No abstract is available for this item.

No abstract is available for this item.

Several ultrasound-based platforms for DNA sample preparation were evaluated in terms of effective fragmentation of DNA (plasmid and genomic DNA)-ultrasonic probe, sonoreactor, ultrasonic bath and the newest Vialtweeter device. The sonoreactor showed the best efficiency of DNA fragmentation while simultaneously assuring no cross-contamination of samples, and was considered the best ultrasonic tool to achieve effective fragmentation of DNA at high-throughput and avoid sample overheating. Several operation variables were studied-ultrasonication time and amplitude, DNA concentration, sample volume and sample pre-treatment-that allowed optimisation of a sonoreactor-based strategy for effective DNA fragmentation. Optimal operating conditions to achieve DNA fragmentation were set to 100% ultrasonic amplitude, 100 μL sample volume, 8 min ultrasonic treatment (2 min/sample) for a DNA concentration of 100 μg mL-1. The proposed ultrasonication strategy can be easily implemented in any laboratory setup, providing fast, simple and reliable means for effective DNA sample preparation when fragmentation is critical for downstream molecular detection and diagnostics protocols.

The investigation of 3,4-methylenedioxymethamphetamine (MDMA: ecstasy) abuse requires very robust methods with high sensitivity and wide linearity ranges for the quantification of this drug of abuse and its main metabolites in body fluids. An optimized gas chromatography-ion trap mass spectrometry (GC-IT/MS) methodology with electron impact ionization addressing these issues is presented. The sample preparation involves an enzymatic hydrolysis of urine and plasma for conjugate cleavage, a SPE extraction, and a derivatization process. The method was fully validated in rat plasma and urine. Linearity for a wide concentration range was achieved for MDMA, and the metabolites 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxyamphetamine (HMA) and 4-hydroxy-3-methoxymethamphetamine (HMMA). Limits of quantification were 2 ng/mL in plasma and 3.5 ng/mL in urine using a Selected Ion Monitoring detection mode. Selectivity, accuracy, precision, and recovery met the required criteria for the method validation. This GC-IT/MS method provides high sensitivity and adequate performance characteristics for the simultaneous quantification of MDMA, MDA, HMA and HMMA in the studied matrices. (C) 2010 Elsevier B.V. All rights reserved.

Mercury, methyl-mercury (MeHg) and selenium were determined in digestive gland and mantle of Octopus vulgaris, from three areas of the Portuguese coast. To our knowledge these are the first data on MeHg in cephalopods. Concentrations were higher in the digestive gland and percentage of MeHg in mantle. Enhanced Hg and MeHg levels were obtained in digestive gland of specimens from Olhao (3.1-7.4 and 2.0-5.0 mu g g(-1) respectively). Differences between areas may be partially related to Hg availability. Relationships between concentrations in mantle and digestive gland pointed to proportional increases of Hg and MeHg in tissues of specimens from Matosinhos and Cascais, but relatively constant values in mantle of individuals from Olhao (higher contamination). Se:Hg molar ratio in digestive gland was 32 and 30 in octopus from Matosinhos and Cascais, respectively, and 5.4 from Olhao. The proximity to the unit suggests demethylation as response to elevated MeHg levels in digestive gland. (C) 2010 Elsevier Ltd. All rights reserved.

We recently reported on the use of caged nucleotides to attain full control of enzymatic polymerization of RNA solely by light. In the absence of light no RNA formation was possible due to the efficient caging by the coumarin moiety; after irradiation, caged ATP was released with quantitative precision and RNA polymerization was resumed. As photolabile protecting group [7-(diethylamino) coumarin-4-yl]methyl] (DEACM) was used due to its high absorbance in the visible region of the spectrum, fast deprotection kinetics and absence of radical intermediates. However, the 7-diethylamino-4-hydroxymethylcoumarin photo-product (DEACM-OH) was shown to inhibit the transcription reaction for concentrations higher than 30 μM [5]. This inhibition has been associated with poor water solubility, which is commonly dealt with via cumbersome chemical modifications of the protecting moiety. To overcome inhibition, we evaluated the use of molecular scavengers to sequester DEACM-OH formed after irradiation. Determination of association constants of coumarin with β-cyclodextrins allowed the assessment of its capability to remove free coumarin molecules from solution. The influence of β-cyclodextrin in transcription reaction was also assessed. Results show that β-cyclodextrin can be successfully used as scavenger as it increases the DEACM-OH threshold concentration for inhibition, amplifying the efficiency of light controlled in vitro transcription.

Molecular nanodiagnostics applied to cancer may provide rapid and sensitive detection of cancer related molecular alterations, which would enable early detection even when those alterations occur only in a small percentage of cells. The use of gold nanoparticles derivatized with thiol modified oligonucleotides (Au-nanoprobes) for the detection of specific nucleic acid targets has been gaining momentum as an alternative to more traditional methodologies. Here, we present an Au-nanoparticles based approach for the molecular recognition and quantification of the BCR-ABL usion transcript (mRNA), which is responsible for chronic myeloid leukemia (CML), and to the best of our knowledge it is the first time quantification of a specific mRNA directly in cancer cells is reported. This inexpensive and very easy to perform Au-nanoprobe based method allows quantification of unamplified total human RNA and specific detection of the oncogene transcript. The sensitivity settled by the Au-nanoprobes allows differential gene expression from 10 ng/μl of total RNA and takes less than 30 min to complete after total RNA extraction, minimizing RNA degradation. Also, at later stages, accumulation of malignant mutations may lead to resistance to chemotherapy and consequently poor outcome. Such a method, allowing for fast and direct detection and quantification of the chimeric BCR-ABL mRNA, could speed up diagnostics and, if appropriate, revision of therapy. This assay may constitute a promising tool in early diagnosis of CML and could easily be extended to further target genes with proven involvement in cancer development.

The effect of kefir grains on the proteolysis of major milk proteins in milk kefir and in a culture of kefir grains in pasteurized cheese whey was followed by reverse phase-HPLC analysis. The reduction of kappa-, alpha-, and beta-caseins (CN), alpha-lactalbumin (alpha-LA), and beta-lactoglobulin (beta-LG) contents during 48 and 90 h of incubation of pasteurized milk (100 mL) and respective cheese whey with kefir grains (6 and 12 g) at 20 degrees C was monitored. Significant proteolysis of alpha-LA and kappa-, alpha-, and beta-caseins was observed. The effect of kefir amount (6 and 12 g/100 mL) was significant for alpha-LA and alpha- and beta-CN. alpha-Lactalbumin and beta-CN were more easily hydrolyzed than alpha-CN. No significant reduction was observed with respect to beta-LG concentration for 6 and 12 g of kefir in 100 mL of milk over 48 h, indicating that no significant proteolysis was carried out. Similar results were observed when the experiment was conducted over 90 h. Regarding the cheese whey kefir samples, similar behavior was observed for the proteolysis of alpha-LA and beta-LG: alpha-LA was hydrolyzed between 60 and 90% after 12 h (for 6 and 12 g of kefir) and no significant beta-LG proteolysis occurred. The proteolytic activity of lactic acid bacteria and yeasts in kefir community was evaluated. Kefir milk prepared under normal conditions contained peptides from proteolysis of alpha-LA and kappa-, alpha-, and beta-caseins. Hydrolysis is dependent on the kefir: milk ratio and incubation time. beta-Lactoglobulin is not hydrolyzed even when higher hydrolysis time is used. Kefir grains are not appropriate as adjunct cultures to increase beta-LG digestibility in whey-based or whey-containing foods.

Single-walled carbon nanotubes (SWCNTs) deposits on glassy carbon and pyrolytic graphite electrodes have dramatically enhanced the direct electron transfer of the multihemic nitrite reductase from Desulfovibrio desulfuricans ATCC 27774, enabling a 10-fold increase in catalytic currents. At optimal conditions, the sensitivity to nitrite and the maximum current density were 2.4 +/- 0.1 A L mol(-1) cm(-2) and 1500 mu A cm(-2), respectively. Since the biosensor performance decreased over time, laponite clay and electropolymerized amphiphilic pyrrole were tested as protecting layers. Both coating materials increased substantially the bioelectrode stability, which kept about 90% and 60% of its initial sensitivity to nitrite after 20 and 248 days, respectively.

The use of gold nanoparticles (AuNPs) has been gaining momentum as vectors for gene silencing strategies, combining the AuNPs' ease of functionalization with DNA and/or siRNA, high loading capacity and fast uptake by target cells. Here, we used AuNP functionalized with thiolated oligonucleotides to specifically inhibit transcription in vitro, demonstrating the synergetic effect between AuNPs and a specific antisense sequence that blocks the T7 promoter region. Also, AuNPs efficiently protect the antisense oligonucleotide against nuclease degradation, which can thus retain its inhibitory potential. In addition, we demonstrate that AuNPs functionalized with a thiolated oligonucleotide complementary to the ribosome binding site and the start codon, effectively shut down in vitro translation. Together, these two approaches can provide for a simple yet robust experimental set up to test for efficient gene silencing of AuNP-DNA conjugates. What is more, these results show that appropriate functionalization of AuNPs can be used as a dual targeting approach to an enhanced control of gene expression-inhibition of both transcription and translation.

n/a

Metallothionein-like proteins (MT) and V, Cr, Co, Ni, Zn, Cu, As and Cd were determined in digestive gland, gills, kidney and gonads of Octopus vulgaris, from the Portuguese coast. To our knowledge these are the first data on MT in octopus. High concentrations (mu g g(-1), dry mass) of Zn (48050) and Cd (555) were found in digestive gland, and MT reached levels one order of magnitude above the ones registered in wild bivalves. Significantly higher levels of MT in digestive gland and gills of specimens from A and B were in line with elevated Cd concentrations. Principal component analyses (PCA) point to MT-Cd and MT-Cr associations in digestive gland and gills. Despite the high levels of Zn in specimens from B, association with Zn was not obtained. Due to the affinity of MT to various elements, it should not be excluded the possibility of Cd replacing Zn in Zn-MT. Kidney presented higher levels of Cd, Co, Ni and As than gills and gonads, and in the case of As surpassing the levels in digestive gland, but PCA showed no relation with MT. Likewise the MT levels in gonads had no correspondence to the metal concentration variation. (C) 2010 Elsevier Inc. All rights reserved.

The final step of bacterial denitrification, the two-electron reduction of N(2)O to N(2), is catalyzed by a multi-copper enzyme named nitrous oxide reductase. The catalytic centre of this enzyme is a tetranuclear copper site called CuZ, unique in biological systems. The in vitro reconstruction of the activity requires a slow activation in the presence of the artificial electron donor, reduced methyl viologen, necessary to reduce CuZ from the resting non-active state (1Cu(II)/3Cu(I)) to the fully reduced state (4Cu(I)), in contrast to the turnover cycle, which is very fast. In the present work, the direct reaction of the activated form of Pseudomonas nautica nitrous oxide reductase with stoichiometric amounts of N(2)O allowed the identification of a new reactive intermediate of the catalytic centre, CuZ degrees , in the turnover cycle, characterized by an intense absorption band at 680 nm. Moreover, the first mediated electrochemical study of Ps. nautica nitrous oxide reductase with its physiological electron donor, cytochrome c-552, was performed. The intermolecular electron transfer was analysed by cyclic voltammetry, under catalytic conditions, and a second-order rate constant of (5.5 +/- 0.9) x 10(5) M(-1 )s(-1) was determined. Both the reaction of stoichiometric amounts of substrate and the electrochemical studies show that the active CuZ degrees species, generated in the absence of reductants, can rearrange to the resting non-active CuZ state. In this light, new aspects of the catalytic and activation/inactivation mechanism of the enzyme are discussed.

n/a

n/a

We studied in this work the performance of the new ultrasonic multiprobe in terms of throughput, handling and robustness. The study was conducted using the multiprobe to speed two different proteomics workflows. The "classic" method relaying on overnight protein digestion (12h), was used as the standard procedure. This work clearly shows the importance of testing variables such as ultrasonic amplitude and ultrasonic time when adapting an ultrasonic-based treatment to a new ultrasonic device. The results here presented also shown and confirm the advantage of speed up sample treatment workflows with the aid of ultrasonic energy in combination with a 96-well plate. The methods compared were similar in terms of robustness, but the desalting free method was the fastest, requiring only 2 min/sample for completion. In addition it was also the simplest in terms of handling, since no desalting step was needed. The following standard proteins were successfully identified using the methods studied: bovine serum albumin, alpha-lactalbumin, ovalbumin, carbonic anhydrase, fructose-bisphosphate aldolase A, catalase, chymotrypsinogen A. As case study, the identification of the protein Split-Soret cytochrome c from D. desulfuricans ATCC 27774 was carried out.

3,4-Methylenedioxymethamphetamine (MDMA; ecstasy), a drug of abuse commonly consumed at rave parties, is often taken in a polydrug abuse scenario, ethanol being one of the most associated drugs. Both MDMA and ethanol are mainly metabolized in the liver with formation of toxic metabolites. Our working hypothesis is that ethanol can modify the metabolism of MDMA through the cytochrome P450 system, and that this effect may be further potentiated by hyperthermia, a well-known consequence of MDMA abuse. To investigate these putative interactions we used primary rat hepatocyte cultures, which were exposed to 300 mM ethanol, 1.6 mM MDMA and the combination of both, at normothermic (36.5 degrees C) and hyperthermic (40.5 degrees C) conditions. After 24 h, the levels of MDA, HMA and HMMA in the cell culture medium were quantified by GC/MS. In addition, we repeated the same experimental design preceded by 1 h incubation with 0.18 mu M ketoconazole or 150 mu M diallyl sulphide (CYP3A and CYP2E1 inhibitors, respectively), to evaluate the putative role of these isoenzymes in the observed effects. The results obtained showed that ethanol exposure increases the formation of some MDMA metabolites such as HMA (1.8 times increase) and MDA (1.5 times increase). This effect was markedly increased under hyperthermic conditions (HMA, MDA and HMMA formation increased 10,6 and 16 times, respectively) and is mediated, at least partially, by CYP3A and CYP2E1. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

A systematic study of the electrochromic (EC) behavior of electropolymerized poly[M(salen)] films (M = Ni, Cu, and Pd) was performed by spectroelectrochemistry. Color contrast between oxidized and reduced states, stability under square wave potential cycling, coloration efficiency, and switching rate were evaluated. Five polymers were selected to assemble solid-state EC cells in a symmetrical configuration (electrode/poly[M(salen)] film/opaque electrolyte/poly[M(salen)] film/electrode). The best EC performance was found for poly[Pd(3-Mesalen)], poly[1], with 38% of initial diffuse reflectance variation and loss of 50% after 6769 cycles. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3457474] All rights reserved.

We recently reported on the use of caged nucleotides to attain full control of enzymatic polymerization of RNA solely by light. In the absence of light no RNA formation was possible due to the efficient caging by the coumarin moiety: after irradiation, caged ATP was released with quantitative precision and RNA polymerization was resumed. As photolabile protecting group [7-(diethylamino)coumarin-4-yl]methyl] (DEACM) was used due to its high absorbance in the visible region of the spectrum, fast deprotection kinetics and absence of radical intermediates. However, the 7-diethylamino-4-hydroxymethylcoumarin photo-product (DEACM-OH) was shown to inhibit the transcription reaction for concentrations higher than 30 mu M [5]. This inhibition has been associated with poor water solubility, which is commonly dealt with via cumbersome chemical modifications of the protecting moiety. To overcome inhibition, we evaluated the use of molecular scavengers to sequester DEACM-OH formed after irradiation. Determination of association constants of coumarin with beta-cyclodextrins allowed the assessment of its capability to remove free coumarin molecules from solution. The influence of beta-cyclodextrin in transcription reaction was also assessed. Results show that beta-cyclodextrin can be successfully used as scavenger as it increases the DEACM-OH threshold concentration for inhibition, amplifying the efficiency of light controlled in vitro transcription. (C) 2010 Elsevier B.V. All rights reserved.

This work aimed at the development of targeted drug delivery systems using nanoparticles fused with antibodies. The antibody anti-human {CD8} was coupled onto {PLGA} nanoparticles, and the ability of these particles to specifically target cells expressing {CD8} was studied. The obtained particles were found to be of spherical shape exhibiting a size between 350 and 600 nm. In vitro experiments with different cellular cultures {(TE671}, {CHO} and {HEK293)} using unmodified nanoparticles containing rhodamine have shown that particles were present on their surface within 48 h of incubation. In vitro tests using {anti-CD8} conjugated nanoparticles in {CHO} cell cultures indicated that all transfected cells which express {CD8} show these particles on their surface within 1h of incubation. These results demonstrated that, in a shorter time, the produced particles can target cells expressing {CD8} on their surface which offers the ability to reduce drug side effects. The antibody-coupled nanoparticles represent a promising approach to improve the efficacy of active targeting for lymphoblastic leukaemia therapy.