Superantigen architecture: Functional decoration on a conserved scaffold

A defining and consistent feature of the bacterial superantigens from Staphylococcus aureus and Streptococcus pyogenes is their strongly conserved three-dimensional structure. Structural studies to date show that the array of more than 280 amino acid sequences known for superantigens (SAgs) and staphylococcal superantigen-like (SSL) proteins all have the same fold-a structure in which the same three-dimensional arrangement of α-helices and β-sheets is traced by each amino acid sequence, with the same topology (for recent reviews, see references 29 and 43). A typical SAg structure comprises two domains-an N-terminal β -barrel domain called an OB-fold (4, 25) and a C-terminal β-grasp domain in which a long α-helix packs on to a mixed parallel and antiparallel β-sheet. These two domains are traversed by an α-helix that lies at the N terminus of the protein and packs against the β-grasp domain, thus linking the N- and C-terminal domains

Race, Xenophobia, and Punitiveness Among the American Public

We outline four connections between xenophobia and punitiveness toward criminals in a national sample of Americans. First, among self-identified whites xenophobia is more predictive of punitiveness than specific forms of racial animus. Second, xenophobia and punitiveness are strongly connected among whites, but are only moderately and weakly related among black and Hispanic Americans, respectively. Third, among whites substantial proportions of the variance between sociodemographic, political, and religious predictors of punitiveness are mediated by levels of xenophobia. Finally, xenophobia is the strongest overall predictor of punitiveness among whites. Overall, xenophobia is an essential aspect of understanding public punitiveness, particularly among whites

Microfiltration in oceanographic research I. Marine sampling with the molecular filter

Molecular filters, composed of cellulose acetate and nitrate membranes, may be used for the quantitative estimation of microplankton populations, for the determination of suspended organic and inorganic matter in natural waters, and in studies of photosynthetic productivity by phytoplankton cells in collected samples...

Accuracy of work history obtained from a spouse

In an evaluation of the usefulness of collecting work exposure information from wives of workers, 26 husband-wife pairs were interviewed separately about exposure of the husband to organic solvents. There was 58% concordance between the husbands and wives for answers to a simple question regarding solvent exposure. Amplification of these answers through the use of a computerized occupation-exposure linkage system yielded 81% concordance. When the analysis was restricted to those reporting exposure to solvents for more than five years, an 88% concordance was achieved with the linkage system. It was concluded that wives can accurately recall their husbands\u27 work histories with respect to jobs having solvent exposure. The exposure specificity of such histories is significantly enhanced by the use of an occupation-exposure linkage system

The structure of glucose-fructose oxidoreductase from Zymomonas mobilis: an osmoprotective periplasmic enzyme containing non-dissociable NADP

AbstractBackground The organism Zymomonas mobilis occurs naturally in sugar-rich environments. To protect the bacterium against osmotic shock, the periplasmic enzyme glucose-fructose oxidoreductase (GFOR) produces the compatible, solute sorbitol by reduction of fructose, coupled with the oxidation of glucose to gluconolactone. Hence, Z. mobilis can tolerate high concentrations of sugars and this property may be useful in the development of an efficient microbial process for ethanol production. Each enzyme subunit contains tightly associated NADP which is not released during the catalytic cycle.Results The structure of GFOR was determined by X-ray crystallography at 2.7 å resolution. Each subunit of the tetrameric enzyme comprises two domains, a classical dinucleotide-binding domain, and a C-terminal domain based on a predominantly antiparallel nine-stranded β sheet. In the tetramer, the subunits associate to form two extended 18-stranded β sheets, which pack against each other in a face to face fashion, creating an extensive interface at the core of the tetramer. An N-terminal arm from each subunit wraps around the dinucleotide-binding domain of an adjacent subunit, covering the adenine ring of NADP.Conclusions In GFOR, the NADP is found associated with a classical dinucleotide-binding domain in a conventional fashion. The NADP is effectively buried in the protein-subunit interior as a result of interactions with the N-terminal arm from an adjacent subunit in the tetramer, and with a short helix from the C-terminal domain of the protein. This accounts for NADP's inability to dissociate. The N-terminal arm may also contribute to stabilization of the tetramer. The enzyme has an unexpected structural similarity with the cytoplasmic enzyme glucose-6-phosphate dehydrogenase (G6PD). We hypothesize that both enzymes have diverged from a common ancestor. The mechanism of catalysis is still unclear, but we have identified a conserved structural motif (Glu–Lys–Pro) in the active site of GFOR and G6PD that may be important for catalysis

Transcranial magnetic stimulation to the occipital place area biases gaze during scene viewing

We can understand viewed scenes and extract task-relevant information within a few hundred milliseconds. This process is generally supported by three cortical regions that show selectivity for scene images: parahippocampal place area (PPA), medial place area (MPA) and occipital place area (OPA). Prior studies have focused on the visual information each region is responsive to, usually within the context of recognition or navigation. Here, we move beyond these tasks to investigate gaze allocation during scene viewing. Eye movements rely on a scene’s visual representation to direct saccades, and thus foveal vision. In particular, we focus on the contribution of OPA, which is i) located in occipito-parietal cortex, likely feeding information into parts of the dorsal pathway critical for eye movements, and ii) contains strong retinotopic representations of the contralateral visual field. Participants viewed scene images for 1034 ms while their eye movements were recorded. On half of the trials, a 500 ms train of five transcranial magnetic stimulation (TMS) pulses was applied to the participant’s cortex, starting at scene onset. TMS was applied to the right hemisphere over either OPA or the occipital face area (OFA), which also exhibits a contralateral visual field bias but shows selectivity for face stimuli. Participants generally made an overall left-to-right, top-to-bottom pattern of eye movements across all conditions. When TMS was applied to OPA, there was an increased saccade latency for eye movements toward the contralateral relative to the ipsilateral visual field after the final TMS pulse (400ms). Additionally, TMS to the OPA biased fixation positions away from the contralateral side of the scene compared to the control condition, while the OFA group showed no such effect. There was no effect on horizontal saccade amplitudes. These combined results suggest that OPA might serve to represent local scene information that can then be utilized by visuomotor control networks to guide gaze allocation in natural scenes

Boundary Effects on the Determination of Metamaterial Parameters from Normal Incidence Reflection and Transmission Measurements

A method is described for the determination of the effective electromagnetic parameters of a metamaterial based only on external measurements or simulations, taking boundary effects at the interfaces between a conventional material and metamaterial into account. Plane-wave reflection and transmission coefficients at the interfaces are regarded as additional unknowns to be determined, rather than explicitly dependent on the material parameters. Our technique is thus analogous to the line-reflect-line (LRL) calibration method in microwave measurements. The refractive index can be determined from S-parameters for two samples of different thickness. The effective wave impedance requires the additional assumption that generalized sheet transition conditions (GSTCs) account for the boundary effects. Expressions for the bulk permittivity and permeability then follow easily. Our method is validated by comparison with the results using the Nicolson-Ross-Weir (NRW) for determining properties of an ordinary material measured in a coaxial line. Utilizing S-parameters obtained from 3-D full wave simulations, we test the method on magnetodielectric metamaterials. We compare the results from our method and the conventional one that does not consider boundary effects. Moreover, it is shown that results from our method are consistent under changes in reference plane location, whereas the results from other methods are not.Comment: 16 pages, 16 figures. Submitted to IEEE Transactions on Antennas and Propagatio

Preventing Leader Derailment—A Strategic Imperative for Public Health Agencies

Public health leaders, such as those who serve as state health officials (SHOs), routinely face challenges that are uncertain and complex. Those who reflect on the challenges they face and use those reflections to improve themselves and their teams develop into more effective leaders. Not addressing challenges can lead to the risk of premature “derailment.” In this column, we review research from the Center for Creative Leadership (CCL), a global authority in leadership development, which explores the underlying dynamics of derailment. We also share insights gained from ongoing research into SHO success discussed in prior Management Moment columns.1 , 2 Finally, we offer several thoughts on strategies for preventing derailment among senior public health leaders

Food Acceptability in Field Studies with US Army Men and Women: Relationship with Food Intake and Food Choice After Repeated Exposures

Laboratory data with single exposures showed that palatability has a positive relationship with food intake. The question addressed in this study is whether this relationship also holds over repeated exposures in non-laboratory contexts in more natural environments. The data were collected in four field studies, lasting 4–11 days with 307 US Army men and 119 Army women, and comprised 5791 main meals and 8831 snacks in total. Acceptability was rated on the nine point hedonic scale, and intake was registered in units of 1/4, 1/2, 3/4, or 1 or more times of the provided portion size. Correlation coefficients between individual acceptability ratings and intakes varied from 0.22 to 0.62 for the main meals (n=193–2267), and between 0.13 and 0.56 for the snacks (n=304–2967). The likelihood of choosing a meal for the second time was positively related to the acceptability rating of the meal when it was consumed for the first time. The results reinforce the importance of liking in food choice and food intake/choice behavior. However, the magnitude of the correlation coefficients between acceptability ratings and food intake suggest that environmental factors also have an important role in determining intake and choice