273 research outputs found
Weakly-supervised localization of diabetic retinopathy lesions in retinal fundus images
Convolutional neural networks (CNNs) show impressive performance for image
classification and detection, extending heavily to the medical image domain.
Nevertheless, medical experts are sceptical in these predictions as the
nonlinear multilayer structure resulting in a classification outcome is not
directly graspable. Recently, approaches have been shown which help the user to
understand the discriminative regions within an image which are decisive for
the CNN to conclude to a certain class. Although these approaches could help to
build trust in the CNNs predictions, they are only slightly shown to work with
medical image data which often poses a challenge as the decision for a class
relies on different lesion areas scattered around the entire image. Using the
DiaretDB1 dataset, we show that on retina images different lesion areas
fundamental for diabetic retinopathy are detected on an image level with high
accuracy, comparable or exceeding supervised methods. On lesion level, we
achieve few false positives with high sensitivity, though, the network is
solely trained on image-level labels which do not include information about
existing lesions. Classifying between diseased and healthy images, we achieve
an AUC of 0.954 on the DiaretDB1.Comment: Accepted in Proc. IEEE International Conference on Image Processing
(ICIP), 201
Challenging Common Assumptions in Multi-task Learning
While multi-task learning (MTL) has gained significant attention in recent
years, its underlying mechanisms remain poorly understood. Recent methods did
not yield consistent performance improvements over single task learning (STL)
baselines, underscoring the importance of gaining more profound insights about
challenges specific to MTL. In our study, we challenge common assumptions in
MTL in the context of STL: First, the choice of optimizer has only been mildly
investigated in MTL. We show the pivotal role of common STL tools such as the
Adam optimizer in MTL. We deduce the effectiveness of Adam to its partial
loss-scale invariance. Second, the notion of gradient conflicts has often been
phrased as a specific problem in MTL. We delve into the role of gradient
conflicts in MTL and compare it to STL. For angular gradient alignment we find
no evidence that this is a unique problem in MTL. We emphasize differences in
gradient magnitude as the main distinguishing factor. Lastly, we compare the
transferability of features learned through MTL and STL on common image
corruptions, and find no conclusive evidence that MTL leads to superior
transferability. Overall, we find surprising similarities between STL and MTL
suggesting to consider methods from both fields in a broader context.Comment:
The human neonatal small intestine has the potential for arginine synthesis; developmental changes in the expression of arginine-synthesizing and -catabolizing enzymes
BACKGROUND: Milk contains too little arginine for normal growth, but its precursors proline and glutamine are abundant; the small intestine of rodents and piglets produces arginine from proline during the suckling period; and parenterally fed premature human neonates frequently suffer from hypoargininemia. These findings raise the question whether the neonatal human small intestine also expresses the enzymes that enable the synthesis of arginine from proline and/or glutamine. Carbamoylphosphate synthetase (CPS), ornithine aminotransferase (OAT), argininosuccinate synthetase (ASS), arginase-1 (ARG1), arginase-2 (ARG2), and nitric-oxide synthase (NOS) were visualized by semiquantitative immunohistochemistry in 89 small-intestinal specimens. RESULTS: Between 23 weeks of gestation and 3 years after birth, CPS- and ASS-protein content in enterocytes was high and then declined to reach adult levels at 5 years. OAT levels declined more gradually, whereas ARG-1 was not expressed. ARG-2 expression increased neonatally to adult levels. Neurons in the enteric plexus strongly expressed ASS, OAT, NOS1 and ARG2, while varicose nerve fibers in the circular layer of the muscularis propria stained for ASS and NOS1 only. The endothelium of small arterioles expressed ASS and NOS3, while their smooth-muscle layer expressed OAT and ARG2. CONCLUSION: The human small intestine acquires the potential to produce arginine well before fetuses become viable outside the uterus. The perinatal human intestine therefore resembles that of rodents and pigs. Enteral ASS behaves as a typical suckling enzyme because its expression all but disappears in the putative weaning period of human infants
Comparative analysis of the immunologic response induced by the Sterne 34F2 live spore Bacillus anthracis vaccine in a ruminant model
The Sterne 34F2 live spore vaccine (SLSV) developed in 1937 is the most widely used
veterinary vaccine against anthrax. However, literature on the immunogenicity of this vaccine
in a target ruminant host is scarce. In this study, we evaluated the humoral response to the
B. anthracis protective antigen (rPA), a recombinant bacillus collagen-like protein of
anthracis (rBclA), formaldehyde inactivated spores (FIS) prepared from strain 34F2
and a vegetative antigen formulation prepared from a capsule and toxin deficient strain
(CDC 1014) in Boer goats. The toxin neutralizing ability of induced antibodies was
evaluated using an in vitro toxin neutralization assay. The protection afforded by the
vaccine was also assessed in vaccinates. Anti-rPA, anti-FIS and lethal toxin neutralizing titres
were superior after booster vaccinations, compared to single vaccinations. Qualitative
analysis of humoral responses to rPA, rBclA and FIS antigens revealed a
preponderance of anti-FIS IgG titres following either single or double vaccinations with
the SLSV. Antibodies against FIS and rPA both increased by 350 and 300-fold following
revaccinations respectively. There was no response to rBclA following vaccinations with
the SLSV. Toxin neutralizing titres increased by 80-fold after single vaccination and
700-fold following a double vaccination. Lethal challenge studies in naïve goats indicated a
minimum infective dose of 36 B. anthracis spores. Single and double vaccination with the
SLSV protected 4/5 and 3/3 of goats challenged with > 800 spores respectively. An early booster vaccination following the first immunization is suggested in order to achieve a robust
immunity. Results from this study indicate that this crucial second vaccination can be
administered as early as 3 months after the initial vaccination.German research foundation (DFG) with grant # BE2157/4-1.http://www.elsevier.com/locate/vetimm2017-10-31hb2016Veterinary Tropical Disease
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