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Biomedical subjects

R Schloo

Publications and source records attributed to R Schloo.

9 recordsLinked to original sources
PubMed1999

[Is sterility a genetic burden?].

Genetic causes of infertility are probably not rare. Today only a fraction of genes directly or indirectly involved in reproduction including sex determination and differentiation are known. Nevertheless, the list of well-defined genetic disorders impairing fertility is impressing already today and growing rapidly. Gonosomal aneuploidy and structural rearrangements represent a significant portion of the genetic causes of infertility in both sexes. Other chromosomal conditions include autosomal balanced structural changes (e.g. translocations), probably due to pairing disturbances of the affected chromosomes during meiosis. Some fundamental mechanisms in sex determination and differentiation have been characterized in recent years. Mutations in some of the genes involved in this process may lead to familial infertility. Genetic defects in gametogenesis of both sexes are currently being investigated using mouse models. Male specific causes of infertility include microdeletion within the AZF region of the euchromatic part of the long arm of the Y chromosome and obstructive azoospermia due congenital aplasia of the vas deferens in the presence of mutations in the CFTR gene.

Animals↗
PubMed1994

[Possibilities for modifying risk factors for chromosome abnormalities--advantages of the so-called "triple" marker studies in comparison with pure "maternal age screening"].

We have offered the so-called "triple-marker screening" since May 1991 to all patients who came for prenatal care and did not select an invasive procedure primarily. First evaluation of 5210 cases revealed that 3.7% were test-positive for neural tube defects, 13.8% for Down's syndrome and 0.5% for both at the same time. The explanation for the comparatively high "test-positive" rate of 13.5% is the maternal age distribution with the median at 31.4 years. The highest number of women selecting triple-marker determinations was in the age group of 35 years. We detected 16 cases of Down's syndrome and in this group the majority of women was below 35 years. The decision of women to have an invasive procedure was obviously very much influenced by the actual risk assessment, because amniocentesis was chosen by 72/85 (84.8%) of women with a risk of more than 1:50, 192/290 (66.2%) of women in the risk category of 1:51 to 1:200 and 182/333 (54.6%) in the risk category of 1:201 to 1:400. The follow-up is not yet complete, but there is already good evidence for the efficiency of the screening program. Triple-marker screening also proved predictive in 10 cases of trisomy 18 and 8 cases of triploidy in this series. As a cut-off value we chose the risk of 1:386 which is equivalent to the odds of a 35 year old to have a child with Down's syndrome at birth.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Distal limb deficiency following chorionic villus sampling?

We have reviewed the follow-up of almost 3000 completed pregnancies in the Münster CVS Program and identified 4 children with distal limb deficiencies. Two cases involved only minor anomalies of distal digital phalanges. One child had a Hanhart anomaly (hypoglossia hypodactylia). We also reviewed 24 cases of limb defects following CVS reported previously. With the exception of a single series, neither the overall incidence of affected children nor cases reported from larger series provide unambiguous evidence of an increased risk of distal limb deficiency caused by CVS.

Child, Preschool↗
PubMed1991

[Prenatal chromosome findings in sonographically conspicuous fetuses].

A retrospective evaluation of 463 prenatal chromosome analyses in a total of 375 patients with suspicious ultrasound findings, revealed a high rate of severe chromosomal abnormalities (16%). The highest risk for an abnormal karyotype was found after sonographic detection of hygroma colli. Abnormal chromosome counts were also frequently found in fetuses with omphaloceles, duodenal atresia and hydrops fetalis, as well as in presence of intrauterine growth retardation and/or anomalies of the amniotic fluid volume. The anomalies mentioned above are, therefore, an urgent indication for a prenatal chromosome analysis. The technical improvements of ultrasound machines and growing experience of operators will lead to an increasing importance of sonography as a method for the identification of pregnancies, that are at high risk for chromosomal abnormalities.

Adolescent↗
PubMed1991

[Prenatal diagnosis with chorionic villi and placenta puncture biopsy in the 1st to 3d trimester of pregnancy: diagnostic value of chromosome studies].

Chorionic villus sampling and placental biopsies became established diagnostic alternatives to amniocentesis worldwide during the 80's. Safety and accuracy are the most important criteria for the evaluation of these newer techniques as compared to amniocentesis. We report on our experience with more than 3400 chromosome analyses between 1985 and 1990 from first to third trimester of pregnancy in a single centre. Most obvious is the higher frequency of mosaicism, which is often, but not always confined to the placenta. Mosaicism accounts for the overwhelming majority of all discrepant (so-called false negative or false positive) cytogenetic findings. The most important prerequisites for diagnostic accuracy of chromosome analyses are meticulous separation of villi immediately after the sampling procedure as well as simultaneous use of direct preparation and cell culture. If mosaicism is not taken as sound evidence for foetal aneuploidy, the accuracy of cytogenetic diagnoses after chorionic villus sampling and placental biopsies is in the same range as the one after amniocentesis.

Adult↗
PubMed1990

'Late CVS' international registry compilation of data from 24 centres.

Data on 2058 late CVS cases, i.e., placental biopsies after 12 completed weeks of pregnancy, were collected from 24 centres. Two major groups of indications with or without ultrasound findings suspicious of fetal chromosomal abnormalities can be differentiated. In the first group, the rates of cytogenetic anomalies (21 per cent) and fetal losses (10 per cent) are high. The respective figures for the low-risk group are 6 per cent for chromosome anomalies and 2 per cent for total fetal losses. To evaluate this rapidly spreading new method further, more data are required and will be collected by the CVS registry based in Philadelphia, U.S.A.

Chorionic Villi Sampling↗
PubMed1990

Acoustic power measurements of Doppler ultrasound devices used for perinatal and infant examinations.

Acoustic power output levels were measured in four different pulsed Doppler systems (transcranial, Duplex mode, colour mode, miniature for continuous monitoring) currently used for examination of fetal and infant blood flow velocities. The frequencies of the transducers ranged from 2 to 8 MHz. The devices were studied at three to five different intensity settings. The measurements were performed using the radiation force balance of the Fraunhofer-Institut, which was especially adapted for this study. Each of the four devices was tested while running in its commonly used mode, and comparison showed that their acoustic power values varied widely: 96.8 mW (2 MHz, EME TC2-64B), 8.7 mW (5 MHz, ATL Mk 500), 61.9 mW (3.5 MHz, Acuson 128) and 13.5 mW (5 MHz, HP 77020). All transducers had total power output levels below the limits recommended by the American Institute for Ultrasound in Medicine and Biology in the conclusions on a thermal bioeffects mechanism, which were approved in October 1987.

Acoustics↗