382 research outputs found
Alteración de las rocas gneisicas con riebeckita del área de Vigo
[Resumen] Se estudian los factores del medio físico, procesos de alteración y cambios químicos y mineralógicos producidos en la meteorización de un grupo de rocas gneisicas de composiciónquímica heterogénea en el área de Vigo. El proceso de alteración origina una saprolita masivade textura arenosa a areno-francosa, constituida por minerales heredados (cuarzo, feldespatos, plagioclasas, micas y anfíboles), micas degradadas y minerales neoformados (caolinita, gibbsita , goethita). El proceso de meteorización es una hidrólisis ácida con pérdida de bases y silicio y enriquecimiento relativo en aluminio. Los minerales de neoformación indican un predominio de la "monosialitización" cuando el sistema presenta drenaje ralentizado y de la "alitización")en fases incipientes de la alteración}cuando el sistema no tiene materia orgánica y el drenaje es excesivo[Abstract] It has been studied the physical environmental factors, alteration processes, and chemical and mineralogical changes produced during the gneisic rocks group from Vigo area ~eathering. ln these rocks great heterogenity in the chemical composition has been found. The weathering prevailing process in the area give rise to the formation of a saprolite with sandy to sandy-loamy textures,increasing permeability and it is composed of inherited minerals :quarz, feldspars and/or plagioclases,micas, amphiboles; neoformed materials, gibbsite,caolinite,goethite and degraded micas)the last two occasionally. The weathering process is an acid hydrolysis with desbasification and Al relative enrichment tendencies. With slow drainage systems the neoformed minerals indicate a monosiallitization predominance (formation of silicates 1:1); while 1ack i ng organ i c matter and in good dra i ned zones, the neoformed minerals indicate an incipient allititatio
Elementos escasos y mineralizaciones metálicas en neises de la provincia de Pontevedra
[Resumen] Se estudió el contenido total, y en minerales no silicatédos, de Ni, Cu, Co, 2P y Ti en doce muestras representativas de los neises existentes en la provincia de Pontevedra. Se estableció la mineralogía y composición de Ios compuestos metálicos demostrándose la existencia de minerales de Ti en todas las muestras, en la mayoría rutilo con pequeñas cantidades de Fe en solucién sólida En otras apaecren cristales de ilmenita con Mn y Mg en solucién sólida al alguna de ellas. Se ha detectado la aparición de cristales de tumalina en la nuestra de neis glandular. Se han establecido las f ómuIas mineralógicas de todas las mineralizaciones metálicas localizada
Assessment of a targeted resequencing assay as a support tool in the diagnosis of lysosomal storage disorders
BACKGROUND:
With over 50 different disorders and a combined incidence of up to 1/3000 births, lysosomal storage diseases (LSDs) constitute a major public health problem and place an enormous burden on affected individuals and their families. Many factors make LSD diagnosis difficult, including phenotype and penetrance variability, shared signs and symptoms, and problems inherent to biochemical diagnosis. Developing a powerful diagnostic tool could mitigate the protracted diagnostic process for these families, lead to better outcomes for current and proposed therapies, and provide the basis for more appropriate genetic counseling.
METHODS:
We have designed a targeted resequencing assay for the simultaneous testing of 57 lysosomal genes, using in-solution capture as the enrichment method and two different sequencing platforms. A total of 84 patients with high to moderate-or low suspicion index for LSD were enrolled in different centers in Spain and Portugal, including 18 positive controls.
RESULTS:
We correctly diagnosed 18 positive blinded controls, provided genetic diagnosis to 25 potential LSD patients, and ended with 18 diagnostic odysseys.
CONCLUSION:
We report the assessment of a next-generation-sequencing-based approach as an accessory tool in the diagnosis of LSDs, a group of disorders which have overlapping clinical profiles and genetic heterogeneity. We have also identified and quantified the strengths and limitations of next generation sequencing (NGS) technology applied to diagnosis
Newborn screening for medium-chain acyl-CoA dehydrogenase deficiency: regional experience and high incidence of carnitine deficiency
Background
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most common inherited defect in the mitochondrial fatty acid oxidation pathway, resulting in significant morbidity and mortality in undiagnosed patients.
Newborn screening (NBS) has considerably improved MCADD outcome, but the risk of complication remains in some patients. The aim of this study was to evaluate the relationship between genotype, biochemical parameters and clinical data at diagnosis and during follow-up, in order to optimize monitoring of these patients.
Methods
We carried out a multicenter study in southwest Europe, of MCADD patients detected by NBS. Evaluated NBS data included free carnitine (C0) and the acylcarnitines C8, C10, C10:1 together with C8/C2 and C8/C10 ratios, clinical presentation parameters and genotype, in 45 patients. Follow-up data included C0 levels, duration of carnitine supplementation and occurrence of metabolic crises.
Results
C8/C2 ratio and C8 were the most accurate biomarkers of MCADD in NBS. We found a high number of patients homozygous for the prevalent c.985A > G mutation (75%). Moreover, in these patients C8, C8/C10 and C8/C2 were higher than in patients with other genotypes, while median value of C0 was significantly lower (23 μmol/L vs 36 μmol/L).
The average follow-up period was 43 months. To keep carnitine levels within the normal range, carnitine supplementation was required in 82% of patients, and for a longer period in patients homozygotes for the c.985A>G mutation than in patients with other genotypes (average 31 vs 18 months). Even with treatment, median C0 levels remained lower in homozygous patients than in those with other genotypes (14 μmol/L vs 22 μmol/L).
Two patients died and another three suffered a metabolic crisis, all of whom were homozygous for the c.985 A>G mutation.
Conclusions
Our data show a direct association between homozygosity for c.985A>G and lower carnitine values at diagnosis, and a higher dose of carnitine supplementation for maintenance within the normal range. This study contributes to a better understanding of the relationship between genotype and phenotype in newborn patients with MCADD detected through screening which could be useful in improving follow-up strategies and clinical outcome
Effects of different arachidonic acid supplementation on psychomotor development in very preterm infants; A randomized controlled trial
Background & aims: Nutritional supplementation with polyunsaturated fatty acids is important in preterm infants
neurodevelopment, but it is not known if the omega-6/omega-3 ratio affects this process. This study was designed to
determine the effects of a balanced contribution of arachidonic acid in very preterm newborns fed with formula milk.
Methods: This was a randomized trial, in which newborns <1500 g and/or <32 weeks gestational age were assigned
to one of two groups, based on the milk formula they would receive during the first year of life. Initially, 60 newborns
entered the study, but ultimately, group A was composed of 24 newborns, who were given formula milk with an ω-6/
ω-3 ratio of 2/1, and Group B was composed of 21 newborns, given formula milk with an ω-6/ω-3 ratio of 1/1. The
infants were followed up for two years: growth, visual-evoked potentials, brainstem auditory-evoked potentials, and
plasma fatty acids were periodically measured, and psychomotor development was assessed using the Brunet Lézine
scale at 24 months corrected age. A control group, for comparison of Brunet Lézine score, was made up of 25
newborns from the SEN1500 project, who were fed exclusively with breast milk.
Results: At 12 months, arachidonic acid values were significantly higher in group A than in group B (6.95 ± 1.55 % vs.
4.55 ± 0.78 %), as were polyunsaturated fatty acids (41.02 ± 2.09 % vs. 38.08 ± 2.32 %) achieved a higher average. Group
A achieved a higher average Brunet Lézine score at 24 months than group B (99.9 ± 9 vs. 90.8 ± 11, p =0.028). The
Brunet Lézine results from group A were compared with the control group results, with very similar scores registered
between the two groups (99.9 ± 9 vs. 100.5 ± 7). There were no significant differences in growth or evoked potentials
between the two formula groups.
Conclusions: Very preterm infants who received formula with an ω-6/ω-3 ratio of 2/1 had higher blood levels of
essential fatty acids during the first year of life, and better psychomotor development, compared with very preterm
newborns who consumed formula with an ω-6/ω-3 of 1/1. Therefore, formula milk with an arachidonic acid quantity
double that of docosahexaenoic acid should be considered for feeding very preterm infants
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Hypermethioninaemia due to methionine adenosyltransferase I/III (MAT I/III) deficiency: diagnosis in an expanded neonatal screening programme
The Expanded Newborn Screening Program (MS/MS) in the region of Galicia (NW Spain) was initiated in 2000 and includes the measurement of methionine levels in dried blood spots. Between June 2000 and June 2007, 140 818 newborns were analysed, and six cases of persistent hypermethioninaemia were detected: one homocystinuria due to cystathionine β-synthase (CβS) deficiency, and five methionine adenosyltransferase I/III (MAT I/III) deficiencies. The five cases of MAT I/III deficiency represent an incidence of 1/28 163 newborns. In these five patients, methionine levels in dried blood spots ranged from 50 to 147 μmol/L. At confirmation of the persistence of the hypermethioninaemia in a subsequent plasma sample, plasma methionine concentrations were moderately elevated in 4 of the 5 patients (mean 256 μmol/L), while total homocysteine (tHcy) was normal; the remaining patient showed plasma methionine of 573 μmol/L and tHcy of 22.8 μmol/L. All five patients were heterozygous for the same dominant mutation, R264H in the MAT1A gene. With a diet not exceeding recommended protein requirements for their age, all patients maintained methionine levels below 300 μmol/L. Currently, with a mean of 2.5 years since diagnosis, the patients are asymptomatic and show developmental quotients within the normal range. Our results show a rather high frequency of hypermethioninaemia due to MAT I/III deficiency in the Galician neonatal population, indicating a need for further studies to evaluate the impact of persistent isolated hypermethioninaemia in neonatal screening programmes
Pyrolysis of medium-density fiberboard: optimized search for kinetics scheme and parameters via a genetic algorithm driven by Kissinger's method
The pyrolysis kinetics of charring
materials plays an important
role in understanding material combustions especially for construction
materials with complex degradation chemistry. Thermogravimetric analysis
(TGA) is frequently used to study the heterogeneous kinetics of solid
fuels; however, there is no agreed method to determine the pyrolysis
scheme and kinetic parameters for charring polymers with multiple
components and competing reaction pathways. This study develops a
new technique to estimate the possible numbers of species and sub-reactions
in pyrolysis by analyzing the second derivatives of thermogravimetry
(DDTG) curves. The pyrolysis of a medium-density fiberboard (MDF)
in nitrogen is studied in detail, and the DDTG curves are used to
locate the temperature of the peak mass-loss rate for each sub-reaction.
Then, on the basis of the TG data under multiple heating rates, Kissinger’s
method is used to quickly find the possible range of values of the
kinetic parameters (<i>A</i> and <i>E</i>). These
ranges are used to accelerate the optimization of the inverse problem
using a genetic algorithm (GA) for the kinetic and stoichiometric
parameters. The proposed method and kinetic scheme found are shown
to match the experimental data and are able to predict accurately
results at different heating rates better than Kissinger’s
method. Moreover, the search method (K–K method) is highly
efficient, faster than the regular GA search alone. Modeling results
show that, as the TG data available increase, the interdependence
among kinetic parameters becomes weak and the accuracy of the first-order
model declines. Furthermore, conducting TG experiment under multiple
heating rates is found to be crucial in obtaining good kinetic parameters
Environmental pleiotropy and demographic history direct adaptation under antibiotic selection
Evolutionary rescue following environmental change requires mutations permitting population growth in the new environment. If change is severe enough to prevent most of the population reproducing, rescue becomes reliant on mutations already present. If change is sustained, the fitness effects in both environments, and how they are associated-termed 'environmental pleiotropy'-may determine which alleles are ultimately favoured. A population's demographic history-its size over time-influences the variation present. Although demographic history is known to affect the probability of evolutionary rescue, how it interacts with environmental pleiotropy during severe and sustained environmental change remains unexplored. Here, we demonstrate how these factors interact during antibiotic resistance evolution, a key example of evolutionary rescue fuelled by pre-existing mutations with pleiotropic fitness effects. We combine published data with novel simulations to characterise environmental pleiotropy and its effects on resistance evolution under different demographic histories. Comparisons among resistance alleles typically revealed no correlation for fitness-i.e., neutral pleiotropy-above and below the sensitive strain's minimum inhibitory concentration. Resistance allele frequency following experimental evolution showed opposing correlations with their fitness effects in the presence and absence of antibiotic. Simulations demonstrated that effects of environmental pleiotropy on allele frequencies depended on demographic history. At the population level, the major influence of environmental pleiotropy was on mean fitness, rather than the probability of evolutionary rescue or diversity. Our work suggests that determining both environmental pleiotropy and demographic history is critical for predicting resistance evolution, and we discuss the practicalities of this during in vivo evolution
Opposing effects of final population density and stress on Escherichia coli mutation rate
Evolution depends on mutations. For an individual genotype, the rate at which mutations arise is known to increase with various stressors (stress-induced mutagenesis-SIM) and decrease at high final population density (density-associated mutation-rate plasticity-DAMP). We hypothesised that these two forms of mutation-rate plasticity would have opposing effects across a nutrient gradient. Here we test this hypothesis, culturing Escherichia coli in increasingly rich media. We distinguish an increase in mutation rate with added nutrients through SIM (dependent on error-prone polymerases Pol IV and Pol V) and an opposing effect of DAMP (dependent on MutT, which removes oxidised G nucleotides). The combination of DAMP and SIM results in a mutation rate minimum at intermediate nutrient levels (which can support 7 × 10 cells ml ). These findings demonstrate a strikingly close and nuanced relationship of ecological factors-stress and population density-with mutation, the fuel of all evolution
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