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Lothar Siekmann

Research Profile

Chemicals & Drugs

Occupations

Chemistry, Clinical

Procedures

Concepts & Ideas

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Publications

TOP 3
Anja Kessler; Jonathan Middle; Orna Dreazen; Wolf-Jochen Geilenkeuser; Lothar Siekmann; cas weykamp; Gerhard Schumann
External Quality Assessment Scheme for reference laboratories - review of 8 years' experience.
Lothar Siekmann
Implementation of the concept of traceability in laboratory medicine in external quality assessment.
Michael Ludwig; Franz Rüschendorf; Kathrin Saar; Norbert Hübner; Lothar Siekmann; Simeon Boyd; Heiko Reutter
Genome-wide linkage scan for bladder exstrophy-epispadias complex.

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All Publications

2013: Anja Kessler; Jonathan Middle; Orna Dreazen; Wolf-Jochen Geilenkeuser; Lothar Siekmann; cas weykamp; Gerhard Schumann
External Quality Assessment Scheme for reference laboratories - review of 8 years' experience.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2013;51(5):997-1005.
2009: Lothar Siekmann
Implementation of the concept of traceability in laboratory medicine in external quality assessment.
Clinical biochemistry 2009;42(4-5):293-4.
2009: Michael Ludwig; Franz Rüschendorf; Kathrin Saar; Norbert Hübner; Lothar Siekmann; Simeon Boyd; Heiko Reutter
Genome-wide linkage scan for bladder exstrophy-epispadias complex.
Birth defects research. Part A, Clinical and molecular teratology 2009;85(2):174-8.
2008: W Greg Miller; Gary L Myers; Edward R Ashwood; Anthony A Killeen; Edward Wang; Glenn W Ehlers; David Hassemer; Stanley F Lo; David Seccombe; Lothar Siekmann; Linda M Thienpont; Alan Toth
State of the art in trueness and interlaboratory harmonization for 10 analytes in general clinical chemistry.
Archives of pathology & laboratory medicine 2008;132(5):838-46.
2007: Lothar Siekmann
Requirements for reference (calibration) laboratories in laboratory medicine.
The Clinical biochemist. Reviews / Australian Association of Clinical Biochemists 2007;28(4):149-54.
2006: Gerhard Schumann; Ryoji Aoki; Carlo A Ferrero; Glenn Ehlers; Georges Férard; F Javier Gella; Poul Jørgen Jørgensen; Takahashi Kanno; Art Kessner; Rainer Klauke; Hans-Joachim Kytzia; Jean-Marc Lessinger; W Greg Miller; Rolf Nagel; Jean Pauwels; Heinz Schimmel; Lothar Siekmann; Gerhard Weidemann; Kyoshi Yoshida; Ferruccio Ceriotti
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2006;44(9):1146-55.
2005: Linda M Thienpont; Katleen Van Uytfanghe; John Marriott; Peter Stokes; Lothar Siekmann; Anja Kessler; David Bunk; Susan Tai
Feasibility study of the use of frozen human sera in split-sample comparison of immunoassays with candidate reference measurement procedures for total thyroxine and total triiodothyronine measurements.
Clinical chemistry 2005;51(12):2303-11.
2005: W Greg Miller; Gary L Myers; Edward R Ashwood; Anthony A Killeen; Edward Wang; Linda M Thienpont; Lothar Siekmann
Creatinine measurement: state of the art in accuracy and interlaboratory harmonization.
Archives of pathology & laboratory medicine 2005;129(3):297-304.
2005: Linda M Thienpont; Katleen Van Uytfanghe; John Marriot; Peter Stokes; Lothar Siekmann; Anja Kessler; David Bunk; Susan Tai
Metrologic traceability of total thyroxine measurements in human serum: efforts to establish a network of reference measurement laboratories.
Clinical chemistry 2005;51(1):161-8.
2004: Stephan Steckelbroeck; Alexander Nassen; Bernhard Ugele; Michael Ludwig; Matthias Watzka; Annette Reissinger; Hans Clusmann; Dieter Lütjohann; Lothar Siekmann; Dietrich Klingmüller; Volkmar H Hans
Steroid sulfatase (STS) expression in the human temporal lobe: enzyme activity, mRNA expression and immunohistochemistry study.
Journal of neurochemistry 2004;89(2):403-17.
2003: Stephan Steckelbroeck; Matthias Watzka; Annette Reissinger; Petra Wegener-Toper; Frank Bidlingmaier; Niclaas Bliesener; Volkmar H Hans; Hans Clusmann; Michael Ludwig; Lothar Siekmann; Dietrich Klingmüller
Characterisation of estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity in the human brain.
The Journal of steroid biochemistry and molecular biology 2003;86(1):79-92.
2002: Stephan Steckelbroeck; Matthias Watzka; Dieter Lütjohann; Paul Makiola; Alexander Nassen; Volkmar H Hans; Hans Clusmann; Annette Reissinger; Michael Ludwig; Lothar Siekmann; Dietrich Klingmüller
Characterization of the dehydroepiandrosterone (DHEA) metabolism via oxysterol 7alpha-hydroxylase and 17-ketosteroid reductase activity in the human brain.
Journal of neurochemistry 2002;83(3):713-26.
2002: Lothar Siekmann; Roberto Bonora; Carl A Burtis; Ferruccio Ceriotti; Pascale Clerc-Renaud; Georges Férard; Carlo A Ferrero; Jean-Claude Forest; Paul F H Franck; F Javier Gella; Wieland Hoelzel; Poul Jørgen Jørgensen; Takashi Kanno; Art Kessner; Rainer Klauke; Nina Kristiansen; Jean-Marc Lessinger; Thomas P J Linsinger; Hideo Misaki; Mathias M. Mueller; Mauro Panteghini; Jean Pauwels; Françoise Schiele; Heinz Schimmel; Arlette Vialle; Gerhard Weidemann; Gerhard Schumann
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 7. Certification of four reference materials for the determination of enzymatic activity of gamma-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase accord.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2002;40(7):739-45.
2002: Gerhard Schumann; Roberto Bonora; Ferruccio Ceriotti; Georges Férard; Carlo A Ferrero; Paul F H Franck; F Javier Gella; Wieland Hoelzel; Poul Jørgen Jørgensen; Takashi Kanno; Art Kessner; Rainer Klauke; Nina Kristiansen; Jean-Marc Lessinger; Thomas P J Linsinger; Hideo Misaki; Mauro Panteghini; Jean Pauwels; Françoise Schiele; Heinz Schimmel; Gerhard Weidemann; Lothar Siekmann
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 6. Reference procedure for the measurement of catalytic concentration of gamma-glutamyltransferase.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2002;40(7):734-8.
2002: Gerhard Schumann; Roberto Bonora; Ferruccio Ceriotti; Georges Férard; Carlo A Ferrero; Paul F H Franck; F Javier Gella; Wieland Hoelzel; Poul Jørgen Jørgensen; Takashi Kanno; Art Kessner; Rainer Klauke; Nina Kristiansen; Jean-Marc Lessinger; Thomas P J Linsinger; Hideo Misaki; Mauro Panteghini; Jean Pauwels; Françoise Schiele; Heinz Schimmel; Gerhard Weidemann; Lothar Siekmann
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2002;40(7):725-33.
2002: Gerhard Schumann; Roberto Bonora; Ferruccio Ceriotti; Georges Férard; Carlo A Ferrero; Paul F H Franck; F Javier Gella; Wieland Hoelzel; Poul Jørgen Jørgensen; Takashi Kanno; Art Kessner; Rainer Klauke; Nina Kristiansen; Jean-Marc Lessinger; Thomas P J Linsinger; Hideo Misaki; Mauro Panteghini; Jean Pauwels; Françoise Schiele; Heinz Schimmel; Gerhard Weidemann; Lothar Siekmann
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2002;40(7):718-24.
2002: Gerhard Schumann; Roberto Bonora; Ferruccio Ceriotti; Pascale Clerc-Renaud; Carlo A Ferrero; Georges Férard; Paul F H Franck; F Javier Gella; Wieland Hoelzel; Poul Jørgen Jørgensen; Takashi Kanno; Art Kessner; Rainer Klauke; Nina Kristiansen; Jean-Marc Lessinger; Thomas P J Linsinger; Hideo Misaki; Mauro Panteghini; Jean Pauwels; Heinz Schimmel; Arlette Vialle; Gerhard Weidemann; Lothar Siekmann
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2002;40(6):643-8.
2002: Gerhard Schumann; Roberto Bonora; Ferruccio Ceriotti; Pascale Clerc-Renaud; Carlo A Ferrero; Georges Férard; Paul F H Franck; F Javier Gella; Wieland Hoelzel; Poul Jørgen Jørgensen; Takashi Kanno; Art Kessne; Rainer Klauker; Nina Kristiansen; Jean-Marc Lessinger; Thomas P J Linsinger; Hideo Misaki; Mauro Panteghini; Jean Pauwels; Heinz Schimmel; Arlette Vialle; Gerhard Weidemann; Lothar Siekmann
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. Part 2. Reference procedure for the measurement of catalytic concentration of creatine kinase.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2002;40(6):635-42.
2002: Lothar Siekmann; Roberto Bonora; Carl A Burtis; Ferruccio Ceriotti; Pascale Clerc-Renaud; Georges Férard; Carlo A Ferrero; Jean-Claude Forest; Paul F H Franck; F Javier Gella; Wieland Hoelzel; Poul Jørgen Jørgensen; Takashi Kanno; Art Kessner; Rainer Klauke; Nina Kristiansen; Jean-Marc Lessinger; Thomas P J Linsinger; Hideo Misaki; Mathias M. Mueller; Mauro Panteghini; Jean Pauwels; Françoise Schiele; Heinz Schimmel; Arlette Vialle; Gerhard Weidemann; Gerhard Schumann
IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. Part 1. The concept of reference procedures for the measurement of catalytic activity concentrations of enzymes.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2002;40(6):631-4.
2001: Natalija Novak; Jörg Haberstok; Stefan Kraft; Lothar Siekmann; Jean-Pierre Allam; Thomas Bieber
Standardized extracts from Chinese herbs induce IL-10 production in human monocyte-derived dendritic cells and alter their differentiation in vitro.
The Journal of allergy and clinical immunology 2001;108(4):588-93.
2001: Mauro Panteghini; Ferruccio Ceriotti; Gerhard Schumann; Lothar Siekmann
Establishing a reference system in clinical enzymology.
Clinical chemistry and laboratory medicine : CCLM / FESCC 2001;39(9):795-800.
2001: Thomas P J Linsinger; Jean Pauwels; A Lamberty; Heinz Schimmel; A M van der Veen; Lothar Siekmann
Estimating the uncertainty of stability for matrix CRMs.
Fresenius' journal of analytical chemistry 2001;370(2-3):183-8.
2000: Thomas P J Linsinger; Jean Pauwels; Heinz Schimmel; A Lamberty; A M van der Veen; G Schumann; Lothar Siekmann
Estimation of the uncertainty of CRMs in accordance with GUM: application to the certification of four enzyme CRMs.
Fresenius' journal of analytical chemistry 2000;368(6):589-94.
2000: Frank Callies; Wiebke Arlt; Lothar Siekmann; Doris Hübler; Frank Bidlingmaier; Bruno Allolio
Influence of oral dehydroepiandrosterone (DHEA) on urinary steroid metabolites in males and females.
Steroids 2000;65(2):98-102.
1999: Anja Kessler; Lothar Siekmann
Measurement of urea in human serum by isotope dilution mass spectrometry: a reference procedure.
Clinical chemistry 1999;45(9):1523-9.
1999: Stephan Steckelbroeck; Birgit Stoffel-Wagner; R Reichelt; Johannes Schramm; Frank Bidlingmaier; Lothar Siekmann; Dietrich Klingmüller
Characterization of 17beta-hydroxysteroid dehydrogenase activity in brain tissue: testosterone formation in the human temporal lobe.
Journal of neuroendocrinology 1999;11(6):457-64.
1998: Lothar Siekmann; A Siekmann; Frank Bidlingmaier; K Brill; M Albring
Gestodene and desogestrel do not have a different influence on concentration profiles of ethinylestradiol in women taking oral contraceptives--results of isotope dilution mass spectrometry measurements.
European journal of endocrinology / European Federation of Endocrine Societies 1998;139(2):167-77.
1996: Dietmar Stöckl; C Franzini; J Kratochvila; J Middle; C Ricós; Lothar Siekmann; Linda M Thienpont
Analytical specifications of reference methods compilation and critical discussion (from the members of the European EQA-Organizers Working Group B).
European journal of clinical chemistry and clinical biochemistry : journal of the Forum of European Clinical Chemistry Societies 1996;34(4):319-37.
1995: Linda M Thienpont; C Franzini; J Kratochvila; J Middle; C Ricós; Lothar Siekmann; Dietmar Stöckl
Analytical quality specifications for reference methods and operating specifications for networks of reference laboratories. discussion paper from the members of the external quality assessment (EQA) Working Group B1) on target values in EQAS.
European journal of clinical chemistry and clinical biochemistry : journal of the Forum of European Clinical Chemistry Societies 1995;33(12):949-57.
1995: Lothar Siekmann; B T Doumas; Linda M Thienpont; G Schumann
Reference materials and reference measurement systems in laboratory medicine. Networks of Reference Laboratories.
European journal of clinical chemistry and clinical biochemistry : journal of the Forum of European Clinical Chemistry Societies 1995;33(12):1013-7.
1993: J P Gosling; J Middle; Lothar Siekmann; G Read
Standardization of hapten immunoprocedures: total cortisol.
Scandinavian journal of clinical and laboratory investigation. Supplementum 1993;216():3-41.
1991: Linda M Thienpont; Lothar Siekmann; A Lawson; E Colinet; André P De Leenheer
Development, validation, and certification by isotope dilution gas chromatography-mass spectrometry of lyophilized human serum reference materials for cortisol (CRM 192 and 193) and progesterone (CRM 347 and 348).
Clinical chemistry 1991;37(4):540-6.
1991: Lothar Siekmann
Reference methods for total cholesterol and total glycerol.
European journal of clinical chemistry and clinical biochemistry : journal of the Forum of European Clinical Chemistry Societies 1991;29(4):277-9.
1990: W R Külpmann; P Maibaum; O Sonntag; G Schumann; Lothar Siekmann
Analyses with the KODAK-Ektachem. Accuracy control using reference method values and the influence of protein concentration. Part II. Substrates.
Journal of clinical chemistry and clinical biochemistry. Zeitschrift für klinische Chemie und klinische Biochemie 1990;28(11):835-43.
1987: Lothar Siekmann
Measurement of thyroxine in human serum by isotope dilution mass spectrometry. Definitive methods in clinical chemistry, V.
Biomedical & environmental mass spectrometry 1987;14(11):683-8.
1983: G Röhle; U Voigt; Lothar Siekmann; H Breuer
[Collaborative tests of steroid hormone determinations: accuracy and precision of analytic results].
Journal of clinical chemistry and clinical biochemistry. Zeitschrift für klinische Chemie und klinische Biochemie 1983;21(3):157-65.
1983: Lothar Siekmann; A Siekmann; H Breuer; L Dehennin
Measurement by isotope dilution mass spectrometry of equiline and oestrone in serum of women taking tablets of equine oestrogens.
Biomedical mass spectrometry 1983;10(3):168-74.
1982: Lothar Siekmann; H Breuer
Determination of cortisol in human plasma by isotope dilution-mass spectrometry. Definitive methods in clinical chemistry, I.
Journal of clinical chemistry and clinical biochemistry. Zeitschrift für klinische Chemie und klinische Biochemie 1982;20(12):883-92.
1981: K Fotherby; J O Akpoviroro; Lothar Siekmann; H Breuer
Measurement of ethynyloestradiol by radioimmunoassay and by isotope dilution-mass spectrometry.
Journal of steroid biochemistry 1981;14(5):499-500.
1980: Lothar Siekmann; A Siekmann; H Breuer
Measurement by isotope dilution mass spectrometry of 17 alpha-ethynyloestradiol-17 beta and norethisterone in serum of women taking oral contraceptives.
Biomedical mass spectrometry 1980;7(11-12):511-4.
1980: Lothar Siekmann; B Disse; H Breuer
Biosynthesis and metabolism of 16 alpha, 17-epoxy-C21-steroids in rat liver microsomes.
Journal of steroid biochemistry 1980;13(10):1181-205.
1980: B Disse; Lothar Siekmann; H Breuer
Biosynthesis of 16 alpha, 17 alpha-epoxy-4-androsten-3-one in rat liver microsomes.
Acta endocrinologica 1980;95(1):58-66.
1980: Lothar Siekmann; P Thull; H Breuer
Biosynthesis of 16 alpha, 17 alpha-epoxy-oestratrienol in rat liver microsomes.
Acta endocrinologica 1980;95(1):49-57.