphate. We have initiated a therapeutic study with vitamin B6 per os accordingly. Comparitively low doses may be sufficient for long term treatment. The necessity to start therapy early in life is emphazised. Possible mechanisms of the pathogenesis of Atrophia gyrata are discussed.

Adult↗
PubMed1981

The dup(3q) syndrome: report of eight cases and review of the literature.

Clinical and cytogenetic examinations were performed on eight unrelated infants with duplication of part of the long arm of chromosome 3. A review of published cases shows a clinical syndrome characterized by statomotoric retardation, shortened life span, and a multiple congenital anomalies (MCA) syndrome of abnormal head configuration, hypertrichosis, hypertelorism, ocular anomalies, anteverted nostrils, long philtrum, maxillary prognathia, down-turned corners of the mouth, highly arched or cleft plate, micrognathia, malformed auricles, short, webbed neck, clinodactyly, simian crease, talipes, and congenital heart disease. The dup(3q) syndrome is a clinically easily recognizable entity.

Abnormalities, Multiple↗