A method for the determination of cocaine (COC) and benzoylecgonine (BZE) in human urine using a column-switching liquid chromatography system is reported. A homemade precolumn (20
mm
×
4.6
mm i.d.) ...dry-packed with Alltech ODS-C18 (35–750
μm) was employed as an extraction precolumn in order to extract and concentrate the COC and BZE from the human urine sample. The analytes were continuously transferred to the analytical column (Spherisorb-C8, 250
mm
×
4.6
mm i.d.; dp
=
5
μm) by means of the switching arrangement in the backflush mode. Detection was carried out at 235
nm in a UV-diode array detector. The validation of the method revealed analytes quantitative recoveries (96–102%) at three concentrations in the range from 0.25 to 4.00 and from 0.5 to 12.0
μg/mL for COC and BZE, respectively. These values demonstrate the excellent extraction efficiency of the precolumn. The detection limits for COC and BZE at a signal-to-noise ratio of 3 were 0.08 and 0.15
μg/mL when a sample volume of 50
μL was injected. The overlap of sample preparation, analysis and recondition of the precolumn increases the sample throughput to four samples per hour. The proposed method has been applied to the determination of COC and BZE in human urine samples from 73 suspecting drug addicts. Urine concentrations of 1.0–118.10
μg of BZE/mL and 0.1–41.0
μg of COC/mL were found.
The ability to evaluate liver stiffness non-invasively in clinical practice by measuring transient elastography using FibroScan(®) has resulted in considerable interest and enthusiasm. A core study ...group, organized by the Italian Association for the Study of the Liver, has assessed the usefulness of FibroScan(®) in the diagnosis and management of liver disease in clinical practice. The group concluded that FibroScan(®) is a valuable, non-invasive technique and have developed a consensus report form for registering transient elastography results. In this article, we report the findings of the study group.
An abstract of a study by de Melo Santos et al evaluating the effects of increasing dietary concentrations of a yeast culture product (YCP) on fecal microbiota of adult healthy dogs is presented. In ...conclusion, supplementation of 0.6% of YCP resulted in modest changes in fecal microbial communities of healthy adult dogs. Further studies should evaluate higher doses of YCP supplementation and its effects on fecal microbiota and gut health of dogs suffering from gastrointestinal disorders.
The adult liver is an organ without constitutive lymphoid components. Therefore, any intrahepatic T cell found in chronic hepatitis should have migrated to the liver after infection and inflammation. ...Because of the little information available on the differences between intrahepatic and peripheral T cells, we used recombinant proteins of the hepatitis C virus (HCV) to establish specific T cell lines and clones from liver biopsies of patients with chronic hepatitis C and compared them with those present in peripheral blood mononuclear cells (PBMC). We found that the protein nonstructural 4 (NS4) was able to stimulate CD4+ T cells isolated from liver biopsies, whereas with all the other HCV proteins we consistently failed to establish liver-derived T cell lines from 16 biopsies. We then compared NS4-specific T cell clones obtained on the same day from PBMC and liver of the same patient. We found that the 22 PBMC-derived T cell clones represent, at least, six distinct clonal populations that differ in major histocompatibility complex restriction and response to superantigens, whereas the 27 liver-derived T cell clones appear all identical, as further confirmed by cloning and sequencing of the T cell receptor (TCR) variable and hypervariable regions. Remarkably, none of the PBMC-derived clones has a TCR identical to the liver-derived clone, and even with polymerase chain reaction oligotyping we did not find the liver-derived clonotypic TCR transcript in the PBMC, indicating a preferential intrahepatic localization of these T cells. Functionally, the liver-derived T cells provided help for polyclonal immunoglobulin (Ig)A production by B cells in vitro that is 10-fold more effective than that provided by the PBMC-derived clones, whereas there is no difference in the help provided for IgM and IgG production. Altogether these results demonstrate that the protein NS4 is highly immunogenic for intrahepatic CD4+ T cells primed by HCV in vivo, and that there can be compartmentalization of some NS4-specific CD4+ T cells to the liver of patients with chronic hepatitis C.
In this paper, the on-line coupling of solid-phase extraction, based on a restricted-access support with high-performance reverse phase chromatography for the analysis of carbamazepine (CBZ) and ...carbamazepine-10,11-epoxide (CBZ-E) in human plasma samples is described. A precolumn packed with 25 μm C
18 alkyl-diol support is used for direct plasma injection. Using column-switching techniques, the analytes were enriched on the precolumn by a 5 mM phosphate buffer (pH 7) with 2% of methanol solution at a flow-rate of 0.8 ml min
−1, while proteins and endogenous hydrophilic substances in plasma were washed off to waste. The enriched analytes were then back-flushed onto the analytical C
18 column, separated by a mixture of 10 mM phosphate buffer (pH 7) acetonitrile (70:30 v/v) solution at a flow-rate of 1.0 ml min
−1 and detected by the ultraviolet absorbance set at 212 and 285 nm and without transfer loss. Linear calibration graphs were obtained for sample injection volumes of 50 (0.2–4.0 of μg of CBZ ml
−1 and 0.1–5.0 μg of CBZ-E ml
−1, respectively), and 20 μl (5.0–20.0 μg of CBZ ml
−1); in either case the
r-value was >0.9963. Recoveries from spiked plasma samples were quantitative for both analytes and the coefficients of variation were below 3.83%. The lowest samples concentrations that can be quantified with acceptable accuracy and precision was 0.2 μg CBZ ml
−1 and 0.1 μg CBZ-E ml
−1 when a sample volume of 50 μl was injected. Concentrations of 0.08 and 0.05 μg ml
−1 of CBZ and CBZ-E were considered the limit of detection for a signal-to-noise ratio of 3. Furthermore, the developed column-switching method was successfully applied to the determination of CBZ and CBZ-E in plasma samples of patients submitted to CBZ therapy.
In this study a flow injection (FI) system used in conjunction with hydride generation (HG), atomic absorption spectrometry (AAS) and microwave (MW) aided pre-reduction of selenite (Se(IV)) to ...selenate (Se(IV)) with HCl:HBr has been developed in order to differentiate both inorganic selenium species. As full control of the MW reduction step is possible, the experimental approach allows the use of milder acidic conditions (10% v/v of HCl and HBr) than those conventionally accomplished with hydrochloric acid alone (≥50% v/v). Experimental parameters were optimized by the univariate optimization method. In either case, the linear range was from 1.0 to 30 μg l
−1. The detection limits based on 3σ of the blank signal were 0.25 μg l
−1 for Se(IV) and 0.30 μg l
−1 for Se(VI). The reproducibility, about 3% RSD and recoveries of different amounts of Se(VI) and Se(IV) added to water and orange juice samples (97–103%) were good. The main advantage of the proposed method is that the sequential determination of Se(IV) and Se(VI) is performed at a high sampling frequency (ca. 50 samples per h) in a closed system without Se losses, and with a minimum sample waste, operator attention, and sample manipulation.
ABSTRACT Meteorites have long been considered as reflections of the compositional diversity of main belt asteroids and consequently they have been used to decipher their origin, formation, and ...evolution. However, while some meteorites are known to sample the surfaces of metallic, rocky and hydrated asteroids (about one-third of the mass of the belt), the low-density icy asteroids (C-, P-, and D-types), representing the rest of the main belt, appear to be unsampled in our meteorite collections. Here we provide conclusive evidence that the surface compositions of these icy bodies are compatible with those of the most common extraterrestrial materials (by mass), namely anhydrous interplanetary dust particles (IDPs). Given that these particles are quite different from known meteorites, it follows that the composition of the asteroid belt consists largely of more friable material not well represented by the cohesive meteorites in our collections. In the light of our current understanding of the early dynamical evolution of the solar system, meteorites likely sample bodies formed in the inner region of the solar system (0.5-4 AU) whereas chondritic porous IDPs sample bodies that formed in the outer region (>5 AU).
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