Refined protocols of tamoxifen injection for inducible DNA recombination in mouse astroglia.

Inducible DNA recombination of floxed alleles in vivo by liver metabolites of tamoxifen (TAM) is an important tool to study gene functions. Here, we describe protocols for optimal DNA recombination in astrocytes, based on the GLAST-Cre/loxP system. In addition, we demonstrate that quantification of genomic recombination allows to determine the proportion of cell types in various brain regions.

Liquid chromatography-high resolution-tandem mass spectrometry using Orbitrap technology for comprehensive screening to detect drugs and their metabolites in blood plasma.

Orbitrap technology was successfully applied for broad metabolite-based LC-high resolution (HR)-MS screening of drugs in clinical and forensic toxicology. This paper aims to elucidate whether this technology can also be used for a corresponding blood plasma screening after simple precipitation without or with consecutive on-line extraction using turbulent flow chromatography (TurboFlow). The analytes were separated within 10 min and detected by a Q-Exactive mass spectrometer in full scan mode after positive/negative switching.

The effect of renal denervation in moderate treatment-resistant hypertension with confirmed medication adherence.

Objectives: Data on the blood pressure (BP)-lowering effect of renal denervation (RDN) in moderate treatment-resistant hypertension (TRH) are limited. Moreover, change of adherence to medication, as one potential confounder of BP response, has never been analyzed rigorously in this group of patients. We analyzed the effect of RDN on BP in patients with moderate TRH who were retrospectively found to be completely adherent to their antihypertensive medication.

LC-HR-MS/MS standard urine screening approach: Pros and cons of automated on-line extraction by turbulent flow chromatography versus dilute-and-shoot and comparison with established urine precipitation.

Comprehensive urine screening for drugs and metabolites by LC-HR-MS/MS using Orbitrap technology has been described with precipitation as simple workup. In order to fasten, automate, and/or simplify the workup, on-line extraction by turbulent flow chromatography and a dilute-and-shoot approach were developed and compared. After chromatographic separation within 10min, the Q-Exactive mass spectrometer was run in full scan mode with positive/negative switching and subsequent data dependent acquisition mode.

Metabolic patterns of JWH-210, RCS-4, and THC in pig urine elucidated using LC-HR-MS/MS: Do they reflect patterns in humans?

The knowledge of pharmacokinetic (PK) properties of synthetic cannabinoids (SCs) is important for interpretation of analytical results found for example in intoxicated individuals. In the absence of human data from controlled studies, animal models elucidating SC PK have to be established. Pigs providing large biofluid sample volumes were tested for prediction of human PK data.

Blood pressure changes after catheter-based renal denervation are related to reductions in total peripheral resistance.

Background: Renal denervation (RDN) can reduce sympathetic activity and blood pressure (BP) in patients with uncontrolled hypertension. The exact mechanisms by which RDN results in BP reductions are yet not fully established.

Methods And Results: This study investigated the effects of RDN on office BP, 24-h ambulatory BP, noninvasive 10-min beat-to-beat digital pulse wave analysis, total peripheral resistance (TPR), cardiac output, and plasma renin and aldosterone serum concentrations in 30 patients with resistant hypertension.

Orbitrap technology for comprehensive metabolite-based liquid chromatographic-high resolution-tandem mass spectrometric urine drug screening - exemplified for cardiovascular drugs.

LC-high resolution (HR)-MS well established in proteomics has become more and more important in bioanalysis of small molecules over the last few years. Its high selectivity and specificity provide best prerequisites for its use in broad screening approaches. Therefore, Orbitrap technology was tested for developing a general metabolite-based LC-HR-MS/MS screening approach for urinalysis of drugs necessary in clinical and forensic toxicology.

Blood pressure reductions following catheter-based renal denervation are not related to improvements in adherence to antihypertensive drugs measured by urine/plasma toxicological analysis.

Renal denervation can reduce blood pressure in patients with uncontrolled hypertension. The adherence to prescribed antihypertensive medication following renal denervation is unknown. This study investigated adherence to prescribed antihypertensive treatment by liquid chromatography-high resolution tandem mass spectrometry in plasma and urine at baseline and 6 months after renal denervation in 100 patients with resistant hypertension, defined as baseline office systolic blood pressure ≥140 mmHg despite treatment with ≥3 antihypertensive agents.

Metabolism of the new psychoactive substances N,N-diallyltryptamine (DALT) and 5-methoxy-DALT and their detectability in urine by GC-MS, LC-MSn, and LC-HR-MS-MS.

N,N-Diallyltryptamine (DALT) and 5-methoxy-DALT (5-MeO-DALT) are synthetic tryptamine derivatives commonly referred to as so-called new psychoactive substances (NPS). They have psychoactive effects that may be similar to those of other tryptamine derivatives. The objectives of this work were to study the metabolic fate and detectability, in urine, of DALT and 5-MeO-DALT.

Studies on the metabolism and toxicological detection of the new psychoactive designer drug 2-(4-iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25I-NBOMe) in human and rat urine using GC-MS, LC-MS(n), and LC-HR-MS/MS.

25I-NBOMe, a new psychoactive substance, is a potent 5-HT2A receptor agonist with strong hallucinogenic potential. Recently, it was involved in several fatal and non-fatal intoxication cases. The aim of the present work was to study its phase I and II metabolism and its detectability in urine screening approaches.

No-carrier-added labeling of the neuroprotective Ebselen with selenium-73 and selenium-75.

Selenium-73 is a positron emitting non-standard radionuclide, which is suitable for positron emission tomography. A copper-catalyzed reaction allowed no-carrier-added labeling of the anti-inflammatory seleno-organic compound Ebselen with (73) Se and (75) Se under addition of sulfur carrier in a one-step reaction. The new authentically labeled radioselenium molecule is thus available for preclinical evaluation and positron emission tomography studies.

Current position of high-resolution MS for drug quantification in clinical & forensic toxicology.

This paper reviews high-resolution MS approaches published from January 2011 until March 2014 for the quantification of drugs (of abuse) and/or their metabolites in biosamples using LC-MS with time-of-flight or Orbitrap™ mass analyzers. Corresponding approaches are discussed including sample preparation and mass spectral settings. The advantages and limitations of high-resolution MS for drug quantification, as well as the demand for a certain resolution or a specific mass accuracy are also explored.

Elucidation of the metabolites of the novel psychoactive substance 4-methyl-N-ethyl-cathinone (4-MEC) in human urine and pooled liver microsomes by GC-MS and LC-HR-MS/MS techniques and of its detectability by GC-MS or LC-MS(n) standard screening approaches.

4-methyl-N-ethcathinone (4-MEC), the N-ethyl homologue of mephedrone, is a novel psychoactive substance of the beta-keto amphetamine (cathinone) group. The aim of the present work was to study the phase I and phase II metabolism of 4-MEC in human urine as well as in pooled human liver microsome (pHLM) incubations. The urine samples were worked up with and without enzymatic cleavage, the pHLM incubations by simple deproteinization.

Direct analysis of the mushroom poisons α- and β-amanitin in human urine using a novel on-line turbulent flow chromatography mode coupled to liquid chromatography-high resolution-mass spectrometry/mass spectrometry.

Poisonings with Amanita phalloides toxins require fast diagnosis in order to avoid expensive and unnecessary therapies. Initial clinical assessment in combination with urinary amanitin analysis is necessary for a definite diagnosis. Therefore, a simple, fast, and robust method was developed for reliable detection of α- and β-amanitin as well as for fully validated quantification of α-amanitin in human urine.

Bis(4-benzyloxyphenyl)iodonium salts as effective precursors for the no-carrier-added radiosynthesis of 4-[¹⁸F]fluorophenol.

4-[¹⁸F]Fluorophenol is a very useful intermediate compound for building-up more complex molecules bearing a 4-[¹⁸F]fluorophenoxy moiety. Bis(4-benzyloxyphenyl)iodonium salts proved very effective as labeling precursors for the radiosynthesis of this compound in no-carrier-added form. Starting from the bromide salt and performing the radiofluorination by conventional heating, 4-[¹⁸F]fluorophenol was obtained in an overall RCY of 43 ± 12% while a yield of 52 ± 3% was achieved more reliably starting from the tosylate salt and employing microwave heating.