RCT of a High‐protein Diet on Hunger Motivation and Weight‐loss in Obese Children: An Extension and Replication

This study aimed to evaluate the weight loss and hunger motivation effects of an energy‐restricted high‐protein (HP) diet in overweight and obese children. In total, 95 overweight and obese children attended an 8‐week (maximum) program of physical activity, reduced‐energy intake, and behavior change education. Children were randomly assigned to one of two isoenergetic diets (standard (SP): 15% protein; HP: 25% protein), based on individually estimated energy requirements. Anthropometry and body composition were assessed at the start and end of the program and appetite and mood ratings completed on the first 3 consecutive weekdays of each week children attended camp. The HP diet had no greater effect on weight loss, body composition, or changes in appetite or mood when compared to the SP diet. Overall, campers lost 5.2 ± 3.0 kg in body weight and reduced their BMI standard deviation score (sds) by 0.25. Ratings of desire to eat increased significantly over the duration of the intervention, irrespective of diet. This is the third time we have reported an increase in hunger motivation in weight‐loss campers and replicates our previous failure to block this with a higher protein diet. Further work is warranted into the management of hunger motivation as a result of negative energy balance.     

Using Short-Term Tests to Predict Carcinogenic Activity in the Long-Term Bioassay

A method for classifying chemicals with respect to carcinogenic potential based on short-term test results is presented. The method utilizes the logistic regression model to translate results from short-term toxicity assays into predictions of the likelihood that a chemical will be carcinogenic if tested in a long-term bioassay. The proposed method differs from previous approaches in two ways. First, statistical confidence limits on probabilities of cancer rather than central estimates of those probabilities are used for classification. Second, the method does not classify all chemicals in a data base with respect to carcinogenic potential. Instead, it identifies chemicals with highest and lowest likelihood of testing positive for carcinogenicity in the bioassay. A subset of chemicals with intermediate likelihood of being positive remains unclassified, and will require further testing, perhaps in a long-term bioassay. Two data bases of binary short-term and long-term test results from the literature are used to illustrate and evaluate the proposed procedure. A cross-validation analysis of one of the data sets suggests that, for a sufficiently rich data base of chemicals, the development of a robust predictive system to replace the bioassay for some unknown chemicals is a realistic goal.     

Connection between internal representation of rigid transformation and cortical activity paths

A canonical unitary representation of the Euclidean group on the range space of the Gabor transform is constructed from mathematical properties of the Euclidean group and the quaternions. The visual cortical activity pattern corresponding to a given retinal image is represented by a point in the range space of the Gabor transform. Paths experienced in apparent motion and mental rotation are represented by paths in the Euclidean group. The key hypothesis of the paper is that an action of the Euclidean group on the Gabor transform space brings the perceived paths into relation with corresponding successive neural microstructure activity patterns. Possible experimental tests are suggested.     

Highly efficient somatic-mutation identification using Escherichia coli mismatch-repair detection

The discovery of somatic mutations in cancer tissue is extremely laborious, time-consuming and costly. In an evaluation comparing mismatch repair detection (MRD) against Sanger sequencing for somatic-mutation detection, we found that MRD had a specificity of 96% and a sensitivity of 92%. Our results showed that MRD is a robust and cost-effective alternative to Sanger sequencing for identifying somatic mutations in human tumors.     

The structure of Mlc titration factor A (MtfA/YeeI) reveals a prototypical zinc metallopeptidase related to anthrax lethal factor

MtfA of Escherichia coli (formerly YeeI) was previously identified as a regulator of the phosphoenolpyruvate (PEP)-dependent:glucose phosphotransferase system. MtfA homolog proteins are highly conserved, especially among beta- and gammaproteobacteria. We determined the crystal structures of the full-length MtfA apoenzyme from Klebsiella pneumoniae and its complex with zinc (holoenzyme) at 2.2 and 1.95 Å, respectively. MtfA contains a conserved H¹⁴⁹E¹⁵⁰XXH¹⁵³+E²¹²+Y²⁰⁵ metallopeptidase motif. The presence of zinc in the active site induces significant conformational changes in the region around Tyr205 compared to the conformation of the apoenzyme. Additionally, the zinc-bound MtfA structure is in a self-inhibitory conformation where a region that was disordered in the unliganded structure is now observed in the active site and a nonproductive state of the enzyme is formed. MtfA is related to the catalytic domain of the anthrax lethal factor and the Mop protein involved in the virulence of Vibrio cholerae, with conservation in both overall structure and in the residues around the active site. These results clearly provide support for MtfA as a prototypical zinc metallopeptidase (gluzincin clan).     

Measurement of replication structures at the nanometer scale using super-resolution light microscopy

DNA replication, similar to other cellular processes, occurs within dynamic macromolecular structures. Any comprehensive understanding ultimately requires quantitative data to establish and test models of genome duplication. We used two different super-resolution light microscopy techniques to directly measure and compare the size and numbers of replication foci in mammalian cells. This analysis showed that replication foci vary in size from 210 nm down to 40 nm. Remarkably, spatially modulated illumination (SMI) and 3D-structured illumination microscopy (3D-SIM) both showed an average size of 125 nm that was conserved throughout S-phase and independent of the labeling method, suggesting a basic unit of genome duplication. Interestingly, the improved optical 3D resolution identified 3- to 5-fold more distinct replication foci than previously reported. These results show that optical nanoscopy techniques enable accurate measurements of cellular structures at a level previously achieved only by electron microscopy and highlight the possibility of high-throughput, multispectral 3D analyses.     

Sequence-dependent sorting of recycling proteins by actin-stabilized endosomal microdomains

The functional consequences of signaling receptor endocytosis are determined by the endosomal sorting of receptors between degradation and recycling pathways. How receptors recycle efficiently, in a sequence-dependent manner that is distinct from bulk membrane recycling, is not known. Here, in live cells, we visualize the sorting of a prototypical sequence-dependent recycling receptor, the beta-2 adrenergic receptor, from bulk recycling proteins and the degrading delta-opioid receptor. Our results reveal a remarkable diversity in recycling routes at the level of individual endosomes, and indicate that sequence-dependent recycling is an active process mediated by distinct endosomal subdomains distinct from those mediating bulk recycling. We identify a specialized subset of tubular microdomains on endosomes, stabilized by a highly localized but dynamic actin machinery, that mediate this sorting, and provide evidence that these actin-stabilized domains provide the physical basis for a two-step kinetic and affinity-based model for protein sorting into the sequence-dependent recycling pathway.