Martin Kratzmeier

Publications (23) View all

• Article: Detection of specific strains of viable bacterial pathogens by using RNA bead assays and flow cytometry with 2100 Bioanalyzer.

  Philip Butterworth, Henrique T M C M Baltar, Martin Kratzmeier, Ewa M Goldys
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  ABSTRACT: Bead assays are an emerging microbial detection technology with the capability for rapid detection of extremely low levels of viable pathogens. Such technologies are of high value in clinical settings and in the food industry. Here, we perform a bead assay for extracted 16S rRNA from Escherichia coli (strain K12) with the flow cytometry readout on a 2100 Bioanalyzer, a highly accurate, small-scale flow cytometer system.
  Methods in molecular biology (Clifton, N.J.) 01/2012; 875:253-62.
• Article: Simple bead assay for detection of live bacteria (Escherichia coli).

  Philip Butterworth, Henrique T M C M Baltar, Martin Kratzmeier, Ewa M Goldys
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  ABSTRACT: Bead assays are an important rapid microbial detection technology suitable for extremely low pathogen levels. We report a bead assay for rRNA extracted from Escherichia coli K12 that does not require amplification steps and has readout on an Agilent 2100 Bioanalyzer flow cytometry system. Our assay was able to detect 125 ng of RNA, which is 16 times less than reported earlier. The specificity was extremely high, with no binding to a negative control organism (Bacillus subtilis). We discuss challenges faced during optimization of the key assay components, such as varying amounts of RNA in the samples, number of beads, aggregation, and reproducibility.
  Analytical Chemistry 02/2011; 83(4):1443-7. · 5.86 Impact Factor
• Article: Molecular weight determination of high molecular mass (glyco)proteins using CGE-on-a-chip, planar SDS-PAGE and MALDI-TOF-MS.

  Roland Müller, Martina Marchetti-Deschmann, Helmut Elgass, Heimo Breiteneder, Martin Kratzmeier, Günter Allmaier
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  ABSTRACT: The molecular weights (MW) of seven (glyco)proteins, of which five were plasma-derived, with MWs higher than 200 kDa were determined with three techniques: CGE-on-a-chip, SDS-PAGE and MALDI-TOF-MS. While the analysis of medium to high MW proteins with SDS-PAGE was an already well-established technique, the usefulness of MALDI-TOF-MS for the exact MW determination of high mass proteins was only partly described in literature so far. CGE-on-a-chip is the newest of all three applied techniques and was so far not applicable. Therefore, it was not evaluated for high MW (glyco)proteins. All proteins were analyzed under nonreducing as well as reducing conditions. In this work, it was demonstrated that all three described techniques were capable of determining the MW of all high molecular weight (glyco)proteins. The noncommercial CGE-on-a-chip assay allowed for the first time the electrophoretic separation of proteins in the MW range from 14 to 1000 kDa. MW assignment was limited to 500 kDa in the case of SDS-PAGE and 660 kDa in the case of the high MW CGE-on-a-chip assay. With the proper matrix and sample preparation, analysis with a standard MALDI-TOF-MS provided accurate MWs for all high MW proteins up to 1 MDa.
  Electrophoresis 11/2010; 31(23-24):3850-62. · 3.30 Impact Factor
• Article: PROCAM Study: risk prediction for myocardial infarction using microfluidic high-density lipoprotein (HDL) subfractionation is independent of HDL cholesterol.

  Odilo Mueller, Elaine Chang, David Deng, Torsten Franz, Debra Jing, Robert Kincaid, Yves Konigshofer, Martin Kratzmeier, Michael McNulty, Hao Qian, Juergen Schneider, Helmut Schulte, Udo Seedorf, Xioadan Tian, Mark Van Cleve, Dorothy Yang, Gerd Assmann
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  ABSTRACT: High-density lipoprotein (HDL) subfractions are among the new emerging risk factors for atherosclerosis. In particular, HDL 2b has been shown to be linked to cardiovascular risk. This study uses a novel microfluidics-based method to establish HDL 2b clinical utility using samples from the Prospective Cardiovascular Muenster (PROCAM) Study. Method performance was established by measuring accuracy, precision, linearity and inter-site precision. Serum samples from 503 individuals collected in the context of the PROCAM study were analyzed by electrophoresis on a microfluidics system. Of these, 251 were male survivors of myocardial infarction (cases), while 252 individuals were matched healthy controls. HDL cholesterol, HDL 2b concentration and HDL 2b percentage were analyzed. This novel method showed satisfactory assay performance with an inter-site coefficient of variance of <10% for HDL 2b percentage. Parallel patient testing on 52 samples between two sites resulted in a correlation coefficient of r=0.95. Significant differences were observed in the HDL 2b subfraction between cases and controls independent of other risk factors. Including HDL 2b percentage in logistic regression reduced the number of false positives from 64 to 39 and the number of false negative cases from 48 to 45, in the context of this study. The novel method showed satisfactory assay performance in addition to drastically reduced analysis times and improved ease of use as compared to other methods. Clinical utility of HDL 2b was demonstrated supporting the findings of previous studies.
  Clinical Chemistry and Laboratory Medicine 01/2008; 46(4):490-8. · 2.15 Impact Factor
• Article: Apoptotic DNA fragmentation is not related to the phosphorylation state of histone H1.

  Wiebke Goebel, Natalie Obermeyer, Nadja Bleicher, Martin Kratzmeier, Hans-Jörg Eibl, Detlef Doenecke, Werner Albig
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  ABSTRACT: Changes in chromatin structure, histone phosphorylation and cleavage of DNA into nucleosome-size fragments are characteristic features of apoptosis. Since H1 histones bind to the site of DNA cleavage between nucleosomal cores, the question arises as to whether the state of H1 phosphorylation influences the rate of internucleosomal cleavage. Here, we tested the relation between DNA fragmentation and H1 phosphorylation both in cultured cells and in vitro. In Jurkat cells, hyperosmotic mannitol concentration resulted in apoptosis, including nucleosomal fragmentation, whereas apoptosis induction by increased NaCl concentration was not accompanied by DNA fragmentation. However, both treatments induced dephosphorylation of H1 histones. In contrast, treatment of Raji cells with alkylphosphocholine led to induction of apoptosis with internucleosomal fragmentation, albeit without notable histone H1 dephosphorylation. These results demonstrate that dephosphorylation of H1 histones is neither a prerequisite for nor a consequence of internucleosomal cleavage. Moreover, we observed with an in vitro assay that the known enhancing effect of H1 histones on the activity of the apoptosis-induced endonuclease DFF40 is independent of the subtype or the phosphorylation state of the linker histone.
  Biological Chemistry 03/2007; 388(2):197-206. · 2.96 Impact Factor