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Biomedical subjects

A M Romero

Publications and source records attributed to A M Romero.

13 recordsLinked to original sources
PubMed2006

Evaluation of a compost obtained from forestry wastes and solid phase of pig slurry as a substrate for seedlings production.

A composted material obtained from forestry wastes and solid phase of pig slurry was evaluated as a substrate component for the production of tomato and lettuce seedlings. Four different substrates were tested: compost (100C), a mixture of 75% compost and 25% peat substrate (75C), a mixture of 50% compost and 50% peat substrate (50C), and peat-based substrate (control). Compost increased the pH of the substrate from 6.3 (control) to 6.9 (100C) but did not affect the electrical conductivity (0.26 and 0.27 mScm(-1), respectively, for control and 100C). Germination and growth of lettuce seedlings were not affected by the substrate type, contrasting with tomato seedlings where the highest growth occurred at 100C substrate. Increasing compost percentage on substrate increased nitrogen, calcium and magnesium availability and, consequently, the concentration of these elements in plant tissues increased. On the contrary, potassium and manganese concentration decreased. Results from the study suggest that the compost studied is a good alternative to peat-based substrates for the production of vegetable seedlings.

Animals↗
PubMed2004

Study of the ratio of non-neutron to neutron dose components of cosmic radiation at typical commercial flight altitudes.

CIEMAT, in close co-operation with Iberia Airlines, carried out an extensive programme of in-flight measurements, covering both hemispheres, during the years 2001 and 2002. Although the instrumentation onboard included different active devices, the results presented here were obtained from a polyethylene/tungsten-moderated rem meter (SWENDI2; Eberline) and an ionisation chamber (RSS-131; Reuter-Stokes) used for measuring the ambient dose equivalent due to the neutron and the non-neutron components of cosmic radiation, respectively. This paper presents a study of each of the dose components mentioned as a function of the vertical cut-off rigidity and the flight altitude. The ratio between the two components is also presented to determine the variations in cosmic radiation composition as a function of the aforementioned parameters. The experimental results have also been compared with those predicted by the code EPCARD3.2 for the non-neutron and the neutron components of the ambient dose equivalent.

Aircraft↗
PubMed2004

A new area multidetector dosemeter for mixed n-gamma fields.

A new instrument to assess neutron ambient doses has been designed and constructed. In its design, spectrometric capabilities have been implemented that allow to take into account the energy spectrum of the neutron field in the evaluation of the operational magnitude, ambient dose equivalent, H*(10). This dosemeter is based on the moderation-absorption technique and can be employed over a wide range of energies from thermal to 20 MeV. It consists of a spherical shaped polyethylene moderator with a set of thermoluminescence dosemeters (TLDs) inserted in different positions of its interior to evaluate the external neutron energy spectrum. At this moment the system uses pairs 6LiF:Mg,Ti (TLD-600) and 7LiF:Mg,Ti (TLD-700) thermoluminescence dosemeters for a better gamma discrimination. The dosemeter response matrix was calculated using the MCNP4C Monte Carlo code (MC). The viability of the dosemeter for area dosemetry has been examined experimentally showing its capabilities over a wide range of energies.

Algorithms↗
PubMed2004

[Vascular malformations as syndromic markers].

Vascular malformations are static lesions, generally present at the moment of birth, formed by displasic vessels that grow in proportion to the growth of the child. They show normal cell replacements that constitute genuine mistakes of morphogenesis. The absence of regression of these malformations implies that they remain throughout the lifetime. The terminology describing this type of lesions gave rise to confusion in the medical literature until the International Society for the Study of Vascular Anomalies adopted a classification based on the dominant vessel of the malformation in 1996. This classification distinguishes between simple and complex forms depending on whether they affect one or several types of vessel. Vascular malformations can show themselves as isolated lesions or can be associated with other lesions, constituting the guide sign or being the principal marker of some syndromic complexes. This paper describes the principal signs and symptoms of those syndromes in which a vascular malformation is the key that raises suspicion about the existence of other associated lesions.

Blood Vessels↗
PubMed2003

Effect of Azospirillum-mediated plant growth promotion on the development of bacterial diseases on fresh-market and cherry tomato.

AIMS: Plant growth-promoting (PGP) activity of two Azospirillum strains and their effects on foliar and vascular bacterial diseases were evaluated on fresh market and cherry tomato. METHODS AND RESULTS: Tomato seeds were inoculated with A. brasilense Sp7 or Azospirillum sp. BNM-65. Four-week-old plants were challenge-inoculated with Clavibacter michiganensis subsp. michiganensis (bacterial canker) or with Xanthomonas campestris pv. vesicatoria (bacterial spot). Azospirillum-induced PGP was greater on cherry than on fresh-market tomato. Cherry tomato was more resistant to bacterial canker but more susceptible to bacterial spot than the fresh-market tomato. Canker severity was not affected by Azospirillum seed treatments. However, leaf- and plant-death were delayed on Azospirillum-treated plants compared with nontreated controls. Azospirillum increased the bacterial spot severity on cherry but not on fresh-market tomato. CONCLUSIONS: PGP was observed on both tomato genotypes, although growth effects were larger on cherry tomato. Also, Azospirillum treatments may alter tomato susceptibility to bacterial diseases. SIGNIFICANCE AND IMPACT OF THE STUDY: The interaction between PGP rhizobacteria like Azospirillum spp., not known to induce systemic resistance, with plant pathogens distantly located is frequently overlooked. This work demonstrates the importance of this kind of evaluation.

Actinomycetales↗
PubMed2002

The use of passive environmental TLDs in the operation of the Spanish early warning network 'REVIRA'.

As required by different international agreements, the regulatory body in Spain (Consejo de Seguridad Nuclear) implemented in 1992 a national automatic network (REVIRA) that continuously monitors radiation levels in order to give early warning of incidents having potential transboundary implications. The detector for environmental gamma-radiation dose rate is an active instrument based on a Geiger-Müller counter. However, the use of passive environmental dosemeters provides an additional low-cost dose estimate with an independent centralised calibration and even better basic features than active instruments. Since 1999, all 25 REVIRA stations have been monitored with passive TL environmental dosemeters based on LiF:Mg,Cu,P and operated according to the procedures established at Ciemat. This paper presents the obtained results and the further analysis considering differences in aspects such as photon energy response, inherent background or response to cosmic rays. The benefits of the use of passive environmental dosemeters in early warning networks are discussed.

Air Pollution, Radioactive↗
PubMed2002

Experience gained from the Ciemat External Dosimetry Service participation in several environmental dosimetry intercomparisons.

This paper summarises the experience gained by the Ciemat External Dosimetry Service (EDS) in the environmental dosimetry intercomparisons organised by the US Department of Energy. During the three latest intercomparisons. important dosimetry aspects such as energy calibration, energy response, dosimetric quantities and signal stability have been tested by the Ciemat EDS on up to seven different thermoluminescent (TL) materials, including hypersensitive phosphors, and employing several dosimetric systems. In last year's intercomparison, in addition to TL dosemeters the Ciemat EDS sent a set of silicon diode active dosemeters, usually used as personal dosemeters, to be tested in environmental conditions without intervention for more than 3 months. All the results obtained from different dosemeters have undergone an exhaustive analysis process in order to find some conclusions that may help to increase the knowledge of field performance of these devices in real but controlled environmental conditions.

Equipment Design↗
PubMed2002

Evaluation of the peripheral dose to uterus in breast carcinoma radiotherapy.

The absorbed dose outside of the direct fields of radiotherapy treatment (or peripheral dose, PD) is responsible for radiation exposure of the fetus in pregnant women. Because the radiological protection of the unborn child is of particular concern in the early period of the pregnancy, the aim of this study is to estimate the PD in order to assess the absorbed dose in the uterus in a pregnant patient irradiated for breast carcinoma therapy. The treatment was simulated on an Alderson-Rando anthropomorphic phantom, and the radiation dose to the fetus was measured using an ionisation chamber and thermoluminescence dosemeters. Two similar treatments plans with and without wedges were delivered, using a 6 MV photon beam with two isocentric opposite tangential fields with a total dose of 50 Gy, in accordance with common established procedures. Average field parameters for more than 300 patients were studied. Measurements showed the fetal dose to be slightly lower than 50 mGy, a level at which the risk to the fetus is uncertain, although several authors consider this value as the dose threshold for deterministic effects. The planning system (PS) underestimated PD values and no significant influence was found with the use of wedge filters.

Breast Neoplasms↗
PubMed1999

XRD, SEM-EDS, and FTIR studies of in vitro growth of an apatite-like layer on sol-gel glasses.

A glass with a composition (in mole %) of: SiO2 (70), CaO (26), and P2O5 (4) was obtained using a sol-gel method. The in vitro bioactivity of the glass was assessed by determining the changes in surface morphology and composition after soaking in simulated body fluid (SBF) for periods of up to 14 days at 37 degrees C. X-ray diffraction, scanning electron microscopy, X-ray energy dispersive spectroscopy, and FTIR analyses of the glass surface after different soaking periods in SBF demonstrated the growth of an apatite-like layer on the glass surface. In the first stage, an amorphous calcium phosphate layer was formed; after 7 days this surface consisted of spheres, with diameters ranging between 2 and 15 microm, composed of needle-like apatite crystallites (250 x 100 nm) with a crystallinity similar to that of a biological apatite.

Apatites↗
PubMed1998

Trace metal levels in chironomid larvae and sediments from a Bolivian river: impact of mining activities.

The effect of mining activity on metal accumulation in sediments and Chironomidae in a river in Bolivia was assessed. Surficial sediments and midge larvae (Chironomidae, Diptera) were collected at five sampling sites. Concentrations of the trace metals Cd, Cu, Cr, Ni, Pb, and Zn were measured in organisms and sediments by inductively coupled plasma atomic emission spectrometry. Sediments were subjected to two different extraction procedures to identify total trace metals and reducible trace metals. Geochemical characteristics of the sediment were analyzed: total organic carbon (TOC), Fe and Mn oxides, and particle size distribution. To determine the relative importance of the different sediment factors contributing to the variation in metal accumulation by the chironomid larvae, nonlinear regression models were constructed. No increase in metal concentration in sediment could be measured downstream of the mining activity. Larval concentrations, however, increased markedly. Only for zinc and chromium was a significant amount of variation (48 and 73%, respectively) found. The lack of relationship for the other metals probably was due to a unmeasured exposure route, the overlying water.

Animals↗
PubMed1987

Source of intrinsic innervation of canine ventricles: a functional study.

Recently it has been suggested that the parasympathetic innervation of the ventricles is by way of postganglionic axones that emanate from ganglion cells in the atria, reaching the ventricles by traversing the atrioventricular (AV) groove. We designed a series of experiments to test this hypothesis. Phenol (89%) was applied to the AV groove and surrounding 5 mm of epicardium in 21 dogs on cardiopulmonary bypass. The effects of intracoronary acetylcholine (ACh; 1-5 micrograms) and intracoronary nicotine (NIC; 25-100 micrograms) on cardiac isovolumic pressures were evaluated after beta-blockade. In another series of experiments, eight dogs were exposed to phenol in the same way and allowed to recover for 7-10 days. Atrial and ventricular responses to NIC were unaffected by phenol application to the AV groove in the acute animals when compared with application of saline alone. However, in the chronic animals, pretreatment with phenol 7-10 days previously reduced the ventricular responses to NIC by 70% while leaving the atrial responses intact. These data indicate that the intrinsic cardiac nerves (ICN) of the canine ventricles consist primarily of postganglionic parasympathetic axones which arise from supraventricular ganglia and cross the AV groove.

Acetylcholine↗