In silico and in vitro metabolism studies support identification of designer drugs in human urine by liquid chromatography/quadrupole-time-of-flight mass spectrometry

Human phase I metabolism of four designer drugs, 2-desoxypipradrol (2-DPMP), 3,4-dimethylmethcathinone (3,4-DMMC), α-pyrrolidinovalerophenone (α-PVP), and methiopropamine (MPA), was studied using in silico and in vitro metabolite prediction. The metabolites were identified in drug abusers’ urine samples using liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/Q-TOF/MS). The aim of the study was to evaluate the ability of the in silico and in vitro methods to generate the main urinary metabolites found in vivo. Meteor 14.0.0 software (Lhasa Limited) was used for in silico metabolite prediction, and in vitro metabolites were produced in human liver microsomes (HLMs). 2-DPMP was metabolized by hydroxylation, dehydrogenation, and oxidation, resulting in six phase I metabolites. Six metabolites were identified for 3,4-DMMC formed via N-demethylation, reduction, hydroxylation, and oxidation reactions. α-PVP was found to undergo reduction, hydroxylation, dehydrogenation, and oxidation reactions, as well as degradation of the pyrrolidine ring, and seven phase I metabolites were identified. For MPA, the nor-MPA metabolite was detected. Meteor software predicted the main human urinary phase I metabolites of 3,4-DMMC, α-PVP, and MPA and two of the four main metabolites of 2-DPMP. It assisted in the identification of the previously unreported metabolic reactions for α-PVP. Eight of the 12 most abundant in vivo phase I metabolites were detected in the in vitro HLM experiments. In vitro tests serve as material for exploitation of in silico data when an authentic urine sample is not available. In silico and in vitro designer drug metabolism studies with LC/Q-TOF/MS produced sufficient metabolic information to support identification of the parent compound in vivo.

Mining for classes and patterns in behavioural data

In this paper we compare and contrast the new data mining activity of pattern search with more traditional cluster analysis methods of data mining, in the context of credit data. In particular, we examine a set of behavioural data from a large UK bank relating to the status of current accounts over a twelve month period. We show how conventional clustering approaches can be used, for example to define broad categories of behaviour, whereas pattern search can be used to find small groups of accounts that exhibit distinctive behaviour.     

Solubility-Driven Isolation of a Metastable Nonagold Cluster with Body-Centered Cubic Structure

The conventional synthetic methodology for atomically precise gold nanoclusters by using reduction in solution offers only the thermodynamically most stable nanoclusters. Herein, a solubility-driven isolation strategy is reported to access a metastable gold cluster. The cluster, with the composition of [Au₉(PPh₃)₈]⁺ ( 1 ), displays an unusual, nearly perfect body-centered cubic (bcc) structure. As revealed by ESI-MS and UV/Vis measurements, the cluster is metastable in solution and converts to the well-known [Au₁₁(PPh₃)₈Cl₂]⁺ ( 2 ) within just 90 min. DFT calculations revealed that although both 1 and 2 are eight-electron superatoms, there is a driving force to convert 1 to 2 as shown by the increased cohesion and larger HOMO–LUMO energy gap of 2 . The isolation and crystallization of the metastable gold cluster were achieved in a biphasic reaction system in which reduction of gold precursors and crystallization of 1 took place concurrently. This synthetic protocol represents a successful strategy for investigations of other metastable species in metal nanocluster chemistry.     

Direction specific interactions of 1,4-dicarboxylic acid with calcite surfaces

Interactions of succinic acid (SUC) with the {104} cleavage faces of calcite show a strong preference in crystallographic directions. In situ atomic force microscopy revealed that the morphology of etch pits on the crystal surfaces experienced a transition from the common rhombus to a hexagon upon the introduction of SUC. The pit shape further evolved from 6-sided to 7-sided and eventually to 5-sided with increasing concentrations of SUC. Analysis indicates that the morphology changes may result from SUC preferentially binding to the [42] and [010] edges of the (104) plane to selectively slow down their step speed.     

A study of stitch line formation during high speed laser patterning of thin film indium tin oxide transparent electrodes

High speed laser patterning of indium tin oxide thin films on glass is part of the production method used to produce transparent conductive electrodes for plasma display panels. Such a design consists of rows of repeating electrode structures which cover the active area of the display. Whilst the patterning process for such electrode structures exceeds the industrial acceptance criteria there are certain features that are yet to be fully understood. The visible line that occurs in-between two adjacent laser processed areas, commonly known as a stitch line, is one such feature. Previously published research claimed that the stitch line was caused by incomplete removal of the thin film however experimental results presented within this paper demonstrate that this cannot be the case and show that the stitch line is formed by redeposition of the plume of ablated material within the area of overlap with the previous pulse, and that heating of the sample by the second pulse plays a key role in stitch line formation.     

A new scalable synthesis of entecavir

A new synthesis of entecavir from d-glucose in an average total yield of 3.5% was achieved via an intramolecular nitrile oxide cycloaddition (INOC) reaction and a Peterson olefination as key-steps. The present process was designed for industrial application, using widely available raw materials, simple and cheap reagents and avoiding low reaction temperatures, which are very common in the synthetic approaches towards similarly complex structures.     

Prediction of liquid chromatographic retention for differentiation of structural isomers

A liquid chromatography (LC) retention time prediction software, ACD/ChromGenius, was employed to calculate retention times for structural isomers, which cannot be differentiated by accurate mass measurement techniques alone. For 486 drug compounds included in an in-house database for urine drug screening by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOFMS), a retention time knowledge base was created with the software. ACD/ChromGenius calculated retention times for compounds based on the drawn molecular structure and given chromatographic parameters. The ability of the software for compound identification was evaluated by calculating the retention order of the 118 isomers, in 50 isomer groups of 2–5 compounds each, included in the database. ACD/ChromGenius predicted the correct elution order for 68% (34) of isomer groups. Of the 16 groups for which the isomer elution order was incorrectly calculated, two were diastereomer pairs and thus difficult to distinguish using the software. Correlation between the calculated and experimental retention times in the knowledge base tested was moderate, r² = 0.8533. The mean and median absolute errors were 1.12 min, and 0.84 min, respectively, and the standard deviation was 1.04 min. The information generated by ACD/ChromGenius, together with other in silico methods employing accurate mass data, makes the identification of substances more reliable. This study demonstrates an approach for tentatively identifying compounds in a large target database without a need for primary reference standards.     

Divergent CH Insertion–Cyclization Cascades of N‐Allyl Ynamides

Gold carbene reactivity patterns were accessed by ynamide insertion into a C(sp³)? H bond. A substantial increase in molecular complexity occurred through the cascade polycyclization of N‐allyl ynamides to form fused nitrogen‐heterocycle scaffolds. Exquisite selectivity was observed despite several competing pathways in an efficient gold‐catalyzed synthesis of densely functionalized C(sp³)‐rich polycycles and a copper‐catalyzed synthesis of fused pyridine derivatives. The respective gold–keteniminium and ketenimine activation pathways have been explored through a structure–reactivity study, and isotopic labeling identified turnover‐limiting C? H bond‐cleavage in both processes.     

Temporally adaptive estimation of logistic classifiers on data streams

Modern technology has allowed real-time data collection in a variety of domains, ranging from environmental monitoring to healthcare. Consequently, there is a growing need for algorithms capable of performing inferential tasks in an online manner, continuously revising their estimates to reflect the current status of the underlying process. In particular, we are interested in constructing online and temporally adaptive classifiers capable of handling the possibly drifting decision boundaries arising in streaming environments. We first make a quadratic approximation to the log-likelihood that yields a recursive algorithm for fitting logistic regression online. We then suggest a novel way of equipping this framework with self-tuning forgetting factors. The resulting scheme is capable of tracking changes in the underlying probability distribution, adapting the decision boundary appropriately and hence maintaining high classification accuracy in dynamic or unstable environments. We demonstrate the scheme’s effectiveness in both real and simulated streaming environments.     

New methodological criteria in rapid multichannel microspectrofluorometry

Summary The application of microspectrofluorometric techniques to the study of various metabolic pathways in the dynamic context of intracellular interactions has gained further versatility through the use of better correlated microtopographic and spectral observations, rapid automatic data processing and a more accurate definition of specific conditions at fluorescence excitation and detection to minimize the action of exciting wavelengths on the stability of fluorochrome emission. The kinetic parameters of metabolic transients due to microinjection of substrate, are evaluated from 50–200 intracellular sites simultaneously at a temporal resolution of ~ 64 msec. Thus, regional asynchronicities and kinetic discrepancies of the metabolic response may be recognized in correlation with intracellular structure. Sequential changes in the topographic fluorescence pattern or in the fluorescence spectra may be used to define various intracellular pathways associated with the catabolism of natural metabolites or the intracellular distribution and conversion of exogenous molecules. The combination with automated data processing makes possible the uninterupted studies at the level of various intracellular compartments simultaneously on a topographic mode or the identification via spectral analysis of rapid intracellular conversion undergone by natural and exogenous fluorochromes.

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Zusammenfassung Die Anwendung spektralfluorometrischer Mikromethoden für das Studium verschiedener Stoffwechselvorgänge im dynamischen Zusammenhang intrazellulärer Reaktionen hat durch besser abgestimmte mikrotopographische und spektrale Beobachtungsmöglichkeiten, rasche automatische Datenermittlung, genauere Angabe spezifischer Bedingungen zur Fluoreszenzanregung und Herabsetzung der Einwirkung bestimmter Wellenlängen auf die Stabilität der Fluorochromemission zu weiteren Fortschritten geführt. Die kinetischen Parameter metabolischer Übergänge infolge einer Mikroinjektion von Substrat wurden gleichzeitig an 50–200 intrazellulären Orten mit einer zeitlichen Auflösung von etwa 64 msec ausgewertet. So können regionale Ungleichzeitigkeiten und kinetische Diskrepanzen der metabolischen Beantwortung in Korrelation zur intrazellulären Struktur erkannt werden. Aufeinander folgende Veränderungen der topographischen Fluoreszenzmuster oder der Fluoreszenzspektren lassen sich zur Definition verschiedener intrazellulärer Vorgänge beim Abbau natürlicher Metaboliten oder der intrazellulären Verteilung und Umsetzung exogener Moleküle verwenden. Die Kombination mit automatischer Datenverarbeitung ermöglicht ununterbrochene Untersuchungen in der Größenordnung verschiedener intrazellulärer Räume gleichzeitig auf topographischem Wege oder den spektralanalytischen Nachweis rascher intrazellulärer Umsetzungen natürlicher oder exogener Fluorochrome.