Biomedical subjects

C Juan

Publications and source records attributed to C Juan.

At least 19 recordsLinked to original sources

PubMed2007

Limited survey for the occurrence of aflatoxins in cereals and poultry feeds from Rabat, Morocco.

Fifty eight (58) samples of cereals for human consumption (20 corn flour, 17 wheat flour) and poultry feeds (n=21) purchased from popular markets of Rabat in Morocco were analyzed for aflatoxins (AF) by HPLC with immunoaffinity column (IAC) clean-up and fluorimetric detection. The incidence of AF in corn, wheat flour and poultry feeds was about 80, 17.6 and 66.6% respectively. High contamination levels were found in corn and poultry feeds samples. Levels of contamination of analyzed samples with AFB1 ranged from 0.23 to 11.2, 0.03 to 0.15 and 0.05 to 5.38 ng/g for corn, wheat and poultry feeds respectively. Results showed also that the contamination of 10% of samples of corn was higher than the limit set by EU regulations for AFB1 and total AF. This is the first report on the determination of AF in corn, wheat and poultry feeds from Morocco by HPLC and IAC.

Aflatoxins↗

PubMed2005

Occurrence and daily intake of ochratoxin A of organic and non-organic rice and rice products.

Ochratoxin A (OTA) was extracted from 84 rice samples and rice products by using accelerated solvent extraction (ASE) and analysed with liquid chromatography coupled with fluorescence detection. Samples were collected from rice cultivars, local markets and supermarkets; 64 were of non-organic and 20 of organic production. 7.8% of non-organic samples had OTA levels from 4.3 to 27.3 microg/kg and in 30% of organic samples was detected the presence of this mycotoxin varying from 1.0 to 7.1 microg/kg. OTA presence was confirmed by methyl-ester derivatization. Rice and rice products labelled with denomination of origin (DO) were not detected OTA due to the fact that its production has implemented food safety measures such as good agricultural practices (GAPs), good manufacturing practices (GMPs), and the hazard analysis and critical control point (HACCP) system. Estimated daily intake of OTA was 0.17 ng/kg b.w./day. This value reflects that the analysed samples have a minimal contribution to toxicological risk.

Chromatography, Liquid↗

PubMed2005

A prospective audit of the complications of loop ileostomy construction and takedown.

AIM: A prospective review of the complications of ileostomy construction and takedown. MATERIALS AND METHODS: One hundred twenty-seven consecutive patients undergoing construction of a loop ileostomy were included in a prospective nonrandomized computer database. Complications of the loop ileostomy were assessed prior to and after closure. Three closure techniques were performed [enterotomy suture (25.7%), resection and hand sewn (31.2%) or stapled anastomosis (43.1%)] and compared. RESULTS: One hundred twenty-seven (73 male, 54 female) patients, mean age 54 years were included from 1992 to 2002. Seventy-two patients underwent anterior resection for low rectal carcinoma, 30 an ileoanal pouch for ulcerative colitis and 25 for miscellaneous conditions. Fifty-nine pre-takedown complications occurred in 50 (39.4%) patients. The most common were dermatitis (12.6%) and erythema (7.1%). The most severe were dehydration in 1 patient and stomal prolapse in 4 patients. Closure was associated with a complication rate of 33.1% and a mortality rate of 0.9%. Wound infection occurred in 18.3% and small bowel obstruction in 4.6%. Anastomotic leak requiring reanastomosis occurred in 2.8% and enterocutaneous fistula treated conservatively in 5.5%. There were no statistically significant differences in morbidity between closure techniques (p = 0.892). There were no statistically significant differences in complications (p = 0.516) between patients with ulcerative colitis and those with neoplasia (39.29% vs. 32.2%). CONCLUSIONS: Loop ileostomy construction and takedown is associated with considerable morbidity, mostly minor. No differences exist between technique used for closure or the baseline pathology of the patient.

Colonic Pouches↗

PubMed2005

Contribution of clonal dissemination and selection of mutants during therapy to Pseudomonas aeruginosa antimicrobial resistance in an intensive care unit setting.

Rates of antibiotic resistance in Pseudomonas aeruginosa isolates from intensive care unit (ICU) patients are expected to be dependent on the selection of resistance mutations during therapy, the availability of exogenous resistance determinants and their dissemination potential, and the efficiency of transmission of the resistant strains. The relative contributions of these three factors were studied in an ICU with no apparent outbreak in 216 sequential P. aeruginosa isolates recovered from 102 patients between September 2002 and November 2003. Analysis of pulsed-field gel electrophoresis patterns revealed the presence of 82 different clones. Thus, the dissemination of particular resistant clones had a minimal effect on the relatively high overall resistance frequencies found for imipenem (32%), cefepime (25%), ceftazidime (24%), meropenem (22%), ciprofloxacin (18%) and tobramycin (2%). Rates of primary resistance were relatively low, and resistance development during treatment (secondary resistance) was the main factor contributing to the overall high resistance rates. In ICU settings with a low prevalence of epidemic resistant strains, the main strategy for resistance control should focus on the design of targeted regimens to avoid the development of resistance.

Anti-Bacterial Agents↗

PubMed2004

Complex structural features of satellite DNA sequences in the genus Pimelia (Coleoptera: Tenebrionidae): random differential amplification from a common 'satellite DNA library'.

The major satellites of the nine species of the subgenera Pimelia s. str. and Amblyptera characterised in this paper are composed of longer monomers (500 and 700 bp) than those described previously in 26 Pimelia s. str. taxa (357 bp, a sequence called PIM357). Sequence analysis reveals partial similarity among these satellites and with the PIM357 monomers. The discrepancy between the phylogeny obtained based on three mitochondrial and two nuclear markers and that deduced from satellite DNA (stDNA) sequences suggests that the different Pimelia satellites were already present in a common ancestor forming what has been called a 'satellite DNA library'. Thus, the satellite profiles in the living species result from a random amplification of sequences from that 'library' during diversification of the species. However, species-specific turnover in the sequences has occurred at different rates. They have included abrupt replacements, a gradual divergence and, in other cases, no apparent change in sequence composition over a considerable evolutionary time. The results also suggest a common evolutionary origin of all these Pimelia satellite sequences, involving several rearrangements. We propose that the repeat unit of about 500 bp has originated from the insertion of a DNA fragment of 141 bp into the PIM357 unit. The 705-bp repeats have originated from a 32-bp direct duplication and the insertion of a 141-bp fragment in inverted orientation relative to a basic structure of 533 bp.

Animals↗

PubMed2004

Evolutionary dynamics of a B chromosome invasion in island populations of the grasshopper Eyprepocnemis plorans.

Four natural populations of the grasshopper Eyprepocnemis plorans in the Mallorca island were analysed for several years revealing the recent invasion of the B1 chromosome from the south-west part of the island (Palma region) towards the north and to the east. In only 10 years, the mean number of Bs in the northern population at Pollença increased from 0.053 to 0.692. Therefore, B chromosome invasion seems to be very rapid and has recently arrived to the north of the island. The south-west (close to Palma) is the most likely point at which B invasion started in the Mallorca Island. Finally, the number of B chromosomes was significantly associated to an increase in chiasma frequency (and thus recombination) in A chromosomes.

Analysis of Variance↗

PubMed2001

Color and duplex Doppler sonography of hemangiopericytoma.

We report the color Doppler sonographic features in a case of hemangiopericytoma of the thigh in a 52-year-old woman. Color Doppler sonography demonstrated the vascularity of the tumor, and spectral analysis showed waveform changes that suggested the presence of intratumoral arteriovenous shunting. The color Doppler findings correlated well with angiographic findings. Color Doppler sonography can demonstrate intratumoral arteriovenous shunting in hemangiopericytoma and may be used to help avoid profuse bleeding when performing a preoperative biopsy.

Angiography↗

PubMed2000

The evolutionary history of the genus Timarcha (Coleoptera, Chrysomelidae) inferred from mitochondrial COII gene and partial 16S rDNA sequences.

The apterous genus Timarcha consists of three subgenera and more than 100 species in its Palearctic distribution, with specialized feeding on few plant families. Fifty-four sequences sampled from 31 taxa of the genus plus three outgroup leaf beetles were studied for their complete cytochrome oxidase II (COII) and a fragment of 16S rDNA mitochondrial genes, representing a total of about 1200 bp. Phylogenetic analyses using maximum-parsimony and distance methods for each gene separately and for the combined data set gave compatible topologies. The subgenus Metallotimarcha consistently appears in a basal position and is well differentiated from the remaining Timarcha, but no clear monophyletic grouping of Timarchostoma and Timarcha s. str. subgenera can be deduced from our analysis. Calibration of the molecular clock has been done using the opening of the Gibraltar Strait after the Messinian salinity crisis (about 5.5 MYA) as the biogeographic event causing disjunction of two particular taxa. Accordingly, the COII evolutionary rate has been estimated to be of 0.76 x 10(-8) substitution/site/year in Timarcha. Relation between phylogeny and host-plant use indicates widening of trophic regime as a derived character in Timarcha.

Animals↗

PubMed2000

Sequence, secondary structure and phylogenetic analyses of the ribosomal internal transcribed spacer 2 (ITS2) in the Timarcha leaf beetles (Coleoptera: Chrysomelidae).

Internal transcribed spacer 2 (ITS2) sequences of the nuclear rDNA in forty-seven specimens (thirty-four species) of the leaf beetle genus Timarcha have been studied. Timarcha ITS2 (523 bp on average) share some sequence features with other Chrysomeloidea relatives (Chrysolina, Diabrotica and Bruchus) but have no clear similarity with any other arthropod ITS2 sequences. Interspecific divergences are in the range 0.002-0.166, and 0.124-0.206 in the comparisons between subgenera. No evidence of intragenomic divergent ITS2 sequences has been found. Secondary structures are concordant with the four-domain model proposed for vertebrates and yeast, but differs from those proposed for dipterans. Phylogenetic analysis of the ITS2 data confirms the results of a previous study based on mitochondrial sequences, as the basality of the Metallotimarcha subgenus and the absence of phylogenetic support for the Timarchostoma subgenus.

Animals↗

PubMed2000

Nested cladistic analysis, phylogeography and speciation in the Timarcha goettingensis complex (Coleoptera, chrysomelidae).

The Timarcha goettingensis complex is a monophyletic assemblage of closely related leaf beetles (Chrysomelidae), distributed from the north half of the Iberian Peninsula to Central Europe. Oligophagy, mountainous habitat and apterism are factors which are assumed to promote speciation in these beetles. We have used cytochrome oxidase subunit II mitochondrial DNA genealogies obtained from 31 sampling localities and a nested geographical distance analysis to assess the population structure and demographic factors explaining the geographical distributions of the mtDNA haplotypes in the T. goettingensis complex. The results show that there is a significant association between genetic structuring and geography. Inferences about the historical population processes in the species complex are discussed, being in general in accordance with contiguous range expansions and past fragmentations. The use of the cohesion species concept approach suggests the existence of several systematic ranks among the different T. goettingensis populations, which is in part supported by ecological traits such as trophic selection and altitudinal distribution.

Animals↗

PubMed2000

Comparative study of satellite sequences and phylogeny of five species from the genus Palorus (Insecta, Coleoptera).

Major satellite sequences are analysed in the three tenebrionid beetles Palorus cerylonoides, P. genalis, and P. ficicola, and compared with the ones from P. ratzeburgii and P. subdepressus reported elsewhere. All of them are A+T rich, pericentromerically located, and with lengths of about 150 bp, either in the form of monomers or formed by more complex repeating units. A preliminary phylogenetic analysis of Palorus species using the 3' end of the mitochondrial Cytochrome Oxidase I gene shows that the five Palorus species have been diverging for a considerable amount of evolutionary time, with the pair P. ratzeburgii and P. genalis being the most closely related. Only these two taxa showed some similarity between their respective high-copy-number satellite sequences, while other satellites are mutually unrelated and might have originated independently. However, all the satellites have in common tertiary structure induced by intrinsic DNA curvature, a characteristic which is conserved within the genus. Palorus major satellites were previously detected in the genomes of congeneric species as low-copy-number clusters (Mestrović et al., Mol. Biol. Evol. 15: 1062-1068. 1998). Given the divergences between the analysed species, the substitution rate deduced from high- and low-copy-number repeats is unexpectedly low. The presence of sequence-induced DNA curvature in all Palorus satellites and similar satellite DNAs in the species pair P. ratzeburgii and P. genalis suggest (i) that constraints are at the tertiary structure; and (ii) that the satellite DNA evolutionary turnover can be dependent on the history of the taxa under study, resulting in retention of similar satellites in related taxa.

Animals↗

PubMed1999

Mitochondrial DNA phylogeny and the evolution of host-plant use in palearctic Chrysolina (Coleoptera, Chrysomelidae) leaf beetles.

The genus Chrysolina consists of specialized phytophagous leaf-beetles (Coleoptera, Chrysomelidae) with feed on several plant families. There is no explicit phylogenetic hypothesis available for this genus, which includes 65 subgenera and more than 400 species with a wide distribution. We obtained 839-bp sequence data from the 16S rDNA and cytochrome oxidase subunit I (COI) mitochondrial genes. Thirty Chrysolina taxa representing eight host-plant affiliations, two species of the closely related genus Oreina, and two outgroups were sampled. These data sets were used separately and combined to obtain the mitochondrial cladogram of the group using maximum-parsimony and maximum-likelihood criteria. The results were compared to current proposals for Chrysolina systematics that are based on morphological, ecological, and karyological data. The trees obtained were in the most part congruent with the proposed ancestral association of Chrysolina to Lamiaceae based on chromosome number in several lineages. A minimum of five host-plant switches from the ancestral state inferred at the family level and two at the subclass level suggests the absence of parallel evolution of beetles and their host plants. Another switch leading to oligophagy at the family level was deduced to have occurred in the lineage of the subgenus Chrysolina s.str.

Animals↗

PubMed1999

Interactive image-guided surgery system with high-performance computing capabilities on low-cost workstations: a prototype.

We present a new frameless stereotatic system prototype that has been initially validated in functional neurosurgery operations and that makes use of an optical position tracker for image-guided neurosurgery. Several devices for tracking different surgical instruments have been designed and manufactured. These devices include an array of infrared light-emitting diodes that are tracked by three charge-coupled device cameras. The system presents several new approaches for surgery planning. For high-quality 3D images of the patient's anatomy, we have developed a parallel version of a volume-rendering algorithm, thus enabling real-time 3D anatomy manipulation on low-cost PC workstations. In order to test the accuracy of the system, the localization of the target by means of a stereotatic frame has been compared with frameless techniques, obtaining a difference of about 1 +/- 1 mm.

Algorithms↗

PubMed1999

A system for the simulation and planning of orthodontic treatment using a low cost 3D laser scanner for dental anatomy capturing.

The detection and correction of malocclusions and other dental abnormalities is a significant area of work in orthodontic diagnosis. To assess the quality of occlusion between the teeth the orthodontist has to estimate distances between specific points located on the teeth of both arches. Distance measuring is based on the observation, by the orthodontist, of a plaster model of the mouth. Gathering of information required to make the diagnosis is a time consuming and costly operation. On the other hand, obtaining and manipulation of plaster casts constitute a huge problem in clinics, due to both the large space needed and high costs associated with plaster casts manufacturing. For this problem we present a new system for three-dimensional orthodontic treatment planning and movement of teeth. We describe a computer vision technique for the acquisition and processing of three-dimensional images of the profile of hydrocolloids dental imprints taken by mean of a own developed 3D laser scanner. Profile measurement is based on the triangulation method which detects deformation of the projection of a laser line on the dental imprints. The system is computer-controlled and designed to achieve depth and lateral resolutions of 0.1 mm and 0.2 mm, respectively, within a depth range of 40 mm. The developed diagnosis software system (named MAGALLANES) and the 3D laser scanner (named 3DENT) are both commercially available and have been designed to replace manual measurement methods, which use costly plaster models, with computer measurements methods and teeth movement simulation using cheap hydrocolloid dental wafers. This procedure will reduce the cost and acquisition time of orthodontic data and facilitate the conduct of epidemiological studies.

Adult↗

PubMed1998

The phylogeography of the darkling beetle, Hegeter politus, in the eastern Canary Islands.

We investigated the phylogeography of Hegeter politus, a saprophagous, flightless darkling beetle endemic to the eastern Canary Islands, using a fragment of the mitochondrial COI gene. Distance and parsimony based gene trees of the mitotypes identified revealed a striking association between mitotype clades and sampling locations. The branching order of the clades suggested that the colonization of the islands by Hegeter politus proceeded from the southern part of Fuerteventura in a north-northeast direction to Lanzarote and the smaller islands. Based on this, a colonization scenario compatible with the reported geological ages and volcanisms of the various parts of the islands has been proposed. The high divergence of the beetles collected from the extreme south of Fuerteventura (the Jandía peninsula) from all other samples has led us to propose that they may be from a new species that has not been described previously. The ecological isolation of Jandía from the rest of Fuerteventura by the sand dunes that cover its narrow isthmus in the north, and the existence of many plant and animal endemisms unique to Jandía, lend supportive evidence to our proposal. The similarities between the evolution of island endemics in the Hawaiian and Canary archipelagos have been discussed. We conclude that many endemics in the Canary archipelago, like the Hawaiian Islands, are most likely to have originated from post-colonization differentiation and divergence.

Animals↗

PubMed1997

Conservation of satellite DNA in species of the genus Pimelia (Tenebrionidae, Coleoptera).

Satellite DNA has been characterized in six allopatric species from the genus Pimelia: P. interjecta, P. integra, P. variolosa and P. baetica, inhabiting Iberian Peninsula, and P. elevata and P. criba, endemic to Balearic Islands Ibiza and Mallorca, respectively. All species show the presence of a single satellite DNA of a basic monomer length of 357 bp and A+T content of 69%, comprising a considerable amount of the genome (39%-45%, corresponding to about 4.5 x 10(5) copies per haploid genome). The sequence analysis of 22 cloned repeats reveals very high intra- and interspecific sequence similarity. Phylogenetic analysis separates the satellite sequences into two clusters, each comprising clones from three species exclusively. Within the clusters, satellite clones are not grouped species-specifically, except those of P. integra where species-diagnostic nt substitutions are detected with a pattern that could be produced by gene conversion. Such high sequence conservation could be related to preservation of satellite DNA curvature, resulting in a higher order helical structure, proposed to act as a specific protein binding domain.

Animals↗

PubMed1996

Mitochondrial DNA sequence variation and phylogeography of Pimelia darkling beetles on the island of Tenerife (Canary Islands).

Four morphological taxa of the beetle genus Pimelia (Coleoptera, Tenebrionidae) are known to exist on the Atlantic island of Tenerife. We have obtained DNA sequences for 61 individuals from these taxa across the island for a 200 bp long fragment of the mitochondrial COI gene. In addition, a restriction site polymorphism in the nuclear rRNA ITS-1 sequence was identified and screened in a sample of these individuals using the enzyme Kpn2I. The results were analysed using approaches which allow inferences to be made about the population genetic structure and the mitochondrial genealogy of these closely related beetles. The mtDNA haplotype distribution and the estimates of sequence divergence revealed the presence of two ancient mtDNA lineages which coincide with the disjunct volcanic evolution of the island. The ITS-1 polymorphism was found to be diagnostic of these two lineages. However, the morphological and mitochondrial phylogenies were found to be discordant. We argue that this is possibly the result of rapid morphological change, produced by selection in different habitats, which has been recently superimposed on an older mitochondrial DNA divergence.

Animals↗

PubMed1996

Phylogeny of the genus Hegeter (Tenebrionidae, Coleoptera) and its colonization of the Canary Islands deduced from Cytochrome Oxidase I mitochondrial DNA sequences.

The genus Hegeter comprises 23 species of darkling beetles (Tenebrionidae) endemic to the Macaronesian archipelagos, with 21 of them exclusive to the Canary Islands. We have sequenced 438 bp of the mitochondrial Cytochrome Oxidase I gene in 17 species (24 taxa) of Canarian Hegeter. Estimates of nucleotide composition, transition/transversion ratios and nucleotide change frequencies are very similar to those found in another tenebrionid Canarian genus Pimelia, indicating that similar molecular mechanisms are driving the sequence evolution. The sequence variation found allows phylogenetic analyses of the genus and the deduction of colonization patterns. These involve sequential island invasion with more rapid establishment and radiation than found in the related beetles of the genus Pimelia.

Animals↗