50 research outputs found
Insights into the influence of priors in posterior mapping of discrete morphological characters: a case study in Annonaceae
No full textBackground - Posterior mapping is an increasingly popular hierarchical Bayesian based method used to infer character histories and reconstruct ancestral states at nodes of molecular phylogenies, notably of morphological characters. As for all Bayesian analyses specification of prior values is an integrative and important part of the analysis. He we provide an example of how alternative prior choices can seriously influence results and mislead interpretations. Methods/Principal Findings - For two contrasting discrete morphological characters, namely a slow and a fast evolving character found in the plant family Annonaceae, we specified a total of eight different prior distributions per character. We investigated how these prior settings affected important summary statistics. Our analyses showed that the different prior distributions had marked effects on the results in terms of average number of character state changes. These differences arise because priors play a crucial role in determining which areas of parameter space the values of the simulation will be drawn from, independent of the data at hand. However, priors seemed to fit the data better if they would result in a more even sampling of parameter space (normal posterior distribution), in which case alternative standard deviation values had little effect on the results. The most probable character history for each character was affected differently by the prior. For the slower evolving character, the same character history always had the highest posterior probability independent of the priors used. In contrast, the faster evolving character showed different most probable character histories depending on the prior. These differences could be related to the level of homoplasy exhibited by each character. Conclusions - Although our analyses were restricted to two morphological characters within a single family, our results underline the importance of carefully choosing prior values for posterior mapping. Prior specification will be of crucial importance when interpreting the results in a meaningful way. It is hard to suggest a statistically sound method for prior specification without more detailed studies. Meanwhile, we propose that the data could be used to estimate the prior value of the gamma distribution placed on the transformation rate in posterior mappin
The genus Idertia (Ochnaceae)
No full textBackground and aims - The genus Idertia belongs to the subfamily Ochnoideae, tribe Ochneae, subtribe Ouratinae. This paper aims at a full taxonomic revision and a critical evaluation of the taxonomic position of the genus along with its diagnostic characters. Methods - All characters are studied using 73 herbarium collections of the following herbaria: B, BM, BR, BRLU, COI, EA, G, K, MO, P and WAG. Specimen data were managed using the BRAHMS herbarium management software. Key results - Idertia is characterized by a gynobasic style, apocarpous fruits, ten stamens, persistent and accrescent sepals and intra-axillary fused stipules. It shares these features with its African relatives Campylospermum and Rhabdophyllum, but its axillary inflorescence, smooth anthers and straight cotyledons renders it distinct. The latter feature is reminiscent of the South American relative Ouratea which lacks the persistent sepals and has free lateral stipules. Other diagnostic characters of the wood, leaves, inflorescence, flowers and fruits are discussed. A key to the four genera of the subtribe Ouratinae is provided. The correct author combination for the name Ouratinae is (Engl.) Kanis. The variation amongst the four species of Idertia recognized by other authors was studied carefully and deemed continuous. Only a single, though variable species distributed from Guinea to Uganda is recognized. A full taxonomic treatment is provided and two lectotypes are designated. Conclusions - Idertia is a well-defined and sufficiently distinct monotypic genus
Clinical challenges in esophageal cancer treatment
No full textDe invoering van een PET-CT-scan na gecombineerde preoperatieve chemo- en radiotherapie voorkomt dat slokdarmkankerpatiënten worden geopereerd die tijdens de therapie uitzaaiingen hebben ontwikkeld. Dit concludeert Rachel Blom in haar onderzoek naar diagnostiek en de uitkomst van de operatie. Ze constateert tevens dat er geen verschil in uitkomst is tussen jonge of oude patiënten en tussen patiënten met een normaal gewicht of overgewicht. De prognose van degenen bij wie slokdarmkanker terugkeert, blijkt de laatste achttien jaar niet verbeterd. Slokdarmkanker komt steeds vaker voor. Door betere diagnostiek en behandeling verbeterde de vijfjaarsoverleving
Evaluation of cocoa land use management in Ghana
No full textDit onderzoek heeft zich gericht op evaluatie van de huidige situatie van cacaoregistratie in Ghana en aangeven van essentieel noodzakelijke verbeteringen daarvoor. De CSD is een van Rijkswege bestaande instantie die zich bezighoudt met de beheersing van de cacaoproduktie en -industrie in Ghana. Zij voelen zich daarin beperkt door een gebrek aan voldoende actuele gegevens. Er is een scheiding aan te geven tussen topografische en administratieve gegevens. De topografische gegevens zijn hopeloos verouderd doordat zij niet in voldoende mate zijn bijgehouden sinds de kaarten werden vervaardigd in 1974, en wegens externe invloeden die de topografie drastisch hebben veranderd.Civil Engineering and Geoscience
Loss of Skeletal Muscle Mass During Neoadjuvant Chemoradiotherapy Predicts Postoperative Mortality in Esophageal Cancer Surgery
No full textBACKGROUND: Esophageal surgery is associated with complications and mortality. It is highly important to develop tools predicting unfavorable postoperative outcome. Esophageal cancer and neoadjuvant chemoradiotherapy (CRT) induce skeletal muscle wasting, which leads to diminished physiologic reserves. The purpose of this study was to investigate whether the degree of muscle mass lost during neoadjuvant CRT predicts postoperative mortality. METHODS: A total of 123 consecutive patients undergoing surgery for esophageal malignancy in the period 2008-2012 were included, of whom 114 received neoadjuvant CRT. Skeletal muscle mass was measured on routinely performed CT scans by assessing L3 muscle index (according to the Prado method) before and after neoadjuvant CRT, and the amount of muscle mass lost during neoadjuvant CRT (muscle loss index) was calculated. It was investigated whether this amount was associated with postoperative 30-day or in-hospital mortality and morbidity. RESULTS: In the complete cohort, no significant association between loss of muscle mass and mortality was found. However, skeletal muscle mass was significantly lower in patients with stage III-IV tumors compared with stage I-II tumors, prior to neoadjuvant CRT. In the stage III-IV subgroup, the amount of muscle mass lost during neoadjuvant CRT was predictive of postoperative mortality: -13.5 % (standard deviation 6.2 %) in patients who died postoperatively compared with -5.0 % (standard deviation 8.3 %) in surviving patients, p = 0.02. CONCLUSIONS: Measurement of muscle mass loss during neoadjuvant chemoradiotherapy may provide a readily available and inexpensive assessment to identify patients at risk for developing unfavorable postoperative outcome after resection of esophageal malignancies, especially in patients with stage III-IV tumors
Treatment of Acute Liver Failure in Pigs Reduces Hepatocyte Function in a Bioartificial Liver Support System
No full text Several different types of bioartificial liver (BAL) support systems have been developed to bridge patients suffering from acute liver failure (ALF) to transplantation or liver regeneration. In this study we assessed the effects of ALF plasma on hepatocyte function in the BAL system that has been developed in our center. Pigs (40–60 kg) were anaesthetised and a total hepatectomy was performed. Cells were isolated from the resected livers and were transferred to the bioreactor of the BAL system. Twenty hours after cell isolation, hepatocytes in the BAL were tested for cell viability and functional activity by using a recirculating test medium in which assessment of LDH leakage, ammonia clearance, urea synthesis, 7-ethoxycoumarin O-deethylase (ECOD) activity and pseudocholine esterase production was performed. Subsequently, two groups were studied. In one group (I, n=5), the cell-loaded bioreactor was used to treat the donor pig, rendered anhepatic, for 24 hours. In the second group (II, n=5) the bioreactor was cultured for 24 h and served as a control. After 24 hours treatment or culturing, the cell viability count and functional activity tests were repeated. The results show that hepatocytes in the BAL remained viable after 24 h treatment of anhepatic pigs, as shown by the LDH release and pseudocholine esterase production. However, metabolic functions such as ammonia clearance, ECOD and urea synthesis were reduced after 24 h exposure of hepatocytes to autologous ALF plasma, whereas these functions were unaltered after 24 h culturing of the cells in the bioreactor. </jats:p
The value of post-neoadjuvant therapy PET-CT in the detection of interval metastases in esophageal carcinoma
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