Search PubMed⌕ Search

Biomedical subjects

N Schumacher

Publications and source records attributed to N Schumacher.

5 recordsLinked to original sources
PubMed2000

Analysis of HeyL expression in wild-type and Notch pathway mutant mouse embryos.

In vertebrates Notch signaling regulates cell fate decisions and boundary formation and it underlies several murine and human diseases. Gene targeting experiments point to key roles of Notch receptors, ligands, modulators and downstream targets in somitogenesis, neurogenesis and vascular development. Here we report the embryonic expression of the hairy-related basic helix-loop-helix gene HeyL in wild-type and Notch pathway mutant mice. We show that HeyL is strongly expressed in the presomitic mesoderm, the somites, the peripheral nervous system and smooth muscle of all arteries. Loss of HeyL expression at the level of nascent somites in Notch1 and Delta-like1 knockout mutants implicates HeyL as a Notch effector during somite formation. Furthermore, HeyL expression in vascular smooth muscle cells and in the thymus strikingly overlaps with that of Notch3, mutations of which underlie the CADASIL vascular disorder.

Animals↗
PubMed1999

A 7.5 Mb sequence-ready PAC contig and gene expression map of human chromosome 11p13-p14.1.

The region p13 of the short arm of human chromosome 11 has been studied intensely during the search for genes involved in the etiology of the Wilms' tumor, aniridia, genitourinary abnormalities, mental retardation (WAGR) syndrome, and related conditions. The gene map for this region is far from being complete, however, strengthening the need for additional gene identification efforts. We describe the extension of an existing contig map with P1-derived artificial chromosomes (PACs) to cover 7.5 Mb of 11p13-14.1. The extended sequence-ready contig was established by end probe walking and fingerprinting and consists of 201 PAC clones. Utilizing bins defined by overlapping PACs, we generated a detailed gene map containing 20 genes as well as 22 anonymous ESTs which have been identified by searching the RH databases. RH maps and our established gene map show global correlation, but the limits of resolution of the current RH panels are evident at this scale. Initial expression studies on the novel genes have been performed by Northern blot analyses. To extend these expression profiles, corresponding mouse cDNA clones were identified by database search and employed for Northern blot analyses and RNA in situ hybridizations to mouse embryo sections. Genomic sequencing of clones along a minimal tiling path through the contig is currently under way and will facilitate these expression studies by in silico gene identification approaches.

Animals↗
PubMed1998

Normal values for fundus perimetry with the scanning laser ophthalmoscope.

PURPOSE: To evaluate the normal light sensitivity values for fundus perimetry and their short time fluctuation (reliability) in normal volunteers of different ages. After the development of full-threshold static fundus perimetry, age-corrected sensitivity values for normal subjects are required to interpret results and to compare them with conventional computerized perimetry. METHOD: Full-threshold fundus perimetry of the central field (33 x 21 degrees) by means of the scanning laser ophthalmoscope was performed on 152 eyes of 99 healthy persons aged 16 to 77 years with normal vision and no eye disease. Fixation was simultaneously documented. Light sensitivity values were evaluated according to each subject's age and test point location. RESULTS: Linear regression analysis disclosed a significant (P < .0001) decrease of the mean sensitivity of 0.275 dB per decade of increasing age, starting with 16.6 dB at age 10 years. Standard deviation around the center of fixation was 0.287 degrees in the first decade, and it increased by 2.82 minutes of arc per decade (P < .0001). Variation in triple examinations of subjects did not differ from short time fluctuation. CONCLUSION: Visual fields examined with fundus perimetry show reliable measurements in a range comparable to conventional computerized perimetry. There is a significant correlation between increase of age and decrease of light sensitivity in fundus perimetry. Visual fields obtained with fundus perimetry seem to correlate well with known data from computerized static threshold perimetry. It should be recognized that even in normal subjects, the stability of fixation decreases with increasing age.

Adolescent↗