Recruitment of pre-dementia participants: main enrollment barriers in a longitudinal amyloid-PET study.

BACKGROUND: The mismatch between the limited availability versus the high demand of participants who are in the pre-dementia phase of Alzheimer's disease (AD) is a bottleneck for clinical studies in AD. Nevertheless, potential enrollment barriers in the pre-dementia population are relatively under-reported. In a large European longitudinal biomarker study (the AMYPAD-PNHS), we investigated main enrollment barriers in individuals with no or mild symptoms recruited from research and clinical parent cohorts (PCs) of ongoing observational studies. METHODS: Logistic regression was used to predict study refusal based on sex, age, education, global cognition (MMSE), family history of dementia, and number of prior study visits. Study refusal rates and categorized enrollment barriers were compared between PCs using chi-squared tests. RESULTS: 535/1856 (28.8%) of the participants recruited from ongoing studies declined participation in the AMYPAD-PNHS. Only for participants recruited from clinical PCs (n = 243), a higher MMSE-score (ß = - 0.22, OR = 0.80, p < .05), more prior study visits (ß = - 0.93, OR = 0.40, p < .001), and positive family history of dementia (ß = 2.08, OR = 8.02, p < .01) resulted in lower odds on study refusal. General study burden was the main enrollment barrier (36.1%), followed by amyloid-PET related burden (PCresearch = 27.4%, PCclinical = 9.0%, X2 = 10.56, p = .001), and loss of research interest (PCclinical = 46.3%, PCresearch = 16.5%, X2 = 32.34, p < .001). CONCLUSIONS: The enrollment rate for the AMYPAD-PNHS was relatively high, suggesting an advantage of recruitment via ongoing studies. In this observational cohort, study burden reduction and tailored strategies may potentially improve participant enrollment into trial readiness cohorts such as for phase-3 early anti-amyloid intervention trials. The AMYPAD-PNHS (EudraCT: 2018-002277-22) was approved by the ethical review board of the VU Medical Center (VUmc) as the Sponsor site and in every affiliated site.

Clinical metabolomics for inborn errors of metabolism.

Metabolism is a highly regulated process that provides nutrients to cells and essential building blocks for the synthesis of protein, DNA and other macromolecules. In healthy biological systems, metabolism maintains a steady state in which the concentrations of metabolites are relatively constant yet are subject to metabolic demands and environmental stimuli. Rare genetic disorders, such as inborn errors of metabolism (IEM), cause defects in regulatory enzymes or proteins leading to metabolic pathway disruption and metabolite accumulation or deficiency. Traditionally, the laboratory diagnosis of IEMs has been limited to analytical methods that target specific metabolites such as amino acids and acyl carnitines. This approach is effective as a screening method for the most common IEM disorders but lacks the comprehensive coverage of metabolites that is necessary to identify rare disorders that present with nonspecific clinical symptoms. Fortunately, advancements in technology and data analytics has introduced a new field of study called metabolomics which has allowed scientists to perform comprehensive metabolite profiling of biological systems to provide insight into mechanism of action and gene function. Since metabolomics seeks to measure all small molecule metabolites in a biological specimen, it provides an innovative approach to evaluating disease in patients with rare genetic disorders. In this review we provide insight into the appropriate application of metabolomics in clinical settings. We discuss the advantages and limitations of the method and provide details related to the technology, data analytics and statistical modeling required for metabolomic profiling of patients with IEMs.

The amyloid imaging for the prevention of Alzheimer's disease consortium: A European collaboration with global impact.

Background: Amyloid-ß (Aß) accumulation is considered the earliest pathological change in Alzheimer's disease (AD). The Amyloid Imaging to Prevent Alzheimer's Disease (AMYPAD) consortium is a collaborative European framework across European Federation of Pharmaceutical Industries Associations (EFPIA), academic, and 'Small and Medium-sized enterprises' (SME) partners aiming to provide evidence on the clinical utility and cost-effectiveness of Positron Emission Tomography (PET) imaging in diagnostic work-up of AD and to support clinical trial design by developing optimal quantitative methodology in an early AD population. The AMYPAD studies: In the Diagnostic and Patient Management Study (DPMS), 844 participants from eight centres across three clinical subgroups (245 subjective cognitive decline, 342 mild cognitive impairment, and 258 dementia) were included. The Prognostic and Natural History Study (PNHS) recruited pre-dementia subjects across 11 European parent cohorts (PCs). Approximately 1600 unique subjects with historical and prospective data were collected within this study. PET acquisition with [18F]flutemetamol or [18F]florbetaben radiotracers was performed and quantified using the Centiloid (CL) method. Results: AMYPAD has significantly contributed to the AD field by furthering our understanding of amyloid deposition in the brain and the optimal methodology to measure this process. Main contributions so far include the validation of the dual-time window acquisition protocol to derive the fully quantitative non-displaceable binding potential (BP ND ), assess the value of this metric in the context of clinical trials, improve PET-sensitivity to emerging Aß burden and utilize its available regional information, establish the quantitative accuracy of the Centiloid method across tracers and support implementation of quantitative amyloid-PET measures in the clinical routine. Future steps: The AMYPAD consortium has succeeded in recruiting and following a large number of prospective subjects and setting up a collaborative framework to integrate data across European PCs. Efforts are currently ongoing in collaboration with ARIDHIA and ADDI to harmonize, integrate, and curate all available clinical data from the PNHS PCs, which will become openly accessible to the wider scientific community.

The effects of JNJ-39393406 a positive allosteric nicotine modulator on mood and cognition in patients with unipolar depression: A double-blind, add-on, placebo-controlled trial.

Nicotinic agonists have been shown to improve cognition and mood, but this improvement is inconsistent and short-lived, possibly due to receptor desensitization. Positive Allosteric Modulators (PAMs) of the nicotinic alpha-7 nicotinic-acetyl-choline receptor (a7nAChR) are hypothesized to change the configuration of the nicotinic receptor and delay desensitization, potentially increasing the duration of the activation of the receptor, and improving clinical efficacy. This was a randomized controlled trial (RCT) adding JNJ-39393406 9 (a PAM of the a7nAChR) (n=35) or placebo (n=36) to treatment as usual for two weeks in 71 patients with unipolar depression. Mixed models for repeated measures analyses were performed Primary outcome measures were the Brief Assessment of Cognition in Schizophrenia (BACS) composite and the Montgomery-Asperg Depression Rating Scale (MADRS) scores. The drug was well tolerated, however mixed models for repeated measures comparing JNJ-39393406 to placebo showed no significant difference for MADRS total score (p=0.78), BACS composite score (p=0.34), or any of the secondary outcome measures. There was no significant difference in adverse events between the study groups (p=0.44). In conclusion, this study's findings do not support the hypothesis that a positive nicotinic receptor modulator can improve cognitive or depressive symptomatology in patients with unipolar depression.

Dementia, Subtype of Seizures, and the Risk of New Onset Seizures: A Cohort Study.

BACKGROUND: Seizure disorders have been identified in patients suffering from different types of dementia. However, the risks associated with the seizure subtypes have not been characterized. OBJECTIVE: To compare the occurrence and risk of various seizure subtypes (focal and generalized) between patients with and without a dementia diagnosis. METHODS: Data from 40.7 million private insured patient individual electronic health records from the U.S., were utilized. Patients 60 years of age or more from the Optum Insight Clinformatics-data Mart database were included in this study. Using ICD-9 diagnoses, the occurrence of generalized or focal seizure disorders was identified. The risk of new-onset seizures and the types of seizures associated with a dementia diagnosis were estimated in a cohort of 2,885,336 patients followed from 2005 to 2014. Group differences were analyzed using continuity-adjusted chi-square and hazard ratios with 95%confidence intervals calculated after a logistic regression analysisResults:A total of 79,561 patient records had a dementia diagnosis, and 56.38%of them were females. Patients with dementia when compared to those without dementia had higher risk for seizure disorders [Hazard ratio (HR) = 6.5 95%CI = 4.4-9.5]; grand mal status (HR = 6.5, 95%CI = 5.7-7.3); focal seizures (HR = 6.0, 95%CI = 5.5-6.6); motor simple focal status (HR = 5.6, 95%CI = 3.5-9.0); epilepsy (HR = 5.0, 95%CI = 4.8-5.2); generalized convulsive epilepsy (HR = 4.8, 95%CI = 4.5-5.0); localization-related epilepsy (HR = 4.5, 95%CI = 4.1-4.9); focal status (HR = 4.2, 95%CI = 2.9-6.1); and fits convulsions (HR = 3.5, 95%CI = 3.4-3.6). CONCLUSION: The study confirms that patients with dementia have higher risks of generalized or focal seizure than patients without dementia.

Global biochemical analysis of plasma, serum and whole blood collected using various anticoagulant additives.

INTRODUCTION: Analysis of blood for the evaluation of clinically relevant biomarkers requires precise collection and sample handling by phlebotomists and laboratory staff. An important consideration for the clinical application of metabolomics are the different anticoagulants utilized for sample collection. Most studies that have characterized differences in metabolite levels in various blood collection tubes have focused on single analytes. We define analyte levels on a global metabolomics platform following blood sampling using five different, but commonly used, clinical laboratory blood collection tubes (i.e., plasma anticoagulated with either EDTA, lithium heparin or sodium citrate, along with no additive (serum), and EDTA anticoagulated whole blood). METHODS: Using an untargeted metabolomics platform we analyzed five sample types after all had been collected and stored at -80°C. The biochemical composition was determined and differences between the samples established using matched-pair t-tests. RESULTS: We identified 1,117 biochemicals across all samples and detected a mean of 1,036 in the sample groups. Compared to the levels of metabolites in EDTA plasma, the number of biochemicals present at statistically significant different levels (p<0.05) ranged from 452 (serum) to 917 (whole blood). Several metabolites linked to screening assays for rare diseases including acylcarnitines, bilirubin and heme metabolites, nucleosides, and redox balance metabolites varied significantly across the sample collection types. CONCLUSIONS: Our study highlights the widespread effects and importance of using consistent additives for assessing small molecule levels in clinical metabolomics. The biochemistry that occurs during the blood collection process creates a reproducible signal that can identify specimens collected with different anticoagulants in metabolomic studies. IMPACT STATEMENT: In this manuscript, normal/healthy donors had peripheral blood collected using multiple anticoagulants as well as serum during a fasted blood draw. Global metabolomics is a new technology being utilized to draw clinical conclusions and we interrogated the effects of different anticoagulants on the levels of biochemicals from each of the donors. Characterizing the effects of the anticoagulants on biochemical levels will help researchers leverage the information using global metabolomics in order to make conclusions regarding important disease biomarkers.

Assessment of the effects of repeated freeze thawing and extended bench top processing of plasma samples using untargeted metabolomics.

INTRODUCTION: Clinical metabolomics has utility as a screen for inborn errors of metabolism (IEM) and variant classification in patients with rare disease. It is important to understand and characterize preanalytical factors that influence assay performance during patient sample testing. OBJECTIVES: To evaluate the impact of extended thawing of human EDTA plasma samples on ice prior to extraction as well as repeated freeze-thaw cycling of samples to identify compounds that are unstable prior to metabolomic analysis. METHODS: Twenty-four (24) donor EDTA plasma samples were collected and immediately frozen at - 80 °C. Twelve samples were thawed on ice and extracted for analysis at time 0, 2, 4, and 6 h. Twelve other donor samples were repeatedly thawed and frozen up to four times and analyzed at each cycle. Compound levels at each time point/freeze-thaw cycle were compared to the control samples using matched-paired t tests to identify analytes affected by each condition. RESULTS: We identified 1026 biochemicals across all samples. Incubation of thawed EDTA plasma samples on ice for up to 6 h resulted in < 1% of biochemicals changing significantly. Freeze-thaw cycles affected a greater percentage of the metabolome; ~ 2% of biochemicals changed after 3 freeze-thaw cycles. CONCLUSIONS: Our study highlights that the number and magnitude of these changes are not as widespread as other aspects of improper sample handling. In total, < 3% of the metabolome detected on our clinical metabolomics platform should be disqualified when multiple freeze-thaw cycles or extended thawing at 4 °C are performed on a given sample.

Precision of a Clinical Metabolomics Profiling Platform for Use in the Identification of Inborn Errors of Metabolism.

BACKGROUND: The application of whole-exome sequencing for the diagnosis of genetic disease has paved the way for systems-based approaches in the clinical laboratory. Here, we describe a clinical metabolomics method for the screening of metabolic diseases through the analysis of a multi-pronged mass spectrometry platform. By simultaneously measuring hundreds of metabolites in a single sample, clinical metabolomics offers a comprehensive approach to identify metabolic perturbations across multiple biochemical pathways. METHODS: We conducted a single- and multi-day precision study on hundreds of metabolites in human plasma on 4, multi-arm, high-throughput metabolomics platforms. RESULTS: The average laboratory coefficient of variation (CV) on the 4 platforms was between 9.3 and 11.5% (median, 6.5-8.4%), average inter-assay CV on the 4 platforms ranged from 9.9 to 12.6% (median, 7.0-8.3%) and average intra-assay CV on the 4 platforms ranged from 5.7 to 6.9% (median, 3.5-4.4%). In relation to patient sample testing, the precision of multiple biomarkers associated with IEM disorders showed CVs that ranged from 0.2 to 11.0% across 4 analytical batches. CONCLUSIONS: This evaluation describes single and multi-day precision across 4 identical metabolomics platforms, comprised each of 4 independent method arms, and reproducibility of the method for the measurement of key IEM metabolites in patient samples across multiple analytical batches, providing evidence that the method is robust and reproducible for the screening of patients with inborn errors of metabolism.

Quantitative amyloid PET in Alzheimer's disease: the AMYPAD prognostic and natural history study.

INTRODUCTION: The Amyloid Imaging to Prevent Alzheimer's Disease (AMYPAD) Prognostic and Natural History Study (PNHS) aims at understanding the role of amyloid imaging in the earliest stages of Alzheimer's disease (AD). AMYPAD PNHS adds (semi-)quantitative amyloid PET imaging to several European parent cohorts (PCs) to predict AD-related progression as well as address methodological challenges in amyloid PET. METHODS: AMYPAD PNHS is an open-label, prospective, multi-center, cohort study recruiting from multiple PCs. Around 2000 participants will undergo baseline amyloid positron emission tomography (PET), half of whom will be invited for a follow-up PET 12 at least 12 months later. RESULTS: Primary include several amyloid PET measurements (Centiloid, SUVr, BPND , R1 ), and secondary are their changes from baseline, relationship to other amyloid markers (cerebrospinal fluid and visual assessment), and predictive value of AD-related decline. EXPECTED IMPACT: Determining the role of amyloid PET for the understanding of this complex disease and potentially improving secondary prevention trials.

Comparison of bony increased offset-reverse shoulder arthroplasty and standard reverse shoulder arthroplasty outcomes.

The purpose of this study is to evaluate functional outcomes and complications between the standard RSA and BIO-RSA. 65 consecutive procedures were performed in 60 patients (40 BIO-RSA and 25 RSA). There was no statistically significant difference in functional outcome, pain and complications. The BIO-RSA can produce comparable, if not better functional results than a standard RSA whilst reducing the rates of scapula notching, prosthesis instability, lost shoulder rotation and poor shoulder contour. It should therefore be considered in all patients presenting with cuff tear arthropathy, massive rotator cuff tear and fracture sequelae.

To err is human: Clinical incident calls to a national travel health advice line.

The National Travel Health Network and Centre (NaTHNaC) offers a telephone advice line for travel health practitioners in the UK. In this study we review clinical incidents concerning vaccines or malaria prophylaxis reported between 2016 and 2018. Two-hundred-and-fifty-one clinical incident calls were recorded, and commonly concerned scheduling or dosing errors. Vaccine scheduling errors accounted for 103 calls (41%), predominantly due to hepatitis A or hepatitis B vaccination either alone or in combination (65/103, 63%). Administration of yellow fever vaccine within 28 days of measles, mumps and rubella accounted for a further 15 (15%) calls. Twenty-six (10%) calls reported administration of a vaccine that was not recommended either for the destination or contraindicated in the traveller. Yellow fever was the commonest single vaccine discussed in 28.4% of vaccine clinical incidents reported. By highlighting common mistakes, we hope to raise awareness of common issues and improve practice in travel health.

Validation of a Metabolite Panel for a More Accurate Estimation of Glomerular Filtration Rate Using Quantitative LC-MS/MS.

BACKGROUND: Clinical practice guidelines recommend estimation of glomerular filtration rate (eGFR) using validated equations based on serum creatinine (eGFRcr), cystatin C (eGFRcys), or both (eGFRcr-cys). However, when compared with the measured GFR (mGFR), only eGFRcr-cys meets recommended performance standards. Our goal was to develop a more accurate eGFR method using a panel of metabolites without creatinine, cystatin C, or demographic variables. METHODS: An ultra-performance liquid chromatography-tandem mass spectrometry assay for acetylthreonine, phenylacetylglutamine, pseudouridine, and tryptophan was developed, and a 20-day, multiinstrument analytical validation was conducted. The assay was tested in 2424 participants with mGFR data from 4 independent research studies. A new GFR equation (eGFRmet) was developed in a random subset (n = 1615) and evaluated in the remaining participants (n = 809). Performance was assessed as the frequency of large errors [estimates that differed from mGFR by at least 30% (1 - P30); goal <10%]. RESULTS: The assay had a mean imprecision (≤10% intraassay, ≤6.9% interassay), linearity over the quantitative range (r 2 > 0.98), and analyte recovery (98.5%-113%). There was no carryover, no interferences observed, and analyte stability was established. In addition, 1 - P30 in the validation set for eGFRmet (10.0%) was more accurate than eGFRcr (13.1%) and eGFRcys (12.0%) but not eGFRcr-cys (8.7%). Combining metabolites, creatinine, cystatin C, and demographics led to the most accurate equation (7.0%). Neither equation had substantial variation among population subgroups. CONCLUSIONS: The new eGFRmet equation could serve as a confirmatory test for GFR estimation.

Metabolomic profiling to improve glomerular filtration rate estimation: a proof-of-concept study.

BACKGROUND: Estimation of glomerular filtration rate (GFR) using estimated glomerular filtration rate creatinine (eGFRcr) is central to clinical practice but has limitations. We tested the hypothesis that serum metabolomic profiling can identify novel markers that in combination can provide more accurate GFR estimates. METHODS: We performed a cross-sectional study of 200 African American Study of Kidney Disease and Hypertension (AASK) and 265 Multi-Ethnic Study of Atherosclerosis (MESA) participants with measured GFR (mGFR). Untargeted gas chromatography/dual mass spectrometry- and liquid chromatography/dual mass spectrometry-based quantification was followed by the development of targeted assays for 15 metabolites. On the log scale, GFR was estimated from single- and multiple-metabolite panels and compared with eGFR using the Chronic Kidney Disease Epidemiology equations with creatinine and/or cystatin C using established metrics, including the proportion of errors >30% of mGFR (1-P30), before and after bias correction. RESULTS: Of untargeted metabolites in the AASK and MESA, 283 of 780 (36%) and 387 of 1447 (27%), respectively, were significantly correlated (P ≤ 0.001) with mGFR. A targeted metabolite panel eGFR developed in the AASK and validated in the MESA was more accurate (1-P30 3.7 and 1.9%, respectively) than eGFRcr [11.2 and 18.5%, respectively (P < 0.001 for both)] and estimating GFR using cystatin C (eGFRcys) [10.6% (P = 0.02) and 9.1% (P < 0.05), respectively] but was not consistently better than eGFR using both creatinine and cystatin C [3.7% (P > 0.05) and 9.1% (P < 0.05), respectively]. A panel excluding creatinine and demographics still performed well [1-P30 6.4% (P = 0.11) and 3.4% (P < 0.001) in the AASK and MESA] versus eGFRcr. CONCLUSIONS: Multimetabolite panels can enable accurate GFR estimation. Metabolomic equations, preferably excluding creatinine and demographic characteristics, should be tested for robustness and generalizability as a potential confirmatory test when eGFRcr is unreliable.

Identification of an Endogenous Organosulfur Metabolite by Interpretation of Mass Spectrometric Data.

The chemical structure of x11564, a new endogenous organosulfur metabolite, was elucidated by de novo interpretation of mass spectrometric data. The structure was confirmed by comparison to a synthetic standard. Metabolite x11564 is structurally related to intermediates in the methionine salvage pathway.

Deep Vein Thrombosis After Complex Posterior Spine Surgery: Does Staged Surgery Make a Difference?

STUDY DESIGN: Retrospective review of a prospectively collected database. OBJECTIVE: To assess the incidence of deep vein thrombosis (DVT) associated with single- versus multistage posterior-only complex spinal surgeries. SUMMARY OF BACKGROUND DATA: Dividing the physiologic burden of spinal deformity surgery into multiple stages has been suggested as a potential means of reducing perioperative complications. DVT is a worrisome complication owing to its potential to lead to pulmonary embolism. Whether or not staging affects DVT incidence in this population is unknown. METHODS: Consecutive patients undergoing either single- or multistage posterior complex spinal surgeries over a 12-year period at a single institution were eligible. All patients received lower extremity venous duplex ultrasonographic (US) examinations 2 to 4 days postoperatively in the single-stage group and 2 to 4 days postoperatively after each stage in the multistage group. Multivariate logistic regression was used to assess the independent contribution of staging to developing a DVT. RESULTS: A total of 107 consecutive patients were enrolled-26 underwent multistage surgery and 81 underwent single-stage surgery. The single-stage group was older (63 years vs. 45 years; p < .01) and had a higher Charlson comorbidity index (2.25 ± 1.27 vs. 1.23 ± 1.58; p < .01). More multistage patients had positive US tests than single-stage patients (5 of 26 vs. 6 of 81; 19% vs. 7%; p = .13). Adjusting for all the above-mentioned covariates, a multistage surgery was 8.17 (95% CI 0.35-250.6) times more likely to yield a DVT than a single-stage surgery. CONCLUSIONS: Patients who undergo multistage posterior complex spine surgery are at a high risk for developing a DVT compared to those who undergo single-stage procedures. The difference in DVT incidence may be understated as the multistage group had a lower pre- and intraoperative risk profile with a younger age, lower medical comorbidities, and less per-stage blood loss.

Initial Cross-Over Test of A Positive Allosteric Modulator of Alpha-7 Nicotinic Receptors to Aid Cessation in Smokers With Or Without Schizophrenia.

Preclinical research shows that compounds acting at α7 nicotinic receptors (nAChRs) can reduce nicotine self-administration, suggesting that a positive allosteric modulator (PAM) of α7 receptors, JNJ-39393406, may aid smoking cessation. Moreover, individuals with schizophrenia, who have very high rates of smoking, have reduced expression of α7 nAChRs and may particularly benefit from this compound. In two parallel studies using a within-subject cross-over design, 36 healthy smokers (Study 1) and 62 smokers with schizophrenia (Study 2), both groups high in quit interest, attempted to initiate quitting temporarily during each of two 3-week phases. Treatments were the α7 nicotinic receptor PAM JNJ-39393406 (100 mg b.i.d.) or placebo (double-blind, counter-balanced). In each phase, all smoked ad lib with no drug on week 1 or during dose run-up on week 2, and then tried to quit every day during week 3. Abstinence (confirmed by CO <5 p.p.m.) and smoking reduction (CO <8), as well as cigarettes/day (in Study 1), were assessed daily (Monday-Friday) each quit week and compared between conditions. Secondary outcomes included abstinence symptoms (withdrawal and craving) and cognitive test responding (N-back; continuous performance task). In both studies, compared with placebo, active JNJ-39393406 did not increase the number of abstinent days nor reduce total smoking exposure. We also found no significant improvements in craving, withdrawal, or cognitive function. With this dose and study duration, our findings do not support further testing of this α7 nAChR PAM compound for possible efficacy in smoking cessation, in smokers with or without schizophrenia.

Structure elucidation of metabolite x17299 by interpretation of mass spectrometric data.

INTRODUCTION: A major bottleneck in metabolomic studies is metabolite identification from accurate mass spectrometric data. Metabolite x17299 was identified in plasma as an unknown in a metabolomic study using a compound-centric approach where the associated ion features of the compound were used to determine the true molecular mass. OBJECTIVES: The aim of this work is to elucidate the chemical structure of x17299, a new compound by de novo interpretation of mass spectrometric data. METHODS: An Orbitrap Elite mass spectrometer was used for acquisition of mass spectra up to MS4 at high resolution. Synthetic standards of N,N,N-trimethyl-l-alanyl-l-proline betaine (l,l-TMAP), a diastereomer, and an enantiomer were chemically prepared. RESULTS: The planar structure of x17299 was successfully proposed by de novo mechanistic interpretation of mass spectrometric data without any laborious purification and nuclear magnetic resonance spectroscopic analysis. The proposed structure was verified by deuterium exchanged mass spectrometric analysis and confirmed by comparison to a synthetic standard. Relative configuration of x17299 was determined by direct chromatographic comparison to a pair of synthetic diastereomers. Absolute configuration was assigned after derivatization of x17299 with a chiral auxiliary group followed by its chromatographic comparison to a pair of synthetic standards. CONCLUSION: The chemical structure of metabolite x17299 was determined to be l,l-TMAP.

Comprehensive review of visual defects reported with topiramate.

OBJECTIVE: The objective of this study was to analyze clinical patterns of visual field defects (VFDs) reported with topiramate treatment and assess possible mechanism of action (MOA) for antiepileptic drug (AED) associated VFDs. METHODS: A comprehensive topiramate database review included preclinical data, sponsor's clinical trials database, postmarketing spontaneous reports, and medical literature. All treatment-emergent adverse events (TEAEs) suggestive of retinal dysfunction/damage were summarized. Relative risk (RR) was computed from topiramate double-blind, placebo-controlled trials (DBPCTs) data. RESULTS: Preclinical studies and medical literature review suggested that despite sharing gamma-aminobutyric acid (GABA)-ergic MOA with other AEDs, topiramate treatment was not associated with VFDs. TEAEs suggestive of retinal dysfunction/damage were observed in 0.3%-0.7% of adults and pediatric patients with topiramate (N=4,679) versus ≤0.1% with placebo (N=1,834) in DBPCTs for approved indications (epilepsy and migraine prophylaxis); open-label trials (OLTs) and DBPCTs for investigational indications had similar incidence. Overall, 88% TEAEs were mild or moderate in severity. Serious TEAEs were very rare (DBPCTs: 0%; OLTs: ≤0.1%), and most were not treatment limiting, and resolved. The most common visual TEAEs (approved indications) were VFD, scotoma, and optic atrophy. The incidence of TEAEs in DBPCTs (approved and investigational indications) was higher in topiramate-treated (N=9,169) versus placebo-treated patients (N=5,023; 0.36% vs 0.24%), but the RR versus placebo-treated patients was not significant (RR: 1.51 [95% confidence interval: 0.78, 2.91]). CONCLUSION: VFDs do not appear to be a class effect for AEDs with GABA-ergic MOA. The RR for VFDs is not significantly different between topiramate and placebo treatment.

LC-MS/MS method for quantitation of seven biomarkers in human plasma for the assessment of insulin resistance and impaired glucose tolerance.

Early detection of insulin resistance (IR) and/or impaired glucose tolerance (IGT) is crucial for delaying and preventing the progression toward type 2 diabetes. We recently developed and validated a straightforward metabolite-based test for the assessment of IR and IGT in a single LC-MS/MS method. Plasma samples were diluted with isotopically-labeled internal standards and extracted by simple protein precipitation. The extracts were analyzed by LC-MS/MS for the quantitation of 2-hydroxybutyric acid (0.500-40.0µg/mL), 3-hydroxybutyric acid (1.00-80.0µg/mL), 4-methyl-2-oxopentanoic acid (0.500-20.0µg/mL), 1-linoleoyl-2-hydroxy-sn-glycero-3-phosphocholine (2.50-100µg/mL), oleic acid (10.0-400µg/mL), pantothenic acid (0.0100-0.800µg/mL), and serine (2.50-100µg/mL). Liquid chromatography was carried out on a reversed phase column with a run time of 3.1min and the mass spectrometer operated in negative MRM mode. Method validation was performed on three identical LC-MS/MS systems with five runs each. Sufficient linearity (R2>0.99) was observed for all the analytes over the ranges. The imprecision (CVs) was found to be less than 5.5% for intra-run and less than 5.8% for inter-run for the seven analytes. The analytical recovery was determined to be between 96.3 and 103% for the seven analytes. This fast and robust method has subsequently been used for patient sample analysis for the assessment of IR and IGT.