Search PubMed⌕ Search

Biomedical subjects

U Sancken

Publications and source records attributed to U Sancken.

13 recordsLinked to original sources
PubMed2003

Characterization, expression pattern and chromosomal localization of the spermatogenesis associated 6 gene (Spata6).

We report the cloning and characterization of the spermatogenesis associated 6 gene (Spata6) encoding a predicted protein of 488 amino acids. It exhibits similarity with the motor domain of kinesin related proteins and with the Caenorhabditis elegans neural calcium sensor protein (NCS-2). The gene encodes three mRNAs of approximately 2.6, approximately 1.8 and approximately 1.2 kb. The expression of the 2.6 kb mRNA is detected at low levels in testis, ovary, thymus and placenta, while the 1.8 and 1.2 kb transcripts are exclusively expressed in testis. The 1.8 and 1.2 kb transcripts are specifically expressed in haploid germ cells. Data from in situ hybridization experiments suggested that mRNA expression of Spata6 in spermatids is higher than in spermatocytes and spermatogonia. RT-PCR analysis and whole mount in situ hybridization demonstrate that the Spata6 transcript is expressed during embryonic development and is localized in neural tube, somites and limb buds of mouse embryo. The Spata6 gene consists of 15 exons ranging in size between 40 and 596 bp. The 2.6 and 1.8 kb transcripts have different 5' untranslated sequences but have the same translational initiation site and therefore may encode the same protein with a predicted molecular weight of 49.7 kDa. The 1.2 kb transcript is derived from a proximal promoter between exons 7 and 8, and contains a translation initiation codon AUG, which is in frame with initiator AUG codon of the 2.6 and 1.8 kb transcripts. Therefore, the 1.2 kb transcript may code for a truncated protein of 32 kDa. Western blot analysis with the antiserum raised against a synthetic peptide from the C-terminal of the deduced Spata6 protein detects only a single protein of 53 kDa in all tissues studied. The Spata6 gene was localized to chromosome 5, region q34-35 in the rat and to chromosome 1, region p32-35 in the human. In an effort to determine the function of Spata6, we inactivated the mouse gene in embryonic stem cells through homologous recombination. Although the heterozygous mutant cells were able to generate low coat colour chimeric mice, all chimeras did not transmit the targeted allele to their progeny suggesting that a high contribution of Spata6(+/-) cells lead to the lethality of the chimeric embryos.

Amino Acid Sequence↗
PubMed2003

Synergistic effects of germ cell expressed genes on male fertility in mice.

Over 200 genes have been shown to be associated with infertility in mouse models. However, knockout mice reveal unexpected functional redundancy of some germ cell expressed genes. Single null mutations in mouse genes encoding four male germ cell proteins, transition protein 2 (Tnp2), proacrosin (Acr), histone H1.1 (H1.1), histone H1t (H1t) and sperm mitochondria-associated cysteine-rich protein (Smcp) have been generated and analysed. Tnp2 is believed to participate in the removal of the nuclear histones and initial condensation of the spermatid nucleus. Proacrosin is an acrosomal protease synthesized as a proenzyme and activated into acrosin during the acrosome reaction. The linker histone subtype H1.1 belongs to the group of main-type histones and is synthesized in somatic tissues as well as in germ cells during the S-phase of the cell cycle. The histone gene Hist1h1t is expressed exclusively in spermatocytes and may have a function in establishing an open chromatin structure for the replacement of histones by transition proteins and protamines. Sperm mitochondria-associated cysteine-rich protein (Smcp) is a major structural element of the mitochondria in the midpiece of the sperm tail. Male mutant mice lacking any of these proteins show no apparent defects in spermatogenesis or fertility. To examine the synergistic effects of these proteins in spermatogenesis and during fertilization four lines of double knockout mice Hist1h1a/Mcsp, Hist1h1t/Mcsp, Tnp2/Mcsp and Acr/Mcsp were established. It was found that even when knockout mice are heterozygous for one allele (-/+) and homozygous for the other allele (-/-), mice were subfertile. Homozygous double knockout mice of all four lines are nearly infertile. However, in the four homozygous double knockout mouse lines, different characteristic abnormalities are prominently manifested: In Hist1h1a-/-/Mcsp-/- the migration of spermatozoa is disturbed in female genital tract, in Hist1h1t-/-/Mcsp-/- spermatozoa show morphological head abnormalities, in Tnp2-/-/Mcsp-/- the motility of sperm is affected, and in Acr-/-/Mcsp-/- the sperm-oocyte interaction is impaired. These findings indicate strongly that male germ cell expressed genes have synergistic effects on male fertility.

Acrosin↗
PubMed2001

Preliminary data on an association between blood groups and serum markers used for the so-called "triple screening": free oestriol MoM values are decreased in rhesus-negative (Rh-) women.

The serum markers human chorionic gonadotrophin (hCG), alpha-fetoprotein (AFP) and unconjugated oestriol (uE3) in 606 rhesus-negative (Rh-) women have been compared with 18 960 controls. There were no significant differences in the distribution of hCG and AFP between these two cohorts. However the uE3 values in Rh- women were significantly lowered (median: 0.85 MoM).

Biomarkers↗
PubMed2001

Biochemical screening for chromosomal disorders and neural tube defects (NTD): is adjustment of maternal alpha-fetoprotein (AFP) still appropriate in insulin-dependent diabetes mellitus (IDDM)?

Maternal serum alpha-fetoprotein (AFP) has been reported to be decreased in insulin-dependent diabetes mellitus (IDDM). The objective of the present study was to reinvestigate this finding in detail. Maternal serum levels of AFP, human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) in 114 diabetic women, of whom 84 had IDDM, were compared to those of 19,251 control pregnancies in the second trimester (15th to 20th gestational weeks). The mean body weight at the date of sampling was 73.7 kg in all diabetic women, 72.7 kg in women with IDDM and 68.3 kg in non-diabetic women, respectively. Body weights were significantly (p < 0.001) elevated in all diabetic pregnancies. Using weight-adjusted MoM (multiple of the median) values no statistical difference of serum levels in diabetic and non-diabetic pregnant women was found. Median MoM levels were 1.01 (hCG), 1.01 (uE3), 1.06 (AFP) in all diabetic women, and 0.95 (hCG), 0.96 (uE3), 0.96 (AFP) in women with IDDM, respectively. Ignoring adjustment for maternal weight leads to a reduction of all serum parameters in diabetic pregnancies. However, median MoM values of all three analytes are not statistically different when compared to non-diabetic pregnancies. This finding is contrary to the results of former studies from the 1970s and 1980s. It is concluded that progress in insulin adjustment and blood glucose surveillance of diabetic patients on the whole has balanced out serum levels. Therefore adjustment of serum AFP values for diabetic status no longer seems reasonable.

Adult↗
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↗
PubMed1995

The effect of thermal instability of intact human chorionic gonadotropin (ihCG) on the application of its free beta-subunit (free beta hCG) as a serum marker in Down syndrome screening.

The kinetics of free beta hCG concentrations were measured in 30 maternal whole blood samples from second-trimester pregnancies during 72 h incubation at 3, 20, and 30 degrees C. Dissociation of intact hCG (ihCG) was undetectable at 3 degrees C and produced a more than 20 per cent increase of free beta hCG at 20 degrees C and a more than 100 per cent increase at 30 degrees C. hCG dissociation at 30 degrees C was not reduced by a protease inhibitor (sodium iodoacetate) and also occurred in purified hCG dissolved in a protease-free incubation medium. These results were reproduced under conditions of sample transport by post at different environmental temperatures. In conclusion, reliable free beta hCG assessment requires that the specimen be kept cool from vene puncture until assay or completely other transport strategies have to be considered. Evaluation of free beta hCG as an effective marker in prenatal Down syndrome screening must be reconsidered from this aspect.

Blood Specimen Collection↗
PubMed1994

Prenatal detection of X-linked ichthyosis by maternal serum screening for Down syndrome.

Maternal serum unconjugated oestriol (uE3) was measured in 15,375 pregnancies during 2 years of second-trimester risk assessment for Down syndrome using biochemical markers. Very low levels of uE3 (< 0.1 MOM) were detected in 22 serum samples (0.14 per cent). Very low uE3 was associated with an adverse outcome in 13 pregnancies including fetal death and miscarriage (N = 11) anencephaly (N = 1), and Meckel-Gruber syndrome (N = 1). Dry scales on the skin appeared in the first year of life in four boys. From dermatological diagnosis, prenatal uE3 levels, and pedigree analysis, it is concluded that at least 5 in approximately 7500 male births in the study population are affected by steroid sulphatase deficiency, which is the biochemical defect in X-linked ichthyosis. Very low uE3 levels in the second trimester are indicative of this disease in pregnancies with normal ultrasound findings.

Down Syndrome↗
PubMed1994

[Prenatal risk index for fetal Down's syndrome with serum markers. Comment on the contribution by R. Benz, U. Müller, M. Krahner-Pilat, S. Wagner-Geuder, R. Terinde: Serum screening for Down's syndrome in women less than 35 years of age with an age-independent index].

5 years ago, maternal serum markers have been established for individual risk estimation of fetal Down syndrome. Recently Benz et al. presented an arbitrary age-independent risk index. Compared to the commonly applied statistical approach a 20% increase in detection rate was obtained by using the index (85% versus 65%). We recalculated data from 19,333 prospectively investigated pregnancies without trisomy 21 and 57 pregnancies with fetal Down syndrome using the proposed risk index. At the corresponding false-positive rate (7.9%) the age-independent detection rate was only 56%. This result indicates that the sensitivity cannot be increased by the Ulm index, when compared to statistical methods of risk estimation.

Biomarkers↗
PubMed1992

[Martin-Bell syndrome. Improved possibilities for molecular genetic diagnosis].

In a former molecular segregation analysis of fra x mental retardation in 27 families at risk we had used marker gene probes with a relatively high recombination fraction. Thus, the resulting risk for a false diagnosis was comparatively high. To diminish this risk, all families were reanalyzed with the newly invented and more closely linked gene probes RN1A, VK23B, VK21C and U6.2. Using these probes as molecular markers we performed Southern hybridization experiments. The remaining diagnostic risk due to recombination events could be reduced to 2% up to 20% compared to preanalysis. The portion of informative families (91%) is in good agreement with the expected cumulative heterozygosis frequency of 93.4% for all 4 markers investigated. This high frequency and the very low remaining risk for a false diagnosis therefore enable a far more precise molecular diagnostic of the Martin-Bell-syndrome.

Abnormalities, Multiple↗
PubMedDate not supplied

Maternal serum placental growth hormone and insulinlike growth factor binding proteins 1 and 3 in pregnancies affected by fetal aneuploidy and other abnormalities: implications for prenatal diagnosis of trisomy 21.

In the present study, we determined circulating serum levels of human placental growth hormone (hPGH) and insulinlike growth factor binding proteins 1 and 3 (IGFBP-1 and IGFBP-3) using two-site radioimmunoassays during the gestational midtrimester of pregnancies affected by chromosomal disorders with the aim of identifying potential marker substances that might have a significant discriminative and predictive value for prenatal diagnosis of fetal chromosomal aberrations and of organ malformations such as neural-tube defect. Our results show that the maternal serum levels of hPGH were significantly elevated in pregnancies affected by chromosomal anomalies or organ malformations as compared with controls. The distribution of IGFBP-1 concentrations for all experimental groups except trisomy 21 were closely similar to the normal population. IGFBP-3 decreased slightly in pregnancies affected by Down syndrome. These findings suggest that hPGH may be useful as an additional marker in prenatal screening for Down syndrome.

Adolescent↗
PubMedDate not supplied

Comparison of triple-risk assessment of fetal trisomy 21 including total human choriogonadotropin (hCG) or its free beta-subunit (free beta hCG).

OBJECTIVE: Second trimester total hCG and free betahCG levels in maternal serum samples of 33 pregnancies affected by fetal trisomy 21 and of 188 matched controls were compared in a retrospective study. To find out differences of discriminating efficacy by using one of these markers a multivariate discriminant analysis was performed. METHOD: Statistical evaluation was performed for hCG/free betahCG frequency distributions. Discriminant analysis was carried out using the status 'affected' or 'unaffected' as the group variable and the serum markers unconjugated estriol (uE3), alpha-fetoprotein (AFP), and alternatively, hCG or free betahCG, as discriminant variables. RESULTS: The median of free betahCG MoM values in affected pregnancies was slightly higher (1.90 MoM) than the median of total hCG MoM values (1.72 MoM) but a lower standard deviation was stated for the logarithmic hCG MoM values (SD = 0.49) compared with free betahCG MoM values (SD = 0.51). A two-tailed Student's t test revealed no significant differences of hCG and free betahCG MoM values in both the affected and unaffected pregnancies. By inclusion of free betahCG the discriminant analysis classified 26 out of 33 affected cases correctly and 45 out of 188 unaffected cases incorrectly. For the inclusion of hCG these ratios were 25/33 and 41/188, respectively. Taking in account the individual maternal age risks at a defined false-positive rate of 5% including free betahCG yielded a higher detection rate than including hCG. However, using 1:380 (age-related at-term risk of a 35-year-old woman) as a cut-off risk including hCG yielded a higher detection rate than including free betahCG. CONCLUSION: For the observed cases none of the markers, hCG or free betahCG, was superior in Down syndrome screening.

Adult↗