From "wet" matrices to "dry" blood spot sampling strategy: a versatile LC-MS/MS assay for simultaneous monitoring caffeine and its three primary metabolites in preterm infants.

OBJECTIVES: To update traditional "wet" matrices to dried blood spot (DBS) sampling, based on the liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technique, and develop a method for simultaneous analyzing caffeine and its three primary metabolites (theobromine, paraxanthine, and theophylline), supporting routine therapeutic drug monitoring (TDM) for preterm infants. METHODS: DBS samples were prepared by a two-step quantitative sampling method, i.e., volumetric sampling of a quantitative 10 µL volume of peripheral blood and an 8 mm diameter whole punch extraction by a methanol/water (80/20, v/v) mixture containing 125 mM formic acid. Four paired stable isotope labeled internal standards and a collision energy defect strategy were applied for the method optimization. The method was fully validated following international guidelines and industrial recommendations on DBS analysis. Cross validation with previously developed plasma method was also proceeded. The validated method was then implemented on the TDM for preterm infants. RESULTS: The two-step quantitative sampling strategy and a high recovery extraction method were developed and optimized. The method validation results were all within the acceptable criteria. Satisfactory parallelism, concordance, and correlation were observed between DBS and plasma concentrations of the four analytes. The method was applied to provide routine TDM services to 20 preterm infants. CONCLUSIONS: A versatile LC-MS/MS platform for simultaneous monitoring caffeine and its three primary metabolites was developed, fully validated, and successfully applied into the routine clinical TDM practices. Sampling method switching from "wet" matrices to "dry" DBS will facilitate and support the precision dosing of caffeine for preterm infants.

Study on energy evolution and fractal characteristics of sandstone with different fracture dip angles under uniaxial compression.

In order to investigate the failure modes and instability mechanism of fractured rock. Uniaxial compression tests were conducted on sandstone specimens with different dip angles. Based on rock energy dissipation theory and fractal theory, the energy evolution characteristics and fragmentation fractal characteristics in the process of deformation and failure of specimens were analyzed. The results show that the peak strength and elastic modulus of fractured rock mass are lower than those of intact samples, and both show an exponential increase with the increase of fracture dip angle. The energy evolution laws of different fracture specimens are roughly similar and can be classified into four stages based on the stress-strain curve: pressure-tight, elastic, plastic, and post-destructive. The total strain energy, elastic strain energy, and dissipated strain energy of the specimen at the peak stress point increased exponentially with crack inclination, and the dissipated strain energy and compressive strength conformed to a power function growth relationship. The distribution of the fragments after the failure of the fracture sample has fractal characteristics, and the fractal dimension increases with the increase of the fracture dip angle. In addition, the higher the compressive strength of the specimen, the greater the energy dissipation, the more serious the degree of fragmentation, and the greater the fractal dimension. The data fitting further shows that there is a power function relationship between the dissipated strain energy and the fractal dimension. The research results can provide a theoretical basis for the stability of rock mass engineering and structural deformation control.

Pars plana vitrectomy for retinal detachment using perfluoro-n-octane as intraoperative tamponade: a multicenter, randomized, non-inferiority trial.

AIM: To evaluate the efficacy and safety of perfluoro-n-octane (PFO) for ophthalmic surgery versus F-Octane as an intraoperative tamponade in pars plana vitrectomy (PPV) in management of retinal detachment. METHODS: This multicenter, prospective, randomized, double-masked, parallel-controlled, non-inferiority trial was conducted in three ophthalmology clinical centers in China. Patients with retinal detachment, who were eligible for PPV were consecutively enrolled. Participants were assigned to PFO for ophthalmic surgery or F-Octane for intraocular tamponade in a 1:1 ratio. Best-corrected visual acuity (BCVA), intraocular pressure (IOP) measurement, and dilated fundus examination were performed preoperatively and at 1, 7±1, 28±3d postoperatively. The primary outcome was complete retinal reattachment rate at postoperative day one. The non-inferiority margin was set at 9.8%. The secondary outcomes included intraoperative retinal reattachment rate, and mean changes in IOP and BCVA from baseline to 1, 7±1, 28±3d postoperatively, respectively. Safety analyses were presented for all randomly assigned participates in this study. RESULTS: Totally 124 eligible patients completed the study between Mar. 14, 2016 and Jun. 7, 2017. Sixty of them were randomly assigned to the PFO for ophthalmic surgery group, and 64 were assigned to the F-Octane group. Baseline characteristics were comparable between the two groups. Both groups achieved 100% retinal reattachment at postoperative day one (difference 0, 95%CI: -6.21% to 5.75%, P=1). The pre-defined noninferiority criterion was met. No significant difference was observed in intraoperative retinal reattachment rate (difference 1.77%, P=0.61), mean changes in IOP (difference 0.36, -0.09, 2.22 mm Hg at 1, 7±1, 28±3d postoperatively, with all P>0.05) and BCVA (difference 0.04, -0.02, 0.06 logMAR at 1, 7±1, 28±3d postoperatively, all P>0.05) between the two groups. No apparent adverse events related to the utilization of PFO were reported. CONCLUSION: In patients with retinal detachment undergoing PPV, PFO for ophthalmic surgery is non-inferior to F-Octane as an intraocular tamponade, and both are safe and well-tolerated.

Individualized atomoxetine response and tolerability in children with ADHD receiving different dosage regimens: the need for CYP2D6 genotyping and therapeutic drug monitoring to dance together.

Integrating CYP2D6 genotyping and therapeutic drug monitoring (TDM) is crucial for guiding individualized atomoxetine therapy in children with attention-deficit/hyperactivity disorder (ADHD). The aim of this retrospective study was (1) to investigate the link between the efficacy and tolerability of atomoxetine in children with ADHD and plasma atomoxetine concentrations based on their CYP2D6 genotypes; (2) to offer TDM reference range recommendations for atomoxetine based on the CYP2D6 genotypes of children receiving different dosage regimens. This retrospective study covered children and adolescents with ADHD between the ages of 6 and <18, who visited the psychological and behavioral clinic of Children's Hospital of Nanjing Medical University from June 1, 2021, to January 31, 2023. The demographic information and laboratory examination data, including CYP2D6 genotype tests and routine TDM of atomoxetine were obtained from the hospital information system. We used univariate analysis, Mann-Whitney U nonparametric test, Kruskal-Wallis test, and the receiver operating characteristic (ROC) curve to investigate outcomes of interest. 515 plasma atomoxetine concentrations of 385 children (325 boys and 60 girls) with ADHD between 6 and 16 years of age were included for statistical analysis in this study. Based on genotyping results, >60% of enrolled children belonged to the CYP2D6 extensive metabolizer (EM), while <40% fell into the intermediate metabolizer (IM). CYP2D6 IMs exhibited higher dose-corrected plasma atomoxetine concentrations by 1.4-2.2 folds than those CYP2D6 EMs. Moreover, CYP2D6 IMs exhibited a higher response rate compare to EMs (93.55% vs 85.71%, P = 0.0132), with higher peak plasma atomoxetine concentrations by 1.67 times than those of EMs. Further ROC analysis revealed that individuals under once daily in the morning (q.m.) dosing regimen exhibited a more effective response to atomoxetine when their levels were ≥ 268 ng/mL (AUC = 0.710, P < 0.001). In addition, CYP2D6 IMs receiving q.m. dosing of atomoxetine were more likely to experience adverse reactions in the central nervous system and gastrointestinal system when plasma atomoxetine concentrations reach 465 and 509 ng/mL, respectively. The findings in this study provided promising treatment strategy for Chinese children with ADHD based on their CYP2D6 genotypes and plasma atomoxetine concentration monitoring. A peak plasma atomoxetine concentration higher than 268 ng/mL might be requisite for q.m. dosing. Assuredly, to validate and reinforce these initial findings, it is necessary to collect further data in controlled studies with a larger sample size.

Population pharmacokinetics of valproic acid in children with epilepsy: Implications for dose tailoring when switching from oral syrup to sustained-release tablets.

Significant pharmacokinetic (PK) differences exist between different forms of valproic acid (VPA), such as syrup and sustained-release (SR) tablets. This study aimed to develop a population pharmacokinetic (PopPK) model for VPA in children with epilepsy and offer dose adjustment recommendation for switching dosage forms as needed. The study collected 1411 VPA steady-state trough concentrations (Ctrough) from 617 children with epilepsy. Using NONMEM software, a PopPK model was developed, employing a stepwise approach to identify possible variables such as demographic information and concomitant medications. The final model underwent internal and external evaluation via graphical and statistical methods. Moreover, Monte Carlo simulations were used to generate a dose tailoring strategy for typical patients weighting 20-50 kg. As a result, the PK characteristics of VPA were described using a one-compartment model with first-order absorption. The absorption rate constant (ka) was set at 2.64 and 0.46 h-1 for syrup and SR tablets. Body weight and sex were identified as significant factors affecting VPA's pharmacokinetics. The final PopPK model demonstrated acceptable prediction performance and stability during internal and external evaluation. For children taking syrup, a daily dose of 25 mg/kg resulted in the highest probability of achieving the desired target Ctrough, while a dose of 20 mg/kg/day was appropriate for those taking SR tablets. In conclusion, we established a PopPK model for VPA in children with epilepsy to tailor VPA dosage when switching between syrup and SR tablets, aiming to improve plasma VPA concentrations fluctuations.

Mediating Effect of White Blood Cells and Tobacco Exposure on Cervical Neoplasm Risk Among Taiwanese Women.

Background: Both the high-risk human papillomavirus (HR-HPV) infection and tobacco exposure are significantly associated with cervical neoplasm risk. Immune cells play important roles in carcinogenesis. However, it is still unclear whether immune cells have a mediating effect on the HR-HPV infection and tobacco exposure with cervical neoplasm development. Aim: The aim of this study was to determine how the increased white blood cell (WBC) count affects the relationship between HR-HPV DNA load and tobacco exposure in the development of cervical neoplasia. Methods: A hospital-based case-control study design was conducted with a total of 108 cases of Taiwanese women with ≥ cervical intraepithelial neoplasia (CIN) I confirmed by biopsy, and 222 healthy Taiwanese female subjects with negative findings on a Pap smear were assigned to the control group. The study evaluated HR-HPV status and immune cell counts (WBCs, natural killer (NK) cells) and tobacco exposure by a self-construct questionnaire. Results: Both HR-HPV DNA load and tobacco exposure significantly independently increased cervical neoplasm risk (AORs: 1.28 and 1.42, respectively). Similar significant results were found for WBCs and NK cells, with respective AORs of 1.20 and 1.00. Moreover, increased WBCs (ß = 0.04, 95% CI corrected: 0.01-0.07) and tobacco exposure (ß = 0.02, 95% CI corrected: 0.01-0.04) mediated the relationship between the high-risk HPV DNA load and cervical neoplasm risk. Conclusions: Elevated WBC count acts as both predictor and mediator in cervical neoplasm development linked to HR-HPV DNA load. Monitoring and maintaining WBC levels within the normal range could be a preventive strategy for cervical neoplasm development.

LC-MS/MS and EMIT measure the whole blood concentration of cyclosporine A: The two methods yield concordant results within the dynamic range of the latter, but the former shows broader application scenarios.

Cyclosporine A (CsA) is a widely used immunosuppressive drug with a narrow therapeutic index and large individual differences. Its therapeutic and toxic effects are closely related to blood drug concentrations, requiring routine therapeutic drug monitoring (TDM). The current main methods for TDM of CsA are enzyme multiplied immunoassay technique (EMIT) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, few study on the method comparison of the EMIT and LC-MS/MS for the measurement of whole blood CsA concentration in children has been reported. In this study, we developed a simple and sensitive LC-MS/MS assay for the determination of CsA, and 657 cases of CsA concentrations were determined from 197 pediatric patients by a routine EMIT assay and by the validated in-house LC-MS/MS method on the same batch of samples, aimed to address the aforementioned concern. Consistency between the two assays was evaluated using linear regression and Bland-Altman analysis. The linear range of LC-MS/MS was 0.500-2000 ng/mL and that of the EMIT was 40-500 ng/mL, respectively. Overall, the correlation between the two methods was significant (r-value ranging from 0.8842 to 0.9441). Unsatisfactory consistency was observed in the concentrations < 40 ng/mL (r = 0.7325) and 200-500 ng/mL (r = 0.6851). Bland-Altman plot showed a mean bias of -18.0 % (±1.96 SD, -73.8 to 37.8 %) between EMIT and LC-MS/MS. For Passing-Bablok regression between EMIT and LC-MS/MS did not differ significantly (p > 0.05). In conclusion, the two methods were closely correlated, but the CsA concentration by LC-MS/MS assay was slightly higher than that by EMIT method. Switching from the EMIT assay to the LC-MS/MS method was acceptable, and the LC-MS/MS method will receive broader application in clinical settings due to its better analytical capabilities, but the results need to be further verified in different laboratories.