Temporal variation in out-of-hospital cardiac arrest occurrence in individuals with or without diabetes.

OBJECTIVE: Out-of-hospital cardiac arrest (OHCA) occurrence has been shown to exhibit a circadian rhythm, following the circadian rhythm of acute myocardial infarction (AMI) occurrence. Diabetes mellitus (DM) is associated with changes in circadian rhythm. We aimed to compare the temporal variation of OHCA occurrence over the day and week between OHCA patients with DM and those without. METHODS: In two population-based OHCA registries (Amsterdam Resuscitation Studies [ARREST] 2010-2016, n = 4163, and Danish Cardiac Arrest Registry [DANCAR], 2010-2014, n = 12,734), adults (≥18y) with presumed cardiac cause of OHCA and available medical history were included. Single and double cosinor analysis was performed to model circadian variation of OHCA occurrence. Stratified analysis of circadian variation was performed in patients with AMI as immediate cause of OHCA. RESULTS: DM patients (22.8% in ARREST, 24.2% in DANCAR) were older and more frequently had cardiovascular risk factors or previous cardiovascular disease. Both cohorts showed 24 h-rhythmicity, with significant amplitudes in single and double cosinor functions (P-range < 0.001). In both registries, a morning peak (10:00-11:00) and an evening peak (20:00-21:00) was observed in both DM and non-DM patients. No septadian variation was observed in either DM or non-DM patients (P-range 0.13-84). CONCLUSIONS: In these two population-based OHCA registries, we observed a similar circadian rhythm of OHCA occurrence in DM and non-DM patients.

Expression of the clock gene Rev-erbα in the brain controls the circadian organisation of food intake and locomotor activity, but not daily variations of energy metabolism.

The nuclear receptor REV-ERBα is part of the molecular clock mechanism and is considered to be involved in a variety of biological processes within metabolically active peripheral tissues as well. To investigate whether Rev-erbα (also known as Nr1d1) in the brain plays a role in the daily variations of energy metabolism, feeding behaviour and the sleep-wake cycle, we studied mice with global (GKO) or brain (BKO) deletion of Rev-erbα. Mice were studied both in a light/dark cycle and in constant darkness, and then 24-hour variations of Respiratory quotient (RQ) and energy expenditure, as well as the temporal patterns of rest-activity and feeding behaviour, were recorded. The RQ increase of GKO mice was not detected in BKO animals, indicating a peripheral origin for this metabolic alteration. Arrhythmic patterns of locomotor activity were only found in BKO mice. By contrast, the circadian rhythm of food intake was lost both in GKO and BKO mice, mostly by increasing the number of daytime meals. These changes in the circadian pattern of feeding behaviour were, to some extent, correlated with a loss of rhythmicity of hypothalamic Hcrt (also named Orx) mRNA levels. Taken together, these findings highlight that Rev-erbα in the brain is involved in the temporal partitioning of feeding and sleep, whereas its effects on energy metabolism are mainly exerted through its peripheral expression.

Effects of meal composition and meal timing on the expression of genes involved in hepatic drug metabolism in rats.

INTRODUCTION: With chronotherapy, drug administration is synchronized with daily rhythms in drug clearance and pharmacokinetics. Daily rhythms in gene expression are centrally mastered by the suprachiasmatic nucleus of the hypothalamus as well as by tissue clocks containing similar molecular mechanisms in peripheral organs. The central timing system is sensitive to changes in the external environment such as those of the light-dark cycle, meal timing and meal composition. We investigated how changes in diet composition and meal timing would affect the daily hepatic expression rhythms of the nuclear receptors PXR and CAR and of enzymes involved in P450 mediated drug metabolism, as such changes could have consequences for the practice of chronotherapy. MATERIALS AND METHODS: Rats were subjected to either a regular chow or a free choice high-fat-high-sugar (fcHFHS) diet. These diets were provided ad libitum, or restricted to either the light phase or the dark phase. In a second experiment, rats had access to chow either ad libitum or in 6 meals equally distributed over 24 hours. RESULTS: Pxr, Alas1 and Por displayed significant day-night rhythms under ad libitum chow fed conditions, which for Pxr was disrupted under fcHFHS diet conditions. Although no daily rhythms were detected in expression of CAR, Cyp2b2 and Cyp3a2, the fcHFHS diet did affect basal expression of these genes. In chow fed rats, dark phase feeding induced a diurnal rhythm in Cyp2b2 expression while light phase feeding induced a diurnal rhythm in Car expression and completely shifted the peak expression of Pxr, Car, Cyp2b2, Alas1 and Por. The 6-meals-a-day feeding only abolished the Pxr rhythm but not the rhythms of the other genes. CONCLUSION: We conclude that although nuclear receptors and enzymes involved in the regulation of hepatic drug metabolism are sensitive to meal composition, changes in meal timing are mainly effectuated via changes in the molecular clock.

Reversed-phase ion-pair HPLC method for the direct analysis of 1-OH midazolam glucuronide in human serum.

In recent years, it has become clear that the presence of high concentrations of 1-OH midazolam glucuronide is probably the cause of unexplained prolonged midazolam comas in patients with poor renal function. Until recently, only indirect methods for the analysis of this glucuronide were known, which had several disadvantages, such as a long analysis period (>6 hours). This article describes the validation of a method for the direct analysis of this compound in human serum, using reversed-phase ion-pair high-performance liquid chromatography (HPLC) in combination with solid phase extraction. The intraday and interday coefficients of variation have values below 6% for different possible serum concentrations. The limit of quantification (0.1 mg/L) is much lower than concentrations found in patients with a coma caused by the accumulation of 1-OH midazolam glucuronide. Recovery of 1-OH midazolam glucuronide is almost 100% at three different serum concentrations. Linearity is confirmed for normal serum levels (<1 mg/L) and for serum levels that might occur in patients with impaired renal function (<20 mg/L). Detection is performed at 254 nm with a diode array detector, which can also be used to check the peak purity in case of unexpected impurities.

Rapid method for the analysis of itraconazole and hydroxyitraconazole in serum by high-performance liquid chromatography.

An assay for the determination of itraconazole and its active metabolite hydroxyitraconazole in serum has been developed, using ketoconazole as internal standard. The procedure involved a one-step liquid-liquid extraction of the drug, its metabolite and the internal standard, followed by their separation by reversed-phase HPLC. In this paper the validation of this method is described.

Evaluation of a fluorescence polarographic immunoassay with increased sensitivity for measurement of low concentrations of tobramycin in serum.

The limits of quantitation of the assay of tobramycin in serum by the fluorescence polarization immunoassay system marketed by Abbott Laboratories (TDxFLx system) are 0.1 and 10.0 mg/L. For some pharmacokinetic studies, however, a more sensitive analysis is needed. The sensitivity of the TDxFLx system can theoretically be increased 10-fold by pipetting buffer solution into the sample well and 450 microliters serum into the predilution well. The assay modified in this way can be run with the usual calibration of the apparatus for normal analysis. The analytical performance of this modification of the TDxFLx assay was assessed. Tobramycin concentrations ranged from 0.01 to 1.0 mg/L. Analytical recovery ranged from 85 to 95%. The coefficients of variation for within-run and between-run precision ranged from 0.5% to 5% and from 2% to 6%, respectively, for control concentrations ranging from 0.05 to 0.75 mg/L. Based on recovery and precision results, the lower limit of quantitation was established as 0.025 mg/L. There was no significant detectable cross-reactivity from ceftazidime, aztreonam, flucloxacillin, cilastatin, or imipenem. There was a small, but significant cross-reactivity from gentamicin and netilmicin. Hyperbilirubinemia did not affect the assay, but hyperlipidemia gave falsely elevated results of the tobramycin assay. It was concluded that modification of the assay resulted in an acceptable method to quantify low concentrations of tobramycin in serum.

Determination of 4-aminopyridine in serum by solid-phase extraction and high-performance liquid chromatography.

An assay for the determination of 4-aminopyridine in serum has been developed using 3,4-diaminopyridine as internal standard and reversed-phase high-performance liquid chromatography with detection at 244 nm. A mobile phase of acetonitrile-methanol-ethanol-1% ammonium carbonate (75:10:10:5) provided excellent separation of both compounds. Samples were extracted on solid-phase columns. The linearity, precision, recovery and the limit of detection were all sufficient for the routine use of this assay in clinical studies of patients treated with 4-aminopyridine.

Sorption of various drugs in polyvinyl chloride, glass, and polyethylene-lined infusion containers.

The sorption of chloroquine sulfate, diazepam, isosorbide dinitrate, lorazepam, midazolam, nitroglycerin, promethazine hydrochloride, thiopental sodium, and warfarin sodium to three types of containers was studied. Appropriate amounts of the drugs were added to 500 mL of 0.9% sodium chloride injection in polyvinyl chloride (PVC) bags, glass bottles, and Clear-Flex bags composed of a laminate of polyethylene, nylon, and polypropylene. The containers were stored in the dark at room temperature for 24 hours. Samples were taken at various intervals and assayed for drug concentration by high-performance liquid chromatography. There were no appreciable changes in pH after 24 hours, and all the admixtures remained clear and colorless. The potency of chloroquine sulfate, lorazepam, midazolam, promethazine hydrochloride, and thiopental sodium remained unchanged in glass, PVC, and Clear-Flex containers. Diazepam, isosorbide dinitrate, nitroglycerin, and warfarin sodium did not show any sorption to glass bottles and Clear-Flex bags. In PVC bags, however, up to 55% of diazepam, 23% of isosorbide dinitrate, 51% of nitroglycerin, and 24% of warfarin sodium was lost during the 24-hour study period. Diazepam, isosorbide dinitrate, nitroglycerin, and warfarin sodium in 0.9% sodium chloride injection showed a loss of potency when stored in PVC containers for 24 hours at room temperature, but none of the drugs studied lost potency when stored in glass bottles and Clear-Flex bags.

Analysis of water-soluble vitamins in total parenteral nutrition solution by high pressure liquid chromatography.

A stability-indicating high pressure liquid chromatographic method was developed to determine the stability of water-soluble vitamins in total parenteral nutrition mixtures. Folic acid and thiamine were determined by direct injection and precolumn enrichment, followed by UV detection. Nicotinamide and pyridoxine were determined simultaneously without sample pretreatment by UV detection of nicotinamide and fluorescence detection of pyridoxine. Riboflavin 5'-phosphate was also determined without elaborate sample handling and by fluorescence detection. Ascorbic acid was determined as the sum of ascorbic acid and dehydroascorbic acid. After derivatization to a quinoxaline the latter substance was determined by direct injection and fluorescence detection.

Simultaneous determination of midazolam and its three hydroxy metabolites in human plasma by electron-capture gas chromatography without derivatization.

Electron-capture gas chromatography was carried out to determine midazolam and its three hydroxy metabolites (1-hydroxymethylmidazolam, 4-hydroxymidazolam and 1-hydroxymethyl-4-hydroxymidazolam) in human plasma. The assay involves extraction from plasma, buffered to pH 9.3, into cyclohexane-dichloromethane (6:4) and analysis by gas chromatography. The use of an HP-17 cross-linked, capillary column makes derivatization unnecessary. The sensitivity of the method was 2-3 ng/ml for midazolam, 1-hydroxymethylmidazolam and 4-hydroxymidazolam, and 20 ng/ml for 1-hydroxymethyl-4-hydroxymidazolam. The extraction recovery of midazolam, 1-hydroxymethylmidazolam, 4-hydroxymidazolam and 1-hydroxymethyl-4-hydroxymidazolam was 99.3 +/- 2.4, 67.0 +/- 4.6, 92.7 +/- 4.7 and 28.7 +/- 6.3%, respectively. This gas chromatographic assay was used to assess the concentration-time profiles of midazolam and its metabolites in human plasma after rectal and intravenous administration of midazolam.

Determination of some anticonvulsants, antiarrhythmics, benzodiazepines, xanthines, paracetamol and chloramphenicol by reversed phase HPLC.

In this article assays are described for caffeine, theophylline, procainamide, N-acetylprocainamide, quinidine, dihydroquinidine, paracetamol, phenobarbital, phenytoin, carbamazepine, chloramphenicol, oxazepam, temazepam, diazepam, desmethyldiazepam, chlordiazepoxide, desmethylchlordiazepoxide and demoxepam using a uniform working procedure, five (slightly) different mobile phases and one HPLC system. Changing from one eluent to another is simple and a stable base-line is achieved within half an hour. Three of the five eluents are interchangeable and recycling of eluent causes no problems. Sample pretreatment is a single step extraction. Interferences can be overcome by changing the selectivity of the eluent by adjusting the tetrahydrofuran or triethylamine content. Furthermore it is shown how triethylamine can improve peak shapes of basic components and shorten their retention times.