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Biomedical subjects

H Voss

Publications and source records attributed to H Voss.

At least 19 recordsLinked to original sources
PubMed2005

["The fungal jungle". Medical mycology on the Internet].

The World Wide Web offers an enormous variety of information about medical mycology. To go through the "fungal jungle" and find the website containing the information that is needed requires a great deal of effort and a lot of time. This article provides help in finding information about medical mycology and describes the contents of preselected websites in German and English. These pages address physicians, scientists, and students interested in dermato-mycology. Most of the pages also contain information about mycoses relevant to other medical specialties.

Databases, Bibliographic↗
PubMed2001

Comparative genomics of Listeria species.

Listeria monocytogenes is a food-borne pathogen with a high mortality rate that has also emerged as a paradigm for intracellular parasitism. We present and compare the genome sequences of L. monocytogenes (2,944,528 base pairs) and a nonpathogenic species, L. innocua (3,011,209 base pairs). We found a large number of predicted genes encoding surface and secreted proteins, transporters, and transcriptional regulators, consistent with the ability of both species to adapt to diverse environments. The presence of 270 L. monocytogenes and 149 L. innocua strain-specific genes (clustered in 100 and 63 islets, respectively) suggests that virulence in Listeria results from multiple gene acquisition and deletion events.

Adaptation, Physiological↗
PubMed2000

Sequence and analysis of chromosome 3 of the plant Arabidopsis thaliana.

Arabidopsis thaliana is an important model system for plant biologists. In 1996 an international collaboration (the Arabidopsis Genome Initiative) was formed to sequence the whole genome of Arabidopsis and in 1999 the sequence of the first two chromosomes was reported. The sequence of the last three chromosomes and an analysis of the whole genome are reported in this issue. Here we present the sequence of chromosome 3, organized into four sequence segments (contigs). The two largest (13.5 and 9.2 Mb) correspond to the top (long) and the bottom (short) arms of chromosome 3, and the two small contigs are located in the genetically defined centromere. This chromosome encodes 5,220 of the roughly 25,500 predicted protein-coding genes in the genome. About 20% of the predicted proteins have significant homology to proteins in eukaryotic genomes for which the complete sequence is available, pointing to important conserved cellular functions among eukaryotes.

Arabidopsis↗
PubMed2000

Two long homologous retroviral sequence blocks in proximal Yq11 cause AZFa microdeletions as a result of intrachromosomal recombination events.

We mapped the breakpoints of the AZoospermia factor a (AZFa) microdeletion located in proximal Yq11 in six men with complete germ cell aplasia, i.e. Sertoli Cell Only syndrome (SCO). The proximal breakpoints were identified in a long retroviral sequence block (HERV15yq1: 9747 nucleotides) at the 5' end of the DYS11 DNA locus in Yq11, interval D3. The distal breakpoints were found in a homologous HERV15 sequence block mapped to the Yq11 interval D6, i.e. in the distal part of the AZFa region (HERV15yq2: 9969 nucleotides). Compared with the HERV15yq1 sequence, HERV15yq2 is marked by a deletion of a HERV15 sequence domain at its 5' end and insertion of an LINE 1 3'-UTR sequence block (L1PA4) of similar length at its 3' end. The deletion of the L1PA4 element was recognized as the molecular origin of the DYS11 12f2 restriction fragment length polymorphism. For all six AZFa patients it was possible to perform PCR experiments bridging both retroviral sequence blocks, which map in a distance of 781.557 kb in proximal Yq11 in fertile men. The AZFa breakpoint-fusion regions were located in their recombined HERV15yq1/HERV15yq2 sequence blocks in either one of two long identical sequence domains (ID1 and ID2). We therefore assume that intrachromosomal recombination events between the two homologous retroviral sequence blocks in proximal Yq11 are probably the causative agents for most of the AZFa microdeletions observed in men with SCO syndrome. A mean value of 792 kb was estimated for their molecular lengths.

Endogenous Retroviruses↗
PubMed2000

Optimization of the hydroxylation of 2-cyclopentylbenzoxazole with Cunninghamella blakesleeana DSMZ 1906.

Biohydroxylation of 2-cyclopentyl-1,3-benzoxazole with the filamentous fungus Cunninghamella blakesleeana DSMZ 1906 was studied in a 15-l stirred tank reactor. The aim of the work was to avoid substrate limitation through sub-optimal mixing by formation of pellets with a uniform pellet size distribution of 250-500 microm, obtained at an inoculum concentration of 10(7) spores ml(-1) and an agitation rate of 390 rpm. Due to the high toxicity of the educt, 2-cyclopentyl-1,3-benzoxazole, on the fungus, the medium composition, the time of educt addition, and the educt starting concentration were optimized to reach high educt tolerance and hydroxylation activity. A good maintenance of biotransformation capacity was obtained without excessive loss of activity of the biocatalyst by addition of 30 mg 2-cyclopentyl-1,3-benzoxazole/g biomass (cell dry mass) during the stationary phase in a medium which was optimized in batch fermentations with experimental designs. An increase in product yield and quality (enantiomeric excess) was achieved by developing feeding strategies combining the educt and medium components. The resulting fermentation broth contained 450 mg l(-1) of the product (1S,3S)-3-(benz-1,3-oxazol-2-yl)cyclopentan-1-ol with an enantiomeric excess of 95%, which represents a 48% increase over former reported results.

Benzoxazoles↗
PubMed1999

Cognitive processing is involved in cluster headache but not in chronic paroxysmal hemicrania.

BACKGROUND: Cognitive processing in migraine is characterized by a loss of habituation during the interval and increased latencies in an attack. No studies are available on event-related potentials (ERPs) in cluster headache or chronic paroxysmal hemicrania. OBJECTIVE: To determine the involvement of cognitive processing in cluster headache and chronic paroxysmal hemicrania as measured by ERPs. METHODS: Visually evoked ERPs were measured in 50 patients with episodic cluster headache, 11 patients with chronic cluster headache, and 12 patients with chronic paroxysmal hemicrania. Measurements were performed in the cluster period outside an attack with and without prophylactic medication and not in the cluster period. RESULTS: Latencies of the endogenous ERP components were significantly increased during the cluster period as compared with outside the cluster period and with healthy subjects. In chronic cluster headache, latencies of both endogenous and exogenous components were increased. Medication with prophylactic drugs normalized the ERP latencies in episodic cluster headache; in chronic cluster headache, ERP latencies were decreased without complete normalization. No changes of ERP latencies and amplitudes could be observed in chronic paroxysmal hemicrania. A loss of cognitive habituation as it is known in migraine could not be observed in either cluster headache or chronic paroxysmal hemicrania. CONCLUSIONS: Our data suggest that central structures generating ERPs are involved in the pathophysiology of cluster headache during the cluster period but not outside the cluster period. This is in concordance with recent neuroimaging findings on the central role of the hypothalamus and the right frontal cortex in cluster headache and supports the hypothesis of a central origin of cluster headache. Furthermore, the data suggest that cluster headache and chronic paroxysmal hemicrania are distinct entities.

Adult↗
PubMed1999

The impact of ergotamine-induced headache and ergotamine withdrawal on information processing.

Ergotamine abuse and subsequent ergotamine-induced headache is a common problem in the pharmacological treatment of migraine and other headache types; often, withdrawal therapy is necessary. This study investigated whether ergotamine abuse affects information processing and whether withdrawal therapy can lead to an improvement of information processing. We designed a standardized neurophysiological retrospective (ergotamine abuse) and prospective (ergotamine withdrawal) study in a supraregional headache outpatient clinic. Seventy-one patients abusing ergotamine derivatives with subsequent daily headache were enrolled and compared to 36 migraine patients without ergotamine intake and 36 healthy subjects. Information processing was evaluated by latencies and amplitudes of visually evoked event-related potentials (ERP) before and after ergotamine withdrawal therapy. P3 latency of the ERP was significantly increased in ergotamine abuse (442 +/- 45 ms) versus migraine (415 +/- 40 ms) and healthy subjects (410 +/- 33 ms), there was no difference between ergotamine tartrate and dihydroergotamine abuse. The migraine specific loss of habituation in information processing as measured by P3 latency could not be observed in migraine patients with ergotamine abuse. After successful withdrawal therapy in 36 patients, the abnormally prolonged P3 latency was significantly shortened (452 +/- 47 ms versus 433 +/- 30 ms; P < 0.004). Our findings imply that information processing is impaired by ergotamine abuse and can be improved but not normalized after withdrawal therapy. Furthermore, our data provide strong evidence that ergotamine, besides its peripheral effects, has a central mode of action.

Adrenergic alpha-Agonists↗
PubMed1998

Genomic organization and promoter identification of the human protein kinase CK2 catalytic subunit alpha (CSNK2A1).

The isolation and characterization of the complete gene coding for human protein kinase CK2 catalytic subunit alpha is described. The gene spans 70 kb and consists of 13 exons, and the exon/intron boundaries conform to the gt/ag rule. Exons range in size from 51 to 2960 bp, introns from 527 to around 34000 bp. The translation start site is located in Exon 2, the stop codon in Exon 13. Two transcription start sites were identified by primer extension analysis: The further 5'-located site defines position 1 of the gene, the second site is located at position 50. The 5' region of the CK2 alpha gene shows features of a housekeeping promoter, such as lack of a TATA box and presence of a CpG island and GC boxes. The region was analyzed by reporter gene assay, and promoter activity was detected within the region ranging from position -256 to 144. Six potential polyadenylation signals were identified in the 3' noncoding region of the CK2 alpha gene. As indicated by comparison with expressed sequence tags from the EMBL databank and by Northern-blot analysis, the most 3' located, active polyadenylation signal seems to be the fourth signal, defining the end of the gene.

Base Sequence↗
PubMed1998

Peripheral autonomic potentials in primary headache and drug-induced headache.

Autonomic functions of different primary headache types have been investigated in several studies, most of them analyzing cardiovascular reflex mechanisms or biochemical changes. The results are contradictory; only in tension-type headache and in cluster headache has a sympathetic hypofunction been shown in a preponderance of studies. We analyzed the peripheral autonomous potentials (PAPs) in different primary headache types and in drug-induced headache and compared the results with those of healthy subjects and of patients with low back pain. Latencies of PAPs were significantly increased in all headache types but not in low back pain; amplitudes of PAPs did not show significant differences compared to healthy subjects. Patients with a long duration of drug abuse had increased PAP latencies, whereas patients with a high number of migraine attacks per year had decreased latencies. Our data suggest that sympathetic hypofunction as measured by PAP latencies is a general phenomenon in headache but not in all pain syndromes. Drug abuse leads to an increase of this hypofunction. While measuring PAPs is not an appropriate method by which to differentiate between headache disorders, it allows assessment of autonomic disturbances in primary and drug-induced headache.

Adult↗
PubMed1998

A chimeric subunit of yeast transcription factor IIIC forms a subcomplex with tau95.

The multisubunit yeast transcription factor IIIC (TFIIIC) is a multifunctional protein required for promoter recognition, transcription factor IIIB recruitment, and chromatin antirepression. We report the isolation and characterization of TFC7, an essential gene encoding the 55-kDa polypeptide, tau55, present in affinity-purified TFIIIC. tau55 is a chimeric protein generated by an ancient chromosomal rearrangement. Its C-terminal half is essential for cell viability and sufficient to ensure TFIIIC function in DNA binding and transcription assays. The N-terminal half is nonessential and highly similar to a putative yeast protein encoded on another chromosome and to a cyanobacterial protein of unknown function. Partial deletions of the N-terminal domain impaired tau55 function at a high temperature or in media containing glycerol or ethanol, suggesting a link between PolIII transcription and metabolic pathways. Interestingly, tau55 was found, together with TFIIIC subunit tau95, in a protein complex which was distinct from TFIIIC and which may play a role in the regulation of PolIII transcription, possibly in relation to cell metabolism.

Amino Acid Sequence↗
PubMed1998

Characterization of SRp46, a novel human SR splicing factor encoded by a PR264/SC35 retropseudogene.

The highly conserved SR family contains a growing number of phosphoproteins acting as both essential and alternative splicing factors. In this study, we have cloned human genomic and cDNA sequences encoding a novel SR protein designated SRp46. Nucleotide sequence analyses have revealed that the SRp46 gene corresponds to an expressed PR264/SC35 retropseudogene. As a result of mutations and amplifications, the SRp46 protein significantly differs from the PR264/SC35 factor, mainly at the level of its RS domain. Northern and Western blot analyses have established that SRp46 sequences are expressed at different levels in several human cell lines and normal tissues, as well as in simian cells. In contrast, sequences homologous to SRp46 are not present in mice. In vitro splicing studies indicate that the human SRp46 recombinant protein functions as an essential splicing factor in complementing a HeLa cell S100 extract deficient in SR proteins. In addition, complementation analyses performed with beta-globin or adenovirus E1A transcripts and different splicing-deficient extracts have revealed that SRp46 does not display the same activity as PR264/SC35. These results demonstrate, for the first time, that an SR splicing factor, which represents a novel member of the SR family, is encoded by a functional retropseudogene.

3T3 Cells↗
PubMed1998

Doublex sequencing in molecular diagnosis of hereditary diseases.

We describe doublex sequencing of human genomic PCR products using two differently labeled primers in a single reaction and analysis on two automated DNA sequencing devices. Feasibility of the methodology is demonstrated by isothermal and cycle sequencing for two different PCR products and by cycle sequencing on both strands of a single product. It was applied to analyze mutations in patient DNAs in routine sample screening. Because it has the advantage of increased throughput and cost reduction while retaining its accuracy and reading length, we found that doublex sequencing is an attractive option for molecular diagnosis of hereditary diseases. This approach would be even more beneficial if it used DNA sequencing devices with several lasers in a single instrument.

Breast Neoplasms↗
PubMed1997

DNA sequencing and analysis of 130 kb from yeast chromosome XV.

We have determined the nucleotide sequence of 129,524 bases of yeast (Saccharomyces cerevisiae) chromosome XV. Sequence analysis revealed the presence of 59 non-overlapping open reading frames (ORFs) of length > 300 bp, three tRNA genes, four delta elements and one Ty-element. Among the 21 previously known yeast genes (36% of all ORFs in this fragment) were nucleoporin (NUP1), ras protein (RAS1), RNA polymerase III (RPC1) and elongation factor 2 (EF2). Further, 31 ORFs (53% of the total) were found to be homologous to known protein or DNA sequences, or sequence patterns. For seven ORFs (11% of the total) no homology was found. Among the most interesting protein identification in this DNA fragment are an inositol polyphosphatase, the second gene of this type found in yeast (homologous to the human OCRL gene involved in Lowe's syndrome), a new ADP ribosylation factor of the arf6 subfamily, the first protein containing three C2 domains, and an ORF similar to a Bacillus subtilis cell-cycle related protein. For each ORF detailed sequence analysis was carried out, with a full consideration of its biological function and pointing out key regions of interest for further functional analysis.

ADP-Ribosylation Factors↗
PubMed1997

Simultaneous loading of 200 sample lanes for DNA sequencing on vertical and horizontal, standard and ultrathin gels.

We have developed a simple and efficient technique for automated parallel loading of >/=200 lanes on a 30 cm-wide gel in automated DNA sequencing, using porous filter materials and an associated manual or robotic system. The samples are loaded onto the teeth of a comb made of the porous material. The comb, with samples, is inserted directly above the straight edge of the polymerized gel. The samples are driven from the comb into the gel by the applied electrical field. A particularly advantageous aspect of this method is the elimination of the thin gel walls separating the sample wells in the standard gel loading technique. The time for sample loading is significantly reduced to a few minutes. The loading technique is applicable to horizontal or vertical systems, with standard or ultrathin gels.

Electrophoresis↗
PubMed1997

Quantitative trait loci for refractoriness of Anopheles gambiae to Plasmodium cynomolgi B.

The severity of the malaria pandemic in the tropics is aggravated by the ongoing spread of parasite resistance to antimalarial drugs and mosquito resistance to insecticides. A strain of Anopheles gambiae, normally a major vector for human malaria in Africa, can encapsulate and kill the malaria parasites within a melanin-rich capsule in the mosquito midgut. Genetic mapping revealed one major and two minor quantitative trait loci (QTLs) for this encapsulation reaction. Understanding such antiparasite mechanisms in mosquitoes may lead to new strategies for malaria control.

Animals↗
PubMed1997

Oxygen diffusion in tissue preparations with Michaelis-Menten kinetics.

A model is introduced for the oxygen consumption in thin vital tissue preparation. The steady uptake kinetics is modelled by a Michaelis-Menten form and for this case it proved that the resulting boundary value problem admits a unique solution for those parameter ranges typical of related physiological experiments. This solution is compared with Otto Warburg's hyperoxia model and with a hypoxia model. Useful and easily computed approximations are derived for the minimum oxygen supply across the tissue and some numerical solutions of the governing equations are discussed.

Culture Techniques↗
PubMed1997

Automated cycle sequencing with Taquenase: protocols for internal labeling, dye primer and "doublex" simultaneous sequencing.

This paper describes automated cycle sequencing protocols for internal labeling, dye primer and "doublex" simultaneous sequencing using Taquenase, a new genetically modified DNA polymerase with increased thermostability. Sequencing performance both with labeled and unlabeled primer yields uniform unambiguous signals up to the resolution limit of the sequencing gels. Primer walking with internal labeling was successfully performed on Pl-derived artificial chromosome (PAC) constructs with 130-kb inserts. Taquenase, a commercially available modified thermostable sequencing enzyme (delta 280, F667Y Taq DNA polymerase), incorporates a variety of fluorescent dNTPs carrying fluorescein isothiocyanate, TexasRed or Cy5 labels during the cycle-sequencing process with higher efficiency than other thermostable DNA polymerases. Comparison to other modified Taq DNA polymerases suggests that the particular N-terminal deletion of Taquenase rather than the presence of the F667Y mutation is responsible for the efficient incorporation and extension of labeled dNTPs. Taquenase makes feasible highly accurate "doublex" simultaneous cylce sequencing on both strands of template DNA with two internal labels or two dye-labeled primers in combination with the EMBL-2-dye DNA sequencing system, ARAKIS, or with two commercial DNA sequencers. It allows up to 2000 bases at > 99% accuracy to be determined in a single reaction.

DNA↗