1,720,993 research outputs found
Ketamine chiral analysis in alternative and innovative biological samples
No full textKetamine ((R,S-2-(2-chlorophenyl)-2-methylamino)cyclohexanone) is a phencyclidine derivative used in human and veterinary clinical practice since 1970. It is a dissociative anaesthetic agent that induces also analgesia by non-opioid mechanisms. Ketamine causes a state of "dissociative anaesthesia", for this reason is used as a recreational drug and has been included in the controlled substance schedules of most countries.
As an anaesthetic drug, Ketamine is commercially available as a racemic mixture however, (R)-Ketamine and (S)-Ketamine have significantly different pharmacodynamic activities: the therapeutic potency of (S)-Ket is 2-4 times greater than the that of the (R)-enantiomer, as regards anaesthetic and analgesic effects. Moreover, the post-hypnotic stimulatory properties and agitated behaviour are associated with
(R)-Ket. On the other hand, even if Ketamine hallucinogenic potency is still largely unclear, some authors claim that the (R)-enantiomer is the most potent one. It has also been reported that (R)- and (S)-Ket have significantly different pharmacokinetic profiles. Thus, it is evident the need to provide analytical methods able to discriminate and simultaneously quantify both Ketamine enantiomers in biological matrices for pharmacokinetic, toxicological and forensic purposes.
The aim of this study is the development of an analytical method for Ketamine chiral analysis in alternative and innovative biological fluids and tissues, such as Dried Blood Spots (DBSs), saliva and hair. Different chromatographic setups were tested to obtain a good enantioseparation by liquid chromatography with fluorimetric detection
(HPLC-F). The assays are currently under validation and seem to be promising for a successfull Ketamine enantiomeric resolution and determination, in order to be applied to real biological samples
Dried Blood Spot and mass spectrometry: an analytical tool to certify Cannabis actual state of intoxication
No full textDriving under the influence of Cannabis (DUI) has become a growing concern. Studies investigating the impact of DUI on traffic safety have shown evidence that, during the acute period of Cannabis intoxication, Cannabis diminishes driving faculties greatly increasing the risk of car accidents. However, the actual state of Cannabis intoxication is not easily assessed, particularly in specific contexts such as roadside testing. Until now, the most reliable biological matrix for this purpose in represented by blood but its sampling is invasive and requires a sanitary environment and subsequent treatments or storage precautions, such as centrifugation, refrigeration or freezing. The time lapse between the individuation of a possible intoxication and the blood sampling is very important, since a long delay can mean that, in the meantime, the drug blood levels physiologically decrease under the cut-off value. To overcome this disadvantage, Dried Blood Spots (DBSs) can be a valid alternative to the normal blood sampling by venipuncture. In fact this innovative biological matrix can be obtained after a fast and easy sampling, does not need any particular storage nor transportation precaution and is stable over time.
To strictly monitor Cannabis consumption, an original LC-MS/MS method has been developed for the analysis of Cannabinoids in DBSs. Attention has been paid to the determination of Δ9- tetrahydrocannabinol (or THC, Figure 1a), the main psychoactive compound whose presence in blood can be taken as a marker of recent exposure, and its two main metabolites 11-hydroxy-Δ9-tetrahydrocannabinol (THC-OH, Figure 1b) and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol.
In particular the intermediate hydroxylated metabolite (THC-OH) is pharmacologically active and, at the same time, it is a marker of recent Cannabis intake, since it appears in blood about 13 minutes after consumption and has a relatively short half-life. The carboxylated metabolite (THC-COOH) is not psychoactive and has a very long half-life up to one month for chronic users. For this reason the presence of this latter compound alone in blood cannot be taken as a marker of recent exposure. Is evident, therefore, that the simultaneous monitoring of all the three analytes is necessary to outline pharmacokinetic and toxicokinetic state of abusers and contribute to the assessment of psychophysical state, distinguishing between acute or former consumption. The analytical method developed has been fully validated and applied to real DBS samples from Cannabis abusers with satisfactory results, thus confirming the methodology suitability for roadside testings
Antifungal prophylaxis in liver transplant patients: A systematic review and meta-analysis
No full textWe performed a meta-analysis to determine whether antifungal prophylaxis decreases infectious morbidity and mortality in liver transplant patients. We searched for randomized trials dealing with prophylaxis with systemic antifungal agents. We used a fixed effect model, with risk ratio (RR) and 95% confidence interval (CI); we assessed study quality for heterogeneity and publication bias. Six studies (5 double-blind), for a total of 698 patients, compared fluconazole, itraconazole, or liposomal amphotericin to placebo (5 studies) or oral nystatin. Prophylaxis reduced colonization (RR, 0.45; CI, 0.37-0.55), total proven fungal infections (RR, 0.31; CI, 0.21-0.46), which included both superficial (RR, 0.27; CI, 0.16-0.45) and invasive (RR, 0.33; CI, 0.18-0.59) infections, and mortality attributable to fungal infection (RR, 0.30; CI, 0.12-0.75). Prophylaxis did not affect overall mortality (RR, 1.06; CI, 0.69-1.64) or empiric treatment for suspected fungal infection (RR, 0.80; CI, 0.39-1.67). The beneficial effect of antifungal prophylaxis was predominantly associated with the reduction of Candida albicans infection and mortality attributable to C. albicans. Compared to controls, however, patients receiving prophylaxis experienced a higher proportion of episodes of non-albicans Candida, and in particular of C. glabrata. No beneficial effect on invasive Aspergillus infection was observed. In conclusion, our analysis shows a clear, though limited, beneficial effect of antifungal prophylaxis in liver transplant patients. Concerns about the selection of triazole-resistant Candida strains, however, are realistic, and the potential disadvantages of prophylaxis should be weighed against the established benefits
Can DBS testing be a response to the “3R concept” in animal testing? Development of an analytical strategy
No full textThe “3R concept”, first introduced by Russell and Burch's 1959 book “The principles of humane experimental technique”, is a widely accepted ethical framework for conducting scientific experiments on animals: Replacement (use of non-animal methods), Reduction (methods which reduce the number of animals used) and Refinement (methods which improve animal welfare). In particular, the refinement priciple refers to the improvement of breeding and of experimental procedures, aiming to minimise actual or potential pain and to improve animal welfare in those situations where animal usage is unavoidable. In animal experimental studies high volumes of blood or plasma are needed for an accurate analysis of the compounds of interest. Because of this, often the animal sacrifice is necessary for small ones, such as rats and mice, which are also the most used in all laboratories.
A possible alternative and innovative sampling in this research field is represented by the Dried Blood Spot (DBS) technique, that needs very small amount of blood. The extension of the DBS procedure to the animal model testing, sampling only a few blood microliters from the rat or mouse tail, would leave the animal alive, allowing to perform serial samplings on the same subject. Other main advantages are represented by a minimally invasive withdrawal, easier storage and transportation issues, a better stability of the analysed compounds and more feasibility of post-sampling procedures. The purpose of this work is the development and validation of a rapid and reliable analytical strategy for the determination of cannabinoids in DBS, obtained from mice treated with Δ9-tetrahydrocannabinol within an immunological research study
Dried blood spots: Liquid chromatography–mass spectrometry analysis of Δ9-tetrahydrocannabinol and its main metabolites
No full textA sensitive and selective HPLC–MS/MS method has been developed for the first time for the anal- ysis of Δ9-tetrahydrocannabinol (the most important active cannabinoid) and its hydroxylated and carboxylated metabolites in human Dried Blood Spots (DBSs). The simultaneous determination of A sensitive and selective HPLC–MS/MS method has been developed for the first time for the anal- ysis of Δ9-tetrahydrocannabinol (the most important active cannabinoid) and its hydroxylated and carboxylated metabolites in human Dried Blood Spots (DBSs). The simultaneous determination of Δ9- tetrahydrocannabinol and its two main metabolites allows assessing the time elapsed after the drug intake and distinguishing between acute or former consumption. This is an important information in specific contexts such as “on street” controls by police forces. DBSs have been chosen as the optimal biological matrix for this kind of testing, since they provide information on the actual state of intoxica- tion, without storage and transportation problems usually associated with classical blood testing. The analysis is carried out on a C8 reversed phase column with a mobile phase composed of 0.1% formic acid in a water/methanol mixture and an electrospray ionisation (ESI) source, coupled to a triple quadrupole mass spectrometer. The method was validated according to international guidelines, with satisfactory results in terms of extraction yields, precision, stability and accuracy. Application to real DBS samples from Cannabis abusers gave reliable results, thus confirming the methodology suitability for roadside testing 9- tetrahydrocannabinol and its two main metabolites allows assessing the time elapsed after the drug intake and distinguishing between acute or former consumption. This is an important information in specific contexts such as “on street” controls by police forces. DBSs have been chosen as the optimal biological matrix for this kind of testing, since they provide information on the actual state of intoxica- tion, without storage and transportation problems usually associated with classical blood testing. The analysis is carried out on a C8 reversed phase column with a mobile phase composed of 0.1% formic acid in a water/methanol mixture and an electrospray ionisation (ESI) source, coupled to a triple quadrupole mass spectrometer. The method was validated according to international guidelines, with satisfactory results in terms of extraction yields, precision, stability and accuracy. Application to real DBS samples from Cannabis abusers gave reliable results, thus confirming the methodology suitability for roadside testing
Dried blood spot testing: an innovative approach to overcome cannabinoid instability in blood
No full textCannabis is the most widely used illicit drug around the world and among the drugs of abuse (DoA) most frequently involved in street accidents. Therefore, it is important to strictly monitor Cannabis abuse. Until now, the most reliable biological matrix for this purpose is represented by blood (whole blood/plasma), which can provide useful information about drug consumption. However, its sampling and storage require complicated and time consuming precautions, such as centrifugation and refrigeration or freezing, in order to preserve analyte stability. To overcome these disadvantages the use of Dried Blood Spots (DBSs) represents a valid alternative to the “classical” blood sampling. This innovative biological matrix reproduces the composition of whole blood but its pre-treatment procedure is faster and more feasible. DBSs can be stored for months at room temperature without any appreciable sample degradation, since most enzymatic and non-enzymatic reactions are stopped by the loss of water. The aim of this work is the specific evaluation of cannabinoid stability in DBSs, namely of Δ9 tetrahydrocannabinol (THC), the most important psychoactive cannabinoid, and of its two main metabolites 11-hydroxy-Δ9-tetrahydrocannabinol (THC-OH) and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). For this study, blank spiked DBSs were stored at room temperature for up to 3 months after sampling and then analysed by ESI-LC-MS/MS. The sample pre-treatment, based on solvent extraction, provides good extraction yields and selectivity. Preliminary results are very satisfactory, since only minimal differences were observed between the samples analysed immediately after spotting and those analysed after storage. Further assays are in progress to confirm these results and to assess cannabinoid stability in DBSs over longer periods of time
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Monitoring of chronic Cannabis abuse: An LC–MS/MS method for hair analysis
No full textAn advanced analytical method based on liquid chromatography–tandem mass spectrometry (LC–MS/MS), has been developed for the identification and determination in hair of Δ9- tetrahydrocannabinol together with its major metabolite 11-nor-9-carboxy-Δ9-tetrahydrocannabinol. Since the latter is formed endogenously, it allows the assessment of chronic use excluding passive exposure to Cannabis. The sample pre-treatment procedure is based on a feasible incubative extrac- tion followed by a liquid–liquid extraction step. Chromatographic separation was performed using a reversed-phase column and gradient elution with a formic acid/acetonitrile/water mobile phase. The lim- its of quantitation and of detection were 3 pg/mg and 1 pg/mg, respectively, for both analytes. The method was successfully applied to the analysis of hair samples from Cannabis abusers; the analyte concentrations found ranged from 55 to 100 pg/mg for Δ9 -tetrahydrocannabinol and from 5 to 10 pg/mg for 11-nor-9- carboxy-Δ9 -tetrahydrocannabinol. Accuracy studies also gave satisfactory results (recovery > 87%), thus confirming the suitability of the assay for chronic consumption monitoring
- …
