16 research outputs found
Corrigendum: Do common infections trigger disease-onset or -severity in CTLA-4 insufficiency?
Do common infections trigger disease-onset or -severity in CTLA-4 insufficiency?
PurposeHeterozygous mutations in CTLA4 lead to an inborn error of immunity characterized by immune dysregulation and immunodeficiency, known as CTLA-4 insufficiency. Cohort studies on CTLA4 mutation carriers showed a reduced penetrance (around 70%) and variable disease expressivity, suggesting the presence of modifying factors. It is well studied that infections can trigger autoimmunity in humans, especially in combination with a genetic predisposition.MethodsTo investigate whether specific infections or the presence of specific persisting pathogens are associated with disease onset or severity in CTLA-4 insufficiency, we have examined the humoral immune response in 13 CTLA4 mutation carriers, seven without clinical manifestation and six with autoimmune manifestations, but without immunoglobulin replacement therapy against cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus 1/2 (HSV 1/2), parvovirus B19 and Toxoplasma gondii. Additionally, we have measured FcγRIII/CD16A activation by EBV-specific IgG antibodies to examine the functional capabilities of immunoglobulins produced by CTLA4 mutation carriers.ResultsThe seroprevalence between affected and unaffected CTLA4 mutation carriers did not differ significantly for the examined pathogens. Additionally, we show here that CTLA4 mutation carriers produce EBV-specific IgG, which are unimpaired in activating FcγRIII/CD16A.ConclusionsOur results show that the investigated pathogens are very unlikely to trigger the disease onset in CTLA-4-insufficient individuals, and their prevalence is not correlated with disease severity or expressivity
Stereoselective quantification of phase 1 and 2 metabolites of clomiphene in human plasma and urine
Quantitative bile acid profiling by liquid chromatography quadrupole time-of-flight mass spectrometry: monitoring hepatitis B therapy by a novel Na+-taurocholate cotransporting polypeptide inhibitor
LC-MS/MS method for the simultaneous quantification of artesunate and its metabolites dihydroartemisinin and dihydroartemisinin glucuronide in human plasma
Artesunate (AS), a hemisuccinate derivative of artemisinin, is readily soluble in water and can easily be used in formulations for parenteral treatment of severe malaria. AS is rapidly hydrolyzed to the active metabolite dihydroartemisinin (DHA) and primarily eliminated by biliary excretion after glucuronidation. To investigate systematically the AS metabolism and pharmacokinetics, a novel liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of AS and its metabolites DHA and DHA glucuronide (DHAG) in human plasma samples was developed. Compared to previous methods, our method includes for the first time the quantification of the glucuronide metabolite using a newly synthesized stable isotope-labeled analogue as internal standard. Sample preparation was performed with only 50 μL plasma by high-throughput solid-phase extraction in the 96-well plate format. Separation of the analytes was achieved on a Poroshell 120 EC-C18 column (50*2.1 mm, 2.7 μm, Agilent Technologies, Waldbronn, Germany). The method was validated according to FDA guidelines. Calibration curves were linear over the entire range from 1 to 2,500 nM (0.4–961.1 ng/mL), 165 to 16,500 nM (46.9–4,691.8 ng/mL), and 4 to 10,000 nM (1.8–4,604.7 ng/mL) for AS, DHA, and DHAG, respectively. Intra- and interbatch accuracy, determined as a deviation between nominal and measured values, ranged from −5.7 to 3.5 % and from 2.7 to 5.8 %, respectively. The assay variability ranged from 1.5 to 10.9 % for intra- and interbatch approaches. All analytes showed extraction recoveries above 85 %. The method was successfully applied to plasma samples from patients under AS treatment
The Influence of Macrolide Antibiotics on the Uptake of Organic Anions and Drugs Mediated by OATP1B1 and OATP1B3
Simultaneous Quantification of Eleven Thiopurine Nucleotides by Liquid Chromatography-Tandem Mass Spectrometry
The prodrugs azathioprine and 6-mercaptopurine, which
are well-established
anticancer and immunosuppressive agents, are extensively metabolized
by activating and inactivating enzymes. Whereas the 6-thioguanine
nucleotides (TGN) are currently being considered as major active metabolites,
methylthioinosine nucleotides seem to contribute to the cytotoxic
effect as well. Thiopurine-related adverse drug reactions and thiopurine
failure are frequent. Thus, therapeutic monitoring of TGN and methylthioinosine
derivatives has been suggested to improve thiopurine therapy, however
with limited success. To elucidate systematically underlying molecular
mechanisms as potential explanation for interindividual variability
of thiopurine response, we developed a novel highly specific and sensitive
liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for
simultaneous quantitation of eleven mono-, di-, and triphosphates
of thioguanosine, methylthioinosine, methylthioguanosine, and thioinosine.
Using stable isotope-labeled analogues as internal standards obtained
by chemical synthesis, an intra- and interassay variability below
8% and an accuracy of 92% to 107% were achieved in spiked quality
control samples with known standards. All eleven metabolites could
be determined in red blood cells from patients with inflammatory bowel
diseases and long-term azathioprine therapy. Thus, our novel method
opens a new avenue for the understanding of the thiopurine metabolism
by quantitation of all important thiopurine nucleotide metabolites
in one run
Simultaneous Quantification of Eleven Thiopurine Nucleotides by Liquid Chromatography-Tandem Mass Spectrometry
The prodrugs azathioprine and 6-mercaptopurine, which
are well-established
anticancer and immunosuppressive agents, are extensively metabolized
by activating and inactivating enzymes. Whereas the 6-thioguanine
nucleotides (TGN) are currently being considered as major active metabolites,
methylthioinosine nucleotides seem to contribute to the cytotoxic
effect as well. Thiopurine-related adverse drug reactions and thiopurine
failure are frequent. Thus, therapeutic monitoring of TGN and methylthioinosine
derivatives has been suggested to improve thiopurine therapy, however
with limited success. To elucidate systematically underlying molecular
mechanisms as potential explanation for interindividual variability
of thiopurine response, we developed a novel highly specific and sensitive
liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for
simultaneous quantitation of eleven mono-, di-, and triphosphates
of thioguanosine, methylthioinosine, methylthioguanosine, and thioinosine.
Using stable isotope-labeled analogues as internal standards obtained
by chemical synthesis, an intra- and interassay variability below
8% and an accuracy of 92% to 107% were achieved in spiked quality
control samples with known standards. All eleven metabolites could
be determined in red blood cells from patients with inflammatory bowel
diseases and long-term azathioprine therapy. Thus, our novel method
opens a new avenue for the understanding of the thiopurine metabolism
by quantitation of all important thiopurine nucleotide metabolites
in one run