Background High-dose methotrexate (HD-MTX) is seen as an effective therapy for acute lymphoblastic leukemia (ALL); however, it is extremely toxic. Monitoring the plasma concentrations of methotrexate (MTX) and its important metabolite, 7-hydroxy-methotrexate (7-OH-MTX), on a routine basis aids in dose modification of rescue medications and in avoiding toxicity. The pharmacologically active and toxic effects of drugs are due to the unbound portion, as most drugs are bound to plasma proteins to some degree. However, the simultaneous measurement of unbound plasma concentrations of MTX and 7-OH-MTX has not been reported.Methods We developed and validated a hollow fiber centrifugal ultrafiltration (HFCF-UF) technology to simultaneously analyze unbound MTX and 7-OH-MTX concentrations in human plasma. In total, 234 plasma samples from 58 children diagnosed with ALL who were administered HD-MTX were used in our study. We investigated the connection between unbound and total plasma concentrations of MTX and 7-OH-MTX, as well as how these concentrations relate to liver and renal function.Results The method that was developed is both simple and accurate. A weak linear relationship was observed between the concentrations of unbound and total 7-OH-MTX (r2 = 0.732). The concentration of total MTX and unbound 7-OH-MTX were both positively correlated with creatinine (Cr) levels and negatively correlated with Creatinine clearance (CCr). There was a wide variation in the concentration ratios of 7-OH-MTX to MTX, both total and unbound, and these ratios were significantly lower in individuals with impaired liver function.Conclusion The total concentration of 7-OH-MTX is an unreliable predictor of unbound concentration, necessitating the monitoring of unbound levels. The concentration ratios of 7-OH-MTX to MTX (both total and unbound) could be more accurate and sensitive biomarkers for predicting hepatotoxicity.
Background: Owing to the long penetration depth of gamma (γ)-rays, individuals working in ionizing radiation environments are chronically exposed to low-dose γ-radiation, resulting in cognitive changes. Dose rate significantly affects radiation-induced biological effects; however, its role in chronic low-dose γ-irradiation-induced cognitive impairment remains unclear. We aimed to investigate whether chronic low-dose γ-irradiation at low-dose-rate (LDR) could induce cognitive impairment and to compare the cognitive alteration caused by chronic low-dose γ-irradiation at LDR and high-dose-rate (HDR).Methods: The rats were exposed to γ-irradiation at a LDR of 6 mGy/h and a HDR of 20 mGy/h for 30 days (5 h/day). Functional imaging was performed to assess the brain inflammation and blood–brain barrier (BBB) destruction of rats. Histological and immunofluorescence analyses were used to reveal the neuron damage and the activation of microglia and astrocytes in the hippocampus. RNA sequencing was conducted to investigate changes in gene expression in hippocampus.Results: The rats in the LDR group exhibited more persistent cognitive impairment than those in the HDR group. Furthermore, irradiated rats showed brain inflammation and a compromised BBB. Histologically, the number of hippocampal neurons were comparable in the LDR group but were markedly decreased in the HDR. Additionally, activated M1-like microglia and A1-like astrocytes were observed in the hippocampus of rats in the LDR group; however, only M1-like microglia were activated in the HDR group. Mechanistically, the PI3K–Akt signaling pathway contributed to the different cognitive function change between the LDR group and HDR group.Conclusion: Compared with chronic low-dose γ-irradiation at HDR, LDR induced more severe cognitive impairment which might involve PI3K/Akt signaling pathway.
In this study, we constructed a novel powder-laden core–shell crosslinked chitosan microneedle patch for high-dose and controllable delivery of various drugs, including both macromolecular biological drugs and small-molecule chemical drugs. Direct loading of drug powders greatly improved drug loading capacity and minimized degradation. The results of the in vitro drug release study suggested that the release behaviors of the most tested drugs (both macromolecular drugs and small-molecule drugs) can be tuned by adjusting the crosslink density of the microneedle shell to achieve either rapid or sustained release of the loaded drug. The in vivo hypoglycemic efficacy test in streptozotocin-induced diabetic mice further proved that the onset and duration of the insulin-laden patch can be customized by adjusting the crosslink density. Furthermore, a combination of microneedle patches with different crosslink densities not only rapidly reduced blood glucose levels to normoglycemic levels (within 1 h) but also maintained normoglycemia for up to 36 h. The insulin loaded in the patch also showed good stability during storage at 40 °C for 6 months. Our results suggest that this powder-laden patch represents a strong candidate for addressing the multiple challenges in the preparation and application of polymeric microneedles and shows promise in clinical applications.
危险品化学品经营许可证（带存储）