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B Eiben

Publications and source records attributed to B Eiben.

At least 19 recordsLinked to original sources
PubMed2000

The long-term effect of external quality assessment on performance in service cytogenetics.

In 1993 a nationwide cytogenetic external quality assessment program (EQA) was initiated in the Federal Republic of Germany. Presently, some 70 laboratories, representing approximately 90% of all cytogenetic diagnostic tests, are participating in the study. Based on the quality assessment scheme of the Association of Clinical Cytogeneticists (1988) in the United Kingdom, quality of chromosome preparation and speed of routine diagnostic services are being evaluated. As a result of continuous external quality assessment, the mean banding level of participating laboratories rose from below 400 bands per haploid set (bphs) in 1994 to approximately 450 bphs in 1999 in prenatal tests and from about 400 to approximately 500 bphs in postnatal tests over the same 5-yr period. The percentage of participants achieving a banding level of 400 bphs or higher rose from approximately 50% to 93% in prenatal tests and from 60% to 96% in postnatal tests. No significant differences were observed in banding scores achieved by private laboratories compared to university institutes. The impact of the assessment of interpretation, reporting, and documentation remains difficult to evaluate. Preliminary data point to a more stringent adherence to ISCN nomenclature in karyotype designation by participants.

Chromosome Aberrations↗
PubMed1999

A retrospective evaluation of second-trimester serum screening for fetal trisomy 18: experience of two laboratories.

A retrospective study on screening methods for fetal trisomy 18 has been carried out in two different laboratories using the serum parameters: total human chorionic gonadotropin (hCG), unconjugated oestriol (uE3), and alpha-fetoprotein (AFP) in different combinations and in single marker protocols. Laboratory A (L(A)) utilized a radio-immunoassay to examine 38 fetal trisomy 18 cases and laboratory B (L(B)) utilized an enzyme-immunoassay to examine 33 trisomy 18 cases. As unaffected references the whole routine cohorts of each laboratory were used (L(A): 29 043; L(B): 4264). In both trisomy 18 study groups the median hCG and uE3 multiples of the median (MoM) values were markedly declined (L(A): 0.21 MoM, 0.37 MoM; L(B): 0.31 MoM, 0.44 MoM). Even after exclusion of trisomy 18 cases with combined neural tube or ventral wall defects the medians of AFP MoM values were only moderately declined (L(A): 0.73 MoM; L(B): 0.8 MoM). Receiver-operator characteristic (ROC) curves after multivariate discriminance analysis and single marker evaluation demonstrated that the difference of efficiency between a combination of hCG, uE3 and AFP, and a combination of hCG and uE3 is small but that any of these combinations are more efficient than a combination of hCG and AFP or single marker protocols, respectively. At a risk cut-off generating a false-positive rate of one per cent the most effective marker combination detected 31 of 38 (81.6 per cent) affected pregnancies in L(A) and 25 of 33 (75.8 per cent) in L(B). The differences in sensitivity and specificity seem to be due to the different analytical systems being utilized by the two laboratories.

Adolescent↗
PubMed1998

A prospective comparative study on fluorescence in situ hybridization (FISH) of uncultured amniocytes and standard karyotype analysis.

Fluorescence in situ hybridization (FISH) on uncultured amniocytes and standard cytogenetic analysis after amniocentesis have been performed for 904 samples. The experience with the FISH method and its clinical relevance is described in a large clinical pilot study. Commercially available chromosome-specific DNA probes for chromosomes 13, 18, 21, X and Y were used. FISH assays were performed from 12 weeks of gestation to the third trimester. In 96 per cent of the cases, hybridization was performed successfully. At least 50 nuclei for all probes could be counted in 88 per cent of the cases and in 8 per cent between 10 and 49 nuclei were scored. All trisomies 13, 18 and 21 and all cases with gonosomal aberrations were detected by FISH analysis with the exception of one case of trisomy 21 in which hybridization failed due to technical problems. Neither false-positive nor false-negative results were obtained with the DNA probes, in complete agreement with standard cytogenetics. In our experience, FISH is a valuable and reliable method for rapid diagnosis. Consequences of FISH diagnosis are discussed.

Amniocentesis↗
PubMed1997

Intracytoplasmic sperm injection pregnancy with fetal trisomy 9p resulting from a balanced paternal translocation.

Infertile men who carry a chromosomal translocation can be successfully treated with intracytoplasmic sperm injection (ICSI). However, such treatment carries a risk that a pregnancy with an abnormal karyotype will be induced. While in all previously published cases the outcome was favourable, we here report the first instance of a parental reciprocal translocation leading to a chromosomally unbalanced ICSI pregnancy. The fetus, one of a pair of dizygotic twins, was found to have trisomy for the short arm of chromosome 9. The parents opted for selective abortion of the affected twin.

Amniocentesis↗
PubMed1997

Villous cytotrophoblast proliferating potential in complete and partial hydatidiform mole: diagnostic value of silver-stained nucleolar organizer region (AgNOR)-associated proteins.

Aside from their typical morphologic features, complete (CHM) and partial hydatidiform mole (PHM) are characterized by variable trophoblastic proliferation and/or atypia. CHM and PHM usually present little diagnostic difficulty. However, some may be extremely difficult to distinguish by morphologic features alone. Therefore, we investigated the diagnostic value of silver-stained nucleolar organizer region (AgNOR)-associated proteins in cytotrophblasts as compared to cytogenetic features of nine CHM, nine PHM and six non-molar spontaneous embryonic abortions (controls), as well as of two suspected CHM and two histologically suspected PHM. Tissue sections were submitted to autoclave pretreatment and to silver colloid solution. The proliferating potential of cytotrophoblasts was determined by the analysis of mean number and mean area of AgNORs per nucleus using a PC-based image analysis system. Mean values of AgNOR parameters were significantly different from each other (p < 0.001). Each of the four cases of tentative diagnosis could be assigned to the corresponding group of examined trophoblastic lesions. The evaluation of AgNORs in cytotrophoblasts contributes to a reliable discrimination of CHM and PHM; this fairly simple and economical method could serve as an useful addition to conventional methods of diagnosis in gestational trophoblastic disease.

Cell Division↗
PubMed1996

Trisomy of human chromosome 18: molecular studies on parental origin and cell stage of nondisjunction.

We investigated the parent and cell division of origin of the extra chromosome 18 in 62 aneuploids with a free trisomy 18 by using chromosome-18-specific pericentromeric short-sequence repeats. In 46 cases, DNA of patients was recovered from archival specimens, such as paraffin-embedded tissues and fixed chromosomal spreads. In 56 families, the supernumerary chromosome was maternal in origin; in six families, it was paternal. Among the 56 maternally derived aneuploids, we could exclude a postzygotic mitotic error in 52 cases. Among those in which the nondisjunction was attributable to an error at meiosis, 11 were the result of a meiosis I nondisjunction and 17 were caused by a meiosis II error. This result differs markedly from findings in acrocentric chromosomes where nondisjunction at maternal meiosis I predominates. Among the six paternally derived cases, two originated from a meiotic error, indicating that a nondisjunction in paternal meiosis is not as rare as previously suggested.

Adult↗