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M Kröger

Publications and source records attributed to M Kröger.

At least 19 recordsLinked to original sources
PubMed1999

[Economic effects of integrated RIS-PACS solution in the university environment].

PROBLEM: The goal of the current article is to demonstrate how qualitative and monetary effects resulting from an integrated RIS/PACS installation can be evaluated. METHODS: First of all, the system concept of a RIS/PACS solution for a university hospital is defined and described. Based on this example, a generic method for the evaluation of qualitative and monetary effects as well as associated risks is depicted and demonstrated. To this end, qualitative analyses, investment calculations and risk analysis are employed. RESULTS: The sample analysis of a RIS/PACS solution specially designed for a university hospital demonstrates positive qualitative and monetary effects of the system. Under ideal conditions the payoff time of the investments is reached after 4 years of an assumed 8 years effective life of the system. Furthermore, under conservative assumptions, the risk analysis shows a probability of 0% for realising a negative net present value at the end of the payoff time period. CONCLUSION: It should be pointed out that the positive result of this sample analysis will not necessarily apply to other clinics or hospitals. However, the same methods may be used for the individual evaluation of the qualitative and monetary effects of a RIS/PACS installation in any clinic.

Cost-Benefit Analysis↗
PubMed1998

Compilation of DNA sequences of Escherichia coli K12: description of the interactive databases ECD and ECDC.

We have compiled the DNA sequence data for Escherichia coli K12 available from the GenBank and EMBL data libraries and independently from the literature. We provide the most definitive version of the ECD Escherichia coli database now exclusively via the World Wide Web System (http://susi.bio.uni-giessen.de/ecdc.html ). Our database encloses the completed genome sequence recently published by two competing groups and an assembled set of all elder sequences. The organisation of the database allows precise physical location of each individual gene or regulatory region, even taking into consideration discrepancies in nomenclature. The WWW program allows to the user to branch into the original EMBL and SWISS-PROT datafiles. A number of links to other WWW servers dealing with E. coli is provided. A FASTA and BLAST search may be performed online. Besides the WWW format a flat file version may be obtained via ftp. A number of discrepancies between the two systematic sequence determinations and/or the literature have not yet been resolved. However, our database may serve as a reference source for resolution and/or the assignment of strain difference.

Computer Communication Networks↗
PubMed1997

Cloning, expression and activation of a truncated 92-kDa gelatinase minienzyme.

The matrix metalloproteinases (MMPs) are a family of highly homologous zinc-endopeptidases that degrade extracellular matrix components. Human 92-kDa gelatinase (MMP-9) represents one of the MMPs that cleaves native collagen type IV. As a basis for structural investigations, the short form (catalytic domain, amino acid residues 113-450) of the 92-kDa gelatinase cDNA was cloned and expressed in E. coli as a minienzyme. By combination of reverse transcription (RT) and polymerase chain reaction (PCR), the truncated 92-kDa gelatinase-cDNA was amplified from the corresponding mRNA derived from ovarian carcinoma cells. The cDNA fragment obtained was cloned in E. coli and sequenced. With the exception of one nucleotide inversion at position 745 (gt-->tg) the cDNA sequence was identical to the nucleotide sequence of the 92-kDa gelatinase as has been previously reported. The protein was expressed in E. coli using the vector pET-12b. The recombinant protein was stored in inclusion bodies and extracted as a 38 kDa species from the inclusion bodies by solubilization in 8 M urea. The product was purified by affinity chromatography and gel filtration. Amino-terminal sequence analysis confirmed the identity with the catalytic domain of 92-kDa gelatinase. The recombinant protein was refolded in the presence of Ca2+ and Zn2+ and yielded an active minienzyme with gelatinolytic activity. It degrades the native substrate collagen type IV and the synthetic substrate Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2 x AcOH like the full-length 92-kDa gelatinase. The catalytic activity could be inhibited by the specific MMP inhibitors TIMP-1 and TIMP-2.

Base Sequence↗
PubMed1997

Compilation of DNA sequences of Escherichia coli K12: description of the interactive databases ECD and ECDC (update 1996).

We have compiled the DNA sequence data forEscherichia coliavailable from the GenBank and EMBL data libraries and independently from the literature. We provide the most definitive version of the ECDEscherichia colidatabase now exclusively via the World Wide Web System: http://susi.bio.uni-giessen.de/usr/local/www/ html/ecdc.html . Our database encloses an assembled set of contiguous sequences. Each of these contigs compiles all available sequence information, including those derived from a variety of elder sequences. The organisation of the database allows precise physical location of each individual gene or regulatory region, even taking into consideration discrepancies in nomenclature. The WWW program allows to branch into the original EMBL and SWISSPROT datafiles. A number of links to other WWW servers is provided. A FASTA and BLAST search may be performed online. Besides the WWW format a flat file version may be obtained via ftp. The ftp version may also be obtained from the EMBL data library as part of the CD-ROM issue of the EMBL sequence database, which is released and updated every 3 months. After deletion of all detected overlaps a total of 3 588 706 individual bp has been determined up to the end of September 1996. This corresponds to a total of 77.09% of the entire E.coli chromosome consisting of approximately 4655 kb. About 479 kb (10.3%) are additionally available from Kyoto (Japan). Another 94 kb (2%) are available, but mapping has not been confirmed. Thus the total may have reached 89.4%.

Base Sequence↗
PubMed1996

Compilation of DNA sequences of Escherichia coli K12 (ECD and ECDC; update 1995).

We have compiled the DNA sequence data for Escherichia coli available from the GenBank and EMBL data libraries and independently from the literature. Unlike the previous updates of our E.coli databases, we provide the most recent version preferentially via the World Wide Web System (use URL: http://susi.bio.unigiessen.de/usr/local/www++ +/html/ecdc.html). Our database includes an assembled set of contiguous sequences. Each of these contigs compiles all available sequence information, including those derived from a variety of elder sequences. The organization of the database allows one to find the exact physical location of each individual gene or regulatory region, even regarding discrepancies in nomenclature. The WWW program allows access into the original EMBL and SWISSPROT datafiles. A FASTA and BLAST search may be performed online. Besides the WWW format a flat file version may be obtained via ftp. The complete compilation, including a full set of genetic map data and the E.coli protein index, can be obtained in machine readable form from the EMBL data library as a part of the CD-ROM issue of the EMBL sequence database, released and updated every three months. After deletion of all detected overlaps a total of 3 333 878 individual bp was determined by the end of September 1995. This corresponds to a total of 71.71% of the entire E.coli chromosome consisting of about 4720 kbp. About 94 kbp (2%) are available additionally, but have not yet been definitely mapped.

Base Sequence↗
PubMed1996

Effects of vitamin B12 on performance and circadian rhythm in normal subjects.

This preliminary study investigates effects of methyl- and cyanocobalamin on circadian rhythms, well-being, alertness, and concentration in healthy subjects. Six women (mean age 35 years) and 14 men (mean age 37 years) were randomly assigned to treatment for 14 days with 3 mg cyano-(CB12) or methylcobalamin (MB12) after 9 days of pre-treatment observation. Levels in the CB12 group increased rapidly in the first, then slowly in the second treatment week, whereas increase in the MB12 group was linear. Urinary aMT6s excretion was reduced by both forms of vitamin B12 over 24 hours with a significant decrease between 0700-1100 hours, whereas urinary excretion of potassium was significantly increased between 0700-1100 hours. Activity from 2300-0700 hours increased significantly under both forms of vitamin B12. Sleep time was significantly reduced under MB12 intake. In this group the change in the visual analogue scales items "sleep quality," "concentration," and "feeling refreshed" between pretreatment and the first week of treatment showed significant correlations with vitamin B12 plasma levels. Cortisol excretion and temperature were not affected by either medication. We conclude that vitamin B12 exerts a direct influence on melatonin. Only MB12 has a positive psychotropic alerting effect with a distribution of the sleep-wake cycle toward sleep reduction.

Adult↗
PubMed1995

Evidence for an evolutionary relationship among type-II restriction endonucleases.

Type-II restriction-modification (R-M) systems comprise two enzymes, a DNA methyltransferase (MTase) and a restriction endonuclease (ENase), each of which specifically interact with the same 4-8 bp sequence. All type-II MTases share several amino acid (aa) sequence motifs, which makes an evolutionary relatedness among these enzymes probable. The type-II ENases, in contrast, except for some homologous isoschizomers, do not share significant aa sequence similarity. Therefore, ENases in general have been considered unrelated. Here we show that in addition to the analysis of the genotype (aa sequence), a comparison of the phenotype (recognition sequence) of these enzymes can provide independent information regarding evolutionary relationships, and thereby, help to analyze the significance of weak aa sequence similarities. Multistep Monte-Carlo analyses were employed to demonstrate that the recognition sequences of those ENases, which were found to be related by a progressive multiple aa sequence alignment, are more similar to each other than would be expected by chance. This analysis supports the notion that not only type-II MTases, but also type-II ENases did not arise independently in evolution, but rather evolved from one or a few primordial DNA-modifying and DNA-cleaving enzymes, respectively.

Amino Acid Sequence↗
PubMed1995

Organization and gene expression within restriction-modification systems of Herpetosiphon giganteus.

We have characterized a family of related restriction-modification (R-M) systems from the soil bacterium Herpetosiphon giganteus (Hgi). A comparison of their genetic organization reveals two types of regulatory proteins, called controlling ORF C. While one of these small reading frames derived from RM.HgiCI seems to be an enhancer of its own promoter, evidence is provided for a silencer function of the other ORF C derived from the closely related AvaII-type systems RM.HgiBI/CII/EI. The respective silencer function is detected during our various attempts to clone three isoschizomers with unusually high differences in their specific activity. Sequencing and site-directed mutagenesis revealed just two amino acids as being responsible for a massive increase in specific activity of these endonucleases.

Base Sequence↗
PubMed1995

PCR-directed preparation and single-step purification of highly active histidine-tagged restriction endonuclease HgiBI (GGWCC).

The polymerase chain reaction was used to produce His6 fusion proteins via deletion of an intervening piece of DNA. The generally applicable method was performed using a standard primer with the advantage that the fusion does not produce additional amino acids. In a single-step purification highly purified, enzymatically active restriction endonuclease was obtained.

Amino Acid Sequence↗
PubMed1995

Autoregulation of actin synthesis in hepatocytes by transcriptional and posttranscriptional mechanisms.

Treatment of rat hepatocytes with the filamentous-actin-stabilizing toxin phalloidin decreased the amount of globular actin by 77% in the cytosol and by 80% in the nucleus within 12 h. Simultaneously, actin mRNA was specifically increased by 230%. The de-novo synthesis of actin mRNA, as measured by nuclear run-on transcription, was enhanced by 250%. Treatment of cells with actinomycin D blocked the increase of actin mRNA. The apparent half-life of actin mRNA was not significantly altered during treatment with phalloidin. In contrast, the globular-actin-stabilizing botulinum C2 toxin increased the amount of cytosolic globular actin by 50% within 12 h. Simultaneously, the actin mRNA level was decreased by 62%. However, de-novo synthesis of actin mRNA was not impaired. The apparent half-life of actin mRNA was decreased by approximately 60% during treatment with C2 toxin. The data strongly suggest an autoregulatory control of actin synthesis on the basis of the globular/filamentous actin ratio in rat hepatocytes at the transcriptional as well as at the posttranscriptional levels.

Actins↗
PubMed1995

ECDC--a totally integrated and interactively usable genetic map of Escherichia coli K12.

A printed version of the interactively usable genetic map of Escherichia coli K12 is provided together with some statistical information about the actual status of the respective genome sequencing project. A total of 3,179,967 bp corresponding to 68.38% of the genome is available through the ECDC database. Contigs as well as individual DNA sequences for each gene or open reading frame are provided. Access to a number of other databases is possible using World Wide Web or local programs.

Chromosome Mapping↗
PubMed1995

Computer-aided studies on the spatial structure of the small hepatitis B surface protein.

Hepatitis B surface proteins play a central role in the assembly of the virus and in the infection of the host cells. Whereas some functional aspects of the proteins have been studied in detail, little is known about their structure. Since X-ray analysis of these proteins appear unlikely in the near future, we chose to use a variety of computer-aided methods to improve the model for the major surface protein (SHBs). We here describe the model, discuss it in light of current results in the literature and discuss new functional implications of SHBs.

Computer Simulation↗
PubMed1994

PCR directed preparation and single step purification of highly active histidine-tagged restriction endonuclease HgiBI (GGWCC).

The polymerase-chain-reaction technique is used to produce fusion proteins via deletion of any intervening piece of DNA. Here a stretch of six histidine codons is fused to the 3'-terminus of any defined gene using a standard plasmid vector or a derivative thereof. The advantage over existing methods is that no other amino acids besides the six histidines are added to the protein terminus and only one oligonucleotide needs to be synthesized as special primer. Genes of interest must only be cloned in the correct orientation into a universal multilinker. Using just one specific primer derived from the 3'-terminus of the gene and one standard primer derived from the six histidine codons the fusion is performed by amplifying the entire vector system as described for inverse PCR. As an example, we report on the modification and purification of the restriction endonuclease HgiBI (GGWCC). Enzymatically active protein was obtained in a single step purification under nondenaturating conditions with a purity greater than 95% according to polyacrylamide gel electrophoresis.

Base Sequence↗
PubMed1994

ECD--a totally integrated database of Escherichia coli K12.

We have compiled the DNA sequence data for E. coli available from the GENBANK and EMBL data libraries and independently from the literature. Starting with this update of our Escherichia coli database (ECD release 20) we provide major changes compared to previous issues. This update not only represents another substantial increase in sequence information, it also allows now to find the exact physical location of each individual gene or regulatory region, even regarding discrepancies in nomenclature. In order to save space this printed version does not contain the database itself anymore, but we provide several examples. The complete database is publically available in electronic form together with a self explaining application program or as a flat file. The complete compilation including a full set of genetic map data and the E. coli protein index can be obtained in machine readable form from the EMBL data library as a part of the CD-ROM issue of the EMBL sequence database, released and updated every three months. After deletion of all detected overlaps a total of 2,878,364 individual bp is found to be determined till the end of June 1994. This corresponds to a total of 60.98% of the entire E. coli chromosome consisting of about 4,720 kbp. This number may actually be higher by 9161 bp derived from other strains of E. coli.

Base Sequence↗
PubMed1993

Compilation of DNA sequences of Escherichia coli (update 1993).

We have compiled the DNA sequence data for E. coli available from the GENBANK and EMBL data libraries and over a period of several years independently from the literature. This is the fifth listing replacing and increasing the former listings substantially. However, in order to save space this printed version contains DNA sequence information only, if they are publically available in electronic form. The complete compilation including a full set of genetic map data and the E. coli protein index can be obtained in machine readable form from the EMBL data library (ECD release 15) as a part of the CD-ROM issue of the EMBL sequence database, released and updated every three months. After deletion of all detected overlaps a total of 2,353,635 individual bp is found to be determined till the end of April 1993. This corresponds to a total of 49.87% of the entire E. coli chromosome consisting of about 4,720 kbp. This number may actually be higher by 9161 bp derived from other strains of E. coli.

Base Sequence↗
PubMed1992

Stepwise cloning and genetic organization of the seemingly unclonable HgiCII restriction-modification system from Herpetosiphon giganteus strain Hpg9, using PCR technique.

The genes, hgiCIIR and hgiCIIM, that encode the HgiCII restriction and modification (R-M) system from Herpetosiphon giganteus strain Hpg9, an AvaII isoschizomer recognizing the sequence, GGATCC, were cloned in Escherichia coli. Cloning the respective hgiCIIM gene was achieved via in vitro selection both from a Sau3AI- and an NheI-generated plasmid gene library using AvaII, a commercially available isoschizomer of HgiCII. However, all attempts to clone the closely linked hgiCIIR and M genes in a single step resulted in deletions spanning parts of the coding region of hgiCIIR. Therefore, cloning of the missing 3'-terminal part of this gene was achieved by applying the inverse polymerase-chain-reaction technique. All attempts to construct an enzymatically active R.HgiCII failed; only the inactivated hgiCIIR gene could be cloned. Sequencing of the hgiCIIRM region (carrying predesigned small mutations in the R gene) disclosed three open reading frames (ORFs): one small ORF preceding the methltransferase (MTase)-encoding gene, plus those encoding M.HgiCII (49,620 Da) and R.HgiCII (30,891 Da). M.HgiCII exhibits the common motif of ten conserved amino-acid blocks typically found within the group of m5C-MTases. The R-M system of HgiCII reveals strong homologies to the isoschizomeric R-M system of HgiBI from H. giganteus strain Hpg5, which, in contrast, could be cloned in one step.

Amino Acid Sequence↗