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Biomedical subjects

O Martínez

Publications and source records attributed to O Martínez.

At least 19 recordsLinked to original sources

Pyrolysis of mixtures of sewage sludge and manure: a comparison of the results obtained in the laboratory (semi-pilot) and in a pilot plant.

A pilot-scale pyrolysis process was carried out for the treatment of a mixture of two types of waste, sewage sludge and cattle manure, comparing the results with others obtained under laboratory conditions (semi-pilot scale). The aim of this study was to obtain the energetic valorization of the products. Owing to the specific characteristics of the plant, two products were obtained from the process: gas and carbonized solid. As no liquid fraction was obtained, the gas fraction is a greater percentage made up of both condensable and non-condensable compounds, which were obtained separately at the laboratory scale. The pilot plant was designed so that the gases produced by thermolysis were burnt continuously in a combustion chamber, while the carbonized fraction was fed in batches for co-combustion. To determine composition and combustion ability, the gas and solid products from the pilot process were characterized by chromatographic analysis of the gaseous fraction and chemical analysis and programmed-temperature combustion of the carbonized solid. The composition of the combustion gases, rich in light hydrocarbons, and the carbon present in the carbonized fraction enable the energetic valorization of these products. The combustion gases were subjected to a cleaning process and their composition analysed twice: before and after the gas cleaning treatment. The study led to a positive assessment of the possible use of the process products as fuel, provided that the combustion gases are treated. As most of the sulphur and chlorine from the original waste are mainly concentrated in the solid fraction, the use of char as a fuel will depend on the effectiveness of clean-up techniques for combustion gases. During gas cleansing, neutralizing with sodium bicarbonate proved effective, especially for the acidic compounds HCl, HF and SO(2).

Animals↗

Influence of the application of sewage sludge on the degradation of pesticides in the soil.

A study was made of the influence of the application of sewage sludge on the degradation of pesticides in the soil. Two kinds of sludge were used, with different characteristics, one from an urban treatment plant and one from a food processing plant. Three organophosphorus insecticides, fenitrothion, diazinon and dimethoate, were studied. The relative importance was determined of the chemical and biological degradation processes, which involved experiments on soil and sterile soil samples. A comparative study was also made of the degradation of pesticide residues and the evolution of the microbial population. The application of sludge seems to have a complex effect on the degradation of pesticides, determined by the bioavailability and biodegradability of their active ingredient. The biodegradation of pesticide residues brings about alterations in the microorganism population of the soil.

Biodegradation, Environmental↗

Application of vernier thinning techniques to segmented annular arrays.

Due to the aperture periodicity, the inter-element spacing of two-dimensional squared arrays is maintained near lambda/2 in order to avoid grating lobes. This condition gives rise to severe problems derived from the huge number of array elements and from their little size that causes the signal to noise ratio to bring down. Vernier techniques have been proposed to lower the number of active elements, but the drastic reduction of the ultrasonic energy is still a great problem for the image contrast. In this work, vernier techniques for segmented annular (SA) arrays are theoretically studied. SA arrays produce lower grating lobes than squared arrays and, therefore, allow the element size to be increased beyond the lambda/2 constraint. Using larger elements, SA arrays have advantage to squared arrays because they have larger active area and smaller thinning order for the same complexity (number of channels) of the image system. Theoretical results of the vernier techniques applied to SA arrays in both radial and tangential directions are presented and compared with the equivalent squared array.

Journal Article↗

Pyrolysis of tyres. Influence of the final temperature of the process on emissions and the calorific value of the products recovered.

A study was made of the pyrolysis of tyre particles, with the aim of determining the possibilities of using the products resulting from the process as fuel. Three final temperatures were used, determined from thermogravimetric data. The design of the experiment was a horizontal oven containing a reactor into which particles of the original tyre were placed. After the process, a solid fraction (char) remained in the reactor, while the gases generated went through a set of scrubbers where most of the condensable fraction (oils) was retained. Finally, once free of this fraction, the gases were collected in glass ampoules. Solid and liquids fractions were subjected to thermogravimetric analyses in order to study their combustibility. The gas fraction was analysed by means of gas chromatography to establish the content of CO, CO2, H2 and hydrocarbons present in the samples (mainly components of gases produced in the pyrolysis process). A special study was made of the sulphur and chlorine content of all the fractions, as the presence of these elements could be problematic if the products are used as fuel. Tyre pyrolysis engenders a solid carbon residue that concentrates sulphur and chorine, with a relatively high calorific value, although not so high as that of the original tyre. The liquid fraction produced by the process has a high calorific value, which rises with the final temperature, up to 40 MJ/kg. The chlorine content of this fraction is negligible. Over 95% of the gas fraction, regardless of the final temperature, is composed of hydrocarbons of a low molecular weight and hydrogen, this fraction also appearing to be free of chlorine.

Air Pollution↗

[Travelling immigrants].

OBJECTIVES: To characterise travelling immigrants and the international movements they undertake. To identify the risk journeys that this population makes and to assess the international preventive activities for them compared with those for autochthonous travellers. DESIGN: Retrospective, observational study. SETTING: Unit of International Health (UIH) Santa Coloma de Gramenet (Barcelona), in the Barcelonès Nord i Maresme Health Area, Primary Care Division of the Catalan Institute of Health. PARTICIPANTS: Patients seen between June 1999 and June 2002 (n=1163) at the UIH. They were divided into two groups, depending on their origins: those born inside (autochthonous group; no=1019) or outside (immigrant group; n1=144) the European Union. MAIN MEASUREMENTS: Age, country of origin, length of residence in Spain, interval between consultation and journey, reason for journey, destination, duration of the journey, kind of journey, stay in rural or isolated area, exposure to malaria, vaccinations and anti-malaria chemoprophylaxis prescribed, and overall risk of journey. RESULTS: Immigrants spent more time abroad than autochthonous people (mean 43.5 days; 95% CI, 37.9-49.1; and 15.8 days, 95% CI, 14.9-16.7, respectively; P<.0001). Periods between the journey and the consultation at the UIH were generally similar in the two groups (mean of 26.8 days for immigrants and 30.41 days for autochthonous people; ns), although the immigrants consulted more often in periods of less than 15 and 7 days (P<.005). 31.9% of immigrants stayed in areas of high malaria transmission (95% CI, 24.4%-39.6%) vs 21.3% (95% CI, 18.8%-23.8%) of autochthonous people (P=.04). Overall, immigrants made more risk journeys than autochthonous people (54.8% vs 43.1%; P<.01). No significant differences between the two groups were found in terms of quality in the administration of the international vaccinations prescribed. Compliance with the guidelines for anti-malaria chemoprophylaxis was less in the immigrant group than in the autochthonous one (36% vs 84%; P<.005). CONCLUSIONS: The immigrant group in our environment needs to be thought of as a risk group for catching and importing tropical diseases during their international movements. They form a population for whom international preventive measures should be prioritized.

Adolescent↗

3D beamforming with ultrasonic divided-ring arrays.

Conventional 2D arrays have a set of squared elements whose inter-element spacing is around lambda/2. This arrangement requires an excessive amount of electronic resources for the generation and processing of ultrasonic signals. In this work, the beam properties of a single divided-ring array are analysed theoretically with the goal of producing volumetric images. Divided-ring arrays are based on a circular pattern, which has a lower periodicity than square arrays, and this property allows increasing the element size while keeping the amplitude of the grating lobes at a reasonably low level. The paper emphasises several advantages of ring arrays, suggesting that these apertures are useful for 3D ultrasonic imaging. First, as the element size may increase, the number of elements can be reduced with little loss of emitting area. Second, ring arrays produce beams of large depth of field in both transmission and reception. This can be used to avoid the complexity associated with dynamic focusing.

Models, Theoretical↗

Beamforming with a reduced sampling rate.

The beamforming process requires a high delay resolution to avoid the deteriorating effects of the delay quantization lobes on the image dynamic range and signal to noise ratio. Wideband transducers require delay resolutions in the order of 1/16 the signal period. If oversampling is used to achieve this timing resolution, a huge data volume has to be acquired and processed in real time. This is usually avoided by sampling just above the Nyquist rate and interpolating to achieve the required delay resolution. However this increases the hardware complexity. Baseband sampling has been alternatively proposed with sampling rates as low as the transducer frequency or even lower. This approach uses two A/D converters and processing chains for every channel, thus doubling the hardware requirements. Quadrature sampling can be used instead with a single A/D converter, but the sampling rate must be a multiple of four times the transducer frequency, decreasing the application flexibility. Furthermore, it produces relatively high errors in the detected envelope if wideband transducers are used. This work presents a new approach, the selective sampling technique (SST), which keeps the lowest sampling rate required by the imaging process or the signal bandwidth (whatever is larger) and, at the same time, provides a high delay resolution to keep the highest image dynamic range. The SST is based on a second order sampling process which, differently from the mentioned approaches, does not pose any constraints in the time interval between samples and produce lower errors in the detected envelope. The hardware requirements are low (a single A/D converter and processing chain for every transducer element), working at the lowest data rate compatible with the Nyquist criterion, thus reducing the data bandwidth. Furthermore, the sampling points can be also freely chosen, so that the SST simplify the usually required scan conversion process to a simple linear interpolation easily carried out by software in real-time.

Journal Article↗

The Aspergillus nidulans carnitine carrier encoded by the acuH gene is exclusively located in the mitochondria.

The location of the Aspergillus nidulans carnitine/acyl-carnitine carrier (ACUH) was studied. ACUH with a His-tag at its N-terminus was over-expressed in Escherichia coli and purified by Ni(2+) affinity chromatography. The purified protein was utilised to raise polyclonal antibodies which were characterised by Western blotting. For localisation studies A. nidulans T1 strain, that contains the acuH gene under control of the strong promoter alcA(p), was derived. Results obtained demonstrate the exclusively mitochondrial localisation of ACUH and therefore exclude the targeting of the acuH gene product to the peroxisomal membrane.

Antibodies↗

Development of a homologous transformation system for the opportunistic human pathogen Aspergillus fumigatus based on the sC gene encoding ATP sulfurylase.

The development of a homologous transformation system for the opportunistic human pathogenic fungus Aspergillus fumigatus is described. The system is based on the sC gene encoding ATP sulfurylase. Several A. fumigatus sC mutant strains were readily isolated by strong selection for selenate resistance. The coding region plus upstream and downstream regulatory sequences of the A. fumigatus sC gene were cloned by inverse PCR and then sequenced. Sequencing of the sC cDNA revealed the presence of five introns located within the first half of the gene. The A. fumigatus sC gene encodes a protein of 574 amino acids which is highly similar to ATP sulfurylases from the filamentous fungal species Aspergillus nidulans, Aspergillus terreus and Penicillium chrysogenum. By contrast, ATP sulfurylases from the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe lack the C-terminal adenosine-5'-phosphosulfate kinase-like domain present in the filamentous fungal orthologues. A 3.8-kb DNA fragment amplified by PCR and containing the sC gene plus 5' and 3' flanking regions was cloned into pUC19 to give the vector pSCFUM. Transformation of two different sC mutant isolates with the plasmid pSCFUM established the functionality of this new homologous transformation system. Molecular analysis of sC+ transformants showed that up to 44% of transformed clones contained one or more copies of the entire plasmid integrated at the sC locus. This result also demonstrates the utility of the sC marker for targeting specific genetic constructs to the A. fumigatus sC locus, facilitating studies of gene regulation and function.

Amino Acid Sequence↗

Standard case management of pneumonia in hospitalized children in Uruguay, 1997 to 1998.

OBJECTIVE: To report the results of the use of antimicrobial guidelines for the management of children with community-acquired bacterial pneumonia. METHODS: Admittance and discharge criteria and algorithms for diagnosis and treatment were established. The decision to treat with antibiotics was based on radiologic findings in pneumonia with pulmonary consolidation and left to the attending physician's criteria in the remaining cases. The use of antibiotics was limited to penicillin and derivatives (ampicillin, amoxicillin) and macrolides. RESULTS: Of the 1163 children treated as bacterial pneumonia, hospitalized in public and private health facilities in Montevideo from September, 1997, through September, 1998, standard case management was applied in 1082 (93%). Age distribution was: <1 month, 1%; between 1 and 11 months, 29%; between 1 and 5 years, 50%; >5 years, 20%. Chest radiography showed evidence of pulmonary consolidation in 843 children (73%). Bacteria were detected in blood culture and/or pleural fluid of 57 children (5%). In 51 the identified microorganism was Streptococcus pneumoniae, susceptible to penicillin in 30, intermediate in 6 and resistant in 5 (maximum MIC, 4 microg/ml); in 10 cases etiologic diagnosis was made by antigen detection. Empyema was present in 62 children (5.3%); 38 (3.27%) required treatment in an intensive care unit; and 5 (0.4%) died. CONCLUSIONS: Compliance with standard case management was highly satisfactory. Outcome of children treated with penicillin and derivatives was good, including children with empyema and pneumatocele and two patients with penicillin-resistant S. pneumoniae. At the present time S. pneumoniae resistant to penicillin is not an important problem in children with pneumonia in Uruguay. Surveillance of identified microorganisms and their antimicrobial susceptibility must continue.

Algorithms↗

Genetic variability among populations of Lutzomyia (Psathyromyia) shannoni (Dyar 1929) (Diptera: Psychodidae: Phlebotominae) in Colombia.

Polyacrylamide gel electrophoresis was used to elucidate genetic variation at 13 isozyme loci among forest populations of Lutzomyia shannoni from three widely separated locations in Colombia: Palambí (Nariño Department), Cimitarra (Santander Department) and Chinácota (Norte de Santander Department). These samples were compared with a laboratory colony originating from the Magdalena Valley in Central Colombia. The mean heterozygosity ranged from 16 to 22%, with 2.1 to 2.6 alleles detected per locus. Nei's genetic distances among populations were low, ranging from 0.011 to 0.049. The estimated number of migrants (Nm=3.8) based on Wright's F-Statistic, F ST, indicated low levels of gene flow among Lu. shannoni forest populations. This low level of migration indicates that the spread of stomatitis virus occurs via infected host, not by infected insect. In the colony sample of 79 individuals, the Gpi locus was homozygotic (0.62/0.62) in all females and heterozygotic (0.62/0.72) in all males. Although this phenomenon is probably a consequence of colonization, it indicates that Gpi is linked to a sex determining locus.

Animals↗

Reproductive biology of Lutzomyia shannoni (Dyar) (Diptera: Psychodidae) under experimental conditions.

Baseline biological growth data of Lutzomyia shannoni (Dyar) were compared under two experimental conditions within insulated styrofoam chests and in standard laboratory incubators. The developmental time from egg to adult was 67 and 52 days, respectively. Based on cohorts of 100 females in each experiment, horizontal life tables were constructed. The following predictive parameters were obtained under each of the two conditions: net rate of reproduction (23.5 and 18.0 females per cohort female), generation time (11.4 and 9.4 weeks), intrinsic rate of population increase (0.27 and 0.30), and finite rate of population increment (1.31 and 1.36). The reproductive value for each class age of the cohort females was calculated. The observed parameters were obtained under each experimental condition: net rate of reproduction (1.9 and 2.5 females per cohort female), generation time (11.7 and 9.6 weeks), intrinsic rate of population increase (0.05 and 0.09), and finite rate of population increment (1.06 and 1.10). Vertical life tables were elaborated and mortality was described for every generation in each cohort. In addition, for two successive generations, additive variance and heritability for fecundity were estimated.

Animals↗

Effect of advanced glycosylation end products on the induction of nitric oxide synthase in murine macrophages.

We studied the role of advanced glycosylation end products on the induction of nitric oxide synthase in peritoneal mouse macrophages previously exposed to modified BSA. A dose-dependent increment in the nitric oxide production induced by LPS and IFN-gamma was observed when cell cultures were pretreated with modified BSA for 48 hours. In addition, the up regulation of nitric oxide production was also time-dependent, being maximal at 24-48 hours. Experiments carried out in the presence of neutralizing antibodies to IL-1 and TNF-alpha, suggested that up regulation was not due to the capacity of modified BSA to induce both proinflammatory signals. The up regulation of nitric oxide production was paralleled with an increase in iNOS mRNA.

Animals↗

Effects of native and hydrolyzed whey protein on intestinal repair of severely starved rats at weaning.

The aim of this study was to evaluate the effect of two sources of dietary nitrogen (isolated whey protein and hydrolyzed whey protein) on the intestinal repair of malnourished rats at weaning. The malnutrition was achieved by a 3 days' starvation period. Normally fed male Wistar rats were used as controls. Intestinal repair was studied after a refeeding period of 4 days. The parameters studied included nitrogen balance, lactase, sucrase, isomaltase, and maltase activities of the jejunum; liver acetylcholinesterase and glutamate dehydrogenase activities; and the serum amino acid profile. In addition, tests of intestinal permeability to macromolecules were performed by measurement of ovalbumin and beta-lactoglobulin in serum. Both diets of led to the recovery of the severely starved rats, in terms of the values of all the parameters evaluated. The serum beta-lactoglobulin was the only exception, because its concentration was significantly lower in the normally fed animals. This study suggests that the intestinal mucosal barrier is not completely repaired, even after a 4-day refeeding period, to the point of being suitable to accept an increase in the uptake of antigens.

Acetylcholinesterase↗

Nutritional value and antigenicity of two milk protein hydrolysates in rats and guinea pigs.

Two milk protein (whey protein and casein) hydrolysates were obtained by enzymatic hydrolysis. In the casein hydrolysate, an ultrafiltration stage was performed to remove all the peptides with molecular weights > 2500. A nutritional value study of both hydrolysates was undertaken. No differences were found between the native proteins and their enzymatic hydrolysates. Neither the enzymatic hydrolysis nor the heat treatments used affected the nutritional value of the protein sources. The two hydrolysates were studied for antigenic properties. The enzymatic hydrolysis of the whey protein concentrate followed by a thermal treatment at 90 degrees C for 10 min reduced significantly its antigenicity. However, the in vivo allergenicity tests showed some positive reactions in both systemic anaphylaxis and passive cutaneous anaphylaxis. The casein hydrolysate, after being ultrafiltered, was devoid of sensitizing capacity by the oral route and was also ineffective in producing local or systemic anaphylaxis in previously sensitized animals, as shown by in vivo assays.

Amino Acids↗