SUMOylation of the ubiquitin ligase component KEAP1 at K39 upregulates NRF2 and its target function in lung cancer cell proliferation.

Nuclear Factor Erythroid 2-Related Factor 2 (NRF2) is important for the expression of genes associated with oxidative stress. The levels of NRF2 are controlled by Kelch-like ECH-associated protein 1 (KEAP1)-dependent degradation. Although oxidative stress is known to suppress KEAP1 activity to stabilize the levels of NRF2, the mechanism for this control is unclear. Here, we identify that KEAP1 is modified by SUMO1 at the lysine residue position 39 (K39). Arginine replacement of this lysine (K39R) in KEAP1 did not affect its stability, subcellular localization, or dimerization but promoted the formation of the Cullin 3 ubiquitin ligase and increased NRF2 ubiquitination. This was accompanied by decreased NRF2 expression. Gene reporter assays showed that the transcription of antioxidant response elements was heightened in KEAP1-WT cells compared to cells expressing the KEAP1-K39R SUMO1 substrate mutant. Consistent with this, chromatin immunoprecipitation assays revealed higher NRF2 binding to the promoter regions of antioxidant genes in cells expressing the KEAP1-WT compared to the KEAP1-K39R mutant protein in H1299 lung cancer cell. The significance of this suppression of KEAP1 activity by its SUMOylation was tested in a subcutaneous tumor model of H1299 lung cancer cell lines that differentially expressed the WT and K39R KEAP1 constructs. This model showed that mutating the SUMOylation site on KEAP1 altered the production of reactive oxygen species and suppressed tumor growth. Taken together, our study recognizes that NRF2-dependent redox control is regulated by the SUMOylation of KEAP1. These findings identify a potential new therapeutic option to counteract oxidative stress.

HDAC6 inhibitor promotes reactive oxygen species-meditated clearance of Staphylococcus aureus in macrophage.

Staphylococcus aureus (S. aureus) pneumonia has become an increasingly important public health problem. Recent evidence suggests that epigenetic modifications are critical in the host immune defence against pathogen infection. In this study, we found that S. aureus infection induces the expression of histone deacetylase 6 (HDAC6) in a dose-dependent manner. Furthermore, by using a S. aureus pneumonia mouse model, we showed that the HDAC6 inhibitor, tubastatin A, demonstrates a protective effect in S. aureus pneumonia, decreasing the mortality and destruction of lung architecture, reducing the bacterial burden in the lungs and inhibiting inflammatory responses. Mechanistic studies in primary bone marrow-derived macrophages demonstrated that the HDAC6 inhibitors, tubastatin A and tubacin, reduced the intracellular bacterial load by promoting bacterial clearance rather than regulating phagocytosis. Finally, N-acetyl-L- cysteine, a widely used reactive oxygen species (ROS) scavenger, antagonized ROS production and significantly inhibited tubastatin A-induced S. aureus clearance. These findings demonstrate that HDAC6 inhibitors promote the bactericidal activity of macrophages by inducing ROS, an important host factor for S. aureus clearance and production. Our study identified HDAC6 as a suitable epigenetic modification target for preventing S. aureus infection, and tubastatin A as a useful compound in treating S. aureus pneumonia.

Metasurfaces with high-Q resonances governed by topological edge state.

Achieving high-quality (Q)-factor resonances in metasurfaces is essential for various applications, including nano-lasers, nonlinear optics, and quantum optics. In this work, we propose a high-Q metasurface using a topological strategy: constructing the metasurface by stacking two conjugated nanopillar arrays with different topological invariants. Our study shows that a topological edge state steadily appears at the interfaces of the nanopillars, and a sharp transmission resonance with a Q-factor of more than 1000 can be obtained. The sensing application of such high-Q topological metasurface is also demonstrated, whose figure of merit reaches approximately 145. The proposed strategy and underlying theory can open up new avenues to realize ultrasharp resonances, which can promote numerous potential applications, such as biosensing, optical modulation, and slow-light devices.

Coherently controllable terahertz plasmon-induced transparency using a coupled Fano-Lorentzian metasurface.

Metamaterials have been engineered to achieve electromagnetically induced transparency (EIT)-like behavior, analogous to those in quantum optical systems. These meta-devices are opening new paradigms in terahertz communication, ultra-sensitive sensing and EIT-like anti-reflection. The controlled coupling between a sub-radiant and a super-radiant particle in the unit cells of these metamaterial can enable multiple narrow plasmon induced transparency (PIT) windows over a broad band, with considerable group delay of electromagnetic field (slow light effect). Phase coherence between these PIT windows is highly desired for next-generation multichannel communication network. Herein, we numerically and experimentally validate a controllable frequency hopping mechanism between "slow light" windows in the terahertz (THz) regime. The effective media are composed of plasmonic "molecules" in which an asymmetric split-ring resonator (ASRR) or Fano resonator is displaced on the side of a cut-wire (Lorentz oscillator). Two metasurfaces where ASRR is on opposite side of the cut-wire are investigated. In these two cases, the proximity of the cut-wire to the gap on the ASRR having asymmetry is different. On one side, when the gap is nearer to the cut wire, displacing the ASRR along the cut-wire, produces only one narrow transparency window at 0.8 THz, corresponding to 20 ps group delay. When the ASRR is positioned on the opposite side, such that the gap is further, two transparency windows are observed when the ASRR is displaced along the cut-wire. That is, the transparency window hops from 0.8 THz to 1.2 THz. This corresponds to an increase from 20 to 30 ps in slow light effect. Numerical simulations suggest these single or multiple PIT windows occur if the couplings between the plasmonic modes in the different arrangements are either in-phase or out-of-phase, respectively.

Cross-reactivity between MUC1 antigen and MCA: false elevation of serum CA 15-3 level in pregnant and lactating women by Ma695-Ma552-based assay.

PURPOSE: Cancer antigen 153 (CA 15-3) is one of the most commonly used biomarkers of breast cancer. However, elevated CA 15-3 is reported in pregnant and lactating women more frequently on Beckman DxI 800 immunoassay system (Ma695-Ma552 antibody pair) than on Abbott ARCHITECT system (115D8-DF3 antibody pair) in laboratory methodological evaluation. We conducted this study in order to figure out the reason behind this phenomenon. METHODS: Serum CA 15-3 concentration was analyzed in 426 subjects, including 180 patients with breast cancer, 121 patients with benign breast disease, and 125 healthy volunteers (45 pregnant and 80 non-pregnant women). CA 15-3 assay was further validated using another cohort of 112 pregnant or postpartum women. Immunological cross reaction was analyzed by Western blotting and immunoprecipitation. RESULTS: The serum CA 15-3 level was abnormally higher in almost 95% of the pregnant and lactating women detected using Ma695-Ma552 antibody pair (median: 71.4 U/mL) than that detected using 115D8-DF3 antibody pair (median: 16.5 U/mL). Western blotting and immunoprecipitation indicated that such a significant difference was mainly due to the cross reaction between monoclonal antibody Ma552 and mucin-like carcinoma-associated antigen (MCA). CONCLUSIONS: The CA 15-3 assay using 115D8-DF3 antibody pair is more suitable for monitoring therapy in pregnancy-associated breast cancer.

Somatic mutational analysis of FAK in breast cancer: a novel gain-of-function mutation due to deletion of exon 33.

Focal adhesion kinase (FAK) regulates cell adhesion, migration, proliferation, and survival. We identified a novel splicing mutant, FAK-Del33 (exon 33 deletion, KF437463), in both breast and thyroid cancers through colony sequencing. Considering the low proportion of mutant transcripts in samples, this mutation was detected by TaqMan-MGB probes based qPCR. In total, three in 21 paired breast tissues were identified with the FAK-Del33 mutation, and no mutations were found in the corresponding normal tissues. When introduced into a breast cell line through lentivirus infection, FAK-Del33 regulated cell motility and migration based on a wound healing assay. We demonstrated that the expression of Tyr397 (main auto-phosphorylation of FAK) was strongly increased in FAK-Del33 overexpressed breast tumor cells compared to wild-type following FAK/Src RTK signaling activation. These results suggest a novel and unique role of the FAK-Del33 mutation in FAK/Src signaling in breast cancer with significant implications for metastatic potential.

NF-kappaB P50/P65 hetero-dimer mediates differential regulation of CD166/ALCAM expression via interaction with micoRNA-9 after serum deprivation, providing evidence for a novel negative auto-regulatory loop.

CD166/ALCAM plays an important role in tumor aggression and progression as well as protecting cancer cells against apoptosis and autophagy. However, the mechanism by which pro-cell death signals control CD166 expression remains unclear. Here we show that following serum deprivation (SD), upregulation of CD166 protein is shorter than that of CD166 mRNA. Molecular analysis revealed both CD166 and miR-9-1 as two novel NF-κB target genes in hepatoma cells. In vivo activation and translocation of the NF-κB P50/P65 hetero-dimer into the nucleus following the phosphorylation and accompanied degradation of its inhibitor, IκBα, contributes to efficient transcription of both genes following SD. We show that following serum starvation, delayed up-regulation of miR-9 represses translation of CD166 protein through its target sites in the 3'-UTR of CD166 mRNA. We also propose that miR-9 promotes cell migration largely due to inhibition of CD166. Collectively, the study elucidates a novel negative auto-regulatory loop in which NF-κB mediates differential regulation of CD166 after SD.

Prognostic Significance of Iron Metabolism Related Genes in Human Lung Adenocarcinoma.

Background: Iron metabolism related genes participate in cell proliferation, cell growth, and redox cycling in multiple cancers. Limited studies have revealed the roles and clinical significance of iron metabolism in the pathogenesis and prognosis of lung cancer. Methods: A total of 119 iron metabolism related genes were extracted from MSigDB database and their prognostic values were determined in The Cancer Genome Atlas lung adenocarcinoma (TCGA-LUAD) dataset and the Gene Expression Profiling Interactive Analysis 2 (GEPIA 2) database. Immunohistochemistry technique and correlations with immune cell infiltration, gene mutation and drug resistance were used to identify the potential and underlying mechanisms of STEAP1 and STEAP2 as prognostic biomarkers of LUAD. Results: The expression of STEAP1 and STEAP2 are negatively associated with the prognosis of LUAD patients both at the mRNA and protein level. The expression of STEAP1 and STEAP2 was not only negatively correlated with the trafficking degree of CD4+ T immune cells and positively related to most immune cells' trafficking degree, but also significantly associated with gene mutation status, particularly with mutations on TP53 and STK11. Four types of drug resistance showed significant correlation with the expression level of STEAP1 while 13 types of drug resistance were associated with the expression level of STEAP2. Conclusion: Multiple iron metabolism related genes including STEAP1 and STEAP2 are significantly associated with the prognosis of LUAD patients. STEAP1 and STEAP2 might affect the prognosis of LUAD patients partially through immune cell infiltration, gene mutation and drug resistance, which indicated they were independent prognostic factors for LUAD patients.

Plasma 25(OH)D Level is Associated with the Nucleic Acid Negative Conversion Time of COVID-19 Patients: An Exploratory Study.

Purpose: Vitamin D, an essential nutrient and a pleiotropic steroid hormone, has been reported to be associated with the risk and severity in patients infected with Coronavirus Disease-2019 (COVID-19). The role of vitamin D in predicting clinical outcome for COVID-19 patients is unknown. Here, we aimed to determine the prognostic value of plasma 25(OH)D level in COVID-19 patients. Patients and Methods: A total of 158 patients infected with novel COVID-19 Omicron variants in Shanghai were recruited in this study and were categorized into three groups by the tertile levels of plasma 25(OH)D. Plasma 25(OH)D level was determined along with routine blood tests related to liver and renal functions in newly diagnosed COVID-19 patients at admission. The nucleic acid negative conversion time of throat swab samples was evaluated as the primary clinical outcome. The prognostic value of clinical characteristics and plasma 25(OH)D level was assessed using the Kaplan-Meier plot and Cox proportional hazards regression tests. Results: Higher level of plasma 25(OH)D level in COVID-19 patients was independently associated with shorter nucleic acid negative conversion time from COVID-19 infection (multivariate adjusted HR: 0.54, 95%CI: 0.35-0.82, P=0.004, tertile 2 vs 1; multivariate adjusted HR: 0.60, 95%CI: 0.39-0.90, P=0.014, tertile 3 vs 1). Conclusion: Plasma 25(OH)D level may serve as an independent prognostic factor in COVID-19 patient. Our findings indicate the protective roles of vitamin D supplementation in the regiment of patients with COVID-19.

Risk factor analysis of omicron patients with mental health problems in the Fangcang shelter hospital based on psychiatric drug intervention during the COVID-19 pandemic in Shanghai, China.

Backgrounds: The widespread coronavirus disease 2019 (COVID-19) outbreak impacted the mental health of infected patients admitted to Fangcang shelter hospital a large-scale, temporary structure converted from existing public venues to isolate patients with mild or moderate symptoms of COVID-19 infection. Objective: This study aimed to investigate the risk factors of the infected patients from a new pharmacological perspective based on psychiatric drug consumption rather than questionnaires for the first time. Methods: We summarised the medical information and analysed the prevalence proportion, characteristics, and the related risk factors of omicron variants infected patients in the Fangcang Shelter Hospital of the National Exhibition and Convention Center (Shanghai) from 9 April 2022 to 31 May 2022. Results: In this study, 6,218 individuals at 3.57% of all admitted patients in the Fangcang shelter were collected suffering from mental health problems in severe conditions including schizophrenia, depression, insomnia, and anxiety who needed psychiatric drug intervention. In the group, 97.44% experienced their first prescription of psychiatric drugs and had no diagnosed historical psychiatric diseases. Further analysis indicated that female sex, no vaccination, older age, longer hospitalization time, and more comorbidities were independent risk factors for the drug-intervened patients. Conclusion: This is the first study to analyse the mental health problems of omicron variants infected patients hospitalised in Fangcang shelter hospitals. The research demonstrated the necessity of potential mental and psychological service development in Fangcang shelters during the COVID-19 pandemic and other public emergency responses.

Effect of tixagevimab/cilgavimab for pre-exposure prophylaxis during the China Omicron outbreak.

OBJECTIVES: By the end of 2022, China had made a pivotal decision to optimize the COVID-19 policy. The dominant Omicron variant in China at that time was highly transmissible. In this study, we aimed to evaluate the real-world safety and efficacy of tixagevimab and cilgavimab against this background in China. METHODS: Participants were enrolled if they were over 12 years old and were planning to receive tixagevimab or cilgavimab. All participants received intramuscular administration of tixagevimab (150 mg) and cilgavimab (150 mg). Data were collected on demographics, underlying illness, prior infection, vaccination, adverse events, and COVID-19 outcomes (e.g., infection rate, hospitalization rate, and severe disease). RESULTS: During the study period, 168 (37.9%) of 443 who received tixagevimab/cilgavimab were diagnosed with SARS-CoV-2 infection. All infected patients had mild COVID-19. Two patients (0.5%) were hospitalized for COVID-19, but none of them were admitted to the ICU. None of the patients died during this study. 4 (0.9%) reported mild local adverse events, and no severe systemic adverse reactions were reported. CONCLUSION: Tixagevimab/cilgavimab may have protected high-risk populations against infection with the Omicron variant, hospitalization and severe disease during the China COVID-19 pandemic.

Identification of novel mitosis regulators through data mining with human centromere/kinetochore proteins as group queries.

BACKGROUND: Proteins functioning in the same biological pathway tend to be transcriptionally co-regulated or form protein-protein interactions (PPI). Multiple spatially and temporally regulated events are coordinated during mitosis to achieve faithful chromosome segregation. The molecular players participating in mitosis regulation are still being unravelled experimentally or using in silico methods. RESULTS: An extensive literature review has led to a compilation of 196 human centromere/kinetochore proteins, all with experimental evidence supporting the subcellular localization. Sixty-four were designated as "core" centromere/kinetochore components based on peak expression and/or well-characterized functions during mitosis. By interrogating and integrating online resources, we have mined for genes/proteins that display transcriptional co-expression or PPI with the core centromere/kinetochore components. Top-ranked hubs in either co-expression or PPI network are not only enriched with known mitosis regulators, but also contain candidates whose mitotic functions are not yet established. Experimental validation found that KIAA1377 is a novel centrosomal protein that also associates with microtubules and midbody; while TRIP13 is a novel kinetochore protein and directly interacts with mitotic checkpoint silencing protein p31(comet). CONCLUSIONS: Transcriptional co-expression and PPI network analyses with known human centromere/kinetochore proteins as a query group help identify novel potential mitosis regulators.

SP1 plays a pivotal role for basal activity of TIGAR promoter in liver cancer cell lines.

TIGAR expression resulted in down-regulation of glycolysis, reduction of intracellular levels of reactive oxygen species, and protection from apoptosis. Despite biological importance, its promoter has not yet been characterized. In this study, we characterized that transcription factor SP1 plays a pivotal role for basal activity of TIGAR promoter. By 5'RACE, the transcription start site was identified locating at 134 bp upstream of the translation initiation site. Different portions of 5'-flanking and 5'-untranslated regions were fused to a luciferase reporter gene to create reporter plasmids, and constructs were transiently transfected into HepG2, Bel-7402, and Smmc-7721 cell lines for luciferase analysis. A minimal region -56/-4 bearing a SP1-binding site was characterized and plays a vital role. Data from electrophoretic mobility shift assay and chromatin immunoprecipitation showed that SP1 can interact with the SP1-binding site within TIGAR promoter in vitro and in vivo. Conclusively, SPl is indispensable for basal activity of TIGAR promoter.

CREB up-regulates long non-coding RNA, HULC expression through interaction with microRNA-372 in liver cancer.

Long non-coding RNA (lncRNA), highly up-regulated in liver cancer (HULC) plays an important role in tumorigenesis. Depletion of HULC resulted in a significant deregulation of several genes involved in liver cancer. Although up-regulation of HULC expression in hepatocellular carcinoma has been reported, the molecular mechanisms remain unknown. In this study, we used in vivo and in vitro approaches to characterize cancer-dependent alterations in the chromatin organization and find a CREB binding site (encompassing from -67 to -53 nt) in the core promoter. Besides, we also provided evidence that PKA pathway may involved in up-regulation of HULC. Furthermore, we demonstrated HULC may act as an endogenous 'sponge', which down-regulates a series of microRNAs (miRNAs) activities, including miR-372. Inhibition of miR-372 leads to reducing translational repression of its target gene, PRKACB, which in turn induces phosphorylation of CREB. Over-expression of miR-372 decreases the association of CREB with the proximal promoter, followed by the dissociation of P300, resulting in a change of the histone 'code', such as in deacetylation and methylation. The study elucidates that fine tuning of HULC expression is part of an auto-regulatory loop in which it's inhibitory to expression and activity of miR-372 allows lncRNA up-regulated expression in liver cancer.

Identification and Characterization of Extrachromosomal Circular DNA in Plasma of Lung Adenocarcinoma Patients.

Background: Chromosome is the basic framework for eukaryotic cells to store genetic information, but certain genes exist in circulation, such as extrachromosomal circular DNA (eccDNA). The unique genetic characteristics and structure of eccDNA provide a new vision on the early diagnosis of cancer; however, whether eccDNA contributes to the early diagnosis and progression of lung cancer remains unclear. Methods: We performed next-generation sequencing (NGS) analysis of eccDNA from the plasma of 6 lung adenocarcinoma (LUAD) patients. The data of plasma eccDNA of healthy people were obtained from public available database. We compared size distribution, chromosome origin, formation and expression patterns of eccDNA between LUAD patients and those of 6 healthy people and 4 healthy gravidas. Results: A total number of 716,059 eccDNA ranging from 22 bp to 3,297,519 bp were detected with an average size less than 800bp and distinctive bimodality in size around 191 bp and 320 bp. After comparison of eccDNA abundance in each sequencing sample, nine eccDNA were ranked on top with higher frequency in lung adenocarcinoma patients than healthy people. Among them, four eccDNA (DOCK1, PPIC, TBC1D16, and RP11-370A5.1) were uniquely expressed in lung adenocarcinoma patients, which may serve as potential biomarkers for early diagnosis LUAD. Conclusion: Cancer-specific eccDNA was presented in LUAD compared to normal people, which might serve as a promising biomarker in LUAD.

Population pharmacokinetic study of cyclosporine in Chinese renal transplant recipients.

PURPOSE: To establish the population pharmacokinetic (PPK) model of cyclosporine (CsA) in Chinese renal transplant recipients and evaluate the influence of various indexes including CYP3A5 and MDR1 genetic polymorphism on pharmacokinetic parameters. METHODS: Trough (C(0)) and peak (C(2)) CsA concentration were monitored conventionally after renal transplantation. C(0) and C(2) were collected for 5 months in 146 patients. The CYP3A5*3 genotype and MDR1 haplotype were determined by methods based on amplification refractory mutant PCR. The data were analyzed by nonlinear mixed-effect modeling (NONMEM). The model was evaluated using goodness of fit plots and relative error measurements. Physiological and pathological factors including CYP3A5 and MDR1 genotypes were evaluated as covariates of CsA pharmacokinetic parameters. RESULTS: Pharmacokinetics of CsA was best described by a one-compartment disposition model followed a first-order absorption process. The estimated clearance (CL/F) was 49.5 l·h(-1), the volume of distribution (Vd/F) was 226 l. K(a) was fixed as 1.25 h(-1). Post-transplant data, body weight, total bilirubin, and MDR1 genotype were covariates of CL/F (P < 0.005). Gender and MDR1 haplotype were covariates of Vd/F (P < 0.005). The AUC estimated based on the Bayesian method was 7,465 ± 1,708 ng·h·ml(-1) (2,946 ∼13,926 ng·h·ml(-1)). CONCLUSION: The PPK model developed in this study could be used to optimize CsA dose for Chinese renal transplant recipients by using conventional therapeutic drug monitoring (TDM) data.

Rapid endogenic rock recycling in magmatic arcs.

In subduction zones, materials on Earth's surface can be transported to the deep crust or mantle, but the exact mechanisms and the nature of the recycled materials are not fully understood. Here, we report a set of migmatites from western Yangtze Block, China. These migmatites have similar bulk compositions as forearc sediments. Zircon age distributions and Hf-O isotopes indicate that the precursors of the sediments were predominantly derived from juvenile arc crust itself. Using phase equilibria modeling, we show that the sediments experienced high temperature-to-pressure ratio metamorphism and were most likely transported to deep arc crust by intracrustal thrust faults. By dating the magmatic zircon cores and overgrowth rims, we find that the entire rock cycle, from arc magmatism, to weathering at the surface, then to burial and remelting in the deep crust, took place within ~10 Myr. Our findings highlight thrust faults as an efficient recycling channel in compressional arcs and endogenic recycling as an important mechanism driving internal redistribution and differentiation of arc crust.

SP1 is required for basal activation and chromatin accessibility of CD151 promoter in liver cancer cells.

CD151 plays an important role in liver cancer metastasis. The mechanism on how CD151 is expressed remains unclear. Here we have identified SP1 is a protein functioning in constitutive activation of CD151. Applying a PCR-based chromatin accessibility assay, an open chromatin conformation was discovered localized around the transcription start site of the CD151 gene. Deletion constructs of the 5' flanking region were fused to a luciferase reporter gene. After transient transfection in HepG2 and Hep3B cells, a minimal region -171/-53 bearing three SP1-binding sites was identified as the core promoter. Results obtained from electrophoretic mobility shift and chromatin immunoprecipitation assays demonstrated that SP1 is bound to the core promoter. Deletion of SP1 consensus sequence resulted in the total loss of the promoter activity. Moreover, knockdown of SP1 reduced both CD151 promoter activity and chromatin accessibility. Conclusively, SP1 is pivotal to CD151 transcription partly via the construction of a local open chromatin configuration across the promoter.

Establishment of high-performance liquid chromatography and enzyme multiplied immunoassay technology methods for determination of free mycophenolic acid and its application in Chinese liver transplant recipients.

The objective of this study is to investigate the correlation between methods of high-performance liquid chromatography (HPLC) and enzyme multiplied immunoassay technology (EMIT) for determination of total mycophenolic acid (tMPA) and free (fMPA) concentration and to study pharmacokinetics of fMPA in Chinese liver transplant recipients. An HPLC method with fluorometric detection and an EMIT assay were established to determine fMPA in plasma ultrafiltrates. Pharmacokinetic parameters of tMPA and fMPA in 51 patients were estimated. The calibration range of fMPA was 0.0025 to 1.0 µg/mL for the HPLC method and 0.0050 to 0.50 µg/mL for the EMIT method. Mean recovery of the two methods was 98.0% and 97.1%, respectively. The intraday and interday coefficient of variations were 0.93% to 3.1% and 1.6% to 2.9% for HPLC and 4.51% to 15.8% and 5.83% to 19.5% for EMIT, respectively. The relationship of the two methods was EMIT = 1.074 × HPLC + 0.582 (r2 = 0.918, n = 470, P < 0.05) for tMPA and EMIT = 1.068 × HPLC + 0.004 (r2 = 0.945, n = 297, P < 0.05) for fMPA. There was a positive mean bias of EMIT for tMPA (27.0%) and fMPA (23.3%). The AUC0-12 of tMPA and fMPA obtained by HPLC in 51 patients was 34.7 ± 11.1 and 0.72 ± 0.38 µg·h/mL, respectively. The free fraction of MPA was 1.60 ± 1.21% (Median:1.36%, interquartile: 0.72, 2.22), [corrected] which was significantly correlated with 7-O-glucuronide conjugate of MPA AUC0-12 (r2 = 0.705, P < 0.001), albumin (r2 = -0.529, P < 0.001), and the clearance of creatinine (r2 = -0.417, r2 = 0.005). Both HPLC and EMIT assay are suitable for the determination of fMPA. A considerable interindividual variability exists in pharmacokinetics of fMPA among Chinese liver transplant recipients. 7-O-Glucuronide conjugate of MPA and albumin concentrations are two factors correlated to fMPA variance.

Models for the prediction of mycophenolic acid area under the curve using a limited-sampling strategy and an enzyme multiplied immunoassay technique in Chinese patients undergoing liver transplantation.

BACKGROUND: An enzyme multiplied immunoassay technique (EMIT) provides convenient and accurate measurements of mycophenolic acid (MPA) concentrations for determination of immunosuppression during treatment with mycophenolate mofetil (MMF). No abbreviated model for estimating the full 12-hour MPA AUC using an EMIT assay in liver transplant recipients has been described previously. OBJECTIVE: This study was conducted to determine the best model for predicting the MPA AUC using the EMIT method and a limited-sampling strategy in Chinese patients undergoing liver transplantation. METHODS: The study enrolled consecutive liver transplant patients who were receiving MMF 1 g BID along with tacrolimus. A complete MPA pharmacokinetic profile was obtained for each patient on a single day, 7 to 14 days after transplantation. The EMIT method was used to determine MPA concentrations before dosing and at 0.5, 1, 1.5, 2, 4, 6, 8, 10, and 12 hours after dosing on the sampling day. Multiple linear regression analysis was used to evaluate potential models for estimating the full 12-hour MPA AUC. The accuracy and robustness of the models were evaluated using bootstrap analysis. Prediction error and prediction bias were calculated. Agreement between the estimated MPA AUC(0-12) and the full 12-hour MPA AUC was investigated using Bland-Altman analysis. RESULTS: The study enrolled 48 Chinese liver transplant recipients (45 male, 3 female) with a mean (SD) age of 50 (12) years, mean weight of 64 (12) kg, and mean height of 169 (6) cm. Twenty-four models that included blood sampling at 1 through 4 time points were developed (r(2) = 0.015-0.950). Four models with the highest r(2) values were selected; the lack of significant differences from the original dataset on bootstrap analysis indicated acceptable accuracy and robustness. The best model for predicting the MPA AUC(0-12) employed concentrations at 1, 2, 4, and 8 hours; 40 of 48 (83.3%) MPA AUC(0-12) values estimated using this model were within 15% of the full 12-hour MPA AUC. This model had a minimal mean prediction error (mean [SD], 0.27% [1.79%]) and mean absolute prediction error (8.83% [1.24%]). On Bland-Altman analysis, this model also had the best agreement between the estimated MAP AUC(0-12) and the full 12-hour MPA AUC, with a mean error of 9.02 mg . h/L. CONCLUSIONS: In this small group of Chinese liver transplant patients receiving MMF and concomitant tacrolimus, models for estimating the MPA AUC(0-12) were developed using the EMIT method and a limited-sampling strategy. The best model for prediction of the full 12-hour MPA AUC was 4.46 + 0.81 . C1 + 1.78 . C(2)+2.51.C(4)+4.94.C8.