Niedmann, Peter D.

[["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Therapeutic Drug Monitoring"],["dc.bibliographiccitation.volume","25"],["dc.contributor.author","Binder, L."],["dc.contributor.author","Puls, Miriam"],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Pouwels, Claudia"],["dc.contributor.author","Nacke, A."],["dc.contributor.author","Oellerich, M."],["dc.contributor.author","Binder, Claudia"],["dc.date.accessioned","2018-11-07T10:37:31Z"],["dc.date.available","2018-11-07T10:37:31Z"],["dc.date.issued","2003"],["dc.format.extent","496"],["dc.identifier.isi","000184445500054"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45586"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Lippincott Williams & Wilkins"],["dc.publisher.place","Philadelphia"],["dc.relation.conference","8th International Congress of Therapeutic Drug Monitoring and Clinical Toxicology"],["dc.relation.eventlocation","BASEL, SWITZERLAND"],["dc.relation.issn","0163-4356"],["dc.title","A simple and rapid HPLC method for the determination of meropenem - Preanalytical and analytical aspects"],["dc.type","conference_abstract"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1485"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Clinical Chemistry"],["dc.bibliographiccitation.lastpage","1488"],["dc.bibliographiccitation.volume","47"],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Armstrong, Victor William"],["dc.contributor.author","Kiehl, M. G."],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Schutz, Ekkehard"],["dc.contributor.author","Oellerich, M."],["dc.contributor.author","Wieland, Eberhard"],["dc.date.accessioned","2018-11-07T08:47:01Z"],["dc.date.available","2018-11-07T08:47:01Z"],["dc.date.issued","2001"],["dc.identifier.isi","000170077300029"],["dc.identifier.pmid","11468247"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/20839"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Assoc Clinical Chemistry"],["dc.relation.issn","0009-9147"],["dc.title","Quantification of mycophenolic acid in plasma samples collected during and immediately after intravenous administration of mycophenolate mofetil"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.subtype","letter_note"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","365"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Clinical Chemistry"],["dc.bibliographiccitation.lastpage","372"],["dc.bibliographiccitation.volume","46"],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Schutz, Ekkehard"],["dc.contributor.author","Armstrong, Victor William"],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Oellerich, M."],["dc.contributor.author","Wieland, Eberhard"],["dc.date.accessioned","2018-11-07T09:04:14Z"],["dc.date.available","2018-11-07T09:04:14Z"],["dc.date.issued","2000"],["dc.description.abstract","Background: The acyl glucuronide (AcMPAG) of mycophenolic acid (MPA) has been found to possess pharmacologic and potentially proinflammatory activity in vitro. To establish its pharmacologic and toxicologic relevance in vivo, a reversed-phase HPLC method was modified to simultaneously determine MPA, the phenolic MPA-glucuronide (7-O-MPAG), and AcMPAG. In addition, cross-reactivity of AcMPAG in the Emit assay for MPA was investigated. Methods: The procedure used simple sample preparation, separation with a Zorbax Eclipse-XDB-C8 column, and gradient elution. AcMPAG was quantified as 7-O-MPAG-equivalents. Results: The assay was linear up to 50 mg/L for MPA, 250 mg/L for 7-O-MPAG, and 10 mg/L for AcMPAG (r >0.999). Detection limits were 0.01, 0.03, and 0.04 mg/L for MPA, 7-O-MPAG, and AcMPAG, respectively. The recoveries were 99-103% for MPA, 95-103% for 7-O-MPAG, and 104-107% for AcMPAG. The within-day imprecision was <5.0% for MPA (0.2-25 mg/L), <4.4% for 7-O-MPAG (10-250 mg/L), and less than or equal to 14% for AcMPAG (0.1-5 mg/L). The between-day imprecision was <6.2%, <4.5%, and less than or equal to 14% for MPA, 7-O-MPAG, and AcMPAG, respectively. When isolated from microsomes, purified AcMPAG (1-10 mg/L) revealed a concentration-dependent cross-reactivity in an Emit assay for the determination of MPA ranging from 135% to 185%. This is in accordance with the bias between HPLC and Emit calculated in 270 samples from kidney transplant recipients receiving mycophenolate mofetil therapy, which was greater (median, 151.2%) than the respective AcMPAG concentrations determined by HPLC. AcMPAG was found to undergo hydrolysis when samples were stored up to 24 h at room temperature or up to 30 days at 4 degrees C or -20 degrees C. Acidified samples (pH 2.5) were stable up to 30 days at -20 OC. Conclusions: The HPLC and Emit methods for AcMPAG described here may allow investigation of its relevance for the immunosuppression and side effects associated with mycophenolate mofetil therapy. (C) 2000 American Association for Clinical Chemistry."],["dc.identifier.isi","000085848400008"],["dc.identifier.pmid","10702523"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25069"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Assoc Clinical Chemistry"],["dc.relation.issn","0009-9147"],["dc.title","Determination of the acyl glucuronide metabolite of mycophenolic acid in human plasma by HPLC and Emit"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1080"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Transplantation Proceedings"],["dc.bibliographiccitation.lastpage","1081"],["dc.bibliographiccitation.volume","33"],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Wieland, Eberhard"],["dc.contributor.author","Schutz, Ekkehard"],["dc.contributor.author","Wiese, Christoph Hermann"],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Oellerich, M."],["dc.contributor.author","Armstrong, Victor William"],["dc.date.accessioned","2018-11-07T09:26:31Z"],["dc.date.available","2018-11-07T09:26:31Z"],["dc.date.issued","2001"],["dc.identifier.doi","10.1016/S0041-1345(00)02424-6"],["dc.identifier.isi","000167629900506"],["dc.identifier.pmid","11267199"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30321"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Inc"],["dc.publisher.place","New york"],["dc.relation.conference","18th World Congress of the Transplantation-Society"],["dc.relation.eventlocation","ROME, ITALY"],["dc.relation.issn","0041-1345"],["dc.title","The acyl glucuronide metabolite of mycophenolic acid inhibits the proliferation of human mononuclear leukocytes"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","438"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Clinical Chemistry"],["dc.bibliographiccitation.lastpage","441"],["dc.bibliographiccitation.volume","50"],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Armstrong, Victor William"],["dc.contributor.author","Oellerich, M."],["dc.contributor.author","Wieland, Eberhard"],["dc.date.accessioned","2018-11-07T10:51:18Z"],["dc.date.available","2018-11-07T10:51:18Z"],["dc.date.issued","2004"],["dc.identifier.doi","10.1373/clinchem.2003.026096"],["dc.identifier.isi","000188663700023"],["dc.identifier.pmid","14752016"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/48861"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Assoc Clinical Chemistry"],["dc.relation.issn","0009-9147"],["dc.title","Determination of thiopurine methyltransferase activity in isolated human erythrocytes does not reflect putative in vivo enzyme inhibition by sulfasalazine"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.subtype","letter_note"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","390"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Therapeutic Drug Monitoring"],["dc.bibliographiccitation.lastpage","399"],["dc.bibliographiccitation.volume","24"],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Armstrong, Victor William"],["dc.contributor.author","Weber, Lutz T."],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Wieland, Eberhard"],["dc.contributor.author","Haley, J."],["dc.contributor.author","Tonshoff, B."],["dc.contributor.author","Oellerich, M."],["dc.date.accessioned","2018-11-07T10:29:47Z"],["dc.date.available","2018-11-07T10:29:47Z"],["dc.date.issued","2002"],["dc.description.abstract","The acyl glucuronide metabolite (AcMPAG) of mycophenolic acid (MPA) has been found to possess both immunosuppressive and pro-inflammatory activity in vitro. In this study its pharmacokinetics were determined in pediatric renal transplant recipients receiving cyclosporine, steroids, and mycophenolate mofetil. Twelve-hour concentration-time profiles for AcMPAG, MPA, and the phenolic glucuronide (MPAG) were determined by high-performance liquid chromatography (HPLC) in the initial (1-3 wk; n=16) and stable (3-12 mo; n=22) phase,, after transplantation. In addition, the formation of covalent adducts between AcMPAG and plasma albumin (AcMPAG-Alb) was investigated using Western Blot analysis. AcMPAG-AUC(12h) showed significant (p<0.05) correlations with MPA-AUC(12h) (r=0.78) and MPAG-AUC(12h) (r=0.78). In molar equivalents the median AcMPAG-AUC(12h) was 10.3% (range, 4.6%-45.5%) of MPA-AUC(12h). Values (median [range]) of AcMPAG-AUC(12h) (10.1 [3.30-30.1] mg.h/L), AcMPAG-C-0 (0.48 [0.08-1.43] mg/L), and AcMPAG-C-max (1.95 [0.88-5.35] mg/L) were significantly (p<0.05) higher in the stable phase than in the initial phase: 3.54 [2.07-20.0] mg.h/L for AUC(12h); 0.25 [<0.04-0.97] mg/L for C-0, and 1.12 [0.32-2.44] mg/L for C-max. The increases in the AcMPAG pharmacokinetic variables were paralleled by significant increases in the corresponding MPA variables. In addition, a strong negative correlation (r=-0.69; p<0.05) was found between AcMPAG concentrations and the creatinine clearance. AcMPAG-Alb adducts were detected in all patient samples. They showed considerable interindividual variation and increased significantly with time from the initial phase to the stable phase. AcMPAG-Alb correlated significantly (p<0.05) with AcMPAG-AUC(12h) (r=0.70) and plasma albumin (r=0.40). AcMPAG plasma concentrations are dependent on renal function, MPA disposition, and glucuronidation. The pharmacokinetics of AcMPAG is characterized by broad interindividual variation. In some patients AcMPAG may significantly contribute to the immunosuppression during mycophenolate mofetil therapy. AcMPAG-Alb adduct formation may serve as a marker for extended AcMPAG exposure. The association of AcMPAG with adverse effects must be further investigated."],["dc.identifier.doi","10.1097/00007691-200206000-00011"],["dc.identifier.isi","000175866900011"],["dc.identifier.pmid","12021631"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/43714"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","0163-4356"],["dc.title","Pharmacokinetics and protein adduct formation of the pharmacologically active acyl glucuronide metabolite of mycophenolic acid in pediatric renal transplant recipients"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","141"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Therapeutic Drug Monitoring"],["dc.bibliographiccitation.lastpage","142"],["dc.bibliographiccitation.volume","22"],["dc.contributor.author","Schutz, Ekkehard"],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Wieland, Eberhard"],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Armstrong, Victor William"],["dc.contributor.author","Oellerich, M."],["dc.date.accessioned","2018-11-07T10:55:57Z"],["dc.date.available","2018-11-07T10:55:57Z"],["dc.date.issued","2000"],["dc.identifier.doi","10.1097/00007691-200002000-00030"],["dc.identifier.isi","000085149700030"],["dc.identifier.pmid","10688278"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/49902"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Lippincott Williams & Wilkins"],["dc.relation.issn","0163-4356"],["dc.title","Evaluation of an immunoassay for mycophenolic acid"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.subtype","letter_note"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1853"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Clinical Chemistry"],["dc.bibliographiccitation.lastpage","1856"],["dc.bibliographiccitation.volume","47"],["dc.contributor.author","Streit, Frank"],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Armstrong, Victor William"],["dc.contributor.author","Oellerich, M."],["dc.date.accessioned","2018-11-07T08:33:52Z"],["dc.date.available","2018-11-07T08:33:52Z"],["dc.date.issued","2001"],["dc.identifier.isi","000171098600021"],["dc.identifier.pmid","11568101"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17695"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Assoc Clinical Chemistry"],["dc.relation.issn","0009-9147"],["dc.title","Rapid and sensitive liquid chromatography-tandem mass spectrometry method for determination of monoethylglycinexylidide"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.subtype","letter_note"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","637"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Therapeutic Drug Monitoring"],["dc.bibliographiccitation.lastpage","644"],["dc.bibliographiccitation.volume","25"],["dc.contributor.author","Indjova, D."],["dc.contributor.author","Shipkova, Maria"],["dc.contributor.author","Atanasova, Srebrena"],["dc.contributor.author","Niedmann, P. D."],["dc.contributor.author","Armstrong, Victor William"],["dc.contributor.author","Svinarov, D."],["dc.contributor.author","Oellerich, M."],["dc.date.accessioned","2018-11-07T10:36:02Z"],["dc.date.available","2018-11-07T10:36:02Z"],["dc.date.issued","2003"],["dc.description.abstract","Genetic polymorphism of the S-methylation pathway catalyzed by thiopurine methyltransferase (TPMT) is responsible for variation in the metabolism, toxicity, and therapeutic efficacy of thiopurine drugs. This paper describe a new simple, nonradioactive HPLC method for determination of TPMT activity in isolated erythrocytes (Ery), based on the conversion of 6-mercaptopurine (pH 7.5, 37degreesC) to 6-methylmercaptopurine (6-MMP) using S-adenosyl-L-methionine as methyl donor. The incubation step was stopped by a mixture of trichloroacetic acid/acetonitrile containing the internal standard 4-aminoacetophenone. 6-MMP was quantified by absorbance at 290 nm after chromatographic separation on a Zorbax SB-Phenyl column (5 mum, 4.6 x 250 mm) using mobile phases (flow rate 1.1 mL/min) consisting of acetonitrile, phosphate buffer pH 3.0, triethylamine, and dithiothreitol. The assay was linear up to 50 nmol/(mL Ery (.) h), and the detection limit was 0.3 nmol/(mL Ery (.) h). The extraction efficiency of 6-MMP was 95-103% (n = 3), and its analytic recovery ranged between 98.3% and 101.8% (n = 12). The within-day imprecision using pooled human erythrocytes (n = 12) was 4.4% at a TPMT activity of 14.3 nmol/(mL Ery (.) h) and 4.9% at 6.5 nmol/(mL Ery (.) h). The between-day imprecision (n = 12) was 6.8% and 7.5% nmol/(mL Ery (.) h), respectively. A very good agreement was found between TPMT activity determined with this method (y) and a widely used radiochemical procedure (x) (r = 0.94; n = 130; y = 0.502 + 0.946x; P < 0.05). Genotype analysis of all individuals with TPMT activity under 12.5 nmol/(mL Ery (.) h) revealed a genotype/phenotype concordance of 86%. The new HPLC method for determination of TPMT activity in Ery is a simple, rapid, and reliable nonradioactive procedure that can be successfully used for both research and routine clinical analysis."],["dc.identifier.doi","10.1097/00007691-200310000-00014"],["dc.identifier.isi","000185579300014"],["dc.identifier.pmid","14508388"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45230"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Lippincott Williams & Wilkins"],["dc.relation.issn","0163-4356"],["dc.title","Determination of thiopurine methyltransferase phenotype in isolated human erythrocytes using a new simple nonradioactive HPLC method"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]