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Background: Acute ischemic stroke (AIS) is one of the most common cerebrovascular diseases which accompanied by a disruption of aminothiols homeostasis. To explore the relationship of aminothiols with neurologic impairment severity, we investigated four aminothiols, homocysteine (Hcy), cysteine (Cys), cysteinylglycine (CG) and glutathione (GSH) in plasma and its influence on ischemic stroke severity in AIS patients. Methods: A total of 150 clinical samples from AIS patients were selected for our study. The concentrations of free reduced Hcy (Hcy), own oxidized Hcy (HHcy), free reduced Cys (Cys), own oxidized Cys (cysteine, Cyss), free reduced CG (CG) and free reduced GSH (GSH) were measured by our previously developed hollow fiber centrifugal ultrafiltration (HFCF-UF) method coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The concentration ratio of Hcy to HHcy (Hcy/HHcy), Cys to Cyss (Cys/Cyss) were also calculated. The neurologic impairment severity of AIS was evaluated using National Institutes of Health Stroke Scale (NIHSS). The Spearman correlation coefficient and logistic regression analysis was used to estimate and perform the correlation between Hcy, HHcy, Cys, Cyss, CG, GSH, Hcy/HHcy, Cys/Cyss and total Hcy with NIHSS score. Results: The reduced Hcy and Hcy/HHcy was both negatively correlated with NIHSS score in AIS patients with P = 0.008, r=-0.215 and P = 0.002, r=-0.249, respectively. There was no significant correlation of Cys, CG, GSH, HHcy, Cyss, Cys/Cyss and total Hcy with NIHSS score in AIS patients with P value > 0.05. Conclusions: The reduced Hcy and Hcy/HHcy, not total Hcy concentration should be used to evaluate neurologic impairment severity of AIS patient. [ABSTRACT FROM AUTHOR]

We developed a hollow fiber centrifugal ultrafiltration (HFCF-UF) method to study the change of plasma levels of free glycine (Gly) in patients with acute ischemic stroke (AIS). Twenty-four patients with AIS confirmed by diffusion-weighted imaging (DWI) were enrolled. During the study period, the patients did not receive any supplemental amino acids therapy that could affect the obtained results. Our results showed that although AIS patients adopted different methods of treatment (thrombolytic and non-thrombolytic), the clinical NIHSS score of AIS showed a downward trend whereas Gly concentration showed increased trend. Moreover, plasma free Gly concentration was positively correlated with ASPECTS score. The correlation between Gly levels and infarct volume showed a statistical significance. That is to say, higher Gly level predicted smaller infarct size. Thus, the change of free Gly level in plasma could be considered as a potential biomarker of AIS. [ABSTRACT FROM AUTHOR]

A simple sample preparation method has been developed for the determination of amoxicillin in human plasma by hollow fiber centrifugal ultrafiltration (HF–CF–UF). A 400-μL plasma sample was placed directly into the HF–CF–UF device, which consisited of a slim glass tube and a U-shaped hollow fiber. After centrifugation at 1.25 × 103 g for 10 min, the filtrate was withdrawn from the hollow fiber and 20 µL was directly injected into the high-performance liquid chromatography (HPLC) for analysis. The calibration curve was linear over the range of 0.1–20 µg/mL (r = 0.9996) and the limit of detection was as low as 0.025 µg/mL. The average recovery and absolute recovery were 99.9% and 84.5%, respectively. Both the intra-day and inter-day precisions (relative standard deviation) were less than 3.1% for three concentrations (0.25, 2.5 and 10 µg/mL). The sample preparation process was simplified. Only after a single centrifugal ultrafiltration can the filtrate be injected directly into HPLC. The present method is simple, sensitive and accurate. It could be effective for the analysis of biological samples with high protein contents, especially for the biopharmaceutical analysis of drugs that use traditional isolation techniques for sample preparation such as the protein precipitation method. [ABSTRACT FROM AUTHOR]

High-dose methotrexate (HD-MTX) can be highly effective as well as extremely toxic. Many drug molecules can bind to plasma proteins to different extents in vivo , whereas only the free drug can reach the site of action to exert a pharmacological effect and cause toxicity. However, free MTX concentrations in plasma have not been reported. Traditional analyses of free drugs are both cumbersome and inaccurate. We collected 92 plasma samples from 52 children diagnosed with ALL or NHL or other lymphomas that were treated with HD-MTX. The hollow fiber centrifugal ultrafiltration (HFCF-UF) was used to prepare plasma samples for analysis of the free MTX concentration. Protein precipitation was employed to measure the total MTX concentration. The HFCF-UF is a simple method involving a step of ordinary centrifugation; the validation parameters for the methodological results were satisfactory and fell within the acceptance criteria. A linearity coefficient r 2 of 0.910 was obtained for the correlation between the free and total MTX plasma concentrations in 92 plasma samples. However, the free and total MTX concentrations was only weakly correlated in 16 clinical plasma specimens with total MTX concentrations >2 μmol L−1 (r 2 = 0.760). Both the free and total MTX concentrations at 42 h were negatively correlated with the creatinine clearance (CCr) level (P = 0.023, r = −0.236 for total MTX and P = 0.020, r = −0.241for free MTX, respectively). The free MTX concentration could not be accurately estimated from the total MTX concentration for patients with high MTX levels which are conditions under which toxic reactions are more likely to occur. High plasma MTX levels could become a predictor of the occurrence of MTX nephrotoxicity to draw people's attention. The proposed HFCF-UF method is a simple and accurate way to evaluate efficacy and toxicity in clinical therapeutic drug monitoring. [ABSTRACT FROM AUTHOR]

A simple and sensitive method for simultaneous derivatization and hollow fiber liquid phase microextraction (HF-LPME) followed by high performance liquid chromatography–fluorescence detection (HPLC–FL) to determine memantine hydrochloride (MT) in human plasma was developed. The derivatization and microextraction was combined to a single step to ensure the precision. What is more, the derivatization reaction accelerated the mass transfer during the process of microextraction. The hollow fiber was filled with cyclohexane and dansyl chloride (derivatization agent) as acceptor phase and submersed in the alkalinized plasma sample. The system was submitted to stirring at 800 rpm for 50 min at 40 °C. Different experimental parameters were systematically evaluated by response surface methodology. Under the optimized conditions, the calibration curve was linear in the range of 1–100 ng/mL ( r = 0.9991) with a limit of detection of 0.1 ng/mL ( S/N = 3). The precision estimated as the relative standard deviation (RSD) was less than 4.5% and the accuracy was 94.3–100.7%. The present method was successfully applied to determine MT in human plasma samples. [ABSTRACT FROM AUTHOR]

Abstract: A simple sample preparation method was developed by using a centrifugal ultrafiltration (CF-UF) device with hollow fiber (HF) for the determination of cefaclor in plasma by HPLC. Samples were placed into a homemade device, which was consisted of a glass tube and a U-shaped hollow fiber. The filtrate was withdrawn from the hollow fiber into a syringe after centrifugation and 20μL was directly injected into the HPLC for analysis. The HPLC method had a linear calibration curve in the concentration range of 6.00×10−2–30.7μgmL−1(r =0.9996). The limit of detection (LOD) and limit of quantitation (LOQ) were 0.02 and 0.06μgmL−1, respectively. The intra and inter-day precisions (RSD) were 1.7%, 1.2%, 1.0% and 3.6%, 2.5%, 1.9%, respectively, for three concentrations. Assay accuracy was higher than 99.2% and the absolute recovery was 86.8–92.5%. It is feasible to use this novel and low cost device for sample pretreatment for the analysis of cefaclor in plasma. [ABSTRACT FROM AUTHOR]

• Polyether sulfone hollow fiber without any modification is selected as adsorbent for sample preparation. • Due to porosity of hollow fiber, high adsorption capacity can be achieved. • This method exhibits excellent sensitivity (pg mL–1). This work focused on the development and validation of a method based on hollow fiber-based solid-phase microextraction coupled to ultra-performance liquid chromatography tandem mass spectrometry (HF-based-SPME-UPLC-MS/MS) for the determination of five antipsychotics at a pg mL–1 level in human whole blood and urine. Four types of hollow fiber membrane materials, including polyether sulfone, polypropylene, polyvinyl chloride and polyvinylidene fluoride were investigated. Finally, polyether sulfone hollow fiber without any modification was selected as the adsorption medium for solid-phase microextraction (SPME) with the following extraction procedure: the analytes were adsorbed onto the hollow fiber in the sample bottle with application of ultrasonication. Subsequently, the hollow fiber was transferred into a slim glass tube containing an appropriate solvent, and the analytes were desorbed by ultrasound treatment before detection by UPLC-MS/MS. In order to obtain satisfactory extraction efficiency, extraction parameters such as hollow fiber membrane material, pH, hollow fiber length, extraction time, desorption solvent and desorption time were investigated. Under the optimum experimental conditions, this method allowed for determination of five antipsychotics in human whole blood with excellent limits of quantification (LOQs) (25.0, 12.5, 25.0, 25.0 and 12.5 pg mL–1 for perphenazine, chlorpromazine, chlorprothixene, promethazine and trifluoperazine, respectively). The corresponding LOQs in human urine were 25.0, 12.5, 12.5, 12.5 and 12.5 pg mL–1 for the respective antipsychotics. The precision (RSD) was no more than 13.3%. The extraction recoveries for human whole blood and urine were in the range of 46.4–96.6% and 65.2–101.9%, respectively. The proposed method was compared with other methods from the literature and the results demonstrate that it is a simple, sensitive, efficient and green technique. It is suitable for analyzing trace target analytes in complex matrices such as biological samples and can provide a reliable tool for drug monitoring especially in forensic analysis and case of drug abuse. [ABSTRACT FROM AUTHOR]

Highlights: [•] Factors that affect the ultrafiltrate volume were comprehensively investigated. [•] Ultrafiltrate volume is a crucial factor on the accurate measurement of unbound drug. [•] The ultrafiltrate volume by HFCF-UF can be easily controlled. [•] The HFCF-UF method has extremely low detection limit and perfect recovery. [Copyright &y& Elsevier]