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C Ferreira

Publications and source records attributed to C Ferreira.

At least 19 recordsLinked to original sources
PubMed2006

Crystallization, data collection and phasing of two digestive lysozymes from Musca domestica.

Lysozymes are mostly known for their defensive role against bacteria, but in several animals lysozymes have a digestive function. Here, the initial crystallographic characterization of two digestive lysozymes from Musca domestica are presented. The proteins were crystallized using the sitting-drop vapour-diffusion method in the presence of ammonium sulfate or PEG/2-propanol as the precipitant. X-ray diffraction data were collected to a maximum resolution of 1.9 angstroms using synchrotron radiation. The lysozyme 1 and 2 crystals belong to the monoclinic space group P2(1) (unit-cell parameters a = 36.52, b = 79.44, c = 45.20 angstroms, beta = 102.97 degrees) and the orthorhombic space group P2(1)2(1)2 (unit-cell parameters a = 73.90, b = 96.40, c = 33.27 angstroms), respectively. The crystal structures were solved by molecular replacement and structure refinement is in progress.

Animals↗
PubMed2006

Gene expression profiling in vLINCL CLN6-deficient fibroblasts: Insights into pathobiology.

The CLN6 vLINCL is caused by molecular defects in CLN6 gene coding for an ER resident transmembrane protein whose function is unknown. In the present study gene expression profiling of CLN6-deficient fibroblasts using cDNA microarray was undertaken in order to provide novel insights into the molecular mechanisms underlying this neurodegenerative fatal disease. Data were validated by qRT-PCR. Statistically significant alterations of expression were observed for 12 transcripts. The two most overexpressed genes, versican and tissue factor pathway inhibitor 2, are related to extracellular matrix (ECM), predicting changes in ECM-related proteins in CLN6-deficient cells. Transcript profiling also suggested alterations in signal transduction pathways, apoptosis and the immune/inflammatory response. Up-regulated genes related to steroidogenesis or signalling, and the relationship between cholesterol dynamics and glycosphingolipid sorting, led to investigation of free cholesterol and gangliosides in CLN6-deficient fibroblasts. Cholesterol accumulation in lysosomes suggests a homeostasis block as a result of CLN6p deficiency. The cholesterol imbalance may affect structure/function of caveolae and lipid rafts, disrupting signalling transduction pathways and sorting cell mechanisms. Alterations in protein/lipid intracellular trafficking would affect the composition and function of endocytic compartments, including lysosomes. Dysfunctional endosomal/lysosomal vesicles may act as one of the triggers for apoptosis and cell death, and for a secondary protective inflammatory response. In conclusion, the data reported provide novel clues into molecular pathophysiological mechanisms of CLN6-deficiency, and may also help in developing disease biomarkers and therapies for this and other neurodegenerative diseases.

Cells, Cultured↗
PubMed2005

Cystic echinococcosis: analysis of the serological profile related to the risk factors in individuals without ultrasound liver changes living in an endemic area of Tacuarembó, Uruguay.

Cystic echinococcosis (CE) is a high prevalence zoonosis among the rural population of Tacuarembó (Uruguay). The correlation between serological data and the incidence of risk factors was studied in a survey carried out in 1998 among rural communities where 480 individuals were examined by means of abdominal sonography (local prevalence = 0.8%). Serum samples (305) were analysed by ELISA to determine specific IgG against crude antigens from Echinococcus granulosus. A total of 27 individuals exhibiting no detectable changes in abdominal sonographic examination were found to be seropositive ('ultrasound normal group'). Of these individuals 9 were seroreactive against purified antigen B. A significant degree of correlation was found between seroreactivity and the incidence of some risk factors (CE antecedent in the family, P < 0.005 and use of rural water, P < 0.0001) among this group. Follow-up of individuals of the 'ultrasound normal group' was carried out after 2 years to evaluate the implications of this serological reactivity. No predictive value for cyst development was assessed with complementary image study; in contrast transient antibodies were observed with both crude and purified antigen as approximately 60% of individuals became negative when re-sampled.

Adult↗
PubMed2004

Management of vascular complications after pediatric liver transplantation.

Sixty-five children underwent liver transplantation (LTx) from March 1995 to December 2002. Cirrhosis due to biliary atresia was the main indication, and hepatic artery thrombosis (HAT) the most common vascular complication (n = 5). Other vascular problems were portal vein thrombosis and stenosis. Another patient developed hepatomegaly and ascites due to a late stenosis of the left hepatic vein anastomosis. The two cases of venous stenosis were successfully treated by percutaneous angioplasty. One graft with HAT was saved, but four children died awaiting retransplant.

Adolescent↗
PubMed2003

Possible applications for municipal solid waste fly ash.

The present study focuses on existing practices related to the reuse of Municipal Solid Waste (MSW) fly ash and identifies new potential uses. Nine possible applications were identified and grouped into four main categories: construction materials (cement, concrete, ceramics, glass and glass-ceramics); geotechnical applications (road pavement, embankments); "agriculture" (soil amendment); and, miscellaneous (sorbent, sludge conditioning). Each application is analysed in detail, including final-product technical characteristics, with a special emphasis on environmental impacts. A comparative analysis of the different options is performed, stressing the advantages but also the weaknesses of each option. This information is systemized in order to provide a framework for the selection of best technology and final products. The results presented here show new possibilities for this waste reuse in a short-term, in a wide range of fields, resulting in great advantages in waste minimization as well as resources conservation.

Agriculture↗
PubMed2003

An island within an island: genetic differentiation of Anopheles gambiae in São Tomé, West Africa, and its relevance to malaria vector control.

Islands are choice settings for experimental studies of vector control strategies based on transgenic insects. Before considering this approach, knowledge of the population structure of the vector is essential. Genetic variation at 12 microsatellite loci was therefore studied in samples of the malaria vector Anopheles gambiae s.s., collected from six localities of São Tomé island (West Africa). The objectives were (i) to assess the demographic stability and effective population size of A. gambiae from these sites, (ii) to determine population differentiation and (iii) to relate the observed patterns of population structure with geographic, ecological and historical aspects of the vector on the island. Significant population differentiation, revealed by FST and RST statistics, was found between the southernmost site, Porto Alegre, and northern localities. The observed patterns of population substructure are probably a result of restrictions to gene flow in the less inhabited, more densely forested and mountainous south. In all localities surveyed, A. gambiae appeared to be experiencing a demographic expansion, consistent with a relatively recent (ca. 500 years) founder effect. The results are discussed with respect to current and future prospects of malaria vector control.

Africa, Western↗
PubMed2003

Mating does not affect the biting behaviour of Anopheles gambiae from the islands of São Tomé and Príncipe, West Africa.

To determine if mating or gonotrophic age influenced the biting behaviour of Anopheles gambiae s.s., a series of all-night landing captures was performed on the islands of São Tomé and Príncipe in the Gulf of Guinea. On São Tomé 49% and on Príncipe 56% of the newly emerged An. gambiae taking their first bloodmeal were virgins. On each island, with the exception of recently mated insects on Príncipe, all age-groups had similar biting cycles. The biting cycle on Príncipe resembled that observed on continental Africa, with a peak in the latter part of the night. Peak biting on São Tomé, however, occurred before midnight. Estimated daily survival rates were 0.77 and 0.29 for São Tomé and Príncipe, respectively. Mating does not affect the biting behaviour of An. gambiae on these islands.

Age Factors↗
PubMed2002

Subsites of trypsin active site favor catalysis or substrate binding.

Enzymes enhance chemical reaction rates by lowering the activation energy, the energy barrier of the reaction leading to products. This occurs because enzymes bind the high-energy intermediate of the reaction (the transition state) more strongly than the substrate. We studied details of this process by determining the substrate binding energy (DeltaG(s), calculated from K(m) values) and the activation energy (DeltaG(T), determined from k(cat)/K(m) values) for the trypsin-catalyzed hydrolysis of oligopeptides. Plots of DeltaG(T) versus DeltaG(s) for oligopeptides with 15 amino acid replacements at each of the positions P(1)', P(1), and P(2) were straight lines, as predicted by a derived equation that relates DeltaG(T) and DeltaG(s). The data led to the conclusion that the trypsin active site has subsites that bind moieties of substrate and of transition state in characteristic ratios, whichever substrate is used. This was unexpected and means that each subsite characteristically favors substrate binding or catalysis.

Amino Acids↗
PubMed2002

Secretion of beta-glycosidase by middle midgut cells and its recycling in the midgut of Tenebrio molitor larvae.

There are four beta-glycosidases (betagly1, betagly2, betagly3, and betagly4) in Tenebrio molitor midgut larvae. betagly1 and betagly2 have identical kinetic properties, and differ in a few amino acid residues. Purified betagly1 was used to raise antibodies in a rabbit. The resulting antiserum recognizes in a Western blot only betagly1 and betagly2 in midgut tissue homogenates and contents. An immunocytochemical study carried out using confocal fluorescence and immunogold techniques showed that betagly1+betagly2 are secreted by exocytosis mainly from the distal part of the second third of T. molitor midguts. This is the first immunocytochemical study of an insect digestive enzyme that does not have polymers as substrates. Enzyme assays with 0.3 mM amygdalin, a condition that detects only betagly1+betagly2, revealed that most of those beta-glycosidases are found in the lumen of anterior and middle midgut. This supports the hypothesis that a countercurrent flux of fluid occurs in T. molitor midgut that is able to carry betagly1 and betagly2 to anterior midgut, in agreement with the enzyme recycling mechanism thought to occur in most insects.

Journal Article↗
PubMed2002

Male size does not affect mating success (of Anopheles gambiae in São Tomé).

For malaria control, the utility of transgenic vector Anopheles mosquitoes (Diptera: Culicidae) refractory to Plasmodium transmission, will depend on their interbreeding with the wild vector population. In many species, larger males are more successful in obtaining mates. In São Tomé island, we determined that size did not affect mating success of male Anopheles gambiae Giles sensu stricto, the main malaria vector in tropical Africa. Also we showed that larval intraspecific competition is probably insignificant in this population of An. gambiae. Thus, the potential success of transgenic An. gambiae is unlikely to be affected by size selection under field conditions.

Animals↗
PubMed2002

Genetic structure of Anopheles gambiae (Diptera: Culicidae) in São Tomé and Príncipe (West Africa): implications for malaria control.

The impact of a vector eradication programme, conducted in the 1980s, on Anopheles gambiae populations from the islands of São Tomé and Príncipe, was evaluated by microsatellite DNA analysis. Significant genetic differentiation was observed within and between the two islands and between the islands and a population from Gabon, suggesting a degree of isolation between them. Large estimates of long-term N(e) suggested that the control programme did not affect the effective population size of the vector. Heterozygosity tests were also not consistent with a recent bottleneck.

Africa, Western↗
PubMed2002

RenaGel efficacy in severe secondary hyperparathyroidism.

BACKGROUND: Haemodialysis patients frequently have simultaneous hypercalcemia and hyperphosphatemia, posing a therapeutic dilemma for the traditional calcium--and aluminum--based binders. RenaGel (sevelamer hydrochloride) is an effective phosphate binder without changes in serum calcium or aluminum levels. However being an expensive medication it is currently used mainly for patients with moderate to severe secondary hyperparathyroidism. However most of the previous studies have not included patients with severe secondary hyperparathyroidism. METHODS: Our purpose is to determine RenaGel binder efficacy in haemodialysis patients with severe secondary hyperparathyroidism. As a secondary purpose we have followed the variations of parathyroid hormone, serum calcium, serum lipids [low- and high-density lipoprotein cholesterol, triglycerides and Lipoprotein(a)], uric acid and bicarbonate. All phosphate binders previously used were suspended one week before RenaGel prescription. Our study included 18 adult haemodialysis patients, with PTHi of 810 +/- 330 pg/ml after the "pre-treatment" washout. The binder was administered during 12 weeks, beginning with a mean dose of 2.4 +/- 0.4 g daily and adjusted to obtain serum phosphorus under 6.5 mg/dl (at the end of the study, the mean RenaGel dose was 2.8 +/- 0.6 g daily. RESULTS: The mean changes after RenaGel in serum phosphorus was -0.7 +/- 1.5. mg/dl (P < 0.05), in serum calcium was 0.5 +/- 1.0 mg/dl (P < 0.05) and in calcium x phosphate product of -4.0 +/- 12.4 mg/dl (P = NS). "Post-treatment" the PTHi levels remained stable (820 +/- 360 pg/ml vs 810 +/- 330) but serum alkaline phosphatase increased (14.3 +/- 14.4 U/l; P < 0.01). LDL cholesterol serum levels decreased by -35 +/- 10 mg/dl (P < 0.01), HDL cholesterol showed a trend to increase (3.0 +/- 8.1 U/l; P = NS), triglycerides decreased by 38 +/- 56 mg/dl (P < 0.05) and Lipoprotein(a) remained stable. Serum albumin increased by 0.1 +/- 0.2 g/L (P < 0.05), uric acid decreased -0.8 +/- 1.2 mg/dl (P < 0.05) and bicarbonate remained unchanged. CONCLUSIONS: RenaGel is an effective phosphate binder, even in haemodialysis patients with severe secondary hyperparathyroidism. The lipid profile improved with the treatment, with the exception of Lipoprotein(a) stabilization. Selection of patients with severe secondary hyperparathyroidism at the beginning of RenaGel disposal, for economic reasons is debatable, but could be correct.

Adult↗
PubMed2002

The swarming and mating behaviour of Anopheles gambiae s.s. (Diptera: Culicidae) from São Tomé Island.

The swarming and mating behaviours of the forest cytoform of Anopheles gambiae s.s. were investigated on 194 evenings and 14 mornings between April 1997 and November 1999 in a peri-urban area of the island of São Tomé, West Africa. Males swarmed 2-3 m above markers of horizontal contrast such as those formed between grass areas and footpaths, or bushes. Evening swarms started 2 min before sunset in sheltered sites and a minute or two later in exposed ones. It took approximately 5 mins from the arrival of the first male for the swarm to reach estimated maximum numbers. Mating pairs were first seen 7 min after the start of swarming. Maximum numbers of pairs in copula were observed 8 min later. Up to 270 pairings were seen in the 20 min period before darkness. Removal of males had no effect on the number of females arriving at the swarm. Males were attracted to sounds that approximated the female flight tone but not to filter paper samples of squashed virgin females swung through the swarm. A much-reduced amount of swarming and a single mating were recorded at dawn. The same locations for swarming were used at different times and at different heights by ants, Culicoides sp. and Culex quinquefasciatus.

Africa, Western↗
PubMed2001

H ferritin knockout mice: a model of hyperferritinemia in the absence of iron overload.

Ferritin, the iron-storing molecule, is made by the assembly of various proportions of 2 different H and L subunits into a 24-mer protein shell. These heteropolymers have distinct physicochemical properties, owing to the ferroxidase activity of the H subunit, which is necessary for iron uptake by the ferritin molecule, and the ability of the L subunit to facilitate iron core formation inside the protein shell. It has previously been shown that H ferritin is indispensable for normal development, since inactivation of the H ferritin gene by homologous recombination in mice is lethal at an early stage during embryonic development. Here the phenotypic analysis of the mice heterozygous for the H ferritin gene (Fth(+/-) mice) is reported, and differences in gene regulation between the 2 subunits are shown. The heterozygous Fth(+/-) mice were healthy and fertile and did not present any apparent abnormalities. Although they had iron-overloaded spleens at the adult stage, this is identical to what is observed in normal Fth(+/+) mice. However, these heterozygous mice had slightly elevated tissue L ferritin content and 7- to 10-fold more L ferritin in the serum than normal mice, but their serum iron remained unchanged. H ferritin synthesis from the remaining allele was not up-regulated. This probably results from subtle changes in the intracellular labile iron pool, which would stimulate L ferritin but not H ferritin synthesis. These results raise the possibility that reduced H ferritin expression might be responsible for unexplained human cases of hyperferritinemia in the absence of iron overload where the hereditary hyperferritinemia-cataract syndrome has been excluded. (Blood. 2001;98:525-532)

Alleles↗
PubMed2001

Prospective risk of morbidity in relation to multiplicity of infection with Plasmodium falciparum in São Tomé.

The prospective risk of acute morbidity was analysed in relation to multiplicity of Plasmodium falciparum infection in 491 individuals in a peri-urban community in São Tomé. In an initial cross-sectional survey, 40.5% of individuals were recorded by microscopy as infected with P. falciparum, and by PCR 60.5%, with the maximum prevalence in children aged 5-10 years. PCR-RFLP typing of the msp-2 gene of P. falciparum found a mean of 2.4 parasite genotypes per infected person, with little age dependence in this multiplicity and a total of 43 different msp-2 alleles identified. None of these were unique for São Tomé. Study participants were encouraged to report to a project worker whenever they suffered a febrile illness. During the 3 months following the parasitological survey the recorded incidence rates decreased with increasing baseline msp-2 multiplicity, both for P. falciparum-positive episodes and for fever without parasitaemia. While this is consistent with suggestions that multiple P. falciparum infections may protect against super-infecting parasites, confounding by patterns of health service usage is an alternative explanation. The incidence of clinical malaria episodes was only a little higher in children than in adults. This weak age-dependence in clinical immunity might be a consequence of a cohort effect resulting from resurgence of the disease after the breakdown of malaria control programs in the 1980s.

Adolescent↗
PubMed2001

Long-term effects of a high-dose methamphetamine regimen on subsequent methamphetamine-induced dopamine release in vivo.

Rats were treated with a high-dose methamphetamine (METH) regimen (40 mg/kg/injection, four times at 2-h intervals) or a saline regimen (four injections at 2-h intervals). Temperature related measures taken during the high-dose METH treatment were maximum core temperature and minimum chamber temperature. Fourteen rats (METH N=7; Saline N=7) were implanted with in-vivo dialysis probes 4-7 weeks post-regimen (average=6 weeks). The next day, they received a challenge dose of METH (4.0 mg/kg) and dopamine release was measured. Results showed a significant decrease in challenge-induced dopamine release in rats previously treated with the high-dose METH regimen. These findings demonstrate a functional deficit in the dopamine system 6 weeks after high-dose METH treatment. Temperature-related measures taken during the high-dose regimen were not correlated with METH-induced dopamine release 6 weeks later. An additional group of rats were sacrificed 6 weeks after the high-dose regimen (METH N=12; Saline N=10), and their brains was analyzed for dopamine and serotonin concentrations. Tissue concentrations of dopamine were significantly depleted in striatum and nucleus accumbens/olfactory tubercle, but not septum, hypothalamus, or ventral mid-brain 6 weeks after the high-dose regimen. Tissue concentrations of serotonin were also significantly depleted in striatum, nucleus accumbens/olfactory tubercle, hippocampus, somatosensory cortex, but not septum, hypothalamus or ventral mid-brain. Significant correlations between the temperature-related measures and post-mortem neurotransmitter tissue concentrations were region and transmitter dependent.

Animals↗