RESUMEN

For crops that are grown for their fruits or seeds, elevated temperatures that occur during flowering and seed or fruit set have a stronger effect on yield than high temperatures during the vegetative stage. Even short-term exposure to heat can have a large impact on yield. In this study, we used Arabidopsis thaliana to study the effect of short-term heat exposure on flower and seed development. The impact of a single hot day (35°C) was determined in more than 250 natural accessions by measuring the lengths of the siliques along the main inflorescence. Two sensitive developmental stages were identified, one before anthesis, during male and female meiosis, and one after anthesis, during fertilization and early embryo development. In addition, we observed a correlation between flowering time and heat tolerance. Genome-wide association mapping revealed four quantitative trait loci (QTLs) strongly associated with the heat response. These QTLs were developmental stage specific, as different QTLs were detected before and after anthesis. For a number of QTLs, T-DNA insertion knockout lines could validate assigned candidate genes. Our findings show that the regulation of complex traits can be highly dependent on the developmental timing.

Asunto(s)

RESUMEN

OBJECTIVES: To determine effective and efficient monitoring criteria for ocular hypertension [raised intraocular pressure (IOP)] through (i) identification and validation of glaucoma risk prediction models; and (ii) development of models to determine optimal surveillance pathways. DESIGN: A discrete event simulation economic modelling evaluation. Data from systematic reviews of risk prediction models and agreement between tonometers, secondary analyses of existing datasets (to validate identified risk models and determine optimal monitoring criteria) and public preferences were used to structure and populate the economic model. SETTING: Primary and secondary care. PARTICIPANTS: Adults with ocular hypertension (IOP > 21 mmHg) and the public (surveillance preferences). INTERVENTIONS: We compared five pathways: two based on National Institute for Health and Clinical Excellence (NICE) guidelines with monitoring interval and treatment depending on initial risk stratification, 'NICE intensive' (4-monthly to annual monitoring) and 'NICE conservative' (6-monthly to biennial monitoring); two pathways, differing in location (hospital and community), with monitoring biennially and treatment initiated for a ≥ 6% 5-year glaucoma risk; and a 'treat all' pathway involving treatment with a prostaglandin analogue if IOP > 21 mmHg and IOP measured annually in the community. MAIN OUTCOME MEASURES: Glaucoma cases detected; tonometer agreement; public preferences; costs; willingness to pay and quality-adjusted life-years (QALYs). RESULTS: The best available glaucoma risk prediction model estimated the 5-year risk based on age and ocular predictors (IOP, central corneal thickness, optic nerve damage and index of visual field status). Taking the average of two IOP readings, by tonometry, true change was detected at two years. Sizeable measurement variability was noted between tonometers. There was a general public preference for monitoring; good communication and understanding of the process predicted service value. 'Treat all' was the least costly and 'NICE intensive' the most costly pathway. Biennial monitoring reduced the number of cases of glaucoma conversion compared with a 'treat all' pathway and provided more QALYs, but the incremental cost-effectiveness ratio (ICER) was considerably more than £30,000. The 'NICE intensive' pathway also avoided glaucoma conversion, but NICE-based pathways were either dominated (more costly and less effective) by biennial hospital monitoring or had a ICERs > £30,000. Results were not sensitive to the risk threshold for initiating surveillance but were sensitive to the risk threshold for initiating treatment, NHS costs and treatment adherence. LIMITATIONS: Optimal monitoring intervals were based on IOP data. There were insufficient data to determine the optimal frequency of measurement of the visual field or optic nerve head for identification of glaucoma. The economic modelling took a 20-year time horizon which may be insufficient to capture long-term benefits. Sensitivity analyses may not fully capture the uncertainty surrounding parameter estimates. CONCLUSIONS: For confirmed ocular hypertension, findings suggest that there is no clear benefit from intensive monitoring. Consideration of the patient experience is important. A cohort study is recommended to provide data to refine the glaucoma risk prediction model, determine the optimum type and frequency of serial glaucoma tests and estimate costs and patient preferences for monitoring and treatment. FUNDING: The National Institute for Health Research Health Technology Assessment Programme.

Asunto(s)

RESUMEN

Tetraploid hybrid tea roses (Rosa hybrida) represent most of the commercial cultivars of cut roses and form the basis for breeding programmes. Due to intensive interspecific hybridizations, modern cut roses are complex tetraploids for which the mode of inheritance is not exactly known. The segregation patterns of molecular markers in a tetraploid mapping population of 184 genotypes, an F(1) progeny from a cross of two heterozygous parents, were investigated for disomic and tetrasomic inheritance. The possible occurrence of double reduction was studied as well. We can exclude disomic inheritance, but while our observations are more in line with a tetrasomic inheritance, we cannot exclude that there is a mixture of both inheritance modes. Two novel parental tetraploid linkage maps were constructed using markers known from literature, combined with newly generated markers. Comparison with the integrated consensus diploid map (ICM) of Spiller et al. (Theor Appl Genet 122:489-500, 2010) allowed assigning numbers to each of the linkage groups of both maps and including small linkage groups. So far, the possibility of using marker-assisted selection in breeding of tetraploid cut roses and of other species with a tetrasomic or partly tetrasomic inheritance, is still limited due to the difficulties in establishing marker-trait associations. We used these tetraploid linkage maps to determine associations between markers, two morphological traits and powdery mildew resistance. The knowledge on inheritance and marker-trait associations in tetraploid cut roses will be of direct use to cut rose breeding.

Asunto(s)

RESUMEN

Current OCT devices provide three-dimensional (3D) in-vivo images of the human retina. The resulting very large data sets are difficult to manually assess. Automated segmentation is required to automatically process the data and produce images that are clinically useful and easy to interpret. In this paper, we present a method to segment the retinal layers in these images. Instead of using complex heuristics to define each layer, simple features are defined and machine learning classifiers are trained based on manually labeled examples. When applied to new data, these classifiers produce labels for every pixel. After regularization of the 3D labeled volume to produce a surface, this results in consistent, three-dimensionally segmented layers that match known retinal morphology. Six labels were defined, corresponding to the following layers: Vitreous, retinal nerve fiber layer (RNFL), ganglion cell layer & inner plexiform layer, inner nuclear layer & outer plexiform layer, photoreceptors & retinal pigment epithelium and choroid. For both normal and glaucomatous eyes that were imaged with a Spectralis (Heidelberg Engineering) OCT system, the five resulting interfaces were compared between automatic and manual segmentation. RMS errors for the top and bottom of the retina were between 4 and 6 µm, while the errors for intra-retinal interfaces were between 6 and 15 µm. The resulting total retinal thickness maps corresponded with known retinal morphology. RNFL thickness maps were compared to GDx (Carl Zeiss Meditec) thickness maps. Both maps were mostly consistent but local defects were better visualized in OCT-derived thickness maps.

RESUMEN

Floating pennywort (Hydrocotyle ranunculoides L.f.), a member of the plant family Araliaceae originating from North America, is an example of an invasive aquatic species posing serious problems to the management of waterways outside of its original distribution area in Australia and Western Europe. As a consequence, its import was banned in the Netherlands. It can be difficult to distinguish H. ranunculoides from other species of the genus on a morphological basis. In this regard, DNA barcoding may become a good alternative once this could be performed on a routine basis. In this study, we show that it is possible to distinguish H. ranunculoides from a series of closely related congeners by using a single plastid DNA sequence, trnH-psbA.

RESUMEN

INTRODUCTION: In evaluating the type of gastrectomy and lymphadenectomy for gastric cancer, adequate prognosis has been dependant on the retrieval of at least 15 lymph nodes. We propose an alternative method in which the prognostic value is evaluated, according to whether or not more than 20% of the retrieved lymph nodes are invaded by tumour. MATERIALS & METHODS: Sixty-five patients (36 men, 29 women) with a median age of 69 years (mean age 68.9 +/-12.1 years) were evaluated, who were operated upon between 1985 and 1999 for gastric cancer by gastrectomy with either D1 or D2 lymphadenectomy. RESULTS: The average number of retrieved lymph nodes was 10.4 +/- 8.6. In 51 patients (78.5%) less than 15 and in 14 patients (21.5%) 15 or more lymph nodes were retrieved, according to the TNM guidelines. In our study, there is a statistically significant difference in prognosis between patients with less than 20% and those with more than 20% of the retrieved lymph nodes invaded by tumour, irrespective of the total number of lymph nodes resected. CONCLUSION: Gastric cancer patients in whom less than 20% of the retrieved lymph nodes are invaded, have a significantly better prognosis compared with patients in whom 20% or more of the lymph nodes retrieved are invaded by tumour, irrespective of the total number of retrieved lymph nodes.

Asunto(s)

RESUMEN

Nitrogen (N) remaining as inorganic ('mineral') soil N at crop harvest (N(minH)) contributes to nitrate leaching. N(minH) data from 20 (grass) and 78 (maize) experiments were examined to identify main determinants of N(minH). N-rate (A) explained 51% (grass) and 34% (maize) of the variance in N(minH). Best models included in addition crop N-offtake (U), offtake in unfertilised plots (U(0)), and N(minH) in unfertilised plots (N(minH,0)) and then explained up to 75% of variance. At low N-rates where apparent N recovery rho keeps to its initial value rho(ini), N(minH) keeps to its base level N(minH,0). At N-rates that exceed the value A(crit) where rho drops below rho(ini), N(minH) rises above N(minH,0) by an amount proportional to (rho(ini)-rho)A. About 80% of (rho(ini)-rho)A was found as N(minH,) in grass as well as in maize. The fraction (1-rho(ini))A does not appear to contribute to N(minH) at low N-rates (A< or =A(crit)) or at high N-rates (A>A(crit)).

Asunto(s)

RESUMEN

INTRODUCTION: Heparin-induced allergic reactions may cause problems if heparin administration is needed for thrombo-embolic disease in pregnancy. CASE REPORTS: We report two cases of hypersensitivity to low molecular weight heparin (LMWH) in pregnancy. DISCUSSION: Alternative methods and new antithrombotic agents are discussed.

Asunto(s)

RESUMEN

Populus nigra L. is a pioneer tree species of riparian ecosystems that is threatened with extinction because of the loss of its natural habitat. To evaluate the existing genetic diversity of P. nigra within ex-situ collections, we analyzed 675 P. nigra L. accessions from nine European gene banks with three amplified fragment length polymorphism (AFLP) and five microsatellite [or simple sequence repeat (SSR)] primer combinations, and 11 isozyme systems. With isozyme analysis, hybrids could be detected, and only 3% were found in the gene bank collection. AFLP and SSR analyses revealed effectively that 26% of the accessions were duplicated and that the level of clonal duplication varied from 0% in the French gene bank collection up to 78% in the Belgian gene bank collection. SSR analysis was preferred because AFLP was technically more demanding and more prone to scoring errors. To assess the genetic diversity, we grouped material from the gene banks according to topography of the location from which the accessions were originally collected (river system or regions separated by mountains). Genetic diversity was expressed in terms of the following parameters: percentage of polymorphic loci, observed and effective number of alleles, and Nei's expected heterozygosity or gene diversity (for AFLP). Genetic diversity varied from region to region and depended, to some extent, on the marker system used. The most unique alleles were identified in the Danube region (Austria), the Rhône region (France), Italy, the Rijn region (The Netherlands), and the Ebro region (Spain). In general, the diversity was largest in the material collected from the regions in Southern Europe. Dendrograms and principal component analysis resulted in a clustering according to topography. Material from the same river systems, but from different countries, clustered together. The genetic differentiation among the regions (F(st)/G(st)) was moderate.

Asunto(s)

RESUMEN

Despite technical difficulties due to mediastinal fibrosis, remediastinoscopy can be a valuable tool in the restaging of non-small cell lung cancer after neoadjuvant therapy. The aim of our study was to evaluate the feasibility, sensitivity and accuracy of remediastinoscopy. From November 1994 to July 2001 we performed a remediastinoscopy in 27 patients after neoadjuvant therapy. Their age ranged from 35 to 80 years (mean 61.9+/-11.9). In all 27 patients it was possible to perform a remediastinoscopy without major technical difficulties and take biopsies of the lymph nodes that were initially invaded by tumour. Remediastinoscopy was positive in 11 patients (40.7%) and negative in 16 (59.3%). In the 11 patients with a positive remediastinoscopy a complete resection was not judged possible and therefore, an unnecessary thoracotomy was avoided. In four patients, remediastinoscopy turned out to be false negative. So, in our series, sensitivity was 73%, specificity 100% and accuracy 85%. The positive and negative predictive values were 100 and 75%, respectively. Previous mediastinoscopy is no contra-indication for a repeat one after neoadjuvant therapy. Although sensitivity and accuracy are lower than that of a first mediastinoscopy, remediastinoscopy is useful to select patients for surgical resection after induction therapy.

Asunto(s)

RESUMEN

Mortality due to trauma in pregnancy is not very common in the Netherlands. More often a pregnant woman presents herself for examination after trauma. Blunt trauma is more common in the third trimester. Minor trauma also needs good care, with special attention for solutio placentae. Maternal mortality after penetrating trauma is low because of the protection of vital organs by the uterus. With good treatment the mortality in pregnant trauma patients will not be higher than in nonpregnant patients. A rapid and effective resuscitation of the mother will give the foetus the best chance of survival.

Asunto(s)

Asunto(s)

RESUMEN

This article emphasizes the role of nuclear medicine in the monitoring of function to prevent or limit injury in organs in which toxicity related to cancer therapy may have implications for the survival and/or the quality of life of the patient. After a brief discussion of the advantages of nuclear medicine techniques in detecting organ injury, the effect of radiation therapy and chemotherapy on normal tissue is discussed, underlining the need to characterize adverse effects of cancer therapy in long-term survivors. The use of radionuclides to document organ injury and effects from cancer therapy in heart, digestive tract, kidneys, lungs, major salivary glands, skeleton and brain is then reviewed. In a short section the potential applicability of positron emission tomography in documenting organ toxicity during cancer therapy is discussed. Thanks to the various available radiopharmaceuticals, the ability of the tracers to document specific functional aspects, the improved methods for visualization and quantitation of organ injury and the possibilities of physiological or pharmacological intervention, nuclear medicine gives the clinician potent tools for the monitoring of organ function at risk during cancer therapy. The trend to intensify cancer treatment by combining various treatment modalities and the increasing chances of prolonged survival in a large number of patients call for effective integration of nuclear medicine methods into the recommended guidelines for grading organ injury in clinical oncology.

Asunto(s)

RESUMEN

67Ga lung uptake, obtained by a standardized computer-assisted quantitative method of 67Ga scintigraphy, was compared to carbon monoxide diffusion capacity (DLCO) in 45 patients with biopsy proven pulmonary sarcoidosis. Increased 67Ga lung uptake was found in 24 (53%) patients and DLCO was decreased in only 16 (36%) patients. An inverse relationship (r = -0.53; p < 0.001) was demonstrated between 67Ga lung uptake and DLCO. Eleven patients had an increased 67Ga lung uptake whereas the DLCO values were normal. There was no correlation between 67Ga lung uptake or DLCO and either chest radiographic stage or mode of clinical presentation. On the basis of the normal limits for 67Ga lung uptake and DLCO, 4 subgroups of patients could be identified. The use of the combined investigations may open an opportunity for an early identification of those patients who require therapy. An increased 67Ga accumulation within the lung seems to be considered as a factor indicating risk for pulmonary disability, which is supported by the follow-up of the 4 subgroups of patients.

Asunto(s)

RESUMEN

Fifty-six patients in Europe were entered into a multi-centre study to compare the accuracy of technetium 99m methoxyisobutylisonitrile (99mTc-MIBI) for the detection of coronary artery disease (CAD) with thallium 201 (201Tl) chloride perfusion scanning. The results showed a high degree of concordance between the two radiopharmaceuticals. Some 81% (678/840) of myocardial segments showed the same result (normal, infarct or ischaemia), and 80% (45/56) of patients had the same diagnosis. Overall detection of CAD in patients was 98% for 201T1 and 96% for 99mTc-MIBI. Detection of CAD in total arteries was 68% for both agents. In this study 99mTc-MIBI was as accurate as 201Tl for the detection of coronary artery stenoses.

Asunto(s)

Asunto(s)

RESUMEN

Thirty-five patients with acute ischaemic stroke were studied within 24 h after hospital admission with thallium 201 diethyldithiocarbamate single photon emission tomography (201Tl-DDC SPET) and X-ray computed tomography (CT). 201Tl-DDC is a non-redistributing agent that allows postponed imaging after early administration and early therapeutic intervention. In 16 patients both investigations were performed within 24 h after stroke onset. The sensitivity of SPET was 94% and of CT 81% in the first 24 h, when hypodensity and obliteration of sulci were used as CT reading criteria. When only hypodensity was used as a criterion, the sensitivity of CT was 50% in this group. Sensitivity of CT compared with SPET became increasingly better in patients with older infarcts (1-18 days). In two-thirds of patients, the lesion demonstrated on SPET was larger than that on CT, and this was especially so with older infarcts. Crossed cerebellar diaschisis occurred in 69% of patients. The high sensitivity of 201Tl-DDC SPET in the first 24 h after ischaemic stroke and the favourable properties of this radiopharmaceutical make it a method of interest in the assessment of initial perfusion defects in early experimental stroke therapies.

Asunto(s)

RESUMEN

A method of standardized quantitative 67Ga scintigraphy in the evaluation of pulmonary sarcoidosis is described. Standardization of 67Ga activity measurements was achieved by using an external attenuated 67Ga standard for comparison. The method was applied to control subjects (n = 24), and to patients (n = 88) suffering from biopsy-proven pulmonary sarcoidosis, whether or not treated with systemic or inhaled corticosteroids. The quantitative 67Ga activity values for pulmonary hili and parenchyma were found to be increased in patients, especially in those patients who were recently diagnosed and untreated. 67Ga accumulation in the liver showed normally a wide variation and appeared to be increased in patients with sarcoidosis, so that use of the liver radioactivity as the standard for comparison may lead to misinterpretation of the intrathoracic 67Ga activity distribution. Standardized quantitative 67Ga scintigraphy appeared to be a valuable tool in the management of pulmonary sarcoidosis and also opens up the possibility for results from different institutions to be compared. Supplementary digitized functional images improved the accuracy of the interpretation of routine analogue unprocessed images. Diffuse or local 67Ga accumulation in the chest was more readily discernible on digitized functional images than on analogue images.

Asunto(s)

RESUMEN

Lung volumes, calculated from 81Krm single-photon emission computed tomography (SPECT) of the lungs, were compared with functional residual capacity (FRC), measured with the helium dilution technique in controls and in patients with various pulmonary diseases. SPECT volume was greater than FRC, which was attributed to non-gas-containing structures in the lung such as the alveolar walls, the interstitium, the blood vessels and the blood, included in the SPECT volume. A good correlation (r = 0.91) was found between the two volumes and there was no difference in this relationship between patients and controls. It was concluded that the relative volume distribution, calculated from SPECT, can be used for the quantification of ventilation from 81Krm SPECT steady-state count distributions.

Asunto(s)

RESUMEN

Medullary thyroid carcinoma (MTC), a calcitonin-producing tumor that occurs in familial and sporadic forms, can be monitored satisfactorily with measurements of calcitonin and CEA in serum. However, locating the tumor site may be difficult. In the current review of the experience with four new radionuclide tracers for MTC, the relative value of each of these procedures is outlined. Total body imaging using TI-201 chloride and Tc-99m(V) DMSA are both sensitive techniques that can be used for the detection and follow-up of MTC. Imaging using I-131 MIBG and I-131 anti-CEA antibodies/fragments should be performed once the diagnosis and the tumor site have been established, to evaluate if patients might be amenable for therapy with one of these radiopharmaceuticals.

Asunto(s)