Regulator trafficking on bacterial transcription units in vivo.

The trafficking patterns of the bacterial regulators of transcript elongation sigma(70), rho, NusA, and NusG on genes in vivo and the explanation for promoter-proximal peaks of RNA polymerase (RNAP) are unknown. Genome-wide, E. coli ChIP-chip revealed distinct association patterns of regulators as RNAP transcribes away from promoters (rho first, then NusA, then NusG). However, the interactions of elongating complexes with these regulators did not differ significantly among most transcription units. A modest variation of NusG signal among genes reflected increased NusG interaction as transcription progresses, rather than functional specialization of elongating complexes. Promoter-proximal RNAP peaks were offset from sigma(70) peaks in the direction of transcription and co-occurred with NusA and rho peaks, suggesting that the RNAP peaks reflected elongating, rather than initiating, complexes. However, inhibition of rho did not increase RNAP levels within genes downstream from the RNAP peaks, suggesting the peaks are caused by a mechanism other than rho-dependent attenuation.

Surface hydrolysis of sphingomyelin by the outer membrane protein Rv0888 supports replication of Mycobacterium tuberculosis in macrophages.

Sphingomyelinases secreted by pathogenic bacteria play important roles in host-pathogen interactions ranging from interfering with phagocytosis and oxidative burst to iron acquisition. This study shows that the Mtb protein Rv0888 possesses potent sphingomyelinase activity cleaving sphingomyelin, a major lipid in eukaryotic cells, into ceramide and phosphocholine, which are then utilized by Mtb as carbon, nitrogen and phosphorus sources, respectively. An Mtb rv0888 deletion mutant did not grow on sphingomyelin as a sole carbon source anymore and replicated poorly in macrophages indicating that Mtb utilizes sphingomyelin during infection. Rv0888 is an unusual membrane protein with a surface-exposed C-terminal sphingomyelinase domain and a putative N-terminal channel domain that mediated glucose and phosphocholine uptake across the outer membrane in an M. smegmatis porin mutant. Hence, we propose to name Rv0888 as SpmT (sphingomyelinase of Mycobacterium tuberculosis). Erythrocyte membranes contain up to 27% sphingomyelin. The finding that Rv0888 accounts for half of Mtb's hemolytic activity is consistent with its sphingomyelinase activity and the observation that Rv0888 levels are increased in the presence of erythrocytes and sphingomyelin by 5- and 100-fold, respectively. Thus, Rv0888 is a novel outer membrane protein that enables Mtb to utilize sphingomyelin as a source of several essential nutrients during intracellular growth.

The scope of pediatric physical therapy practice in health promotion and fitness for youth with disabilities.

PURPOSE: The purpose of this report is to discuss the scope of pediatric physical therapy practice in health promotion and fitness for youth with disabilities. SUMMARY OF KEY POINTS: Evidence is provided that supports integration of health promotion and fitness strategies in physical therapy clinical management. Physical therapists' roles in community-based adapted sports and fitness interventions and reimbursement considerations are discussed. CONCLUSIONS: Physical therapists are in a unique position to provide expertise in the design and implementation of health promotion and fitness programs for youth with disabilities. These programs are important to promote active, healthy lifestyles and reduce comorbidities associated with sedentary behaviors and unhealthy weight, which are often seen in youth with disabilities. RECOMMENDATIONS FOR CLINICAL PRACTICE: Pediatric physical therapists should incorporate health promotion and fitness strategies into practice.

Behavior change techniques implemented in electronic lifestyle activity monitors: a systematic content analysis.

BACKGROUND: Electronic activity monitors (such as those manufactured by Fitbit, Jawbone, and Nike) improve on standard pedometers by providing automated feedback and interactive behavior change tools via mobile device or personal computer. These monitors are commercially popular and show promise for use in public health interventions. However, little is known about the content of their feedback applications and how individual monitors may differ from one another. OBJECTIVE: The purpose of this study was to describe the behavior change techniques implemented in commercially available electronic activity monitors. METHODS: Electronic activity monitors (N=13) were systematically identified and tested by 3 trained coders for at least 1 week each. All monitors measured lifestyle physical activity and provided feedback via an app (computer or mobile). Coding was based on a hierarchical list of 93 behavior change techniques. Further coding of potentially effective techniques and adherence to theory-based recommendations were based on findings from meta-analyses and meta-regressions in the research literature. RESULTS: All monitors provided tools for self-monitoring, feedback, and environmental change by definition. The next most prevalent techniques (13 out of 13 monitors) were goal-setting and emphasizing discrepancy between current and goal behavior. Review of behavioral goals, social support, social comparison, prompts/cues, rewards, and a focus on past success were found in more than half of the systems. The monitors included a range of 5-10 of 14 total techniques identified from the research literature as potentially effective. Most of the monitors included goal-setting, self-monitoring, and feedback content that closely matched recommendations from social cognitive theory. CONCLUSIONS: Electronic activity monitors contain a wide range of behavior change techniques typically used in clinical behavioral interventions. Thus, the monitors may represent a medium by which these interventions could be translated for widespread use. This technology has broad applications for use in clinical, public health, and rehabilitation settings.

A multicopper oxidase is required for copper resistance in Mycobacterium tuberculosis.

Mycobacterium tuberculosis, the causative agent of tuberculosis, is one of the most important bacterial pathogens. Recent work has revealed that the natural bactericidal properties of copper are utilized by the host immune system to combat infections with bacteria, including M. tuberculosis. However, M. tuberculosis employs multiple mechanisms to reduce the internal copper amount by efflux and sequestration, which are required for virulence of M. tuberculosis. Here, we describe an alternative mechanism of copper resistance by M. tuberculosis. Deletion of the rv0846c gene increased the susceptibility of M. tuberculosis to copper at least 10-fold, establishing Rv0846c as a major component of copper resistance in M. tuberculosis. In vitro assays showed that Rv0846c oxidized organic substrates and Fe(II). Importantly, mutation of the predicted copper-coordinating cysteine 486 resulted in inactive Rv0846c protein which did not protect M. tuberculosis against copper stress. Hence, Rv0846c is a multicopper oxidase of M. tuberculosis and was renamed mycobacterial multicopper oxidase (MmcO). MmcO is membrane associated, probably by lipidation after export across the inner membrane by the twin-arginine translocation system. However, mutation of the lipidation site did not affect the oxidase activity or the copper protective function of MmcO. Our study revealed MmcO as an important copper resistance mechanism of M. tuberculosis, which possibly acts by oxidation of toxic Cu(I) in the periplasm.

Porins increase copper susceptibility of Mycobacterium tuberculosis.

Copper resistance mechanisms are crucial for many pathogenic bacteria, including Mycobacterium tuberculosis, during infection because the innate immune system utilizes copper ions to kill bacterial intruders. Despite several studies detailing responses of mycobacteria to copper, the pathways by which copper ions cross the mycobacterial cell envelope are unknown. Deletion of porin genes in Mycobacterium smegmatis leads to a severe growth defect on trace copper medium but simultaneously increases tolerance for copper at elevated concentrations, indicating that porins mediate copper uptake across the outer membrane. Heterologous expression of the mycobacterial porin gene mspA reduced growth of M. tuberculosis in the presence of 2.5 µM copper by 40% and completely suppressed growth at 15 µM copper, while wild-type M. tuberculosis reached its normal cell density at that copper concentration. Moreover, the polyamine spermine, a known inhibitor of porin activity in Gram-negative bacteria, enhanced tolerance of M. tuberculosis for copper, suggesting that copper ions utilize endogenous outer membrane channel proteins of M. tuberculosis to gain access to interior cellular compartments. In summary, these findings highlight the outer membrane as the first barrier against copper ions and the role of porins in mediating copper uptake in M. smegmatis and M. tuberculosis.

Rho directs widespread termination of intragenic and stable RNA transcription.

The transcription termination factor Rho is a global regulator of RNA polymerase (RNAP). Although individual Rho-dependent terminators have been studied extensively, less is known about the sites of RNAP regulation by Rho on a genome-wide scale. Using chromatin immunoprecipitation and microarrays (ChIP-chip), we examined changes in the distribution of Escherichia coli RNAP in response to the Rho-specific inhibitor bicyclomycin (BCM). We found approximately 200 Rho-terminated loci that were divided evenly into 2 classes: intergenic (at the ends of genes) and intragenic (within genes). The intergenic class contained noncoding RNAs such as small RNAs (sRNAs) and transfer RNAs (tRNAs), establishing a previously unappreciated role of Rho in termination of stable RNA synthesis. The intragenic class of terminators included a previously uncharacterized set of short antisense transcripts, as judged by a shift in the distribution of RNAP in BCM-treated cells that was opposite to the direction of the corresponding gene. These Rho-terminated antisense transcripts point to a role of noncoding transcription in E. coli gene regulation that may resemble the ubiquitous noncoding transcription recently found to play myriad roles in eukaryotic gene regulation.

Microbial Inoculants: Silver Bullet or Microbial Jurassic Park?

The appeal of using microbial inoculants to mediate plant traits and productivity in managed ecosystems has increased over the past decade, because microbes represent an alternative to fertilizers, pesticides, and direct genetic modification of plants. Using microbes bypasses many societal and environmental concerns because microbial products are considered a more sustainable and benign technology. In our desire to harness the power of plant-microbial symbioses, are we ignoring the possibility of precipitating microbial invasions, potentially setting ourselves up for a microbial Jurassic Park? Here, we outline potential negative consequences of microbial invasions and describe a set of practices (Testing, Regulation, Engineering, and Eradication, TREE) based on the four stages of invasion to prevent microbial inoculants from becoming invasive. We aim to stimulate discussion about best practices to proactively prevent microbial invasions.

Multiple Salmonella-pathogenicity island 2 effectors are required to facilitate bacterial establishment of its intracellular niche and virulence.

The pathogenesis of Salmonella Typhimurium depends on the bacterium's ability to survive and replicate within host cells. The formation and maintenance of a unique membrane-bound compartment, termed the Salmonella-containing vacuole (SCV), is essential for S. Typhimurium pathogenesis. SCV-bound S. Typhimurium induces formation of filamentous tubules that radiate outwards from the SCV, termed Salmonella-induced filaments (SIFs). SIF formation is concomitant with the onset of replication within host epithelial cells. SIF biogenesis, formation and maintenance of the SCV, and the intracellular positioning of the SCV within the host cell requires translocation of bacterial proteins (effectors) into the host cell. Effectors secreted by the type III secretion system encoded on Salmonella pathogenicity island 2 (T3SS2) function to interfere with host cellular processes and promote both intracellular survival and replication of S. Typhimurium. Seven T3SS2-secreted effectors, SifA, SopD2, PipB2, SteA, SseJ, SseF, and SseG have previously been implicated to play complementary, redundant, and/or antagonistic roles with respect to SIF biogenesis, intracellular positioning of the SCV, and SCV membrane dynamics modulation during infection. We undertook a systematic study to delineate the contribution of each effector to these processes by (i) deleting all seven of these effectors in a single S. Typhimurium strain; and (ii) deleting combinations of multiple effectors based on putative effector function. Using this deletion mutant library, we show that each of SIF biogenesis, intracellular SCV localization, intramacrophage replication, colonization, and virulence depends on the activities of multiple effectors. Together, our data demonstrates the complex interplay between these seven effectors and highlights the necessity to study T3SS2-secreted effectors as groups, rather than studies of individual effectors.

Environmental barriers to and availability of healthy foods for people with mobility disabilities living in urban and suburban neighborhoods.

OBJECTIVE: To assess the impact of the built environment on access to healthy foods for people with mobility disabilities by measuring wheelchair accessibility of grocery stores and availability of healthy affordable foods. DESIGN: A survey consisting of 87 questions. SETTING: A low-income, multiracial urban Chicago neighborhood with a 3-mile radius was compared with a suburban neighborhood of the same size in which the population is similar in income level and racial distribution. PARTICIPANTS: Not applicable. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Accessibility issues outside and within grocery stores and the availability of healthy affordable food items in these grocery stores. RESULTS: The urban area had more stores (n=48) than the suburban area (n=34); however, only 46% of urban stores had an entrance that would allow an individual requiring a ramp or level entrance to gain access compared with 88% of suburban stores (P<.001). Wheelchair accessibility characteristics of grocery and convenience stores did not differ between the urban and suburban areas. The availability of healthy affordable foods in urban and suburban stores was relatively low, with only 33% to 40% of the 18 items available, and did not differ between urban and suburban stores. CONCLUSIONS: People with mobility impairments are at a disadvantage in maintaining healthy food choices because of limited access to stores and healthy foods.

Assembly, structure, function and regulation of type III secretion systems.

Type III secretion systems (T3SSs) are protein transport nanomachines that are found in Gram-negative bacterial pathogens and symbionts. Resembling molecular syringes, T3SSs form channels that cross the bacterial envelope and the host cell membrane, which enable bacteria to inject numerous effector proteins into the host cell cytoplasm and establish trans-kingdom interactions with diverse hosts. Recent advances in cryo-electron microscopy and integrative imaging have provided unprecedented views of the architecture and structure of T3SSs. Furthermore, genetic and molecular analyses have elucidated the functions of many effectors and key regulators of T3SS assembly and secretion hierarchy, which is the sequential order by which the protein substrates are secreted. As essential virulence factors, T3SSs are attractive targets for vaccines and therapeutics. This Review summarizes our current knowledge of the structure and function of this important protein secretion machinery. A greater understanding of T3SSs should aid mechanism-based drug design and facilitate their manipulation for biotechnological applications.

Perspectives on Active Video Gaming as a New Frontier in Accessible Physical Activity for Youth With Physical Disabilities.

This perspective article explores the utility of active video gaming as a means of reducing sedentary behavior and increasing physical activity among youth with physical disabilities and limitations in lower extremity function who typically are excluded from mainstream exercise options. Youth with physical disabilities are disproportionately affected by health problems that result from sedentary behavior, lack of physical activity, and low fitness levels. Physical, programmatic, and attitudinal barriers have a synergistic and compounded impact on youths' ability to participate in physical activity. A recent health and wellness task force recommendation from the American Physical Therapy Association's Section on Pediatrics supports analyzing individualized health behaviors and preferences that are designed to improve fitness, physical activity, and participation in pediatric rehabilitation. This recommendation represents an opportunity to explore nontraditional options to maximize effectiveness and sustainability of pediatric rehabilitation techniques for youth with disabilities who could best benefit from customized programming. One new frontier in promoting physical activity and addressing common physical activity barriers for youth with physical disabilities is active video games (AVGs), which have received growing attention as a promising strategy for promoting health and fitness in children with and without disabilities. The purpose of this article is to discuss the potential for AVGs as an accessible option to increase physical activity participation for youth with physical disabilities and limitations in lower extremity function. A conceptual model on the use of AVGs to increase physical activity participation for youth with physical disabilities is introduced, and future research potential is discussed, including a development project for game controller adaptations within the Rehabilitation Engineering Research Center on Interactive Exercise Technologies and Exercise Physiology for People With Disabilities (RERC RecTech) at the University of Alabama at Birmingham (UAB)/Lakeshore Foundation Research Collaborative.

Active Videogaming in Youth with Physical Disability: Gameplay and Enjoyment.

OBJECTIVE: For active videogaming (AVG) to be a meaningful, health-enhancing physical activity option for youth with physical disability, factors related to game performance and enjoyment must be understood. The objective was to explore associations between quality of gameplay, controller usage, heart rate (HR), physical function, and enjoyment during AVG play in youth with physical disability. METHODS: Participants (5 girls, 11 boys, mean age 13.8 ± 2.7 years) played four AVGs on three platforms (Nintendo® Wii™, Sony PlayStation3 Move, and Microsoft Xbox® Kinect), across three sessions. Participants' primary means of mobility were manual (n = 13) and power (n = 3) wheelchairs; majority were diagnosed with cerebral palsy or spina bifida. Functional level was assessed using 17 International Classification of Functioning, Disability and Health mobility items. Participants played each AVG for 8 minutes with a 5-minute rest. Quality of gameplay and ability to use controller were recorded on a five-point Likert scale. HR was recorded immediately following each game and participants completed the Physical Activity Enjoyment Scale (PACES). PACES scores were compared across games and correlations were examined among the variables. RESULTS: PACES scores were significantly greater for Wii Punch-Out compared to Xbox Fitness, Sports Rivals, and Zumba, and for PS3 Sports Champions compared to Xbox Zumba. Higher HR was associated with higher quality of gameplay and a higher PACES score. As quality of gameplay increased, the PACES score increased. CONCLUSION: Game performance and exercise intensity were positively correlated with AVG enjoyment in youth with physical disability, specifically mobility impairments. Further research is warranted to examine the capacity of AVG play to be an enjoyable health-enhancing activity for individuals with physical disability.

Recommendations for the Optimal Design of Exergame Interventions for Persons with Disabilities: Challenges, Best Practices, and Future Research.

A group discussion of individuals with expertise working in the field of exergaming and rehabilitation focused on the issue of designing exergames for persons with disabilities as well as appropriate interventions using exergames. The purpose of these discussions was to develop recommendations for the design, evaluation, and application of exergames in therapy serving as potential guidelines for researchers, developers, and therapists. The following key issues were addressed: (1) Challenges in exergame design for persons with disabilities, (2) adaptation of exergames for persons with disabilities, (3) exergame interventions, and (4) future research directions. It is the hope of the group that the results of these recommendations will help improve the quality of exergame design and interventions and thereby increase opportunities for persons with disabilities to engage sustainably in exergaming.

Mycobacterium tuberculosis is resistant to streptolydigin.

Drug resistant strains of Mycobacterium tuberculosis (Mtb) undermine tuberculosis (TB) control. Streptolydigin is a broadly effective antibiotic which inhibits RNA polymerase, similarly to rifampicin, a key drug in current TB chemotherapeutic regimens. Due to a vastly improved chemical synthesis streptolydigin and derivatives are being promoted as putative TB drugs. The microplate Alamar Blue assay revealed that Streptococcus salivarius and Mycobacterium smegmatis were susceptible to streptolydigin with minimum inhibitory concentrations (MICs) of 1.6 mg/L and 6.25 mg/L, respectively. By contrast, the MICs of streptolydigin and two derivatives, streptolydiginone and dihydrostreptolydigin, against Mtb were ≥ 100 mg/L demonstrating that Mtb is resistant to streptolydigin in contrast to previous reports. Further, a porin mutant of M. smegmatis is resistant to streptolydigin indicating that porins mediate uptake of streptolydigin across the outer membrane. Since the RNA polymerase is a validated drug target in Mtb and porins are required for susceptibility of M. smegmatis, the absence of MspA-like porins probably contributes to the resistance of Mtb to streptolydigin. This study shows that streptolydigin is not a suitable drug in TB treatment regimens.

Resistance mechanisms of Mycobacterium tuberculosis against phagosomal copper overload.

Mycobacterium tuberculosis is an important bacterial pathogen with an extremely slow growth rate, an unusual outer membrane of very low permeability and a cunning ability to survive inside the human host despite a potent immune response. A key trait of M. tuberculosis is to acquire essential nutrients while still preserving its natural resistance to toxic compounds. In this regard, copper homeostasis mechanisms are particularly interesting, because copper is an important element for bacterial growth, but copper overload is toxic. In M. tuberculosis at least two enzymes require copper as a cofactor: the Cu/Zn-superoxide dismutase SodC and the cytochrome c oxidase which is essential for growth in vitro. Mutants of M. tuberculosis lacking the copper metallothionein MymT, the efflux pump CtpV and the membrane protein MctB are more susceptible to copper indicating that these proteins are part of a multipronged system to balance intracellular copper levels. Recent evidence showed that part of copper toxicity is a reversible damage of Fe-S clusters of dehydratases and the displacement of other divalent cations such as zinc and manganese as cofactors in proteins. There is accumulating evidence that macrophages use copper to poison bacteria trapped inside phagosomes. Here, we review the rapidly increasing knowledge about copper homeostasis in M. tuberculosis and contrast those with similar mechanisms in Escherichia coli. These findings reveal an intricate interplay between the host which aims to overload the phagosome with copper and M. tuberculosis which utilizes several mechanisms to reduce the toxic effects of excess copper.

Feasibility of using active video gaming as a means for increasing energy expenditure in three nonambulatory young adults with disabilities.

OBJECTIVE: To examine the feasibility of adapting active video games (AVGs) for nonambulatory wheelchair users at functionally diverse levels and to examine these AVGs as a method for increasing energy expenditure (EE) for 3 young adults with severe (SEV), moderate (MOD), and no upper extremity limitation (NL). DESIGN: Case study. SETTING: Residential special education school for youth and young adults with physical disabilities. PARTICIPANTS: Two young adults with spastic cerebral palsy (SEV, MOD) and one young adult with spina bifida (NL). All participants were nonambulatory wheelchair users. METHODS: Each participant performed Wii bowling and tennis and an adapted upper extremity version of a Dance Dance Revolution (DDR) game pad. MAIN OUTCOME MEASUREMENTS: EE was measured through indirect calorimetry (VO(2)). Heart rate data were collected with the use of a Polar Heart Rate Monitor. RESULTS: SEV and MOD participants showed a higher percentage increase in EE for the Wii games (SEV, 25.6%; MOD, 30.8%) compared with DDR (SEV, 10.8%; MOD, 29.1%), whereas the participant with NL had a greater EE increase for the DDR (173.5%) compared with Wii (59.5%). CONCLUSIONS: AVGs showed clinically significant increases in EE for all 3 participants and can be performed by nonambulatory wheelchair users ranging from those with NL to those with SEV upper extremity limitation with the appropriate adaptations.

Physical activity for youth with disabilities: a critical need in an underserved population.

The recommended amount of daily physical activity for youth is 60 minutes a day, most days of the week. Youth with disabilities are not achieving this target and are significantly less active and more obese than their non-disabled peers. The combination of the health risks associated with physical inactivity and obesity presents a serious health concern in this population. While there is a small amount of research on interventions aimed at improving fitness among youth with disabilities, the majority of these studies were conducted in clinical settings where most or all of the common barriers to participation were eliminated (e.g. transportation, lack of knowledgeable staff, adaptation of programmes and/or facilities to child's needs). One of the most important challenges for paediatric rehabilitation and healthcare professionals is finding ways to increase physical activity and fitness among youth with disabilities in community-based settings. The use of information technology (IT) to customize physical activity programmes for youth with disabilities offers a promising approach to addressing this important health issue in the future.

Determining paralysis prevalence in the United States.

BACKGROUND: Estimates of paralysis vary widely, largely owing to a lack of standard definition and nontargeted survey approaches. Like other poorly understood conditions such as fibromyalgia, chronic fatigue, or chronic pain, paralysis falls outside the scope of clearly defined medical diagnosis, further complicating surveillance efforts. This inability to identify accurate prevalence makes developing policy interventions around the needs of many persons with these disabilities problematic. The objectives were to investigate how paralysis is being measured in the United States and to examine the validity of prevalence estimates based on current approaches. METHODS: We reviewed existing measurement instruments and surveyed 139 agencies and organizations to determine how they capture paralysis data. RESULTS: There is a widespread reliance on ICD coding or broad functional capabilities for most state or federal agencies. Many organizations serving consumers depend on state registries for discrete conditions in which paralysis is not directly measured. CONCLUSIONS: Improved paralysis prevalence data will benefit from a more functional definition consistent with ICF guidelines, which can be part of future surveillance efforts at state and federal levels.