Performance of the Roche Total Mycophenolic Acid® assay on the Cobas Integra 400®, Cobas 6000® and comparison to LC-MS/MS in liver transplant patients

Background: Mycophenolic acid (MPA) is an immunosuppressant for which therapeutic drug monitoring (TDM) is performed for optimal prophylaxis and avoidance of toxicity in transplant patients. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is ideally suited for TDM of MPA. There have been several method comparisons of the Roche Total MPA assay, but none have been performed with respect to liver transplant patients. Methods: We validated the Roche Total MPA assay on the Cobas Integra 400 and Cobas 6000 and compared it to a validated LC-MS/MS (API 2000 (TM)) method. Fifty-five EDTA plasma samples from liver transplant patients were measured with the Roche assay on these platforms and compared to the LC-MS/MS results. Results: Validation of the LC-MS/MS, Cobas Integra 400 and 6000 was performed with good results. The LC-MS/MS/Integra 400/Cobas 6000 were linear up to 30, 15 and 17 mg/L, respectively. Imprecision was <10% for LC-MS/MS and <7% for the Roche assay on both platforms. The samples showed good agreement with LC-MS/MS. Passing-Bablok regression analysis showed Cobas Integra (mg/L) = 1.02 x LC-MS/MS (mg/L)-0.50 and Cobas 6000 (mg/L) = 0.98 x LC-MS/MS-0.47. Conclusions: The Roche Total Mycophenolic Acid-assay is suitable for measuring total MPA in plasma from liver transplant patients and is a good alternative for LC-MS/MS

Mycophenolic Acid and Other Metabolites of Penicillium brevicompactum

The major part of this thesis describes studies on the biosynthesis of the benzoylated drimane sesquiterpene pebrolide and on mycophenolic acid. The location of tritium in pebrolide biosynthesised from [2-T, 2-14C] mevalonate was established by degradation and in particular the 4alpha-oxymethylene group was shown to be derived from the methylene group of mevalonate, in agreement with the specificity of cyclisation found in di- and tri-terpene biosynthesis. A number of degradative sequences for the determining of the level of tritium incorporation into different parts of mycophenolic acid were studied. Application of one of these to material biosynthesised from [2-T, 2-14C] sodium acetate showed that the incorporation of acetate into the phthalide methylene group was in accord with the intermediacy of a tetraketide precursor. A farnesyl analogue of mycophenolic acid, its methyl ether (which were isolated from cultures of P. stoloniferum) and desmethylmycophenolic acid were tested (by radiotracer methods) as precursors, and the final steps in the biosynthesis of mycophenolic acid elucidated. The stereochemistry of a dibydrobenzofuran metabolite of P. brevicomoactum, related to mycophenolic acid, has been established by synthesis from mycophenolic acid. A minor metabolite (brevigellin) of P. brevicompactum was isolated and shown by chemical and spectroscopic means to be a cyclodepsipeptiae containing a previously unreported amino acid residue

Mycophenolic acid suppresses granulopoiesis by inhibition of interleukin-17 production

Mycophenolic acid is a commonly used immunosuppressant after organ transplantation and in autoimmune diseases; however, myelosuppression is a major complication despite its largely favorable side-effect profile. Mycophenolic acid targets inosine monophosphate dehydrogenase, which is essential for T-cell proliferation. The T-cell cytokine interleukin-17 (IL-17 or IL-17A) and its receptor maintain normal neutrophilic granulocyte numbers in mice by induction of granulocyte-colony-stimulating factor. To test whether mycophenolic acid induces neutropenia by inhibiting IL-17-producing T cells, we treated C57Bl/6 mice with mycophenolate-mofetil (the orally available pro-drug) and found a dose-dependent decrease in blood neutrophils. This myelosuppressive effect was completely abolished in mice that lack the IL-17 receptor. Mycophenolic acid delayed myeloid recovery after bone marrow transplantation and decreased the percentage of IL-17-producing T cells in the spleen and thymus, and inhibited IL-17 production in human and mouse T cells in vitro. Injection of IL-17 during mycophenolic acid treatment overcame the suppression of the circulating neutrophil levels. Our study shows that mycophenolic acid suppresses neutrophil production by inhibiting IL-17 expression, suggesting that measurement of this interleukin might be useful in estimating the risk of neutropenia in clinical settings

Mycophenolic acid (MPA) modulates host cellular autophagy progression in sub genomic dengue virus-2 replicon cells

Cellular autophagy (Macrophagy) is a self-degradative process, executed through the network of autophagy associated genes (ATGs) encoded proteins. Both in vitro and in vivo studies suggest that dengue virus (DENV) induces autophagy and supports the viral genome replication and translation. Therefore, the cellular autophagy induced by dengue virus can be a good target for antiviral drug development. The action of mycophenolic acid (MPA), a specific inhibitor of DENV replication, was investigated in the stable BHK-21/DENV2 replicon cells. The inhibition was mediated by enhanced degradation of autophagic substrates in stable BHK-21/DENV2 replicon cells as evidenced by a decrease in lapidated LC3 (LC3II) and p62 expression in the presence of MPA. In contrast, the results indicated that four gene sets, namely Trans membrane protein 74 (TMEM74), Unc-51-like kinase 2 (ULK2), Cathepsin D (CTSD) and Estrogen receptor 1 (ESR1) were upregulated in stable BHK-21/DENV2 replicon cells, due to the sustained dynamic replication of DENV2 genome. These ATGs involved in the pre-autophagosomal structure (PAS) formation, were suppressed in the presence MPA. Instead, MPA induced the expression of different set of autophagy genes such as ATG4, AKT1, APP, ATG16L1, ATG16L2, B2M and HPRT1. An enzyme involved in the nucleotide salvage pathway, HPRT1, was highly expressed in the presence of MPA. The study shows that DENV2 replication is dependent on PAS formation and is inhibited in the presence of MPA by enhancing the degradation of autophagic substrates and suppression of PAS formation. This study provides impetus in designing MPA analogues to effectively inhibit dengue viral replication

First-principles molecular structure search with a genetic algorithm

The identification of low-energy conformers for a given molecule is a fundamental problem in computational chemistry and cheminformatics. We assess here a conformer search that employs a genetic algorithm for sampling the low-energy segment of the conformation space of molecules. The algorithm is designed to work with first-principles methods, facilitated by the incorporation of local optimization and blacklisting conformers to prevent repeated evaluations of very similar solutions. The aim of the search is not only to find the global minimum, but to predict all conformers within an energy window above the global minimum. The performance of the search strategy is: (i) evaluated for a reference data set extracted from a database with amino acid dipeptide conformers obtained by an extensive combined force field and first-principles search and (ii) compared to the performance of a systematic search and a random conformer generator for the example of a drug-like ligand with 43 atoms, 8 rotatable bonds and 1 cis/trans bond

Influence of mycophenolate mofetil dosage and plasma levels on the occurrence of chronic lung allograft dysfunction in lung transplants: a retrospective cohort analysis

INTRODUCTION: Development of chronic lung allograft dysfunction is a limiting factor for post-lung transplant survival. We evaluated whether the dose of the immunosuppressant mycophenolate mofetil or plasma concentrations of the active metabolite mycophenolic acid affect the development of chronic lung allograft dysfunction. METHODS: In this retrospective cohort study we recruited 71 patients with a lung transplant between 2010 and 2014 which survived the first year after transplantation up to 1 July 2021. An event-time-analytical Cox proportional-hazards regression model with time-varying-covariates (18,431 measurements for MPA, mycophenolate mofetil dosage, lymphocytes) was used to predict chronic lung allograft dysfunction, with adjustment for sociodemographic factors and lung function at baseline. RESULTS: 37 patients did not develop chronic lung allograft dysfunction (age 41.3 ± 15.6 years, baseline FEV1 95.5 ± 19.1% predicted) and 34 patients developed chronic lung allograft dysfunction (age 50.9 ± 13.3 years, baseline FEV1 102.2 ± 25.4% predicted). Mean mycophenolic acid did not differ significantly between the groups (2.8 ± 1.7 and 3.0 ± 2.3 mg/l; p = 0.724). In the first 4 post-transplant years the death rate was 25%. A total of 50% of the patients died by the ninth post-transplant year. There was a dose-effect relationship between mycophenolate mofetil dosage, mycophenolic acid (r2 = 0.02, p <0.001), as well as lymphocyte levels (r2 = –0.007, p <0.001), but only the traditional risk factor age predicted chronic lung allograft dysfunction. Continuously measured mycophenolic acid did not predict chronic lung allograft dysfunction (hazard ratio 0.98, 95% confidence interval 0.90–1.06, p = 0.64 over a period of 382.97 patient-years). CONCLUSION: Mycophenolate mofetil dosage and mycophenolic acid were not associated with chronic lung allograft dysfunction development. Thus, the mycophenolate mofetil dose or mycophenolic acid plasma concentration are not a primary factor related to organ rejection, but chronic lung allograft dysfunction may be influenced by other components of immunosuppression or other factors

In vitro rumen simulations show a reduced disappearance of deoxynivalenol, nivalenol and enniatin B at conditions of rumen acidosis and lower microbial activity

Ruminants are generally considered to be less susceptible to the effects of mycotoxins than monogastric animals as the rumen microbiota are capable of detoxifying some of these toxins. Despite this potential degradation, mycotoxin-associated subclinical health problems are seen in dairy cows. In this research, the disappearance of several mycotoxins was determined in an in vitro rumen model and the effect of realistic concentrations of those mycotoxins on fermentation was assessed by volatile fatty acid production. In addition, two hypotheses were tested: (1) a lower rumen pH leads to a decreased degradation of mycotoxins and (2) rumen fluid of lactating cows degrade mycotoxins better than rumen fluid of non-lactating cows. Maize silage was spiked with a mixture of deoxynivalenol (DON), nivalenol (NIV), enniatin B (ENN B), mycophenolic acid (MPA), roquefortine C (ROQ-C) and zearalenone (ZEN). Fresh rumen fluid of two lactating cows (L) and two non-lactating cows (N) was added to a buffer of normal pH (6.8) and low pH (5.8), leading to four combinations (L6.8, L5.8, N6.8, N5.8), which were added to the spiked maize substrate. In this study, mycotoxins had no effect on volatile fatty acid production. However, not all mycotoxins fully disappeared during incubation. ENN B and ROQ-C disappeared only partially, whereas MPA showed almost no disappearance. The disappearance of DON, NIV, and ENN B was hampered when pH was low, especially when the inoculum of non-lactating cows was used. For ZEN, a limited transformation of ZEN to alpha-ZEL and beta-ZEL was observed, but only at pH 6.8. In conclusion, based on the type of mycotoxin and the ruminal conditions, mycotoxins can stay intact in the rumen

Effects of combined administration of FK 506 and the purine biosynthesis inhibitors mizoribine or mycophenolic acid on lymphocyte DNA synthesis and T cell activation molecule expression in human mixed lymphocyte cultures

Our objective was to obtain new information on the in vitro antilymphocytic action of the cytokine synthesis inhibitor FK 506 and the purine biosynthesis inhibitors mycophenolic acid (MPA; the active moiety of RS61443) and mizoribine (MZB) when used alone or in combination. When added at the initiation of six-day human mixed lymphocyte cultures (MLC), FK 506, MPA or MZB exhibited dose-dependent inhibition of T-lymphocyte DNA synthesis. FK 506, however, was 100-fold more potent than MPA, and 10000-fold more potent than MZB. Combination of FK 506 with either MPA or MZB, each at suboptional concentrations, produced no more than additive inhibitory effects on 3H thymidine incorporation. Two-colour flow cytometric analysis of lymphocytes revealed that none of the drugs affected cell surface activation molecule expression (CD25 = IL-2R 55 kD α-chain, HLA-DR or CD71 = transferrin receptor [TR]) on allostimulated CD4+ or CD8+ cells harvested at three days of culture. By day six, however, all three agents, at levels which markedly inhibited proliferation, suppressed the expression of activation markers on both CD4+ and CD8+ cells. Also at day six, inhibition of activation molecule expression on CD4+ cells was achieved with the combination of FK 506 and either MPA or MZB at concentrations which, on their own, were ineffective. These data provide new, additional information on the in vitro antilymphocytic action of FK 506, MPA and MZB when used alone and in combination. © 1993