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Background: Deep learning (DL) CT denoising models have the potential to improve image quality for lower radiation dose exams. These models are generally trained with large quantities of adult patient image data. However, CT, and increasingly DL denoising methods, are used in both adult and pediatric populations. Pediatric body habitus and size can differ significantly from adults and vary dramatically from newborns to adolescents. Ensuring that pediatric subgroups of different body sizes are not disadvantaged by DL methods requires evaluations capable of assessing performance in each subgroup. Purpose: To assess DL CT denoising in pediatric and adult‐sized patients, we built a framework of computer simulated image quality (IQ) control phantoms and evaluation methodology. Methods: The computer simulated IQ phantoms in the framework featured pediatric‐sized versions of standard CatPhan 600 and MITA‐LCD phantoms with a range of diameters matching the mean effective diameters of pediatric patients ranging from newborns to 18 years old. These phantoms were used in simulating CT images that were then inputs for a DL denoiser to evaluate performance in different sized patients. Adult CT test images were simulated using standard‐sized phantoms scanned with adult scan protocols. Pediatric CT test images were simulated with pediatric‐sized phantoms and adjusted pediatric protocols. The framework's evaluation methodology consisted of denoising both adult and pediatric test images then assessing changes in image quality, including noise, image sharpness, CT number accuracy, and low contrast detectability. To demonstrate the use of the framework, a REDCNN denoising model trained on adult patient images was evaluated. To validate that the DL model performance measured with the proposed pediatric IQ phantoms was representative of performance in more realistic patient anatomy, anthropomorphic pediatric XCAT phantoms of the same age range were also used to compare noise reduction performance. Results: Using the proposed pediatric‐sized IQ phantom framework, size differences between adult and pediatric‐sized phantoms were observed to substantially influence the adult trained DL denoising model's performance. When applied to adult images, the DL model achieved a 60% reduction in noise standard deviation without substantial loss in sharpness in mid or high spatial frequencies. However, in smaller phantoms the denoising performance dropped due to different image noise textures resulting from the smaller field of view (FOV) between adult and pediatric protocols. In the validation study, noise reduction trends in the pediatric‐sized IQ phantoms were found to be consistent with those found in anthropomorphic phantoms. Conclusion: We developed a framework of using pediatric‐sized IQ phantoms for pediatric subgroup evaluation of DL denoising models. Using the framework, we found the performance of an adult trained DL denoiser did not generalize well in the smaller diameter phantoms corresponding to younger pediatric patient sizes. Our work suggests noise texture differences from FOV changes between adult and pediatric protocols can contribute to poor generalizability in DL denoising and that the proposed framework is an effective means to identify these performance disparities for a given model. [ABSTRACT FROM AUTHOR]

The 14-3-3 proteins mediate phosphorylation-dependent protein-protein interactions. Through binding to numerous client proteins, 14-3-3 controls a wide range of physiological processes and has been implicated in a variety of diseases, [...]

The 14-3-3 proteins are eukaryotic factors that are needed to activate the Exoenzyme S (ExoS) mechanism. A family of dimeric molecules with seven isoforms known to exist in mammalian cells, the 14-3-3 proteins have been linked to diverse biological activities including cell-cycle progression, apoptosis, viral transformation and bacterial pathogenesis. Using a defined ADP-ribosylation assay, a basic cluster in the binding groove of the 14-3-3(zeta) isoform is shown to have a pivotal role in ExoS activation.

A study on the 14-3-3 eukaryotic proteins demonstrates that 14-3-3 and exoenzyme S from Pseudomonas aeruginosa interact in a direct manner and provides evidence that this interaction does not require phosphoserine. Exoenzyme S may represent a novel class of 14-3-3 ligands which are not phosphoserine-dependent. The binding of 14-3-3 proteins to non-phosphorylated ligands could have significant implications for 14-3-3 signaling.

Experiment was conducted to examine the hypothesis that the Pl3'K/Akt pathway may result in BAD phosphorylation and may, thus, suppress cell death and promote cell survival. Growth factors can promote cell survival by activating the phosphatidylinositide-3'-OH kinase and its downstream target, the serine-threonine kinase Akt but the mechanism by which Akt functions need to be examined. Akt phosphorylates BAD in vitro and in vivo, and blocks the BAD-induced death of primary neurons. Results suggest a mechanism by which growth factors inactivate a vital component of cell-death machinery.

The proteins commonly referred to as 14-3-3s have recently come to prominence in the study of protein:protein interactions, having been shown to act as allosteric or steric regulators and possibly scaffolds. The binding of 14-3-3 proteins to the regulatory phosphorylation site of nitrate reductase (NR) was studied in real-time by surface plasmon resonance, using primarily an immobilized synthetic phosphopeptide based on spinach NR-Ser543. Both plant and yeast 14-3-3 proteins were shown to bind the immobilized peptide ligand in a Mg2+-stimulated manner. Stimulation resulted from a reduction in KD and an increase in steady-state binding level (Req). As shown previously for plant 14-3-3s, fluorescent probes also indicated that yeast BMH2 interacted directly with cations, which bind and affect surface hydrophobicity. Binding of 14-3-3s to the phosphopeptide ligand occurred in the absence of divalent cations when the pH was reduced below neutral, and the basis for enhanced binding was a reduction in KD. At pH 7.5 (+Mg2+), AMP inhibited binding of plant 14-3-3s to the NR based peptide ligand. The binding of AMP to 14-3-3s was directly demonstrated by equilibrium dialysis (plant), and from the observation that recombinant plant 14-3-3s have a low, but detectable, AMP phosphatase activity. [ABSTRACT FROM AUTHOR]

One of the most commonly used methods for determining whether two proteins can interact is co-immunoprecipitation. Co-immunoprecipitation relies on the ability of an antibody to stably and specifically bind complexes containing a bait protein. The antibody provides a means of immobilizing these complexes on a solid matrix, which in the protocol presented here is accomplished through interaction with Protein A, so that irrelevant proteins can be washed away. The presence of target proteins in the bait complexes is determined by Western blot. Because of the biochemical diversity of protein-protein interactions, it is not possible to describe a single set of conditions that will work for every immunoprecipitation experiment. Instead, the goal of this chapter is to provide practical starting conditions for co-immunoprecipitation assays and to describe potential modifications to the procedure so that conditions can be optimized.

The Internet is now an essential tool for scientists. This chapter presents a beginner's guide to some of the valuable resources freely available on the Internet that are relevant to the study of protein-protein interactions. The format is designed to parallel a typical experimental project, indicating web sites to visit at each step. Although detailed instructions for using each site are not provided, the goal of each visit and what kind of information you can expect to obtain are indicated. A final section lists some directory sites that can point to additional web tools.