Important Structural Features of Thiolate-Rich Four-Helix Bundles for Cu(I) Uptake and Removal.

A family of bacterial copper storage proteins (the Csps) possess thiolate-lined four-helix bundles whose cores can be filled with Cu(I) ions. The majority of Csps are cytosolic (Csp3s), and in vitro studies carried out to date indicate that the Csp3s from Methylosinus trichosporium OB3b (MtCsp3), Bacillus subtilis (BsCsp3), and Streptomyces lividans (SlCsp3) are alike. Bioinformatics have highlighted homologues with potentially different Cu(I)-binding properties from these characterized "classical" Csp3s. Determination herein of the crystal structure of the protein (RkCsp3) from the methanotroph Methylocystis sp. strain Rockwell with Cu(I) bound identifies this as the first studied example of a new subgroup of Csp3s. The most significant structural difference from classical Csp3s is the presence of only two Cu(I) sites at the mouth of the bundle via which Cu(I) ions enter and leave. This is due to the absence of three Cys residues and a His-containing motif, which allow classical Csp3s to bind five to six Cu(I) ions in this region. Regardless, RkCsp3 exhibits rapid Cu(I) binding and the fastest measured Cu(I) removal rate for a Csp3 when using high-affinity ligands as surrogate partners. New experiments on classical Csp3s demonstrate that their His-containing motif is not essential for fast Cu(I) uptake and removal. Other structural features that could be important for these functionally relevant in vitro properties are discussed.

Review of Mechanisms and Research Methods for Blunt Ballistic Head Injury.

Head injuries account for 15%-20% of all military injuries and pose a high risk of causing functional disability and fatality. Blunt ballistic impacts are one of the threats that can lead to severe head injuries. This review aims to examine the mechanisms and injury risk assessment associated with blunt ballistic head injury (BBHI). The review further discusses research methods and instrumentation used in BBHI studies, focusing on their limitations and challenges. Studies on the mechanisms of focal and diffuse brain injuries remain largely inconclusive and require further effort. Some studies have attempted to associate BBHIs with head mechanics, but more research is required to establish correlations between head mechanics and injury severity. Limited access to experimental models and a lack of instrumentation capable of measuring the mechanics of brain tissue in situ are potential reasons for the lack of understanding of injury mechanisms, injury correlations, and injury tolerance levels specific to this loading regime. Targeted research for understanding and assessing head injuries in blunt ballistic impacts is a necessary step in improving our ability to design protection systems to mitigate these injuries.

The Mechanical Characterization and Comparions of Male and Female Calvaria Under Four-Point Bending Impacts.

The circumstances in which we mechanically test and critically assess human calvarium tissue would find relevance under conditions encompassing real-world head impacts. These conditions include, among other variables, impact velocities, and strain rates. Compared to quasi-static loading on calvaria, there is less reporting on the impact loading of the calvaria and consequently, there are relatively fewer mechanical properties on calvaria at relevant impact loading rates available in the literature. The purpose of this work was to report on the mechanical response of 23 human calvarium specimens subjected to dynamic four-point bending impacts. Impacts were performed using a custom-built four-point impact apparatus at impact velocities of 0.86-0.89 m/s resulting in surface strain rates of 2-3/s-representative of strain rates observed in vehicle collisions and blunt impacts. The study revealed comparable effective bending moduli (11-15 GPa) to the limited work reported on the impact mechanics of calvaria in the literature, however, fracture bending stress (10-47 MPa) was relatively less. As expected, surface strains at fracture (0.21-0.25%) were less compared to studies that performed quasi-static bending. Moreover, the study revealed no significant differences in mechanical response between male and female calvaria. The findings presented in this work are relevant to many areas including validating surrogate skull fracture models in silico or laboratory during impact and optimizing protective devices used by civilians to reduce the risk of a serious head injury.

A four-helix bundle stores copper for methane oxidation.

Methane-oxidizing bacteria (methanotrophs) require large quantities of copper for the membrane-bound (particulate) methane monooxygenase. Certain methanotrophs are also able to switch to using the iron-containing soluble methane monooxygenase to catalyse methane oxidation, with this switchover regulated by copper. Methane monooxygenases are nature's primary biological mechanism for suppressing atmospheric levels of methane, a potent greenhouse gas. Furthermore, methanotrophs and methane monooxygenases have enormous potential in bioremediation and for biotransformations producing bulk and fine chemicals, and in bioenergy, particularly considering increased methane availability from renewable sources and hydraulic fracturing of shale rock. Here we discover and characterize a novel copper storage protein (Csp1) from the methanotroph Methylosinus trichosporium OB3b that is exported from the cytosol, and stores copper for particulate methane monooxygenase. Csp1 is a tetramer of four-helix bundles with each monomer binding up to 13 Cu(I) ions in a previously unseen manner via mainly Cys residues that point into the core of the bundle. Csp1 is the first example of a protein that stores a metal within an established protein-folding motif. This work provides a detailed insight into how methanotrophs accumulate copper for the oxidation of methane. Understanding this process is essential if the wide-ranging biotechnological applications of methanotrophs are to be realized. Cytosolic homologues of Csp1 are present in diverse bacteria, thus challenging the dogma that such organisms do not use copper in this location.

Evaluation of the Kinematic Biofidelity and Inter-Test Repeatability of Global Accelerations and Brain Parenchyma Pressure for a Head-Brain Physical Model.

Head surrogates are widely used in biomechanical research and headgear assessment. They are designed to approximate the inertial and mechanical properties of the head and are instrumented to measure global head kinematics. Due to the recent interest in studying disruption to the brain, some head models include internal fluid layers and brain tissue, and instrumentation to measure head intracranial biomechanics. However, it is unknown whether such models exhibit realistic human responses. Therefore, this study aims to assess the biofidelity and repeatability of a head model, the Blast Injury Protection Evaluation Device (BIPED), that can measure both global head kinematics and intraparenchymal pressure (IPP) for application in blunt impact, a common loading scenario in civilian life. Drop tests were conducted with the BIPED and the widely used Hybrid III headform. BIPED measures were compared to the Hybrid III data and published cadaveric data, and the biofidelity level of the global linear acceleration was quantified using CORrelation and Analysis (CORA) ratings. The repeatability of the acceleration and IPP measurements in multiple impact scenarios was evaluated via the coefficient of variation (COV) of the magnitudes and pulse durations. BIPED acceleration peaks were generally not significantly different from cadaver and Hybrid III data. The CORA ratings for the BIPED and Hybrid III accelerations ranged from 0.50 to 0.61 and 0.51 to 0.77, respectively. The COVs of acceleration and IPP were generally below 10%. This study is an important step toward a biofidelic head surrogate measuring both global kinematics and IPP in blunt impact.

Confounding Bias in the Relationship Between Problem Gambling and Crime.

Although the relationship between problem gambling and criminal behavior has been widely researched, concerns over the causal nature of this association remain. Some argue that problem gambling does not lead to crime; instead, the same background characteristics that predict problem gambling also predict criminal behavior. Yet, studies suggestive of a spurious association often rely on small, non-random, and cross-sectional samples; thus, the extent to which the findings are generalizable to the broader population is unknown. With this in mind, the present study uses data from The National Longitudinal Study of Adolescent to Adult Health and a series of propensity score weighting and matching techniques to examine the role of confounding bias in the relationship between problem gambling and criminal behavior in young adulthood. On the surface, results show a positive and significant relationship between problem gambling and a range of criminal behaviors. However, after statistically balancing differences in several background measures between problem gamblers and non-problem gamblers, such as low self-control, past substance use, and juvenile delinquency, we find no significant relationship between problem gambling and crime. These patterns are consistent across several propensity score weighting and matching algorithms. Our results therefore parallel those in support of the "generality of deviance" framework, whereby a similar set of covariates known to be associated with criminal behavior also predict problem gambling.

On the ability of experimental impact measures to predict tooth injuries in an ex vivo swine model.

BACKGROUND/AIM: Impact to the orofacial region, in particular teeth, is a frequent incident leading to injury in many sports and can result in health and economic costs for the injured individual. The majority of previous work has applied synthetic models such as plaster or stone, to form analogs of relevant structures to study the potential for impact-induced injury. Biomechanical studies that have applied tissue models (animal or human) for the purpose of determining the biomechanical measures associated with dental injury are rare. The aim of this study was to apply a simple ex vivo model based on swine dentition to ascertain which of a select list of measurable quantities associated with impact mechanics could predict luxation and fracture of teeth due to impact. METHODS: Mandibular central incisors of ex vivo swine dentitions were impacted using a linear drop tower with heights ranging from 1.20 m to 2.42 m. Seven mechanical predictors were assessed at impact and were then subjected to binary logistic regression techniques to determine which was the best predictor of luxations or fractures of the teeth. RESULTS: Of the seven mechanical predictors, (1) the velocity of the impacting body (R2  = 0.477), (2) a proxy measure for the change in kinetic energy of the impacting body (R2  = 0.586), and (3) the approximate energy absorbed by the tissue (R2  = 0.722) were found to be statistically significantly different (p < .05), offering the greatest specificity as indicated by receiver operator characteristics. Other measures that are frequently used in impact mechanics, including peak linear acceleration and velocity change, were not statistically significant predictors of tooth injury. CONCLUSION: Identifying mechanical predictors for dental injury of unprotected teeth provides a first step in understanding which aspects of an impact event attribute to dental injury and can lay the foundation for future studies that examine alteration in injury mechanics associated with protection devices.

Protective Headgear Attenuates Forces on the Inner Table and Pressure in the Brain Parenchyma During Blast and Impact: An Experimental Study Using a Simulant-Based Surrogate Model of the Human Head.

Military personnel sustain head and brain injuries as a result of ballistic, blast, and blunt impact threats. Combat helmets are meant to protect the heads of these personnel during injury events. Studies show peak kinematics and kinetics are attenuated using protective headgear during impacts; however, there is limited experimental biomechanical literature that examines whether or not helmets mitigate peak mechanics delivered to the head and brain during blast. While the mechanical links between blast and brain injury are not universally agreed upon, one hypothesis is that blast energy can be transmitted through the head and into the brain. These transmissions can lead to rapid skull flexure and elevated pressures in the cranial vault, and, therefore, may be relevant in determining injury likelihood. Therefore, it could be argued that assessing a helmet for the ability to mitigate mechanics may be an appropriate paradigm for assessing the potential protective benefits of helmets against blast. In this work, we use a surrogate model of the head and brain to assess whether or not helmets and eye protection can alter mechanical measures during both head-level face-on blast and high forehead blunt impact events. Measurements near the forehead suggest head protection can attenuate brain parenchyma pressures by as much as 49% during blast and 52% during impact, and forces on the inner table of the skull by as much as 80% during blast and 84% during impact, relative to an unprotected head.

Bacterial copper storage proteins.

Copper is essential for most organisms as a cofactor for key enzymes involved in fundamental processes such as respiration and photosynthesis. However, copper also has toxic effects in cells, which is why eukaryotes and prokaryotes have evolved mechanisms for safe copper handling. A new family of bacterial proteins uses a Cys-rich four-helix bundle to safely store large quantities of Cu(I). The work leading to the discovery of these proteins, their properties and physiological functions, and how their presence potentially impacts the current views of bacterial copper handling and use are discussed in this review.

The Coordination Chemistry of Copper Uptake and Storage for Methane Oxidation.

Methanotrophs are remarkable bacteria that utilise large quantities of copper (Cu) to oxidize the potent greenhouse gas methane. To assist in providing the Cu they require for this process some methanotrophs can secrete the Cu-sequestering modified peptide methanobactin. These small molecules bind CuI with very high affinity and crystal structures have given insight into why this is the case, and also how the metal ion may be released within the cell. A much greater proportion of methanotrophs, genomes of which have been sequenced, possess a member of a newly discovered bacterial family of copper storage proteins (the Csps). These are tetramers of four-helix bundles whose cores are lined with Cys residues enabling the binding of large numbers of CuI ions. In methanotrophs, a Csp exported from the cytosol stores CuI for the active site of the ubiquitous enzyme that catalyses the oxidation of methane. The presence of cytosolic Csps, not only in methanotrophs but in a wide range of bacteria, challenges the dogma that these organisms have no requirement for Cu in this location. The properties of the Csps, with an emphasis on CuI binding and the structures of the sites formed, are the primary focus of this review.

A Laboratory Study on Effects of Cycling Helmet Fit on Biomechanical Measures Associated With Head and Neck Injury and Dynamic Helmet Retention.

There is a scant biomechanical literature that tests, in a laboratory setting, whether or not determinants of helmet fit affect biomechanical parameters associated with injury. Using conventional cycling helmets and repeatable models of the human head and neck, integrated into a guided drop impact experiment at speeds up to 6 m/s, this study tests the hypothesis that fit affects head kinematics, neck kinetics, and the extent to which the helmet moves relative to the underlying head (an indicator of helmet positional stability). While there were a small subset of cases where head kinematics were statistically significantly altered by fit, when viewed as a whole our measures of head kinematics suggest that fit does not systematically alter kinematics of the head secondary to impact. Similarly, when viewed as a whole, our data suggest that fit does not systematically alter resultant neck compression and resultant moment and associated biomechanical measures. Our data suggest that backward fit helmets exhibit the worst dynamic stability, in particular when the torso is impacted before the helmeted head is impacted, suggesting that the typical certification method of dynamical loading of a helmet to quantify retention may not be representative of highly plausible cycling incident scenarios where impact forces are first applied to the torso leading to loading of the neck prior to the head. Further study is warranted so that factors of fit that affect injury outcome are uncovered in both laboratory and real-world settings.

Cytosolic Copper Binding by a Bacterial Storage Protein and Interplay with Copper Efflux.

Escherichia coli has a well-characterized copper (Cu) transporting ATPase (CopA) that removes this potentially toxic metal ion from the cytosol. Growth of the strain lacking CopA (ΔcopA) is inhibited above 0.5 mM Cu, whilst a similar effect does not occur in wild type (WT) E. coli until over 2.5 mM Cu. Limited expression of CopA can restore growth to WT levels in ΔcopA E. coli in the presence of Cu. To study the influence of a bacterial cytosolic Cu storage protein (Csp3) on how E. coli handles Cu, the protein from Bacillus subtilis (BsCsp3) has been expressed in the WT and ΔcopA strains. BsCsp3 can protect both strains from Cu toxicity, promoting growth at up to ~1.5 and ~3.5 mM Cu, respectively. Higher levels of Csp3 expression are needed to provide resistance to Cu toxicity in ΔcopA E. coli. At 1.5 mM Cu, BsCsp3 purified from ΔcopA E. coli binds up to approximately four equivalents of Cu(I) per monomer. A similar number of Cu(I) equivalents can be bound by BsCsp3 purified from WT E. coli also grown at 1.5 mM Cu, a concentration that does not cause toxicity in this strain. Much lower amounts of BsCsp3 are produced in WT E. coli grown in the presence of 3.4 mM Cu, but the protein still counteracts toxicity and is almost half loaded with Cu(I). Csp3s can protect E. coli from Cu toxicity by sequestering cuprous ions in the cytosol. This appears to include an ability to acquire and withhold Cu(I) from the main efflux system in a heterologous host.

Postsecondary Education, Neighborhood Disadvantage, and Crime: An Examination of Life Course Relative Deprivation.

The growing importance of a college degree for economic stability, coupled with increasing educational inequality in the United States, suggest potential criminogenic implications for downward educational mobility. Using data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), this article examines the associations between intergenerational educational mobility, neighborhood disadvantage in adulthood, and crime. Drawing on the few extant studies of educational mobility and crime, as well as social comparison theory, it tests whether the consequences of downward educational mobility are moderated by neighborhood contexts. Results suggest that downward mobility is associated with increases in crime, and most strongly in more advantaged neighborhoods. The implications of these findings for future research on social mobility, education, and crime are discussed.

Insight into Metal Removal from Peptides that Sequester Copper for Methane Oxidation.

Methanobactins (Mbns) are modified peptides that sequester copper (Cu) methanotrophs use to oxidize methane. Limited structural information is available for this class of natural products, as is an understanding of how cells are able to utilize Mbn-bound Cu. The crystal structure of Methylosinus sporium NR3K CuI -Mbn provides further information about the structural diversity of Mbns and the first insight into their Cu-release mechanism. Nitrogen ligands from oxazolone and pyrazinediol rings chelate CuI along with adjacent coordinating sulfurs from thioamides. In vitro solution data are consistent with a CuI -Mbn monomer as found for previously characterized Mbns. In the crystal structure, the N-terminal region has undergone a conformational change allowing the formation of a CuI2 -Mbn2 dimer with CuI sites bound by chelating units from adjacent chains. Such a structural alteration will facilitate CuI release from Mbns.

The More You Have, The More You Lose: Criminal Justice Involvement, Ascribed Socioeconomic Status, and Achieved SES.

In the present study, we examine the relationship between involvement in the criminal justice system and achieved socioeconomic status (SES), as well as the moderating effect of ascribed SES. Using data from the National Longitudinal Study of Adolescent to Adult Health, we find a nonlinear relationship between criminal justice involvement and achieved SES, such that deeper involvement leads to increasingly negative consequences on achieved SES. Furthermore, those coming from the highest socioeconomic backgrounds are not "protected" from the deleterious consequences of system involvement, but instead experience the greatest declines in achieved SES relative to where they started. In contrast, the effect of criminal justice involvement for those from below average ascribed SES is not significant. Our findings reinforce how normal such experiences are for people with the fewest resources, and also how system involvement inevitably destroys human capital, undermines future life chances, and ultimately promotes a "rabble" class.

Accuracy of a Wearable Sensor for Measures of Head Kinematics and Calculation of Brain Tissue Strain.

Wearable kinematic sensors can be used to study head injury biomechanics based on kinematics and, more recently, based on tissue strain metrics using kinematics-driven brain models. These sensors require in-situ calibration and there is currently no data conveying wearable ability to estimate tissue strain. We simulated head impact (n = 871) to a 50th percentile Hybrid III (H-III) head wearing a hockey helmet instrumented with wearable GForceTracker (GFT) sensors measuring linear acceleration and angular velocity. A GFT was also fixed within the H-III head to establish a lower boundary on systematic errors. We quantified GFT errors relative to H-III measures based on peak kinematics and cumulative strain damage measure (CSDM). The smallest mean errors were 12% (peak resultant linear acceleration) and 15% (peak resultant angular velocity) for the GFT within the H-III. Errors for GFTs on the helmet were on average 54% (peak resultant linear acceleration) and 21% (peak resultant angular velocity). On average, the GFT inside the helmet overestimated CSDM by 0.15.

Visualizing Biological Copper Storage: The Importance of Thiolate-Coordinated Tetranuclear Clusters.

Bacteria possess cytosolic proteins (Csp3s) capable of binding large quantities of copper and preventing toxicity. Crystal structures of a Csp3 plus increasing amounts of CuI provide atomic-level information about how a storage protein loads with metal ions. Many more sites are occupied than CuI equiv added, with binding by twelve central sites dominating. These can form [Cu4 (S-Cys)4 ] intermediates leading to [Cu4 (S-Cys)5 ]- , [Cu4 (S-Cys)6 ]2- , and [Cu4 (S-Cys)5 (O-Asn)]- clusters. Construction of the five CuI sites at the opening of the bundle lags behind the main core, and the two least accessible sites at the opposite end of the bundle are occupied last. Facile CuI cluster formation, reminiscent of that for inorganic complexes with organothiolate ligands, is largely avoided in biology but is used by proteins that store copper in the cytosol of prokaryotes and eukaryotes, where this reactivity is also key to toxicity.

Educational Pathways and Change in Crime Between Adolescence and Early Adulthood.

OBJECTIVES: This article examines the relationship between intergenerational educational pathways and change in crime. Moreover, it examines the potential mediating roles of family and employment transitions, economic stressors, and social psychological factors. METHOD: Data from the National Longitudinal Study of Adolescent to Adult Health (N = 14,742) and negative binomial models are used to assess associations between educational pathways (i.e., upward, downward, and stable) and change in crime between adolescence and early adulthood. Selection effects are assessed with lagged dependent variables and controls for self-control, grades, and the Add Health Picture Vocabulary Test. RESULTS: Intergenerational educational pathways are significantly associated with changes in crime. Downward educational pathways were predictive of increases in crime, whereas upward pathways were associated with decreases in crime. These associations were partly mediated by family transitions, and more strongly by economic stressors. These results were robust to controls for selection related variables. CONCLUSIONS: This study is among the first to examine the relationship between intergenerational educational pathways and crime in the United States. Both upward and downward changes in educational attainments were found to be significant for crime. These findings are notable given the continuing expansion of higher education as well as concerns regarding increasing stratification and downward mobility in the United States.

Variations in methanobactin structure influences copper utilization by methane-oxidizing bacteria.

Methane-oxidizing bacteria are nature's primary biological mechanism for suppressing atmospheric levels of the second-most important greenhouse gas via methane monooxygenases (MMOs). The copper-containing particulate enzyme is the most widespread and efficient MMO. Under low-copper conditions methane-oxidizing bacteria secrete the small copper-binding peptide methanobactin (mbtin) to acquire copper, but how variations in the structures of mbtins influence copper metabolism and species selection are unknown. Methanobactins have been isolated from Methylocystis strains M and hirsuta CSC1, organisms that can switch to using an iron-containing soluble MMO when copper is limiting, and the nonswitchover Methylocystis rosea. These mbtins are shorter, and have different amino acid compositions, than the characterized mbtin from Methylosinus trichosporium OB3b. A coordinating pyrazinedione ring in the Methylocystis mbtins has little influence on the Cu(I) site structure. The Methylocystis mbtins have a sulfate group that helps stabilize the Cu(I) forms, resulting in affinities of approximately 10(21) M(-1). The Cu(II) affinities vary over three orders of magnitude with reduction potentials covering approximately 250 mV, which may dictate the mechanism of intracellular copper release. Copper uptake and the switchover from using the iron-containing soluble MMO to the copper-containing particulate enzyme is faster when mediated by the native mbtin, suggesting that the amino acid sequence is important for the interaction of mbtins with receptors. The differences in structures and properties of mbtins, and their influence on copper utilization by methane-oxidizing bacteria, have important implications for the ecology and global function of these environmentally vital organisms.

A qualitative review of sports concussion education: prime time for evidence-based knowledge translation.

BACKGROUND: Educating athletes, coaches, parents and healthcare providers about concussion management is a public health priority. There is an abundance of information on sports concussions supported by position statements from governing sport and medical organisations. Yet surveys of athletes, parents, coaches and healthcare providers continue to identify multiple barriers to the successful management of sports concussion. To date, efforts to provide education using empirically sound methodologies are lacking. PURPOSE: To provide a comprehensive review of scientific research on concussion education efforts and make recommendations for enhancing these efforts. STUDY DESIGN: Qualitative literature review of sports concussion education. METHODS: Databases including PubMed, Sport Discus and MEDLINE were searched using standardised terms, alone and in combination, including 'concussion', 'sport', 'knowledge', 'education' and 'outcome'. RESULTS: Studies measuring the success of education interventions suggest that simply presenting available information may help to increase knowledge about concussions, but it does not produce long-term changes in behaviour among athletes. Currently, no empirical reviews have evaluated the success of commercially available sports concussion applications. The most successful education efforts have taken steps to ensure materials are user-friendly, interactive, utilise more than one modality to present information and are embedded in mandated training programmes or support legislation. Psychosocial theory-driven methods used to understand and improve 'buy in' from intended audiences have shown promise in changing behaviour. CONCLUSIONS: More deliberate and methodologically sound steps must be taken to optimise education and knowledge translation efforts in sports concussion.