Advantages and Challenges of Total-Body PET/CT at a Tertiary Cancer Center: Insights from Sun Yat-sen University Cancer Center.

In recent decades, researchers worldwide have directed their efforts toward enhancing the quality of PET imaging. The detection sensitivity and image resolution of conventional PET scanners with a short axial field of view have been constrained, leading to a suboptimal signal-to-noise ratio. The advent of long-axial-field-of-view PET scanners, exemplified by the uEXPLORER system, marked a significant advancement. Total-body PET imaging possesses an extensive scan range of 194 cm and an ultrahigh detection sensitivity, and it has emerged as a promising avenue for improving image quality while reducing the administered radioactivity dose and shortening acquisition times. In this review, we elucidate the application of the uEXPLORER system at the Sun Yat-sen University Cancer Center, including the disease distribution, patient selection workflow, scanning protocol, and several enhanced clinical applications, along with encountered challenges. We anticipate that this review will provide insights into routine clinical practice and ultimately improve patient care.

Multiobjective Flexible Job-Shop Rescheduling With New Job Insertion and Machine Preventive Maintenance.

In the actual production, the insertion of new job and machine preventive maintenance (PM) are very common phenomena. Under these situations, a flexible job-shop rescheduling problem (FJRP) with both new job insertion and machine PM is investigated. First, an imperfect PM (IPM) model is established to determine the optimal maintenance plan for each machine, and the optimality is proven. Second, in order to jointly optimize the production scheduling and maintenance planning, a multiobjective optimization model is developed. Third, to deal with this model, an improved nondominated sorting genetic algorithm III with adaptive reference vector (NSGA-III/ARV) is proposed, in which a hybrid initialization method is designed to obtain a high-quality initial population and a critical-path-based local search (LS) mechanism is constructed to accelerate the convergence speed of the algorithm. In the numerical simulation, the effect of parameter setting on the NSGA-III/ARV is investigated by the Taguchi experimental design. After that, the superiority of the improved operators and the overall performance of the proposed algorithm are demonstrated. Next, the comparison of two IPM models is carried out, which verifies the effectiveness of the designed IPM model. Last but not least, we have analyzed the impact of different maintenance effects on both the optimal maintenance decisions and integrated maintenance-production scheduling schemes.

18F-FDG PET-Based Combined Baseline and End-Of-Treatment Radiomics Model Improves the Prognosis Prediction in Diffuse Large B Cell Lymphoma After First-Line Therapy.

RATIONALE AND OBJECTIVES: To develop a combined model incorporating the clinical and PET features for identifying patients with diffuse large B-cell lymphoma (DLBCL) at high risk of progression or relapse after first-line therapy, compared to International Prognostic Index (IPI) and Deauville score (DS) assessment. MATERIALS AND METHODS: 271 18F-FDG PET images with DLBCL were retrospectively collected and randomly divided into the training (n=190) and test dataset (n=81). All visible lesions were annotated. Baseline, end-of-treatment (EoT), and delta PET radiomics features were extracted. IPI model, the baseline clinical model group (MG), DS model, the combined clinical MG, the PET-based radiomics MG, and the combined MG were constructed to predict 2-year time to progression (2Y-TTP). For each MG, the cross-combination method was performed to generate 1680 candidate models based on three normalization methods, 20 features, 4 feature-selection methods, and 7 classifiers. The model achieving the highest AUC was selected as the best for each MG. Cox regression analysis was further performed. RESULTS: In the test set, the best combined model showed better discriminative power compared to IPI model, the best baseline clinical model, DS model, the best combined clinical model, and the best PET-based radiomics model (AUC 0.898 vs. 0.584, 0.695, 0.756, 0.824, 0.832; p < 0.001, 0.014, 0.018, 0.152, 0.042, respectively). The combined model was superior to other models for progression-free-survival prediction (C-index: 0.853 vs. 0.568, 0.666, 0.753, 0.808, 0.814, respectively). CONCLUSION: A combined model for identifying patients at high risk of progression or relapse after first-line therapy was constructed, superior to IPI and DS assessment.

Significant CT dose reduction of 2-[18F]FDG PET/CT in pretreatment pediatric lymphoma without compromising the diagnostic and staging efficacy.

OBJECTIVES: To compare the diagnostic and staging efficacy of PET/diagnostic-level CT (PET/DxCT) and PET/low-dose CT (PET/LDCT) in pretreatment pediatric lymphoma patients and to estimate the reduction of the CT effective dose in the PET/CT scan. METHODS: One hundred and five pediatric patients who underwent total-body PET/CT examination were enrolled and divided into the DxCT group (n = 47) and LDCT group (n = 58) according to their dose levels. The sensitivity, specificity, PPV, and NPV of PET/DxCT and PET/LDCT for detecting the involvement of lymph node, spleen, bone marrow, and other extranodal organs in pretreatment lymphoma were compared. ROC analysis was performed to evaluate the integral efficiency. The staging accuracies based on PET/DxCT and PET/LDCT were also evaluated. Dosimetry was calculated for DxCT and LDCT, and the reduction in the effective dose was estimated. RESULTS: In the diagnosis of nodal, splenic, bone marrow, and other extranodal involvement, the differences in sensitivity, specificity, PPV, and NPV between PET/LDCT and PET/DxCT were not significant (all p values ∈ [0.332, 1.000]). Both modalities had accuracies above 90% and the ROC analysis indicated good or high efficiency in diagnosing all patterns of lymphoma involvement. PET/LDCT and PET/DxCT each had a staging accuracy of 89.7% and 89.4%, respectively. LDCT had a comparable image quality score with DxCT, with a significant increase in noise (p < 0.001) and a 66.1% reduction in effective dose. CONCLUSIONS: PET/LDCT allowed for a 66.1% CT effective dose reduction compared to PET/DxCT in pediatric lymphoma patients without compromising the diagnostic and staging efficacy. KEY POINTS: • Pediatric lymphoma patients can benefit from a reduced effective dose of PET/CT. • This retrospective study showed that the diagnostic and staging efficacies of PET/low-dose CT are comparable to those of PET/diagnostic-level CT, both with satisfactory efficiency in diagnosing all patterns of lymphoma involvement. • PET/low-dose CT allowed for a 66.1% CT effective dose reduction compared to PET/diagnostic-level CT.

Evaluation of pediatric malignancies using total-body PET/CT with half-dose [18F]-FDG.

PURPOSE: To explore the impact of a true half dose of [18F]-FDG on image quality in pediatric oncological patients undergoing total-body PET/CT and investigate short acquisition times with half-dose injected activity. METHODS: One hundred pediatric oncological patients who underwent total-body PET/CT using the uEXPLORER scanner after receiving a true half dose of [18F]-FDG (1.85 MBq/kg) were retrospectively enrolled. The PET images were first reconstructed using complete 600-s data and then split into 300-s, 180-s, 60-s, 40-s, and 20-s duration groups (G600 to G20). The subjective analysis was performed using 5-point Likert scales. Objective quantitative metrics included the maximum standard uptake value (SUVmax), SUVmean, standard deviation (SD), signal-to-noise ratio (SNR), and SNRnorm of the background. The variabilities in lesion SUVmean, SUVmax, and tumor-to-background ratio (TBR) were also calculated. RESULTS: The overall image quality scores in the G600, G300, G180, and G60 groups were 4.9 ± 0.2, 4.9 ± 0.3, 4.4 ± 0.5, and 3.5 ± 0.5 points, respectively. All the lesions identified in the half-dose images were localized in the G60 images, while 56% of the lesions could be clearly identified in the G20 images. With reduced acquisition time, the SUVmax and SD of the backgrounds were gradually increased, while the TBR values showed no statistically significant differences among the groups (all p > 0.1). Using the half-dose images as a reference, the variability in the lesion SUVmax gradually increased from the G180 to G20 images, while the lesion SUVmean remained stable across all age groups. SNRnorm was highly negatively correlated with age. CONCLUSION: Total-body PET/CT with a half dose of [18F]-FDG (1.85 MBq/kg, estimated whole-body effective dose: 1.76-2.57 mSv) achieved good performance in pediatric patients, with sufficient image quality and good lesion conspicuity. Sufficient image quality and lesion conspicuity could be maintained at a fast scanning time of 60 s with half-dose activity.

[Structural Characteristics of Zooplankton and Phytoplankton Communities and Its Relationship with Environmental Factors in Different Regions of Nanhu Lake in Jiaxing City].

Nanhu Lake is a red tourist attraction in Jiaxing city and the birthplace of the "Red Boat Spirit."To identify the influence of environmental factors on the distribution of plankton communities after ecological restoration in different regions, the environmental factors and plankton community in areas A, B, C, D, and S of Nanhu Lake were investigated in January 2021 after the completion of the ecological restoration projects. The concentrations of total nitrogen(TN), dissolved total nitrogen (DTN), ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N), total phosphorus (TP), and dissolved total phosphorus (DTP) in the ecological restoration areas were significantly lower, and the content of dissolved oxygen (DO) was significantly higher (P<0.05) than those in the non-restoration area. The main phytoplankton species in the study area belonged to Cyanophyta and Bacillariophyta, and the main zooplankton species were protozoans and rotifers. The phytoplankton biomass in the restored area was lower than that in the unrestored area, and the number of phytoplankton and zooplankton species increased. Clustering and principal coordinate analysis results showed significant differences in plankton communities among the restoration areas (P<0.05), and plankton structures in regions A and B were similar. Redundancy analysis (RDA) showed that the main environmental factors affecting the distribution of phytoplankton communities were DO, NO3--N, pH, and water temperature (WT). The main driving factors of zooplankton community distribution were DO, NO3--N, NH4+-N, and TP. The results clarified the phytoplankton community characteristics and environmental correlation in different regions of Nanhu Lake, which can provide data support and reference for water ecological restoration of the lake.

The prognostic value of end-of-treatment FDG-PET/CT in diffuse large B cell lymphoma: comparison of visual Deauville criteria and a lesion-to-liver SUVmax ratio-based evaluation system.

PURPOSE: The aim of this study was to determine a better criterion for end-of-treatment PET (EoT-PET) assessment and prognostic evaluation of patients with diffuse large B cell lymphoma (DLBCL). METHOD: EoT-PET scans were assessed using the visual Deauville 5-point scale (5PS) and LLR, the maximum standard uptake value ratio between the lesion and the liver. The cutoff value of LLR was obtained by receiver operator characteristic curve analysis. Patient outcomes were compared using Kaplan-Meier survival analysis. Prognostic indexes of different criteria were compared. Multivariate Cox regression analysis was performed to evaluate the prognostic factors. RESULTS: Four hundred forty-nine newly diagnosed DLBCL patients who received rituximab-based immunochemotherapy were included, and the median follow-up duration was 41.4 months. Patients with Deauville score (DS) 4 displayed significantly longer PFS and OS compared with patients with DS 5 (both p < 0.001), and they had significantly shorter PFS (p < 0.01) but similar OS (p = 0.057) compared with patients with DS 1-3. The differences in PFS and OS between groups were all significant whether positive EoT-PET was defined as DS 4-5 or DS 5 (all p < 0.001). The optimal cutoff of LLR was 1.83, and both PFS and OS were significantly different between EoT-PET-positive and EoT-PET-negative patients as defined by the cutoff (both p < 0.001). LLR-based criterion displayed higher specificity, positive predictive value, and accuracy than 5PS-based criterion in the prediction of disease progression and death events. In the multivariate analysis, positive EoT-PET (as defined by LLR) was related to unfavorable PFS and OS (both p < 0.001). Additional treatment was not correlated with outcomes of EoT-PET-negative patients either defined by LLR or 5PS or EoT-PET-positive patients classified by 5PS, but it was the only beneficial factor for OS (p < 0.05) in EoT-PET-positive patients with LLR ≥ 1.83. CONCLUSION: The optimal cutoff of LLR may be superior to Deauville criteria in identifying low-risk DLBCL patients with negative EoT-PET after the first-line immunochemotherapy and sparing them the cost and toxicity of additional treatment.

Relationship between clinical features and intestinal microbiota in Chinese patients with ulcerative colitis.

BACKGROUND: Dysbacteriosis may be a crucial environmental factor for ulcerative colitis (UC). Further study is required on microbiota alterations in the gastrointestinal tract of patients with UC for better clinical management and treatment. AIM: To analyze the relationship between different clinical features and the intestinal microbiota, including bacteria and fungi, in Chinese patients with UC. METHODS: Eligible inpatients were enrolled from January 1, 2018 to June 30, 2019, and stool and mucosa samples were collected. UC was diagnosed by endoscopy, pathology, Mayo Score, and Montreal classification. Gene amplicon sequencing of 16S rRNA gene and fungal internal transcribed spacer gene was used to detect the intestinal microbiota composition. Alpha diversity, principal component analysis, similarity analysis, and Metastats analysis were employed to evaluate differences among groups. RESULTS: A total of 89 patients with UC and 33 non-inflammatory bowel disease (IBD) controls were enrolled. For bacterial analysis, 72 stool and 48 mucosa samples were obtained from patients with UC and 21 stool and 12 mucosa samples were obtained from the controls. For fungal analysis, stool samples were obtained from 43 patients with UC and 15 controls. A significant difference existed between the fecal and mucosal bacteria of patients with UC. The α-diversity of intestinal bacteria and the relative abundance of some families, such as Lachnospiraceae and Ruminococcaceae, decreased with the increasing severity of bowel inflammation, while Escherichia-Shigella showed the opposite trend. More intermicrobial correlations in UC in remission than in active patients were observed. The bacteria-fungi correlations became single and uneven in patients with UC. CONCLUSION: The intestinal bacteria flora of patients with UC differs significantly in terms of various sample types and disease activities. The intermicrobial correlations change in patients with UC compared with non-IBD controls.

Image quality and lesion detectability in low-dose pediatric 18F-FDG scans using total-body PET/CT.

PURPOSE: To investigate the effects of dose reduction on image quality and lesion detectability of oncological 18F-FDG total-body PET/CT in pediatric oncological patients and explore the minimum threshold of administered tracer activity. METHODS: A total of 33 pediatric patients (weight 8.5-58.5 kg; age 0.8-17.6 years) underwent total-body PET/CT using uEXPLORER scanner with an 18F-FDG administered dose of 3.7 MBq/kg and an acquisition time of 600 s were retrospectively enrolled. Low-dose images (0.12-1.85 MBq/kg) were simulated by truncating the list-mode PET data to reducing count density. Subjective image quality was rated on a 5-point scale. Semi-quantitative uptake metrics for low-dose images were assessed using region-of-interest (ROI) analysis of healthy liver and suspected lesions and were compared with full-dose images. The micro-lesion detectability was compared among the dose-dependent PET images. RESULTS: Our analysis shows that sufficient subjective image quality and lesion conspicuity could be maintained down to 1/30th (0.12 MBq/kg) of the administered dose of 18F-FDG, where good image quality scores were given to 1/2- and 1/10- dose groups. The image noise was significantly more deranged than the overall quality and lesion conspicuity in 1/30- to 1/10-dose groups (all p < 0.05). With reduced doses, quantitative analysis of ROIs showed that SUVmax and SD in the liver increased gradually (p < 0.05), but SUVmax in the lesions and lesion-to-background ratio (LBR) showed no significant deviation down to 1/30-dose. One hundred percent of the 18F-FDG-avid micro-lesions identified in full-dose images were localized down to 1/15-dose images, while 97% of the lesion were localized in 1/30-dose images. CONCLUSION: The total-body PET/CT might significantly decrease the administered dose upon maintaining the image quality and diagnostic performance of micro-lesions in pediatric patients. Data suggests that using total-body PET/CT, optimal image quality could be achieved with an administered dose-reduction down to 1/10-dose (0.37 MBq/kg).

Antibody Subunit LC-MS Analysis for Pharmacokinetic and Biotransformation Determination from In-Life Studies for Complex Biotherapeutics.

Complex biotherapeutics present challenges from drug discovery, screening, and development perspectives. While monoclonal antibody drugs are not monitored for metabolites in the same manner as small molecules, biotherapeutics such as fusion proteins, antibody-drug conjugates, or bispecific antibodies may undergo biotransformation (such as clipping, deamidation, or oxidation) in vivo, resulting in catabolites that can have a direct impact on drug safety or efficacy. Here antibody subunit LC-MS is utilized for evaluation of two classes of complex biotherapeutics: an antibody-drug conjugate and a mAb-fusion biotherapeutic. Pharmacokinetic concentration, biotransformation, and DAR data are collectively presented using the subunit LC-MS approach for the two molecules, and the methods shared in detail can be applied to any humanized IgG1 mAb biotherapeutic for preclinical study support. Overall, the data generated from antibody LC-MS analyses can provide key information in early phase development and deliver multiple study end points with a single data set.

Primary hypertrophic osteoarthropathy related gastrointestinal complication has distinctive clinical and pathological characteristics: two cases report and review of the literature.

BACKGROUND: Primary hypertrophic osteoarthropathy (PHO) is a rare disease related to HPGD and SLCO2A1 gene mutation. Gastrointestinal involvement of PHO is even rarer with unknown pathogenesis. Clinical features of GI complication in PHO mimics other auto-immune based bowel entities, such as inflammatory bowel diseases and cryptogenic multifocal ulcerous stenosing enteritis (CMUSE). We aimed to analyze the clinical, genetic, radiological and pathological features of Chinese patients with PHO and determine the difference between PHO patients presenting with and without GI involvement. METHODS: We reported two PHO cases with gastrointestinal involvement and reviewed all the studies of PHO in Chinese population published from January 1, 2000, to April 30, 2018. Clinical and genetic presentations of PHO in Chinese patients were analyzed. We compared the characteristics of those patients with gastrointestinal involvement against those without. RESULTS: The two patients were both males with complete-form PHO for more than 10 years. GI related symptoms included diarrhea, chronic gastrointestinal hemorrhage, incomplete intestinal obstruction, anemia, and edema, which were unresponsive to etoricoxib treatment. Radiological examinations revealed segmental intestinal stenosis and thickened intestinal wall. Endoscopic findings included multiple ulcers and mucosal inflammation. Both patients had mutations of SLCO2A1 according to sequence analysis. The surgical pathology revealed chronic inflammation involving the intestinal mucosa and submucosa, similar to histological changes in CMUSE. According to the systemic review of 158 Chinese patients with PHO, 17.2% had gastrointestinal involvement, including peptic ulcer, gastric polyps, hypertrophic gastritis, and segmental intestinal stenosis. Patients with gastrointestinal involvement were more likely to have anemia (40.0% vs. 4.5%, P < 0.001), hypoalbuminemia (16.7% vs. 0.9%, P = 0.003), and myelofibrosis (19.0% vs. 0.9%, P = 0.002) than those without. Most patients with gastrointestinal complication had SLCO2A1 mutation (86.7%, 13 /15). CONCLUSIONS: Digestive tract involvement is uncommon in patients with PHO and often presents with anemia, and hypoalbuminemia resulted from intestinal inflammation. The intestinal pathologic characteristics are distinct from Crohn's disease but similar to CMUSE. Mutations in SLCO2A1 might be the pathogenic cause of GI involvement of PHO. NSAIDs may not be effective for PHO patients with gastrointestinal complications.

Extended Multiple Aperture Mapdrift-Based Doppler Parameter Estimation and Compensation for Very-High-Squint Airborne SAR Imaging.

Doppler parameter estimation and compensation (DPEC) is an important technique for airborne SAR imaging due to the unpredictable disturbance of real aircraft trajectory. Traditional DPEC methods can be only applied for broadside, small- or medium-squint geometries, as they at most consider the spatial variance of the second-order Doppler phase. To implement the DPEC in very-high-squint geometries, we propose an extended multiple aperture mapdrift (EMAM) method in this paper for better accuracy. This advantage is achieved by further estimating and compensating the spatial variation of the third-order Doppler phase, i.e., the derivative of the Doppler rate. The main procedures of the EMAM, including the steps of sub-view image generation, sliding-window-based cross-correlation, and image-offset-based Doppler parameter estimation, are derived in detail, followed by the analyses for the EMAM performance. The presented approach is evaluated by both computer simulations and real airborne data.

The impact of multi-walled carbon nanotubes (MWCNTs) on macrophages: contribution of MWCNT characteristics.

Multi-walled carbon nanotubes (MWCNTs) have wide application prospects but also exhibit notable biotoxicity that is tightly associated with macrophages. Macrophages simultaneously act as initiators and defenders in MWCNT-induced organ lesions, and targeting macrophages with MWCNTs may be a potential immunotherapy and oncotherapy approach. This review focuses on the impacts of MWCNTs on macrophages and further discusses the influence of MWCNT characteristics on their bioactivity. Based on existing studies, MWCNTs stimulate macrophage migration, induce secretion of various cytokines and activate inflammatory pathways in macrophages, especially NLRP3-mediated IL-1ß production. This inflammatory state, together with the oxidative stress and cell membrane lesions induced by MWCNTs, contributes to decreased phagocytic ability and cell viability, which finally results in cell apoptosis and necrosis. A series of intracellular and systemic components, such as toll-like receptor, high-mobility group box 1, Rho-associated kinases, scavenger receptor and complement components, may be involved in the above-mentioned cell-MWCNT interactions. The characteristics of MWCNTs can influence their bioactivity in macrophages both mechanically and chemically. The size (length and/or diameter), functionalization, purification and even the experimental method can affect the influence of MWCNTs on macrophages, and a better understanding of these MWCNT characteristics may benefit utilization of this nanomaterial in associated nanomedical applications.

Validation of an LC-MS/MS method for simultaneous quantification of venlafaxine and its five metabolites in rat plasma and its application in a pharmacokinetic study.

A sensitive, selective, and reliable LC-MS/MS method was developed and validated for simultaneous quantification of venlafaxine (VEN) and its 5 metabolites (ODV, NDV, NNDDV, OHV and NODDV) in rat plasma. The calibration ranges are 15.0 to 6000 ng/mL for VEN, 1.00 to 400 ng/mL for ODV, 5.00 to 2000 ng/mL for NDV, 1.00 to 400 ng/mL for NNDDV, 10.0 to 4000 ng/mL for OHV, and 0.200 to 20.0 ng/mL for NODDV. Briefly, 50 µL of rat plasma was extracted using liquid-liquid extraction (LLE) with methyl tert-butyl ether (MTBE). The analytes were separated on an Agilent SB-Phenyl (50 mm × 4.6 mm, 3.5 µm) column using a binary gradient of 0.1% formic acid in water versus 0.1% formic acid in acetonitrile at a flow rate of 0.8 mL/min. The method was validated following FDA guidance for bioanalytical method validation. Validated method was successfully applied to a pharmacokinetic study of VEN orally administered to rats.

The 10th GCC Closed Forum: rejected data, GCP in bioanalysis, extract stability, BAV, processed batch acceptance, matrix stability, critical reagents, ELN and data integrity and counteracting fraud.

The 10th Global CRO Council (GCC) Closed Forum was held in Orlando, FL, USA on 18 April 2016. In attendance were decision makers from international CRO member companies offering bioanalytical services. The objective of this meeting was for GCC members to meet and discuss scientific and regulatory issues specific to bioanalysis. The issues discussed at this closed forum included reporting data from failed method validation runs, GCP for clinical sample bioanalysis, extracted sample stability, biomarker assay validation, processed batch acceptance criteria, electronic laboratory notebooks and data integrity, Health Canada's Notice regarding replicates in matrix stability evaluations, critical reagents and regulatory approaches to counteract fraud. In order to obtain the pharma perspectives on some of these topics, the first joint CRO-Pharma Scientific Interchange Meeting was held on 12 November 2016, in Denver, Colorado, USA. The five topics discussed at this Interchange meeting were reporting data from failed method validation runs, GCP for clinical sample bioanalysis, extracted sample stability, processed batch acceptance criteria and electronic laboratory notebooks and data integrity. The conclusions from the discussions of these topics at both meetings are included in this report.

Quantitative hydrophilic interaction chromatography-mass spectrometry analysis of N-acetylneuraminic acid and N-acetylmannosamine in human plasma.

N-acetylneuraminic acid (Neu5Ac or NANA) is the most predominant sialic acid in mammals. As a terminal component in many glycoproteins and glycolipids, sialic acid is believed to be an important biomarker related to various diseases. Its precursor, N-acetylmannosamine (ManNAc), is being investigated as a potential treatment for GNE myopathy. In this work, we developed two highly sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for the quantitation of ManNAc and free Neu5Ac in human plasma. A fit-for-purpose approach was adopted during method validation and sample analysis. To measure the endogenous compounds and overcome the interference from plasma samples, a surrogate matrix that contained 5% bovine serum albumin (BSA) was used for the preparation of calibration standards and certain levels of quality control (QC) samples. QC samples at higher concentrations were prepared in the authentic matrix (human plasma) to best mimic incurred samples. For both methods, an Ostro 96-well phospholipid removal plate was used for sample extraction, which efficiently removed the phospholipids from the plasma samples prior to LC injection, eliminated matrix effect, and improved sensitivity. Chromatographic separation was achieved using hydrophilic interaction chromatography (HILIC) and gradient elution in order to retain the two polar compounds. The lower limit of quantitation (LLOQ) for ManNAc and Neu5Ac was 10.0 and 25.0ng/mL, respectively. The overall accuracy of the two assays was within 100%±8.3% based on three levels of QC samples. Inter- and intra-run precision (coefficient of variation (%CV)) across three analytical runs was less than 6.7% for ManNAc and less than 10.8% for Neu5Ac. These methods have been validated to support clinical studies.

Study of dried blood spots technique for the determination of dextromethorphan and its metabolite dextrorphan in human whole blood by LC-MS/MS.

Dried blood spots (DBSs) technology was evaluated in an assay for the quantitation of dextromethorphan (DM) and its metabolite, dextrorphan (DT), in human whole blood using high performance liquid chromatography with tandem mass spectrometry method (LC-MS/MS). Both the parent drug and metabolite were spiked in the blood matrix and subsequently allowed to dry on a specimen collection card. The dried blood spots were removed using a manual punch and then extracted into methyl tert-butyl ether (MTBE). The organic supernatant was transferred and evaporated and the residue was reconstituted in 20% acetonitrile. The overall method recovery of DM and DT was 87.8% and 95.4%, respectively. The assay was linear over the concentration range of 0.2-200ng/mL for both analytes. Several factors that potentially affect DBS assay quantitation were investigated, such as punch size, DBS sample punch-out location, and the volume of the blood sample pipetted on the specimen collection cards. The study determined that punch size does not affect assay quantitation accuracy. Indeed, a larger punch size increases the sensitivity due to the larger sampled blood spots. Sampling from different location on the specimen collection cards shows no significant variation for both drugs. The study also shows that acceptable results can be achieved with some variation of the sample volume, which allows a simple blood sampling procedure at the test sites. To achieve the similar lower limit of quantitation (LLOQ) as the plasma assay, several blood spots at the same concentration level were stacked together and extracted. Bioanalytical assays using the DBS technique are promising given the advantages of the method over the plasma assay.

Determination of molindone enantiomers in human plasma by high-performance liquid chromatography-tandem mass spectrometry using macrocyclic antibiotic chiral stationary phases.

A sensitive and selective bioanalytical assay was developed and validated for the determination of enantiomeric molindone in human plasma using high-performance liquid chromatography-tandem mass spectrometry along with supported liquid extraction procedures. The chiral separation was evaluated and optimized on macrocyclic antibiotic type chiral stationary phases (CSPs) based on teicoplanin aglycone (Chirobiotic TAG) in polar organic, polar ionic, and reversed-phase mode chromatography, respectively. Complete baseline separation was achieved on a Chirobiotic TAG column under isocratic condition in reversed-phase chromatography. The method validation was conducted using a Chirobiotic TAG column (100 mm x 2.1 mm) over the curve range 0.100-100 ng/ml for each molindone enantiomer using 0.0500 ml of plasma sample. The flow rate was 0.8 ml/min and the total run time was 9 min. Supported liquid extraction in a 96-well plate format was used for sample preparation. Parameters including recovery, matrix effect, linearity, sensitivity, specificity, carryover, precision, accuracy, dilution integrity, and stability were evaluated. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels were RSD

Advantages of using tetrahydrofuran-water as mobile phases in the quantitation of cyclosporin A in monkey and rat plasma by liquid chromatography-tandem mass spectrometry.

A new analytical method is described here for the quantitation of anti-inflammatory drug cyclosporin A (CyA) in monkey and rat plasma. The method used tetrahydrofuran (THF)-water mobile phases to elute the analyte and internal standard, cyclosporin C (CyC). The gradient mobile phase program successfully eluted CyA into a sharp peak and therefore improved resolution between the analyte and possible interfering materials compared with previously reported analytical approaches, where CyA was eluted as a broad peak due to the rapid conversion between different conformers. The sharp peak resulted from this method facilitated the quantitative calculation as multiple smoothing and large number of bunching factors were not necessary. The chromatography in the new method was performed at 30 degrees C instead of 65-70 degrees C as reported previously. Other advantages of the method included simple and fast sample extraction-protein precipitation, direct injection of the extraction supernatant to column for analysis, and elimination of evaporation and reconstitution steps, which were needed in solid phase extraction or liquid-liquid extraction reported before. This method is amenable to high-throughput analysis with a total chromatographic run time of 3 min. This approach has been verified as sensitive, linear (0.977-4000 ng/mL), accurate and precise for the quantitation of CyA in monkey and rat plasma. However, compared with the usage of conventional mobile phases, the only drawback of this approach was the reduced detection response from the mass spectrometer that was possibly caused by poor desolvation in the ionization source. This is the first report to demonstrate the advantages of using THF-water mobile phases to elute CyA in liquid chromatography.