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C Gonçalves

Publications and source records attributed to C Gonçalves.

At least 19 recordsLinked to original sources
PubMed2006

Optimisation and validation of a solid-phase microextraction method for simultaneous determination of different types of pesticides in water by gas chromatography-mass spectrometry.

A solid-phase microextraction (SPME) method for the simultaneous determination of a large number of pesticides (46) with a wide range of polarities and chemical structures (organochlorine, organophosphorous, triazines, pyrethroids and others) in water samples by GC-MS has been developed. Three different fibres and parameters that influence the extraction and desorption efficiency were studied. The selected conditions were: a 60 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre, 45 min of extraction time, sample agitation and temperature control at 60 degrees C; neither pH adjustment nor ionic strength correction were applied. Good detection limits, linearity and repeatability were obtained with this method for the 46 pesticides studied. The method was validated for 29 pesticides following the recommendations of the international norm ISO/IEC 17025 including the calculation of the uncertainties. The detection limits ranged from 4 to 17 ng l(-1). Furthermore, repeatability (6.9-20.5%) and intermediate precision (4.5-19.7%) were shown to be satisfactory. To validate matrix effects for drinking and surface water analytical recoveries were calculated for these matrices. The accuracy of the method was also evaluated by participating in a proficiency inter-laboratory test.

Gas Chromatography-Mass Spectrometry↗
PubMed2006

Photolytic degradation of quinalphos in natural waters and on soil matrices under simulated solar irradiation.

The photochemical persistence of quinalphos, one of the most widely used organophosphorous insecticides, was investigated in a variety of environmental matrices such as natural waters and soils of different composition. Simulated solar irradiation was obtained using a xenon arc lamp (Suntest CPS+ apparatus) giving an irradiation intensity of 750 W m(-2) equivalent to a light dose per hour of irradiation of 2,700 kJ m(-2). The phototransformation rates were determined using solid-phase microextraction (SPME) and ultrasonic extraction (USE) coupled to GC-FTD, while the identification of photoproducts was carried out by GC-MS. In water samples, the degradation kinetics followed a pseudo-first-order reaction and photolysis half-lives ranged between 11.6 and 19.0 h depending on the constitution of the irradiated media. Dissolved organic matter (DOM) has a predominant retarding effect, while nitrate ions accelerated the photodegradation kinetics. In soil samples, the degradation kinetics was monitored on 1mm soil layer prepared on glass TLC plates. The kinetic behaviour of quinalphos was complex and characterized by a double step photoreaction, fast in the first 4h of irradiation followed by a slow degradation rate up to 64 h. The photolysis half-life of quinalphos was shorter in sandy soil compared to the rest of the soil samples, varying between 16.9 and 47.5 h, and showing a strong dependence on the composition of the irradiated media. Among the transformation products formed mainly through photohydrolysis and photoisomerization processes, some photoproduct structures were proposed according to their mass spectral information.

Chromatography, Gas↗
PubMed2006

Optimization of supercritical fluid extraction of pesticide residues in soil by means of central composite design and analysis by gas chromatography-tandem mass spectrometry.

An environmentally friendly methodology is proposed for the analysis of pesticides in soil samples based on supercritical fluid extraction (SFE) and analysis at high selectivity and sensitivity, by gas chromatography-tandem mass spectrometry (GC-MS-MS). The pesticides investigated are among the most commonly used in intensive horticulture activities comprising organochlorine and organophosphorous insecticides, triazine and acetanilide herbicides, amongst others. An experimental design approach was used for modelling SFE and optimised extraction conditions were derived for the total pesticides extraction or for specific sub-groups of interest. Pesticide residues could be detected in soils in the sub-ppb range (0.1-3.7microgkg(-1)), with quite good precision (4.2-15.7%) and extraction efficiency (80.4-106.5%). The analysis of soil samples from an intensive horticulture area in Póvoa de Varzim, north of Portugal, revealed the presence of persistent pesticides, parent compounds and degradation products among the following: endosulfan, endosulfan sulfate, dieldrin, 4,4'-DDE, 4,4'-DDD, atrazine, alachlor, metolachlor, chlorpyrifos, pendimethalin and lindane. The important features to point out are the easy interpretation of chromatograms and straightforward confirmation of analytes that greatly facilitates the analyst judgement on the contamination of the sample.

Acetanilides↗
PubMed2006

Quantification by image analysis of the Gallus gallus lung elastic fibres from embryonic to adult birds.

The organization of the lung's elastic fibres is amazingly uniform in all vertebrates, with the possible exception of birds, whose pulmonary architecture and air movement are unique. The overall goal of this work was to study and quantify elastic fibre distribution patterns and relative amounts in the parabronchi, during the incubation period until the 42nd day after hatching. Chick embryo lungs were examined on the 14th, 16th, 18th and 20th days of incubation and chick lungs on the 1st, 2nd, 7th, 14th, 35th and 42nd days after hatching. Four animals were used daily, and the observations were randomly performed on both lungs. A morphometric study was carried out focusing on the computerized image analysis of histological sections stained according to a modified Gomori technique. The values obtained for each day result from the observation and processing of 20 images. Complementary studies were performed using transmission electron microscopy, as on the 14th embryonic day the fibres were not visible on light microscopy. The results show that the area occupied by the elastic fibres increases gradually from the 16th day of incubation up till the 7th day after hatching and decreases slowly in the following days of the study. A prominent increase takes place before hatching, which points out to the adequate and essential structural roles played by the elastic fibres in the pulmonary maturation process.

Aging↗
PubMed2005

Scaling and root planing, systemic metronidazole and professional plaque removal in the treatment of chronic periodontitis in a Brazilian population II--microbiological results.

OBJECTIVE: The current investigation evaluated changes in levels and proportions of 39 bacterial species in subgingival plaque samples after scaling and root planing (SRP) alone or in combination with systemic metronidazole and/or professional cleaning in subjects with chronic periodontitis. METHODS: Forty-four adult subjects (mean age 45+/-6 years) with periodontitis were randomly assigned in four treatment groups, a control (C, n=10) that received SRP and placebo and three test groups treated as follows: T1 (n=12): SRP and metronidazole (M, 400 mg tid) for 10 days; T2 (n=12): SRP, weekly professional supragingival plaque removal for 3 months (PC) and placebo; and T3 (n=10): SRP, M and PC. Subgingival plaque samples were taken from seven sites per subject at baseline and 90 days post-therapy. Counts of 39 subgingival species were determined using checkerboard DNA-DNA hybridization. Significance of differences over time was determined using the Wilcoxon signed ranks test and among groups using ancova. RESULTS: The mean counts of the majority of the species were reduced post-therapy in the 4 treatment groups. Counts (x 10(5)+/-SEM) of Porphyromonas gingivalis, Tannerella forsythensis and Treponema denticola were significantly reduced in groups T2 and T3. Levels of beneficial species, such as some Actinomyces species, Veillonella parvula, Streptococcus sanguis, Streptococcus oralis and Streptococcus gordonii were minimally affected in levels when the combined therapy was applied (T3). Mean proportions of red complex species decreased from 18.4% at baseline to 3% at 90 days post-therapy in group T3 (p<0.01), from 25.8% to 2.3% in group T2 (p<0.01), from 17.7% to 5.6% in group T1 (p<0.05) and from 19.4% to 8.8% in group C (NS). Proportions of the suspected periodontal pathogens from the orange complex were also markedly reduced in groups T2 and T3. CONCLUSIONS: All treatments reduced counts and proportions of red complex species. Adjunctive therapy appeared to have a greater effect and also affected members of the orange complex.

Administration, Oral↗
PubMed2004

Further insights into the role of methional and phenylacetaldehyde in lager beer flavor stability.

This work attempts to measure the importance of methional and phenylacetaldehyde on the flavor stability of beer, as direct participants or as indicators of aroma deterioration. A trained sensory panel identified the most important descriptors related to the typical aroma of aged beer: "malty", "honey-like", "cooked potato", and "metallic". By GC-olfactometry analysis, six aromatic zones related to the selected descriptors were highlighted, and by using GC-MS techniques it was possible to identify methional and phenylacetaldehyde as being responsible for two odor zones. The quantification of these molecules in samples submitted to forced aging treatments showed that the levels of methional and phenylacetaldehyde are dependent on the temperature of storage. Normal aged beers were also analyzed, and it was observed that these compounds accumulate with time of storage. Furthermore, these molecules were negatively correlated with the aroma quality of beer as evaluated by a sensorial panel. To validate the sensory impact of these substances, a fresh beer was spiked with these molecules and also with trans-2-nonenal, singly and in combination, and the similarity value between samples and the aged beer was then determined. The highest value from the similarity tests was 72% when the three compounds were added simultaneously. The combination of the two Strecker aldehydes increases by 54% the degree of similarity, indicating the key role played by these molecules in the aroma deterioration of beer. Finally, the kinetic parameters, Ea and k, were calculated, and it was observed that the Arrhenius equation described well the temperature dependence of the reaction rate constant. Measuring the concentration of methional and phenylacetaldehyde may provide information about the key steps along the process that most affect the flavor stability of beer, which may be useful in establishing the best storage conditions.

Acetaldehyde↗
PubMed2004

Solid-phase micro-extraction-gas chromatography-(tandem) mass spectrometry as a tool for pesticide residue analysis in water samples at high sensitivity and selectivity with confirmation capabilities.

Gas chromatography-mass spectrometry (GC-MS) has been widely applied for pesticide monitoring because of its high sensitivity and specificity and for the potential of multi-residue and multi-class analysis. An analytical procedure was developed for the determination of pesticide multi-residues in water samples combining solid-phase micro-extraction (SPME) and gas chromatography-ion trap mass spectrometry. For SPME extraction a poly(dimethylsiloxane)-divinylbenzene coated fibre was selected whereas the mass spectrometer was operated under full scan, selected ion storage (SIS), microSIS (SIM) and MS-MS and the figures of merit compared. Quantitative and qualitative (confirmatory) capabilities of each operation mode are discussed. Using MS-MS, precision was typically below 10% and limits of detection (LODs) were improved by 1.3 to 20 times (to low- or sub-ppt levels) compared to microSIS, with the advantage of maintaining identification capabilities. The combination of selective extraction by SPME and highly selective determination by GC-MS-MS made possible ultra-selective and essentially error-free determination of pesticides in complex environmental samples. This aspect will be highlighted in the paper.

Gas Chromatography-Mass Spectrometry↗
PubMed2002

Multiresidue method for the simultaneous determination of four groups of pesticides in ground and drinking waters, using solid-phase microextraction-gas chromatography with electron-capture and thermionic specific detection.

A common sample preparation procedure capable of efficiently concentrating various groups of pesticides, taking advantage of universal detectors like the mass spectrometer or combined techniques of group selective detectors like gas chromatography-electron capture detection (ECD)/thermionic specific detection (TSD), is desirable in environmental analysis. Six solid-phase microextraction fibres available for analysis of semi-volatiles (7, 30 and 100 microm poly(dimethylsiloxane) (PDMS), 85 microm polyacrylate, 60 microm PDMS-divinylbenzene (PDMS-DVB) and 65 microm Carbowax-DVB) were evaluated and the 60 microm PDMS-DVB was selected for the simultaneous extraction of 34 compounds, included in the organochlorine (OCPs), organophosphorous (OPPs), pyrethroid and triazine pesticide groups. All parameters affecting the extraction efficiency from water samples, namely fibre coating, sample agitation, pH and ionic strength, extraction temperature and time, were optimised. The analytical procedure involves solid-phase microextraction extraction, gas chromatographic separation and subsequent ECD and TSD via a post-column splitter adjusted to a split ratio of 1:10, respectively. Detection limits in the range of 1-10 ng l(-1) for OCPs, 1-30 ng l(-1) for OPPs, 20-30 ng l(-1) for pyrethroids and 8-50 ng l(-1) for triazines are easily attainable with the optimised procedure. The method validated for ground and drinking waters has low cost of implementation and operation although it requires careful maintenance.

Chromatography, Gas↗
PubMed2002

Comparison of three different poly(dimethylsiloxane)-divinylbenzene fibres for the analysis of pesticide multiresidues in water samples: structure and efficiency.

Despite the continuing development of SPME (solid-phase microextraction) fibre coatings, their selection presents some difficulties for analysts in choosing the appropriate fibre for a certain application. There are two distinct types of SPME coatings available commercially. The most widely used are poly(dimethylsiloxane) (PDMS) and poly(acrylate) (PA). Supelco has developed new mixed phases consisting of porous polymer particles, either poly(divinylbenzene) (DVB) or Carboxen suspended in a matrix of PDMS or Carbowax for extracting analytes via adsorption. In addition to the nature of the extracting phase, the thickness of the polymeric film must be taken into account and, surprisingly, the construction of the fibres when apparently they bear the same coating, as it is the case of the three PDMS-DVB fibres available. Other fibre structure properties not well explored were identified and must be taken into consideration. To elucidate their extraction efficiency, three PDMS-DVB fibres, namely 60 microm for HPLC use, 65 microm for GC use and 65 microm StableFlex for GC use, were compared with regard to the extraction of 36 compounds included in four pesticide groups. The first was particularly suited for the extraction of organophosphorus pesticides and triazines whereas the StableFlex exhibited advantages in the analysis of organochlorine pesticides and pyrethroids. An explanation for the extraction differences is suggested based on the different structure of the fibres. Detection limits in the range of 1-10 ng/l for organochlorine pesticides, 1-30 ng/l for organophosphorus pesticides, 8-50 ng/l for triazines and 10-20 ng/l for pyrethroids were attained in a method using the 60 microm PDMS-DVB fibre. The fibre maintains its performance at well above 100 extractions with between-day precision below 10%.

Chromatography, Gas↗
PubMed2002

Pesticide toxicity assessment using an electrochemical biosensor with Pseudomonas putida and a bioluminescence inhibition assay with Vibrio fischeri.

Two different toxicity tests, an electrochemical biosensor Cellsense and a bioluminescence inhibition assay ToxAlert were performed in order to establish and compare the acute toxicity responses of different types of raw and spiked water for a selected group of pesticides. The selected compounds were endosulfan, chlorfenvinphos, dimethoate, fenamiphos, ametryn, deltamethrin and alpha-cypermethrin; all of them are used in large quantities for agricultural purposes. In the first step, the study of the toxicity responses for each individual pesticide with Milli-Q water was carried out. Next, the toxic responses of different mixtures of these pesticides in different water matrices, i.e., Milli-Q water, surface water, groundwater and wastewater were studied in order to evaluate (i) device advantages and limitations for the toxicity evaluation of real environmental samples, (ii) antagonistic or synergistic effects and (iii) the influence of the water matrices. The survey of pesticides in real samples was carried out using a combined method involving both chemical analysis and toxicity bioassays. Chemical analysis involved the use of solid-phase micro-extraction (SPME) followed by gas chromatography with electron capture detection (GC/ECD) or thermoionic specific detection (GC/TSD) with mass spectrometric confirmation (GC/MS).

Biosensing Techniques↗
PubMed2001

Histidine-rich peptides and polymers for nucleic acids delivery.

Nucleic acids transfer into mammalian cells requires devices to improve their escape from endocytic vesicles where they are mainly confined following cellular uptake. In this review, we describe histidine-rich molecules that enable the transfer of plasmid and oligonucleotides (ODN) in human and non-human cultured cells. An histidine-rich peptide which permeabilizes biological membrane at pH 6.4, favored the transfection mediated by lactosylated polylysine/pDNA complexes. Histidylated polylysine forms cationic particles of 100 nm with a plasmid and yielded a transfection of 3-4.5 orders of magnitude higher than polylysine. The biological activity of antisense ODN was increased more than 20-fold when it was complexed with highly histidylated oligolysine into small cationic spherical particles of 35 nm. Evidence that imidazole protonation mediates the effect of these molecules in endosomes are provided. We also describe a disulfide-containing polylysine conjugate capable of mediating DNA unpackaging in a reductive medium and to increase the transfection efficiency. Overall, these molecules constitute interesting devices for developing non-viral gene delivery systems.

Animals↗
PubMed2001

Vena cava thrombosis associated with nephrotic syndrome in the puerperal gestational cycle.

CONTEXT: The puerperal gestational cycle is accompanied by a state of physiological hypercoagulability. Thromboembolic phenomena may occur at this time. OBJECTIVE: To report on a clinic case involving a patient that presented a family history of thromboembolism and developed deep vein thrombosis in a lower limb and vena cava thrombosis during the puerperal gestational cycle, displaying nephrotic syndrome as the main complication. DESIGN: Case report.

Adult↗
PubMed2001

Association of CD4+/CD56+/CD57+/CD8+(dim) large granular lymphocytic leukemia, splenic B-cell lymphoma with circulating villous lymphocytes, and idiopathic erythrocytosis.

In this paper we report a rare association of a splenic marginal zone B-cell lymphoma with villous lymphocytes and a T-cell large granular lymphocytic leukemia coexpressing CD4 and CD8 as well as CD56 and CD57 natural killer-associated markers in an asymptomatic patient investigated because of an occasional finding of erythrocytosis and leukocytosis in routine blood analysis. We also discuss the possible reasons for this particular association.

Aged↗
PubMed2000

Immunophenotypic aberrations, DNA content, and cell cycle analysis of plasma cells in patients with myeloma and monoclonal gammopathies.

We describe the immunophenotypic and gross DNA defects in 55 patients with myeloma and 50 patients with monoclonal gammopathy and review the literature on this subject (MedLine, 1994-2000). Our data confirmed previous reports indicating that in myeloma nearly all marrow plasma cells are abnormal (98.7 +/- 8.1%). In monoclonal gammopathy the fraction of abnormal plasma cells was 35.0 +/- 32.8%. In both myeloma and monoclonal gammopathy, the most frequent aberrant phenotypic features consisted of absence of expression of CD19, strong expression of CD56, and decreased intensity of expression of CD38; aberrant expression of CD10, CD20, CD22, or CD28 was observed in less than one-third of myeloma cases. The vast majority of cases had two or more phenotypic aberrations. In the DNA studies, 7% of myeloma cases were biclonal and 93% of cases were monoclonal. In those studies with only one plasma cell mitotic cycle, 37% had normal DNA content and 63% were aneuploid (hyperploid, 61%; hypoploid, 2%). The mean percentages of plasma cells in S- and G2M phases were 4.9 +/- 8.5 and 4.4 +/- 6.9%, respectively. Thirty-eight percent of cases had more than 3% of plasma cells in S phase. In monoclonal gammopathy, the DNA index of abnormal plasma cells ranged from 0.89 to 1.30 and the percentage of diploid (31%) and aneuploid (69%) cases was not different from the results found in myeloma. The differences in percentage of abnormal plasma cells in S- (7.4 +/- 8.6%) and G2M-phases (2.4 +/- 1.7%) in patients with monoclonal gammopathy were not statistically significant.

Adult↗
PubMed1998

Consistent fusion of ZNF198 to the fibroblast growth factor receptor-1 in the t(8;13)(p11;q12) myeloproliferative syndrome.

The 8p11 myeloproliferative syndrome is a rare, aggressive condition associated with reciprocal translocations of chromosome band 8p11, most commonly the t(8;13)(p11;q12). To identify the genes involved in this translocation, we used fluorescence in situ hybridization (FISH) analysis to show that the chromosome 8 breakpoints fell within YAC 899e2 and that the chromosome 13 breakpoints are clustered in a region flanked by YACs 929f11 and 911h8. FISH using chromosome 13 PAC clones indicated that the t(8;13) is not simply a reciprocal translocation but also involves an inversion of 13q11-12. Exon trapping of a PAC that spanned the chromosome 13 translocation breakpoints led to the identification of a gene, ZNF198, that detected rearranged bands when used as a probe against Southern blots of patient DNA. Conceptual translation of the full-length ZNF198 cDNA sequence predicts a protein of 1377 amino acids that shows significant homology to the DXS6673E/KIAA0385 and KIAA0425 proteins. Alignment of these three proteins revealed a novel, conserved Zn-finger-related motif (MYM domain) of the general form CX2C19-22CX3CX13-19CX2CX19-25FCX3CX3F/Y that is repeated five times in each protein. To identify the translocation partner gene on chromosome 8, 5' and 3' RACE polymerase chain reactions (PCRs) were performed on patient RNA with several combinations of ZNF198 primers. Clones were identified in which the ZNF198 was fused to exon 9 of the fibroblast growth factor receptor-1 (FGFR1), a gene known to map to 8p11. An identical ZNF198-FGFR1 fusion was detected in the three patients with a t(8;13) for whom RNA was available; reciprocal FGFR1-ZNF198 transcripts were not detected. Rearrangements of both ZNF198 and FGFR1 were found in two further patients by Southern blotting. ZNF198-FGFR1 includes the five MYM domains of ZNF198 and the intracellular tyrosine kinase domain of FGFR1. We hypothesize that this fusion leads to constitutive activation of the FGFR1 tyrosine kinase in a manner analogous to the activation of ABL by BCR in chronic myeloid leukemia.

Amino Acid Sequence↗