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Andreas Kremer

Publications and source records attributed to Andreas Kremer.

7 recordsLinked to original sources
PubMed2006

Nucleosomes in colorectal cancer patients during radiochemotherapy.

Apoptotic markers and tumor-associated antigens might be suitable to indicate the response to radiochemotherapy early. We analyzed the courses of nucleosomes, CEA, CA 19-9 and CYFRA 21-1 in 25 colorectal cancer patients during radiochemotherapy (4 postoperative, 13 preoperative, 8 local relapse therapy). Blood was taken before therapy, daily during the first week, once weekly during the following weeks, and at the end of the radiochemotherapy. After a temporary decline 6 h after the first irradiation, nucleosomes rose in most patients rapidly reaching a maximum during the first days which was followed by a subsequent decrease. In patients receiving postoperative therapy after complete resection of tumor, nucleosome levels generally were lower than in patients with preoperative or relapse therapy. Correspondingly, CEA, CA 19-9 and CYFRA 21-1 levels of postoperatively treated patients were the lowest whereas those with tumor relapse had the highest ones. During preoperative therapy, lower nucleosome concentrations were found in patients with response to therapy resulting in a smaller area under the curve of days 1-3 (AUC) than in those with progressive disease (p = 0.028). The other parameters did not indicate the response to therapy at the initial treatment phase. In conclusion, the course of nucleosomes (AUC) might be valuable for the early prediction of therapy response in preoperatively treated colorectal cancer patients.

Aged↗
PubMed2005

Nucleosomes in pancreatic cancer patients during radiochemotherapy.

Nucleosomes appear spontaneously in elevated concentrations in the serum of patients with malignant diseases as well as during chemo- and radiotherapy. We analyzed whether their kinetics show typical characteristics during radiochemotherapy and enable an early estimation of therapy efficacy. We used the Cell Death Detection Elisa plus (Roche Diagnostics) and investigated the course of nucleosomes in the serum of 32 patients with a local stage of pancreatic cancer who were treated with radiochemotherapy for several weeks. Ten of them received postsurgical therapy, 21 received primary therapy and 1 received therapy for local relapse. Blood was taken before the beginning of therapy, daily during the first week, once weekly during the following weeks and at the end of radiochemotherapy. The response to therapy was defined according to the kinetics of CA 19-9: a decrease of CA 19-9 > or =50% after radiochemotherapy was considered as 'remission'; an increase of > or =100% (which was confirmed by two following values) was defined as 'progression'. Patients with 'stable disease' ranged intermediately. Most of the examined patients showed a decrease of the concentration of nucleosomes within 6 h after the first dose of radiation. Afterwards, nucleosome levels increased rapidly, reaching their maximum during the following days. Patients receiving postsurgery, primary or relapse therapies did not show significant differences in nucleosome values during the time of treatment. Single nucleosome values, measured at 6, 24 and 48 h after the application of therapy, could not discriminate significantly between patients with no progression and those with progression of disease. However, the area under the curve of the first 3 days, which integrated all variables of the initial therapeutic phase, showed a significant correlation with the progression-free interval (p=0.008). Our results indicate that the area under the curve of nucleosomes during the initial phase of radiochemotherapy could be valuable for the early prediction of the progression-free interval.

Antimetabolites, Antineoplastic↗
PubMed2003

Gemini surfactants: new synthetic vectors for gene transfection.

The superior surfactant properties of cationic gemini surfactants are applied to the complex problem of introducing genes into cells. Of almost 250 new compounds tested, of some 20 different structural types, a majority showed very good transfection activity in vitro. The surfactant is shown to bind and compact DNA efficiently, and structural studies and calculations provide a working picture of the "lipoplex" formed. The lipoplex can penetrate the outer membranes of many cell types, to appear in the cytoplasm encapsulated within endosomes. Escape from the endosome--a key step for transfection--may be controlled by changes in the aggregation behavior of the lipoplex as the pH falls. The evidence suggests that DNA may be released from the lipoplex before entry into the nucleus, where the new gene can be expressed with high efficiency.

Genetic Therapy↗
PubMed2003

Are gene expression microarray analyses reliable? A review of studies of retinoic acid responsive genes.

Microarray analyses of gene expression are widely used, but reports of the same analyses by different groups give widely divergent results, and raise questions regarding reproducibility and reliability. We take as an example recent published reports on microarray experiments that were designed to identify retinoic acid responsive genes. These reports show substantial differences in their results. In this article, we review the methodology, results, and potential causes of differences in these applications of microarrays. Finally, we suggest practices to improve the reliability and reproducibility of microarray experiments.

Animals↗
PubMed2002

Baculovirus infection raises the level of TATA-binding protein that colocalizes with viral DNA replication sites.

During the infection cycle of Autographa californica multicapsid nuclear polyhedrosis virus, the TATA-binding protein (TBP) of the insect host cell likely participates in early viral transcription, which is mediated by the host RNA polymerase II. However, the role of TBP in late and very late viral transcription, which is accomplished by an alpha-amanitin-resistant RNA polymerase, is unclear. We observed a dramatic increase of TBP protein during the late phases of infection. TBP mRNA levels, however, were not coordinately increased. Indirect-immunofluorescence studies revealed a nuclear redistribution of TBP during infection. After labeling of viral replication centers with bromodeoxyuridine (BrdU), costaining of TBP and BrdU showed that TBP localized to viral DNA replication centers. These results suggest a putative role of TBP during late viral transcription, which may occur in close proximity to viral DNA replication.

Animals↗
PubMedDate not supplied

A bioinformatics perspective on proteomics: data storage, analysis, and integration.

The field of proteomics is advancing rapidly as a result of powerful new technologies and proteomics experiments yield a vast and increasing amount of information. Data regarding protein occurrence, abundance, identity, sequence, structure, properties, and interactions need to be stored. Currently, a common standard has not yet been established and open access to results is needed for further development of robust analysis algorithms. Databases for proteomics will evolve from pure storage into knowledge resources, providing a repository for information (meta-data) which is mainly not stored in simple flat files. This review will shed light on recent steps towards the generation of a common standard in proteomics data storage and integration, but is not meant to be a comprehensive overview of all available databases and tools in the proteomics community.

Computational Biology↗