Direct Ionic Liquid Extractant Injection for Volatile Chemical Analysis - A Gas Chromatography Sampling Technique

A green sampling approach by direct injection of ionic liquid (IL) solvent containing a variety of analytes using programmable temperature vaporisation (PTV) injection with gas chromatography (GC) is presented. The method was developed using test mixtures of n-alkanes, n-alcohols and polyaromatic compounds, whilst back extraction of isolated compounds from the IL with organic solvent is not required. In the final method, 2 μL of IL, 1-butyl-3 methylimidazolium bis(trifluoromethylsulfonyl)amide containing analytes, was diluted to different volumes (ranging from 10 to 70%) with solvent then injected into the system. Several PTV injector parameters were investigated to ensure analyte volatilisation and transfer into the GC column. Concentration calibration curves (10–150 μg mL−1 and 10–100 μg mL−1 for n-alkanes and n-alcohols, respectively) were constructed, and showed addition of IL increased the peak area of each analyte, with good precision, and acceptable linearity with correlation coefficient, r2 > 0.93. This method was successfully applied in analysis of a polynuclear aromatic hydrocarbons (PAHs) mixture, with addition of IL in the mixture and suitable operation of the PTV injector. The method was also applied to eucalyptus leaf essential oil compounds as a test sample in a single drop microextraction experiment

Določanje benzodiazepinov v urinu preko benzofenonskih derivatov z uporabo tekočinske kromatografije sklopljene s tandemsko masno spektrometrijo

The aim of this study was to validate a new method for determining benzodiazepines in urine via their benzophenone derivatives, based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Selected benzodiazepines were analysed after acid hydrolysis of urine and extraction by ethyl acetate in the presence of an internal standard. Samples were analysed using electrospray ionization LC-MS/MS in a multiple reaction monitoring mode. The chromatographic run time on a reversed phase C18 analytical column was set for 9 min. This method was validated in 21 patients receiving methadone. Benzodiazepines intake was established in two out of three patients. LC-MS/MS results were also compared with the rapid immunoassay and the methods showed good agreement. However, in three cases benzodiazepines were detected by LC-MS/MS, but not by the immunoassay. The sensitivity of the developed LC-MS/MS method is comparable to or even higher than of previously reported methods, which makes it suitable as a confi rmatory method.Razvili smo selektivno in občutljivo metodo za določanje nekaterih benzodiazepinov v urinu preko določanja njihovih benzofenonov. Metoda temelji na tekočinski kromatografi ji, sklopljeni s tandemsko masno spektrometrijo (LC-MS/MS). Izbrane benzodiazepine smo analizirali po kisli hidrolizi urinskih vzorcev in ekstrakciji z etilacetatom v prisotnosti internega standarda. Vzorce smo analizirali z elektrorazprševalno ionizacijo z MRM načinom detekcije. Čas kromatografske ločbe na reverznofazni (C18) analitski koloni je bil 9 min. Metoda je bila validirana in preizkušena na 21 pacientih, ki so prejemali metadonsko terapijo. Pri dveh tretjinah primerov je bil vnos benzodiazepinov tudi potrjen. Vzorce smo testirali tudi s hitro imunokemijsko metodo in rezultate primerjali z rezultati pridobljenimi z LC-MS/MS metodo. Ugotovili smo dobro ujemanje med rezultati pridobljenimi z obe a metodama. Kljub temu smo v treh primerih določili prisotnost benzodiazepinov z LC-MS/MS metodo, ki je z imunokemijsko metodo nismo. Občutljivost razvite metode je primerljiva ali celo boljša od predhodno opisanih metod, zato jo lahko uporabimo kot potrditveno metodo

A new panel of epitope mapped monoclonal antibodies recognising the prototypical tetraspanin CD81

Background: Tetraspanins are small transmembrane proteins, found in all higher eukaryotes, that compartmentalize cellular membranes through interactions with partner proteins. CD81 is a prototypical tetraspanin and contributes to numerous physiological and pathological processes, including acting as a critical entry receptor for hepatitis C virus (HCV). Antibody engagement of tetraspanins can induce a variety of effects, including actin cytoskeletal rearrangements, activation of MAPK-ERK signaling and cell migration. However, the epitope specificity of most anti-tetraspanin antibodies is not known, limiting mechanistic interpretation of these studies. Methods: We generated a panel of monoclonal antibodies (mAbs) specific for CD81 second extracellular domain (EC2) and performed detailed epitope mapping with a panel of CD81 mutants. All mAbs were screened for their ability to inhibit HCV infection and E2-CD81 association. Nanoscale distribution of cell surface CD81 was investigated by scanning electron microscopy. Results: The antibodies were classified in two epitope groups targeting opposing sides of EC2. We observed a wide range of anti-HCV potencies that were independent of their epitope grouping, but associated with their relative affinity for cell-surface expressed CD81. Scanning electron microscopy identified at least two populations of CD81; monodisperse and higher-order assemblies, consistent with tetraspanin-enriched microdomains. Conclusions: These novel antibodies provide well-characterised tools to investigate CD81 function, including HCV entry, and have the potential to provide insights into tetraspanin biology in general

Hepatocyte Permissiveness to Plasmodium Infection Is Conveyed by a Short and Structurally Conserved Region of the CD81 Large Extracellular Domain

Invasion of hepatocytes by Plasmodium sporozoites is a prerequisite for establishment of a malaria infection, and thus represents an attractive target for anti-malarial interventions. Still, the molecular mechanisms underlying sporozoite invasion are largely unknown. We have previously reported that the tetraspanin CD81, a known receptor for the hepatitis C virus (HCV), is required on hepatocytes for infection by sporozoites of several Plasmodium species. Here we have characterized CD81 molecular determinants required for infection of hepatocytic cells by P. yoelii sporozoites. Using CD9/CD81 chimeras, we have identified in CD81 a 21 amino acid stretch located in a domain structurally conserved in the large extracellular loop of tetraspanins, which is sufficient in an otherwise CD9 background to confer susceptibility to P. yoelii infection. By site-directed mutagenesis, we have demonstrated the key role of a solvent-exposed region around residue D137 within this domain. A mAb that requires this region for optimal binding did not block infection, in contrast to other CD81 mAbs. This study has uncovered a new functionally important region of CD81, independent of HCV E2 envelope protein binding domain, and further suggests that CD81 may not interact directly with a parasite ligand during Plasmodium infection, but instead may regulate the function of a yet unknown partner protein

High Rates of Hepatitis C Virus Reinfection and Spontaneous Clearance of Reinfection in People Who Inject Drugs: A Prospective Cohort Study

Hepatitis C virus reinfection and spontaneous clearance of reinfection were examined in a highly characterisedcohort of 188 people who inject drugs over a five-year period. Nine confirmed reinfections and 17 possiblereinfections were identified (confirmed reinfections were those genetically distinct from the previous infection andpossible reinfections were used to define instances where genetic differences between infections could not beassessed due to lack of availability of hepatitis C virus sequence data). The incidence of confirmed reinfection was28.8 per 100 person-years (PY), 95%CI: 15.0-55.4; the combined incidence of confirmed and possible reinfectionwas 24.6 per 100 PY (95%CI: 16.8-36.1). The hazard of hepatitis C reinfection was approximately double that ofprimary hepatitis C infection; it did not reach statistical significance in confirmed reinfections alone (hazard ratio [HR]:2.45, 95%CI: 0.87-6.86, p=0.089), but did in confirmed and possible hepatitis C reinfections combined (HR: 1.93,95%CI: 1.01-3.69, p=0.047) and after adjustment for the number of recent injecting partners and duration of injecting.In multivariable analysis, shorter duration of injection (HR: 0.91; 95%CI: 0.83-0.98; p=0.019) and multiple recentinjecting partners (HR: 3.12; 95%CI: 1.08-9.00, p=0.035) were independent predictors of possible and confirmedreinfection. Time to spontaneous clearance was shorter in confirmed reinfection (HR: 5.34, 95%CI: 1.67-17.03,p=0.005) and confirmed and possible reinfection (HR: 3.10, 95%CI: 1.10-8.76, p-value=0.033) than primary infection.Nonetheless, 50% of confirmed reinfections and 41% of confirmed or possible reinfections did not spontaneouslyclear.Conclusions: Hepatitis C reinfection and spontaneous clearance of hepatitis C reinfection were observed at highrates, suggesting partial acquired natural immunity to hepatitis C virus. Public health campaigns about the risks ofhepatitis C reinfection are required

Mechanisms of viral entry: sneaking in the front door

Recent developments in methods to study virus internalisation are providing clearer insights into mechanisms used by viruses to enter host cells. The use of dominant negative constructs, specific inhibitory drugs and RNAi to selectively prevent entry through particular pathways has provided evidence for the clathrin-mediated entry of hepatitis C virus (HCV) as well as the caveolar entry of Simian Virus 40. Moreover, the ability to image and track fluorescent-labelled virus particles in real-time has begun to challenge the classical plasma membrane entry mechanisms described for poliovirus and human immunodeficiency virus. This review will cover both well-documented entry mechanisms as well as more recent discoveries in the entry pathways of enveloped and non-enveloped viruses. This will include viruses which enter the cytosol directly at the plasma membrane and those which enter via endocytosis and traversal of internal membrane barrier(s). Recent developments in imaging and inhibition of entry pathways have provided insights into the ill-defined entry mechanism of HCV, bringing it to the forefront of viral entry research. Finally, as high-affinity receptors often define viral internalisation pathways, and tropism in vivo, host membrane proteins to which viral particles specifically bind will be discussed throughout

Demands on scientific studies in different fields of forensic medicine and forensic sciences. Traffic medicine--impaired driver: alcohol, drugs, diseases

Since human performance is a key factor in crash causation detailed knowledge of the involvement of alcohol, drugs and diseases is of fundamental interest for road safety. To better understand the effect of these influencing factors it is important to use a combination of witness observations and a range of experimental and epidemiological Studies. Epidemiological approaches to research such as road-side-surveys, case-control-studies, culpability analysis, pharmaco-epidemiological studies are usually seen as being able to provide the best answers. This article discusses the relative merits of experimental and epidemiological approaches