Diethelm Tschoepe

Publications (3)8.47 Total impact

• Article: Simultaneous determination and validated quantification of human insulin and its synthetic analogues in human blood serum by immunoaffinity purification and liquid chromatography-mass spectrometry.

  Cornelius Hess, Andreas Thomas, Mario Thevis, Bernd Stratmann, Wulf Quester, Diethelm Tschoepe, Burkhard Madea, Frank Musshoff
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  ABSTRACT: Possible fatal complications of human insulin and its synthetic analogues like hypoglycemia require precise classification and quantitative determination of these drugs both for clinical purposes as well as for forensic toxicologists. A procedure was developed for the identification and quantification of human insulin and different long-acting as well as short-acting synthetic insulins in human blood serum specimens. After an immunoaffinity purification step and separation by liquid chromatography, the insulins were characterized by their five- or sixfold protonated molecule ions and diagnostic product ions. Clinical samples of 207 diabetic and 50 non-diabetic patients after the administration of human insulin or oral antidiabetics and forensic samples were analyzed for human/synthetic insulin concentrations. The method was validated according to international guidelines. Limits of detection of the insulins ranged between 1.3 and 2.8 μU/ml. Recoveries ranged between 33.2 % and 51.7 %. Precision data was in accordance with international guidelines. Clinical samples showed concentrations of human insulin lower than 301 μU/ml. Our liquid chromatography tandem mass spectrometry procedure allows unambiguous identification and quantification of the intact human insulin and its intact synthetic analogues Humalog®, Novolog®, Apidra®, Lantus®, and Levemir® in human blood serum in clinical and overdose cases. The assay could be successfully tested in patients with diabetes mellitus on therapy with insulins or oral antidiabetics.
  Analytical and Bioanalytical Chemistry 08/2012; 404(6-7):1813-22. · 3.78 Impact Factor
• Article: Clinical and forensic examinations of glycaemic marker methylglyoxal by means of high performance liquid chromatography-tandem mass spectrometry.

  Cornelius Hess, Bernd Stratmann, Wulf Quester, Diethelm Tschoepe, Burkhard Madea, Frank Musshoff
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  ABSTRACT: The postmortem determination of hyperglycaemic coma is quite difficult because of the lack of morphological findings and the difficult interpretation of biochemical parameters. Methylglyoxal (MG) is a reactive oxoaldehyde, which is mainly derived from glycolysis. An electrospray ionisation liquid chromatography-tandem mass spectrometric procedure for the determination of methylglyoxal in human serum and postmortem blood was developed. It involves protein precipitation with perchloric acid and a derivatisation step with 2,3-diaminonaphthalene. The assay was validated according to international guidelines. Serum samples from diabetics obtained at a diabetes clinic and from non-diabetics were used to assess data about reference concentrations in human serum. The assay showed linearity within the physiological concentrations in serum (5-500 ng/ml). Intraday imprecision at three concentrations was 10.3, 9.2 and 8.3 %, and interday imprecision was 15.3, 14.2 and 9.4 %; the limit of detection was 1.3 ng/ml, and limit of quantification, 3.2 ng/ml. One hundred and eighteen clinical (100 diabetics, 18 non-diabetics) and 98 forensic samples (84 non-diabetics, 14 in a status of hyperglycaemic coma) were measured. During life, diabetics showed significantly (p < 0.001) higher serum concentrations of MG than non-diabetics. After death, concentrations of MG increased significantly (p < 0.001). However, there was no correlation between the sum formula of Traub in vitreous humour and MG femoral blood concentrations (R = 0.237). This indicates that MG concentrations in the deceased cannot distinguish deaths due to a hyperglycaemic coma from other causes of death.
  Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin 07/2012; · 2.59 Impact Factor
• Article: Clinical and forensic examinations of glycemic marker 1,5-anhydroglucitol by means of high performance liquid chromatography tandem mass spectrometry.

  Cornelius Hess, Bernd Stratmann, Wulf Quester, Burkhard Madea, Frank Musshoff, Diethelm Tschoepe
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  ABSTRACT: Postmortem diagnosis of diabetes and a diabetic coma can be difficult because of the lack of characteristic morphological findings. 1,5-Anhydroglucitol (1,5-AG), the 1-deoxy form of glucose, competes with glucose for reabsorption in the kidneys. Therefore, diabetics with a permanent hyperglycemia show significantly lower serum concentrations of 1,5-AG than non-diabetics. A liquid chromatography-mass spectrometric method for the determination of 1,5-AG in serum and postmortem blood was developed and validated according to international guidelines. Linearity was given between 1 μg/ml and 50 μg/ml. Recovery rates ranged between 70.8% and 89.8%, the limit of quantification of the procedure was 0.20 μg/ml, limit of quantification was 0.55 μg/ml. Serum of 199 diabetics and 116 non-diabetics and femoral blood of 31 diabetic and 27 non-diabetic deceased was measured. Average concentrations were significantly (p<0.001) higher in non-diabetics compared to diabetics ante and postmortem. Seven of the diabetics may have died because of a hyperglycemic coma indicated by a sum formula of Traub>450 mg/dl. 1,5-AG average concentrations in these deceased were not significantly different to diabetics which did not die because of a diabetic coma. Concentrations of 1,5-AG give a hint for not well controlled diabetes antemortem and postmortem and can be assumed as an additional and alternative information postmortem to the measurement of HbA1c or fructosamine.
  Forensic science international 06/2012; 222(1-3):132-6. · 2.10 Impact Factor