926 resultados para discriminant analyses
Resumo:
Actinic keratosis (AK) and Bowenoid in situ carcinoma (BISC) are two distinct forms of in situ squamous cell carcinoma in felines. They usually occur on different locations and present with specific clinical and histologic features. However, in some cases, these diseases cannot be distinguished either clinically or histopathologically. The aim of the present study was to determine the accuracy of diagnosis based on clinical or histologic criteria alone, and whether immunohistochemistry for papillomavirus or p53 can improve the accuracy of diagnosis. A series of in situ squamous cell carcinoma cases (n = 45) were selected according to their location and initial histologic classification and subsequently classified as AK (n = 22) or BISC (n = 23) according to the clinical criteria and were reevaluated histologically by 2 dermatopathologists. All BISC cases and most of the AK cases (n = 15) were confirmed histologically. In 7 cases clinically classified as AK, this diagnosis was not unanimously confirmed histologically because of the presence of overlapping features. P53 immunoreactivity was observed in 11/14 (79%) confirmed AK cases and in 4/22 (18%) BISC cases, while papillomavirus antigen was not detected in any confirmed AK case but was detected in 11/23 (48%) BISC cases. It was concluded that BISC can usually be reliably diagnosed histologically. The histologic diagnosis of lesions clinically suggestive of AK might sometimes be difficult. Results of immunohistochemistry for p53 and papillomavirus antigen were supportive for a role of sun exposure and papillomavirus in the pathogenesis of AK and BISC, respectively.
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European annual species of the genus Rhinanthus often exhibit seasonal ecotypic variation, a phenomenon also known from related genera of hemiparasitic Orobanchaceae. Populations with different flowering times exist, correlated with differences in a number of morphological characters. The present study evaluates the correlation of morphological characters and genetic differentiation of populations of Rhinanthus alectorolophus. Thirty-nine populations of three different subspecies from southwestern Germany were sampled. A total of 798 individuals were used for morphological analyses and 187 of these for AFLP analyses. Principal component analysis showed that morphological variation is mostly continuous. In a discriminant analysis based on morphological characters, only 89.7 % of all individuals were correctly assigned to their previously determined subspecies, indicating that subspecies identification is ambiguous for some populations. Using AFLP data and Bayesian assignment analysis, the sampled individuals could be grouped in three genetic clusters which do not correspond to the three subspecies. Instead, the clustering shows a clear geographic pattern and a Mantel test likewise revealed a significant correlation between genetic and geographic distances. Correlations of genetic distances with differences in morphological characters were weak and mostly insignificant. The results indicate that the subspecies of R. alectorolophus do not form discrete entities and that the character combinations distinguishing them are homoplastic.
Resumo:
The neurocognitive processes underlying the formation and maintenance of paranormal beliefs are important for understanding schizotypal ideation. Behavioral studies indicated that both schizotypal and paranormal ideation are based on an overreliance on the right hemisphere, whose coarse rather than focussed semantic processing may favor the emergence of 'loose' and 'uncommon' associations. To elucidate the electrophysiological basis of these behavioral observations, 35-channel resting EEG was recorded in pre-screened female strong believers and disbelievers during resting baseline. EEG data were subjected to FFT-Dipole-Approximation analysis, a reference-free frequency-domain dipole source modeling, and Regional (hemispheric) Omega Complexity analysis, a linear approach estimating the complexity of the trajectories of momentary EEG map series in state space. Compared to disbelievers, believers showed: more right-located sources of the beta2 band (18.5-21 Hz, excitatory activity); reduced interhemispheric differences in Omega complexity values; higher scores on the Magical Ideation scale; more general negative affect; and more hypnagogic-like reveries after a 4-min eyes-closed resting period. Thus, subjects differing in their declared paranormal belief displayed different active, cerebral neural populations during resting, task-free conditions. As hypothesized, believers showed relatively higher right hemispheric activation and reduced hemispheric asymmetry of functional complexity. These markers may constitute the neurophysiological basis for paranormal and schizotypal ideation.
Resumo:
Objectives: Although behavioral studies have demonstrated that normative affective traits modulate the processing of facial and emotionally charged stimuli, direct electrophysiological evidence for this modulation is still lacking. Methods: Event-related potential (ERP) data associated with personal, traitlike approach- or withdrawal-related attitude (assessed post-recording and 14 months later) were investigated in 18 subjects during task-free (i.e. unrequested, spontaneous) emotional evaluation of faces. Temporal and spatial aspects of 27 channel ERP were analyzed with microstate analysis and low resolution electromagnetic tomography (LORETA), a new method to compute 3 dimensional cortical current density implemented in the Talairach brain atlas. Results: Microstate analysis showed group differences 132-196 and 196-272 ms poststimulus, with right-shifted electric gravity centers for subjects with negative affective attitude. During these (over subjects reliably identifiable) personality-modulated, face-elicited microstates, LORETA revealed activation of bilateral occipito-temporal regions, reportedly associated with facial configuration extraction processes. Negative compared to positive affective attitude showed higher activity right temporal; positive compared to negative attitude showed higher activity left temporo-parieto-occipital. Conclusions: These temporal and spatial aspects suggest that the subject groups differed in brain activity at early, automatic, stimulus-related face processing steps when structural face encoding (configuration extraction) occurs. In sum, the brain functional microstates associated with affect-related personality features modulate brain mechanisms during face processing already at early information processing stages.
Resumo:
Phyteuma is a chromosomally and ecologically diverse vascular plant genus and constitutes an excellent system for studying both the role of chromosomal change for species diversification and the evolution of high-mountain biota. This kind of research is, however, hampered by the lack of a sound phylogenetic framework exacerbated by the notoriously low predictive power of traditional taxonomy with respect to phylogenetic relationships in Campanulaceae. Based on a comprehensive taxon sampling and analyses of nuclear and plastid sequence and AFLP fingerprint data, Phyteuma is confirmed as a monophyletic group sister to the monotypic Physoplexis, which is in line with their peculiar flower morphologies. Within Phyteuma two clades, largely corresponding to previously recognized sections, are consistently found. The traditional circumscription of taxonomic series is largely rejected. Whereas distinctness of the currently recognized species is mostly corroborated, some interspecific relationships remain ambiguous due to incongruences between nuclear and plastid data. Major forces for diversification and evolution of Phyteuma are descending dysploidy (i.e., a decrease in chromosome base number) as well as allopatric and ecological differentiation within the Alps, the genus' center of species diversity. (C) 2013 Elsevier Inc. All rights reserved.
Resumo:
Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the delta N-15 and delta C-13 isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Delta delta N-15 (delta N-15 plant - delta N-15 soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in delta C-13 in hay and delta C-13 in both soil and hay between management types, but showed that delta C-13 abundances were significantly lower in soil of organic compared to conventional grasslands. delta C-15 values implied that management types did not substantially differ in nitrogen cycling. Only delta C-13 in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently used in practice.
Resumo:
OBJECTIVE To investigate whether it is valid to combine follow-up and change data when conducting meta-analyses of continuous outcomes. STUDY DESIGN AND SETTING Meta-epidemiological study of randomized controlled trials in patients with osteoarthritis of the knee/hip, which assessed patient-reported pain. We calculated standardized mean differences (SMDs) based on follow-up and change data, and pooled within-trial differences in SMDs. We also derived pooled SMDs indicating the largest treatment effect within a trial (optimistic selection of SMDs) and derived pooled SMDs from the estimate indicating the smallest treatment effect within a trial (pessimistic selection of SMDs). RESULTS A total of 21 meta-analyses with 189 trials with 292 randomized comparisons in 41,256 patients were included. On average, SMDs were 0.04 standard deviation units more beneficial when follow-up values were used (difference in SMDs: -0.04; 95% confidence interval: -0.13, 0.06; P=0.44). In 13 meta-analyses (62%), there was a relevant difference in clinical and/or significance level between optimistic and pessimistic pooled SMDs. CONCLUSION On average, there is no relevant difference between follow-up and change data SMDs, and combining these estimates in meta-analysis is generally valid. Decision on which type of data to use when both follow-up and change data are available should be prespecified in the meta-analysis protocol.
Resumo:
Systematic reviews and meta-analyses of randomized trials that include patient-reported outcomes (PROs) often provide crucial information for patients, clinicians and policy-makers facing challenging health care decisions. Based on emerging methods, guidance on improving the interpretability of meta-analysis of patient-reported outcomes, typically continuous in nature, is likely to enhance decision-making. The objective of this paper is to summarize approaches to enhancing the interpretability of pooled estimates of PROs in meta-analyses. When differences in PROs between groups are statistically significant, decision-makers must be able to interpret the magnitude of effect. This is challenging when, as is often the case, clinical trial investigators use different measurement instruments for the same construct within and between individual randomized trials. For such cases, in addition to pooling results as a standardized mean difference, we recommend that systematic review authors use other methods to present results such as relative (relative risk, odds ratio) or absolute (risk difference) dichotomized treatment effects, complimented by presentation in either: natural units (e.g. overall depression reduced by 2.4 points when measured on a 50-point Hamilton Rating Scale for Depression); minimal important difference units (e.g. where 1.0 unit represents the smallest difference in depression that patients, on average, perceive as important the depression score was 0.38 (95%CI 0.30 to 0.47) units less than the control group); or a ratio of means (e.g. where the mean in the treatment group is divided by the mean in the control group, the ratio of means is 1.27, representing a 27%relative reduction in the mean depression score).
Resumo:
Human embryonic kidney cells 293 (HEK293) are widely used as cellular heterologous expression systems to study transfected ion channels. This work characterizes the endogenous expression of TRPM4 channels in HEK293 cells. TRPM4 is an intracellular Ca(2+)-activated non-selective cationic channel expressed in many cell types. Western blot analyses have revealed the endogenous expression of TRPM4. Single channel 22pS conductance with a linear current-voltage relationship was observed using the inside-out patch clamp configuration in the presence of intracellular Ca(2+). The channels were permeable to the monovalent cations Na(+) and K(+), but not to Ca(2+). The open probability was voltage-dependent, being higher at positive potentials. Using the whole-cell patch clamp "ruptured patch" configuration, the amplitude of the intracellular Ca(2+)-activated macroscopic current was dependent on time after patch rupture. Initial transient activation followed by a steady-increase reaching a plateau phase was observed. Biophysical analyses of the macroscopic current showed common properties with those from HEK293 cells stably transfected with human TRPM4b, with the exception of current time course and Ca(2+) sensitivity. The endogenous macroscopic current reached the plateau faster and required 61.9±3.5μM Ca(2+) to be half-maximally activated versus 84.2±1.5μM for the transfected current. The pharmacological properties, however, were similar in both conditions. One hundred μM of flufenamic acid and 9-phenanthrol strongly inhibited the endogenous current. Altogether, the data demonstrate the expression of endogenous TRMP4 channels in HEK293 cells. This observation should be taken into account when using this cell line to study TRPM4 or other types of Ca(2+)-activated channels.
Resumo:
A 318-metre-long sedimentary profile drilled by the International Continental Scientific Drilling Program (ICDP) at Site 5011-1 in Lake El’gygytgyn, Far East Russian Arctic, has been analysed for its sedimentologic response to global climate modes by chronostratigraphic methods. The 12 km wide lake is sited off-centre in an 18 km large crater that was created by the impact of a meteorite 3.58 Ma ago. Since then sediments have been continuously deposited. For establishing their chronology, major reversals of the earth’s magnetic field provided initial tie points for the age model, confirming that the impact occurred in the earliest geomagnetic Gauss chron. Various stratigraphic parameters, reflecting redox conditions at the lake floor and climatic conditions in the catchment were tuned synchronously to Northern Hemisphere insolation variations and the marine oxygen isotope stack, respectively. Thus, a robust age model comprising more than 600 tie points could be defined. It could be shown that deposition of sediments in Lake El’gygytgyn occurred in concert with global climatic cycles. The upper �160m of sediments represent the past 3.3 Ma, equivalent to sedimentation rates of 4 to 5 cm ka−1, whereas the lower 160m represent just the first 0.3 Ma after the impact, equivalent to sedimentation rates in the order of 45 cm ka−1. This study also provides orbitally tuned ages for a total of 8 tephras deposited in Lake El’gygytgyn.