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Rüdiger Lehmann

Publications and source records attributed to Rüdiger Lehmann.

12 recordsLinked to original sources
PubMed2006

DNA sequence and analysis of human chromosome 8.

The International Human Genome Sequencing Consortium (IHGSC) recently completed a sequence of the human genome. As part of this project, we have focused on chromosome 8. Although some chromosomes exhibit extreme characteristics in terms of length, gene content, repeat content and fraction segmentally duplicated, chromosome 8 is distinctly typical in character, being very close to the genome median in each of these aspects. This work describes a finished sequence and gene catalogue for the chromosome, which represents just over 5% of the euchromatic human genome. A unique feature of the chromosome is a vast region of approximately 15 megabases on distal 8p that appears to have a strikingly high mutation rate, which has accelerated in the hominids relative to other sequenced mammals. This fast-evolving region contains a number of genes related to innate immunity and the nervous system, including loci that appear to be under positive selection--these include the major defensin (DEF) gene cluster and MCPH1, a gene that may have contributed to the evolution of expanded brain size in the great apes. The data from chromosome 8 should allow a better understanding of both normal and disease biology and genome evolution.

Animals↗
PubMed2005

GenColors: accelerated comparative analysis and annotation of prokaryotic genomes at various stages of completeness.

SUMMARY: GenColors is a new web-based software/database system aimed at an improved and accelerated annotation of prokaryotic genomes, considering information on related genomes and making extensive use of genome comparison. It offers a seamless integration of data from ongoing sequencing projects and annotated genomic sequences obtained from GenBank. The genome comparison tools determine, for example, best-bidirectional hits, gene conservation, syntenies and gene core sets. Swiss-Prot/TrEMBL hits allow annotations in an effective manner. To further support the annotation base-specific quality data can also be displayed if available. With GenColors dedicated genome browsers containing a group of related genomes can be easily set up and maintained. It has been efficiently used for Borrelia garinii and is currently applied to various ongoing genome projects. AVAILABILITY: Detailed information on GenColors is available at http://gencolors.imb-jena.de. Online usage of GenColors-based genome browsers is the preferred application mode. The system is also available upon request for local installation.

Borrelia↗
PubMed2005

DictyMOLD-a Dictyostelium discoideum genome browser database.

UNLABELLED: With the Dictyostelium Genome Project nearing completion, we initiated the construction of a data repository for all Dictyostelium discoideum genomic data. Up to now this database, called DictyMOLD (Dicty Map Of Linked Data), incorporates the recently completed D.discoideum chromosomes 1 and 2 sequences together with related annotations. To visualise maps, sequences and annotations and to provide access for the scientific community a perl-based browser was developed. AVAILABILITY: The DictyMOLD database is freely accessible via http://genome.imb-jena.de/dictyostelium/ CONTACT: gernot@imb-jena.de.

Animals↗
PubMed2005

Gene organization features in A/T-rich organisms.

Several species have genomes in which the four nucleotides are not equally represented (Glöckner 2000). Interestingly, shifts to very high A/T or G/C levels can occur in several distinct branches of the tree of life. The underlying reasons for these shifts therefore may be of different origin. Now entire chromosome sequences from two different A/T-rich genomes, Dictyostelium discoideum and Plasmodium falciparum, are available (Bowman et al. 1999; Gardner et al. 2002; Glöckner et al. 2002). This gives us the opportunity to investigate how a high A/T content may influence the signals that are the landmarks for gene specification. We found that, in contrast with most known metazoan and plant genomes, splice signals contain, little information other than the canonical GT-AG dinucleotides. Intron lengths in A/T rich organisms, on the other hand, are comparable to those of other lower eukaryotes. Intergenic regions show, dependent on the orientation of adjacent genes, a size pattern with a ratio of 1 (3'-3') to 2 (3'-5') to 3 (5'-5'). Overall, gene organization patterns seem not to be influenced by the A/T bias. Surprisingly, the slightly higher A/T content of the P. falciparum genome compared to that of D. discoideum (80.1 versus 77.4%) is not achieved by increased A/T richness in intergenic regions. Instead both the shift of the nucleotide usage in coding regions to A/T-rich codons and the longer intergenic regions make an equal contribution to the higher A/T content in this organism.

AT Rich Sequence↗
PubMed2004

Doppler sonographic evaluation of shunts in patients with dural arteriovenous fistulas.

BACKGROUND AND PURPOSE: Doppler sonography has been used to assess global cerebral circulation time (CCT) in healthy volunteers and a small number of patients with cerebral arteriovenous malformations. We evaluated the effect of arteriovenous shunts on global CCT in patients with dural arteriovenous fistulas (DAVFs) by using this Doppler echo contrast-bolus tracking test. METHODS: We measured CCT as the time delay in a contrast bolus to the internal carotid artery (ICA) and internal jugular vein (IJV) in 13 patients with DAVF and 30 age-matched control subjects. Mean CCT and mean arterial and venous rise times (Delta t = 80% of total signal-intensity increase) were compared. Posttreatment follow-up measurements were performed in five patients. RESULTS: Mean CCT and venous Delta t were significantly different between patients and controls (CCT, 1.1 +/- 0.9 vs 6.9 +/- 1.2 seconds, P <.0001; venous Delta t, 5.2 +/- 2.0 vs 7.0 +/- 2.6 seconds, P =.024), but arterial Delta t values were not (4.4 +/- 1.8 vs 4.7 +/- 2.0 seconds). Posttreatment follow-up of two occluded fistulas showed CCT normalization. One near-occlusion showed a two-step increase in signal intensity, and incomplete occlusion in two patients left the CCT unchanged. One patient with an extracranial, highly vascularized glomus tumor draining into the IJV had a CCT of 1.8 seconds. CONCLUSION: In DAVF patients, sonographic CCT is significantly shortened. Our test is highly sensitive for arteriovenous shunts but not specific for DAVF alone. Follow-up measurements in DAVF patients are well correlated with results of angiographic treatment. CCT assessment might become an additional tool for evaluating these patients and monitoring their treatment.

Adult↗
PubMed2003

Two brothers with findings resembling congenital intrauterine infection-like syndrome (pseudo-TORCH syndrome).

Clinical, pathological, and X-ray findings of two brothers with features resembling congenital intrauterine infection-like syndrome are presented. Extensive screening for intrauterine infection was performed. Nevertheless all confirmatory tests were normal. Both brothers showed extensive intra- and extra-cranial calcifications, thrombocytopenia, a septum pellucidum cyst, one-sided paresis of the diaphragm, and metaphyseal changes on X-ray scans resembling intrauterine infection. Within the first days of life, they developed seizures and died from severe cerebral hemorrhage. The MRI scan of the brain showed cerebellar hypoplasia in one of the boys, while the cerebellum had normal size in the other. No indication of a metabolic disorder, especially in calcium metabolism, was identified. Due to the clinical overlap with Hoyeraal-Hreidarsson syndrome, mutations in the DKC1 gene (Xq28) and the hTR gene (RNA component of telomerase on chromosome 3q) have been excluded. The parents are non-consanguineous and further family history was unremarkable. The findings in these boys overlap with features described in congenital intrauterine infection-like syndrome (pseudo-TORCH syndrome).

Abnormalities, Multiple↗
PubMed2003

MR imaging features in Marinesco-Sjögren syndrome: severe cerebellar atrophy is not an obligatory finding.

BACKGROUND AND PURPOSE: Cerebellar atrophy is considered the most prominent neuroradiologic finding in Marinesco-Sjögren syndrome (MSS). Our purpose was to investigate this neuroradiologic feature in a series of patients with MSS. METHODS: Five patients with MSS (age range, 5-19 years) underwent native MR imaging of the brain. The findings were assessed with particular attention to the cerebellum and the supratentorial structures. RESULTS: Only two patients had slight cerebellar atrophy; the cerebellum was normal in size and configuration in the other patients. Additional supratentorial findings were present in some of the patients, with an apparently small anterior pituitary gland in two and the absence of the posterior pituitary bright spot in three of the patients. CONCLUSION: Cerebellar atrophy is not an obligatory finding in MSS, and almost normal cranial MR imaging results are compatible with the diagnosis. Morphologic changes of the pituitary gland seem to be common in patients with MSS and are not associated with endocrine dysfunction.

Adolescent↗
PubMed2002

Sequence and analysis of chromosome 2 of Dictyostelium discoideum.

The genome of the lower eukaryote Dictyostelium discoideum comprises six chromosomes. Here we report the sequence of the largest, chromosome 2, which at 8 megabases (Mb) represents about 25% of the genome. Despite an A + T content of nearly 80%, the chromosome codes for 2,799 predicted protein coding genes and 73 transfer RNA genes. This gene density, about 1 gene per 2.6 kilobases (kb), is surpassed only by Saccharomyces cerevisiae (one per 2 kb) and is similar to that of Schizosaccharomyces pombe (one per 2.5 kb). If we assume that the other chromosomes have a similar gene density, we can expect around 11,000 genes in the D. discoideum genome. A significant number of the genes show higher similarities to genes of vertebrates than to those of other fully sequenced eukaryotes. This analysis strengthens the view that the evolutionary position of D. discoideum is located before the branching of metazoa and fungi but after the divergence of the plant kingdom, placing it close to the base of metazoan evolution.

Animals↗
PubMed2002

Three-dimensional imaging of the inner ear by volume-rendered reconstructions of magnetic resonance data.

OBJECTIVE: To evaluate 3-dimensional inner ear visualization by volume rendering of high-resolution magnetic resonance data in patients with clinically suspected inner ear abnormality. DESIGN: Prospective comparative study of different postprocessing techniques, based on blinded film readings. SETTING: Tertiary referral hospital. SUBJECTS: Fifty patients (17 females and 33 males) aged 1 to 77 years (average age, 42 years) with sensorineural hearing loss, vertigo, and/or tinnitus. INTERVENTION: Postprocessing of magnetic resonance data to inner ear reconstructions by the use of volume rendering as well as maximum-intensity projection; caloric testing by electronystagmography. MAIN OUTCOME MEASURES: Film was read blindly by 4 radiologists using a 5-point parameter scale for image quality and diagnostic value. The assessibility of inner ear subsegments was evaluated. The specificity of volume-rendered reconstructions for detecting semicircular canal obliterations was assessed in a subgroup of 9 patients by caloric testing. The time required for data postprocessing as well as film reading was recorded by means of a stopwatch. RESULTS: Volume-rendered inner ear reconstructions were superior in image quality (P<.001), diagnostic value (P<.001), subsegment inner ear assessment (P<.01 to P<.001), and film reading time (P<.001) compared with maximum-intensity projections. The data postprocessing time was comparable for both techniques. Caloric weakness was noted in all patients assessed by electronystagmography. CONCLUSION: Volume rendering is the postprocessing technique of choice for 3-dimensional inner ear visualization, performing better than maximum-intensity projections with respect to various parameters.

Adolescent↗
PubMed2002

Multislice computed tomographic imaging in temporal bone dysplasia.

OBJECTIVES: To evaluate the impact of multislice computed tomographic (MSCT) imaging, a recently developed computed tomographic technique, on imaging of temporal bone malformations. STUDY DESIGN: Retrospective case review. SETTING: The study was performed at a tertiary referral center. PATIENTS: High-resolution temporal bone studies of 168 consecutive patients were reviewed for various temporal bone malformations. MAIN OUTCOME MEASURES: Visualization of various dysplastic conditions of the temporal bone without the need for supplementary scan procedures or additional imaging techniques. INTERVENTION: MSCT imaging was performed on a scanner with four detector rows by using the following parameters: 120 kV, 50 mA/s, 0.5-mm slice thickness, 0.2-mm reconstruction increment, pitch factor of 0.75, and a field of view of 160 mm. Two-dimensional and three-dimensional image reconstructions were performed subsequent to data transfer to a workstation. In one patient suspected of having a vascular dysplasia, high-resolution MSCT imaging was supplemented by multislice computed tomographic angiography. RESULTS Temporal bone dysplasias were encountered in 28 patients (16.7%), affecting the external auditory canal (n = 15), the middle ear (n = 18), the inner ear (n = 5), and the vascular system (n = 3). All temporal bone dysplasias were visualized by two-dimensional and three-dimensional images of excellent detail resolution. In none of the patients were supplementary computed tomographic scans necessary, except for one patient with evidence of an aberrant course of the internal carotid artery. Multislice computed tomographic angiography obviated the need for invasive diagnostic procedures. CONCLUSION: MSCT imaging of the temporal bone allows for comprehensively assessing various dysplasias through high-quality two-dimensional and three-dimensional image reconstructions.

Adolescent↗
PubMedDate not supplied

Neurofibroma in the mastoid segment of the facial canal.

Neural tissue-derived facial nerve tumours usually present as neurinomas. We describe the extremely rare occurrence of a histologically verified neurofibroma primarily arising in the mastoid segment of the facial canal in a patient not fulfilling diagnostic criteria for neurofibromatosis. The tumour showed evidence of perineural growth into the jugular foramen, as suggested by cross-sectional imaging and intraoperative findings.

Facial Nerve Diseases↗