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Biomedical subjects

I Hansmann

Publications and source records attributed to I Hansmann.

At least 55 records · Page 3Linked to original sources
PubMed1991

Mapping of the ribophorin II (RPN II) gene to human chromosome 20q12-q13.1 by in-situ hybridization.

Ribophorin I and II (RPN I and RPN II), two specific glycoproteins, span the rough regions of the endoplasmic reticulum (RER) and are thought to play an important role either in translocation or in the maintenance of RER. Studies with human-mouse somatic cell hybrids have localized the gene for RPN I on human chromosome 3q, while RPN II is on chromosome 20. Using a radioactive labelled cDNA probe, we have regionally mapped the RPN II gene to human chromosome 20q12-q13.1 by in situ hybridization. This assignment predicts a location of the murine homologue, Rpn-2, to the syntenic segment on mouse chromosome 2 in close proximity to Ada, Src and Gnas.

Chromosome Mapping↗
PubMed1991

Characterization and regional mapping of new anonymous chromosome 20-specific DNA markers isolated from a flow-sorted DNA library.

Employing the flow-sorted chromosome 20-specific DNA library LL20NS01, we isolated seven novel unique poly- and monomorphic DNA markers specific to human chromosome 20. Initially, 201 phage clones were analyzed regarding insert size and repetitivity. By testing 14 single- and low-copy number clones for their ability to detect RFLPs, three polymorphisms were revealed by two probes, pFMS22-1.4 [D20S22] and pFMS76 [D20S23]. Seven of twenty probes (35%) were assigned to chromosome 20 using a somatic cell hybrid DNA panel. Five of them were regionally mapped by in situ hybridization. Three DNA markers, pFMS51 [D20S29], pFMS76 [D20S23], and pFMS106 [D20S30], were assigned to 20p11.2-p12, and two markers, pFMS22-1.4 [D20S22] and pFMS135 [D20S31], to 20q12-q13.3. Our new chromosome 20-specific DNA markers should be useful for the molecular characterization of this rather underpopulated human chromosome.

Bacteriophages↗
PubMed1991

The gene for the novel vasoactive peptide endothelin 3 (EDN3) is localized to human chromosome 20q13.2-qter.

Endothelin 3 is a novel vasoactive peptide of unique structure and belongs to the endothelin gene family. Though it mainly functions as a vasoconstrictor/pressor, it plays a major role in a wide variety of other biological functions, possibly as a novel neuropeptide. Studies with human-mouse somatic cell hybrids have suggested that the gene EDN3 is localized on human chromosome 20. We confirmed this localization and regionally mapped the gene to the region 20q13.2-q13.3.

Animals↗
PubMed1991

G protein Gs alpha (GNAS 1), the probable candidate gene for Albright hereditary osteodystrophy, is assigned to human chromosome 20q12-q13.2.

Guanine nucleotide-binding proteins, also known as G proteins, mediate intracellular responses to a wide variety of extracellular stimuli. A variety of genes that specify the synthesis of the components of guanine nucleotide proteins have been identified. One of these proteins, termed Gs alpha (GNAS1), is the G protein component of the olfactory signal transduction cascade. Mutations in the GNAS1 gene leading to Gs alpha protein deficiency are known to be associated with pseudohypoparathyroidism Ia (Albright hereditary osteodystrophy) and certain pituitary tumors with acromegaly. Studies on the human--mouse somatic cell hybrids provisionally assigned this gene to chromosome 20. We have now confirmed this localization on chromosome 20 and regionally assigned the GNAS1 gene to 20q12-q13.2 by in situ hybridization.

Chromosome Banding↗
PubMed1991

The gene for human growth hormone-releasing factor (GHRF) maps to or near chromosome 20p12.

Growth hormone-releasing factor (GHRF), a hypothalamic releasing factor also named somatocrinin, influences the secretion and synthesis of growth hormone. Human GHRF is encoded by a single gene which was assigned to chromosome 20 by dot-blot analysis of DNA from dual laser sorted chromosomes. Using a radioactive cDNA probe, we localized the GHRF gene to chromosome 20p12 or near band 20p12.

Chromosome Banding↗
PubMed1989

Down syndrome at birth not detected by first-trimester chorionic villus sampling.

A case of a false-negative first-trimester diagnosis following chorionic villus sampling is reported that ended with the birth of a child with Down syndrome. Chromosome analysis of 30 metaphases from 24 h-cultured chorionic villi obtained in week 12 of gestation showed a normal chromosome constitution. However, the newborn showed manifestations of Down syndrome, and 99 of 100 metaphases analysed from cultured lymphocytes showed 47, XY, + 21. The remaining metaphase was normal (46, XY).

Chorionic Villi Sampling↗
PubMed1989

The predictive value of chorionic villus histology for identifying chromosomally normal and abnormal spontaneous abortions.

To evaluate the significance of placental histology, a collaborative histological and cytogenetic study on the products of 123 spontaneous abortions of 6-19 week pregnancies was performed. From each sample, 2-3 g was dissected randomly and analysed histologically with no prior knowledge of the karyotype. Chromosomes were prepared from the remaining chorionic villi after an overnight incubation in culture medium; they were analysed by Q- or G-banding. The frequency and type of chromosome anomalies detected are comparable to those seen in other studies. Altogether, 49.6% were chromosomally abnormal, trisomies predominating (49.2%), followed by polyploidy (27.9%) and monosomy X (14.5%). The histological classification failed for technical reasons in 11 cases (8.9%). To classify the remaining cases, 18 different histological criteria were considered independently by two pathologists. A definite diagnosis was not possible for 27 abortions (22.0%), and 50 were classified as being chromosomally abnormal. This proved to be correct in 36 (72.0%), but incorrect in as many as 14 (28.0%). No evidence for an abnormal karyotype was found histologically in samples from 35 abortuses. Nevertheless, 9 of them (25.7%) had an abnormal karyotype. The predictive value of chorionic villus histology seems to be inadequate, as only 62 of 112 samples were correctly classified by histology (55.4%). The value differs little from the a priori probability of an abnormal or normal karyotype in abortuses of corresponding gestational ages.

Abortion, Spontaneous↗
PubMed1989

Molecular and cytogenetic analysis of an interstitial 20p deletion associated with syndromic intrahepatic ductular hypoplasia (Alagille syndrome).

High-resolution chromosome analysis of a 19-year-old female proband with syndromic intrahepatic ductular hypoplasia (Alagille syndrome, AWS) revealed an interstitial deletion of chromosome 20p with breakpoints provisionally located in or close to p11.22 and p12.2. Southern blots from digests of DNA of the proband and her chromosomally normal parents were hybridized with the human DNA probes pR12.21, HuPrPcDNA2, and pDS6-SgI, which have been mapped to the region 20 (p12-pter), and rehybridized with the F IX probe for calibration. Comparing the hybridization signals of the normally sized DNA fragments of the family, we found no evidence for loss of any of the three tested distal chromosome 20p loci in our proband. Furthermore, in situ hybridization with HuPrPcDNA2 revealed a specific accumulation of grains at or around the faint distal G band suspected to represent all or most of band p12.3 of the proband's deleted 20p and at p12 of the normal chromosome 20. Thus the AWS of our proband is associated with an interstitial deletion that preserved the three tested distal loci on 20p. Since nine further reported cases of 20p deletion are clinically similar, we propose AWS as a further "contiguous gene syndrome" and assign it to an approximately 8-Mb-large chromosome 20p segment (provisionally, p11.23-p12.1).

Adult↗
PubMed1988

Maternal modulation of the inheritable meiosis I error Dipl I in mouse oocytes is associated with the type of mitochondrial DNA.

The ovulation of diploid oocytes, abnormally arrested at or during the first meiotic division, is an inheritable trait (DiplI) in mice and modulated by a maternally transmitted factor. By repeated backcrossing, mouse strains with identical nuclear encoded genes and differing only in their mitochondrial genomes can be created. NMB mice represent such a strain having acquired the nuclear genome of C57BL/6J but still possessing mitochondria and therewith mitochondrial DNA (mtDNA) of NMRI/Bom, their female progenitor. The strains NMB and C57BL/6J were used to characterize a new mitochondrial trait, namely the ability to modulate the expression of the inheritable meiosis I error Dipl I in oocytes. We show that an increased rate of ovulated diploid oocytes is associated with the mtDNA type of C57BL/6J. These results corroborate the assumption that mitochondria do play an important role in meiosis of mammalian oocytes and hence seem to be involved also in the orderly segregation of chromosomes.

Animals↗
PubMed1988

Pattern and frequency of nondisjunction in oocytes from the Djungarian hamster are determined by the stage of first meiotic spindle inhibition.

In order to study the mechanisms of nondisjunction at meiosis I in oocytes gonadotropin-stimulated Djungarian hamsters were treated at two stages [4.5 and 6 h post human chorionic gonadotropin (HCG)] during the preovulatory period with 1000 mg/kg Carbendazim (MBC). The compound, known to bind fast but reversibly to mammalian tubulin, was chosen to investigate whether the stage at which spindle function is inhibited affects the pattern of nondisjunction. Ovulated oocytes were cytologically prepared and scored for hyperhaploidy, diploidy and presegregation. Application at an early spindle phase, 4.5 h post HCG, to females stimulated with a low gonadotropin dose [3 IU pregnant mares serum (PMS); 2 IU HCG] caused a high frequency of nondisjunction (40.6%) with a more or less nonspecific pattern of malsegregated bivalents. Treatment at a late stage of spindle function (6 h post HCG) resulted in a less frequent (22.5%) but highly preferential malsegregation of those A-D group bivalents thought earlier to be late segregators. On the other hand, oocytes from females primed with a high (10 IU PMS and HCG) gonadotropin dose, a treatment assumed to delay meiosis by approximately 1.5 h, responded to MBC treatment at the late stage (6 h) with a nonspecific pattern and a high frequency (71.2%) of nondisjunction. The latter result is comparable to that in which MBC was given at the early stage (4.5 h) and after a low gonadotropin dose. The high nondisjunction response additionally indicates that spindles in hypergonadotropic stimulated oocytes are more susceptible and/or that the concentration of the inhibitor is higher in such oocytes. Only few oocytes with presegregation (3.1%; 0.0%; 1.7%) and few diploid oocytes (3.3%; 1.5%; 3.2%) with complete inhibition of meiosis I were observed. We conclude, that in Djungarian hamsters (1) the segregation of bivalents at meiosis I is asynchronous with the large A-D bivalents segregating last, (2) the phase in which spindle function is inhibited determines the pattern of nondisjunction, and (3) the resumption of meiosis I - from dictyotene to metaphase II - does not follow a rigidly timed programme but depends on the conditions of follicular maturation.

Aneuploidy↗
PubMed1988

Partial deletion of 4p in fetal cells not present in chorionic villi.

A case of a prenatal diagnosis at the second trimester is presented showing a normal karyotype in 12 metaphases from chorionic villi. In all cultured amniotic cells, however, and also in all fetal fibroblasts analyzed after abortion a structural anomaly (46,XY;del 4(pter----p15.2) was detected. Prenatal diagnosis was performed because of intrauterine growth retardation, cleft lip and esophagus atresia by ultrasound. The fetal stigmata are compatible with the Wolf Hirschhorn syndrome. We conclude that amniocentesis may be indicated notwithstanding a normal CV-diagnosis in those rare pregnancies with a characteristically abnormal ultrasound.

Abnormalities, Multiple↗