Development of a carbohydrate silylation method in ionic liquids for their gas chromatographic analysis

This paper reports on the feasibility of silylation of low molecular weight carbohydrates dissolved in different ionic liquids (ILs) for their further analysis by gas chromatography (GC). Derivatization reagents (nature and amounts), temperature and time of reaction and stirring conditions were evaluated for different carbohydrates (i.e., glucose, mannose, fructose and lactose) dissolved in 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA]. Evaluation of conformational isomerism of glucose dissolved in [EMIM][DCA] revealed the effect of the time of dissolution in the equilibration of α- and β-furanoses (up to 3% and 6%, respectively, after 70 h of incubation) and that 21 h sufficed to obtain results similar to those provided by the reference method involving pyridine. Once optimized, the proposed derivatization procedure provided satisfactory yields (i.e., close to 100%) using 100 μL of trimethylsilylimidazole (TMSI) at mild conditions (25°C) for a relatively short time (1h) for most of the investigated carbohydrates. Under these experimental conditions, linear responses (i.e., R(2) better than 0.974) were obtained in the tested range of 0.25-1mg of the derivatized target compounds. Other reagents, such as N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)+1% trimethylchlorosilane (TMCS), were successfully used under ultrasonic conditions for aldose monosaccharides and disaccharides derivatization, while BSTFA was useful for ketose monosaccharides. The possibility of using the proposed method for the derivatization of selected carbohydrates dissolved in different ILs and the efficiency of the method applied to the analysis of carbohydrates present in real samples (fruit juices) have also been investigated.

Double-balloon jejunal perfusion to compare absorption of vitamin E and vitamin E acetate in healthy volunteers under maldigestion conditions

BACKGROUND/OBJECTIVES

The vitamin E derivative, α-tocopheryl acetate, is often included in formulations used in enteral nutrition. In this respect, we compared α-tocopherol and α-tocopheryl acetate absorption under 'maldigestion' conditions, such as occurring during enteral tube feeding, using differentially labeled RRR-[5,7-methyl-((2)H(6))]-α-tocopherol and RRR-[5-methyl-(2)H(3)]-α-tocopheryl acetate allowing direct comparison between free and esterified forms.

SUBJECTS/METHODS

The two derivatives were given together in a single dose to six volunteers directly into the jejunum using a double-balloon perfusion system. Perfusion lasted for 1 h, and the collected blood and effluent samples were analyzed by liquid chromatography-mass spectrometry.

RESULTS

In the isolated 20-cm length of exposed jejunum, on average ~ 6% of the two vitamin E forms were absorbed >1 h based on subtraction of effluent from influent. There was substantial difference in the absolute absorbed quantity between individuals, but no significant differences were observed in the absorption between the two labeled forms as assessed in the plasma. (2)H(3)-α-tocopherol was not present in the influent, but appeared in the effluent, indicating that the acetylated form of vitamin E is cleaved by brush border enzymes in the small intestine.

CONCLUSIONS

This study shows that even in the absence of digestive enzymes and bile salts, the appropriately solubilized acetylated form of α-tocopherol exhibits the same bioavailability as free α-tocopherol. This suggests that both forms can be absorbed equally under maldigestion conditions such as present clinically during enteral tube feeding.

Oral infections caused by yeasts in patients with head and neck cancer undergoing radiotherapy. Identification of the yeasts and evaluation of their antifungal susceptibility

Yeasts occur as part of the normal human microbiota. Nevertheless, some species are opportunistic, affecting immunocompromised patients such as those undergoing oncologic treatment.

OBJECTIVE

To detect the presence of yeasts in patients suffering from head and neck cancer who are receiving radiation therapy and display lesions in the oral cavity, compatible with candidiasis; and to evaluate the antifungal susceptibility of the isolates recovered.

METHODS

Sixty samples from patients were obtained by swabbing the oral mucosa. Identification of isolates were performed by classical taxonomic, morphological and biochemical methods as well as by using commercial identification kits. Susceptibility to antifungal drugs was determined by the agar diffusion method with Neosensitabs(®) disks.

RESULTS

Forty-six samples (77%) yielded positive findings, and species recovered were: Candida albicans (22 isolates), Candida tropicalis (13 isolates), Candida parapsilosis (six strains), Candida krusei (three strains), Candida dubliniensis and Saccharomyces cerevisiae (one each). All strains were susceptible to itraconazole, clotrimazole, voriconazole, nystatin and amphotericin B. On the other hand, 65% of strains were miconazole-susceptible while 35%, showed intermediate susceptibility. With regard to ketoconazole, only three strains (7%) corresponding to C. albicans (one isolate) and C. krusei (two isolates) displayed intermediate susceptibility. Only C. krusei strains were resistant to fluconazole while all the other species were susceptible. Eventually, only six isolates (13%) were susceptible to terbinafine while the remaining strains were resistant in vitro.

CONCLUSION

Early detection of etiological agents causing lesions, as well as the evaluation of their susceptibility to commonly used drugs, are crucial in order to choose the appropriate treatment that will minimize complications while improving the quality of patients' lives.

First successful double-factor PGD for Lynch syndrome: monogenic analysis and comprehensive aneuploidy screening

Preimplantation genetic diagnosis (PGD) has been applied worldwide for a great variety of single-gene disorders over the last 20 years. The aim of this work was to perform a double-factor preimplantation genetic diagnosis (DF-PGD) protocol in a family at risk for Lynch syndrome. The family underwent a DF-PGD approach in which two blastomeres from each cleavage-stage embryo were biopsied and used for monogenic and comprehensive cytogenetic analysis, respectively. Fourteen embryos were biopsied for the monogenic disease and after multiple displacement amplification (MDA), 12 embryos were diagnosed; 5 being non-affected and 7 affected by the disease. Thirteen were biopsied to perform the aneuploidy screening by short-comparative genomic hybridization (CGH). The improved DF-PGD approach permitted the selection of not only healthy but also euploid embryos for transfer. This has been the first time a double analysis of embryos has been performed in a family affected by Lynch syndrome, resulting in the birth of two healthy children. The protocol described in this work offers a reliable alternative for single-gene disorder assessment together with a comprehensive aneuploidy screening of the embryos that may increase the chances of pregnancy and birth of transferred embryos.

Acute experimental stress evokes a differential gender-determined increase in human intestinal macromolecular permeability

BACKGROUND

Intestinal epithelial dysfunction is a common pathophysiologic feature in irritable bowel syndrome (IBS) patients and might be the link to its clinical manifestations. We previously showed that chronic psychosocial stress induces jejunal epithelial barrier dysfunction; however, whether this epithelial response is gender-specific and might thus explain the enhanced female susceptibility to IBS remains unknown.

METHODS

Intestinal responses to acute stress were compared in age-matched groups of healthy women and men (n = 10 each) experiencing low background stress. A 20-cm jejunal segment, was perfused with an isosmotic solution, and intestinal effluents were collected under basal conditions, for 15 min during cold pain stress and for a 45-min recovery period. Epithelial function (net water flux and albumin output), changes in stress hormones, and cardiovascular and psychologic responses to cold stress were measured.

KEY RESULTS

Heart rate and blood pressure significantly increased during cold pain stress with no differences between men and women. Adrenocorticotropic hormone and cortisol levels during cold pain stress were significantly higher in men. Basal net water flux and epithelial permeability were similar in men and women. Cold pain stress increased water flux in both groups (72 ± 23 and 107 ± 18 μL min(-1) cm(-1) , respectively; F(5, 90) = 5.5; P = 0.003 for Time) and, interestingly, this was associated with a marked increase of albumin permeability in women but not in men (0.8 ± 0.2 vs.-0.7 ± 0.2 mg/15 min; P < 0.0001).

CONCLUSIONS & INFERENCES

Intestinal macromolecular permeability in response to acute experimental stress is increased in healthy women, a mechanism that may contribute to female oversusceptibility to IBS.

Evaluation of comprehensive two-dimensional gas chromatography-time-of-flight-mass spectrometry for the analysis of polycyclic aromatic hydrocarbons in sediments

This study evaluates the feasibility of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-ToF MS) for the determination of the 15+1 EU PAHs in sediments. Experimental variables affecting the injection, chromatographic separation and analytical detection of the analytes have systematically been optimised. Under finally proposed conditions, a satisfactory resolution among critical pairs/groups of PAHs, including benz[a]anthracene, cyclopenta[cd]pyrene and chrysene, the three benzofluoranthene isomers, indeno[1,2,3-cd]pyrene from dibenz[a,h]anthracene (DahA), and DahA from dibenz[a,c]anthracene, has been achieved using DB-5 × BPX-50 as column combination with a run time of 1 h. The feasibility of the method for the analysis of real-life samples has been demonstrated by accurate determination of relevant target PAHs in the certified harbour sediment BCR-535 (deviations among certified concentration values and those calculated using the proposed method lower than 3%); and by successful application to sediments sampled from a relevant protected area located in the South of Spain. The low methodological limits of detection (LODs) obtained for most of the targeted PAHs (in the 5.7-60 μg/kg range, as calculated for real samples) guarantied accurate quantification of the target compounds at the low levels expected in these types of pristine matrices. The strong retention experienced by the heaviest dibenzopyrene isomers included in the study resulted in relatively high LODs for these analytes; nevertheless, these compounds were detected at concentration levels above the corresponding LOD in some of the analysed sediments. In addition, the enhanced identification power provided by GC × GC-ToF MS for the identification of non-target analytes allowed the tentative identification of a group of polynuclear aromatic thiophenes in some of the test samples. Finally, the potential of the use of normalised bubble plots for the fast screening of the potential PAH sources has been demonstrated.

Low molecular weight carbohydrates in pine nuts from Pinus pinea L

Low molecular weight carbohydrates in pine nuts from Pinus pinea L. (n = 7) have been studied by gas chromatography-mass spectrometry as their trimethylsilyl oximes. Besides previously reported components, such as glucose, fructose, sucrose, and raffinose, several soluble carbohydrates have been identified for the first time in this product, including saccharides (galactose, maltose, and planteose) and cyclitols (pinitol, galactinol, galactopinitol A1, fagopyritol B1, and other glycosyl-inositols). Most abundant cyclitols were chiro-inositol, fagopyritol B1, and pinitol, with concentrations ranging from 126.7 to 222.1 mg (100 g)(-1), 94.2 to 177.1 mg (100 g)(-1), and 51.2 to 282.8 mg (100 g)(-1), respectively.

Bioconcentration of pesticides in zebrafish eleutheroembryos (Danio rerio)

The feasibility of a bioaccumulation test based on the use of zebrafish eleutheroembryos as an alternative to adult-individual-based approaches for REACH application has been evaluated for three test compounds, chlorpyrifos, dicofol and atrazine. Following the OECD 305 guidelines, zebrafish eleutheroembryos (72 h after hatching, hpf) were separately exposed to the investigated pesticides at two nominal concentrations below 1% of its corresponding LC(50). The uptake experiments lasted for 48 h. Then, the exposure medium was replaced by a non-contaminated medium for depuration experiments (up to 72 h). Zebrafish eleutheroembryos (larvae 144 hpf, i.e. at the end of the depuration step) and their corresponding exposure media was sampled at ten different times during each experiment and the concentration of the investigated pesticide determined in both the organisms and in the exposure medium. The experimentally determined pesticide accumulation profiles in the eleutheroembryos demonstrated that atrazine has a very fast accumulation kinetic, reaching steady sate (SS) within 24h. Chlorpyrifos and dicofol did not reach the SS within the 48-h uptake experiments although they exhibit higher accumulations than the former pesticide. Two toxicokinetic models were used to calculate the bioconcentration factor (BCF) of the studied pesticide in zebrafish eleutheroembryos. In the former, the BCF was calculated under SS conditions (BCF(SS)). The second was used when the compounds did not reach the SS during the uptake experiment (BCF(k)). Log BCF values of 3.55 and 3.84 for chlorpyrifos; 0.6 and 1.17 for atrazine, and 3.90 for dicofol were experimentally calculated at selected exposure concentrations. These values have been compared with those reported in related bioaccumulation studies and official databases.

Clinical validation of the European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE) II criteria in an open-access unit: a prospective study

BACKGROUND AND STUDY AIMS

The European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE I) criteria were recently updated (EPAGE II), but no prospective studies have used these criteria in clinical practice. The aim of the current study was to validate the EPAGE II criteria in an open-access endoscopy unit.

PATIENTS AND METHODS

A prospective observational study was conducted in an open-access endoscopy unit at a tertiary care referral center. Consecutive outpatients (n = 1004; mean age 58.9 ± 13.1 years; 45 % men) were referred for diagnostic colonoscopy between September 2009 and February 2010. The appropriateness of colonoscopy was assessed based on EPAGE II criteria, and the relationship between appropriateness and both referral doctor and detection of significant lesions was examined. The effectiveness of EPAGE II criteria in assessing appropriateness was measured by means of sensitivity, specificity, and positive and negative predictive values for detecting significant lesions.

RESULTS

Colonoscopic cecal intubation was achieved in 956 patients (95.2 %). Most referral doctors were gastroenterologists (58.0 %) and the most common indication was colorectal cancer (CRC) screening (35.2 %). EPAGE II criteria were applicable in 968 patients (96.4 %); of these patients, the indication was appropriate in 778 (80.4 %), inappropriate in 102 (10.5 %), and uncertain in 88 (9.1 %). Patients with appropriate or uncertain indications based on EPAGE II criteria had more relevant endoscopic findings than those with inappropriate indications (38.8 % vs. 24.5 %; OR 1.95, 95 %CI 1.22 - 3.13; P < 0.005). Sensitivity and negative predictive value of EPAGE II criteria for detecting significant lesions were 93.1 % (95 %CI 90 % - 96 %) and 75.5 % (95 %CI 67 % - 84 %), respectively, whereas for advanced neoplastic lesions these values were 98.0 % (95 %CI 95 % - 100 %) and 98.0 % (95 % CI 95 % - 100 %), respectively. Adherence to EPAGE II recommendations was an independent predictor of finding a significant lesion (OR 1.93, 95 %CI 1.20 - 3.11; P = 0.007).

CONCLUSIONS

EPAGE II is a simple, valid score for detecting inappropriate colonoscopies in clinical practice.

Improvement in chromatin maturity of human spermatozoa selected through density gradient centrifugation

A two-step gradient density centrifugation system has been set up to isolate two contrasting sperm populations of normozoospermic and oligoasthenoteratozoospermic (OAT) men. High- and low-density fractions were characterized by total and free thiol fluorescence as determined by monobromobimane-flow cytometry and by protamine/DNA ratios after protamine extraction and polyacrylamide acid-urea gel electrophoresis. Further chromatin characterization was performed through immunofluorescence (IF) with specific antibodies to nucleosomes, histone subtypes (H3.1/H3.2 and TH2B), histone modifications (KM-2 and H4K8ac) and precursor protamine 2. The native sperm samples from normozoospermic and OAT patients showed a biphasic distribution of total thiol levels, which changed in the sperm fractions obtained using the density isolation protocol presented here. Moreover, significant differences were detected in the protamine content in the different fractions of OAT and fertile donor samples. In addition, in the high-density fractions from OAT and normozoospermics, higher IF levels for H4K8ac and TH2B were seen. These results would be consistent with the intended beneficial effect on chromatin maturity of the density selection techniques currently being used in assisted fertilization procedures. However, most nucleosome and related proteins/modifications differ between OAT and normozoospermic men, even after gradient centrifugation, providing evidence for incomplete nuclear maturity in OAT patients.