Structure of the Acinetobacter baumannii PmrA receiver domain and insights into clinical mutants affecting DNA-binding and promoting colistin resistance

Acinetobacter baumannii is an insidious emerging nosocomial pathogen that has developed resistance to all available antimicrobials, including the last resort antibiotic, colistin. Colistin resistance often occurs due to mutations in the PmrAB two component regulatory system. To better understand the regulatory mechanisms contributing to colistin resistance, we have biochemically characterized the A. baumannii PmrA response regulator. Initial DNA-binding analysis shows that A. baumannii PmrA bound to the Klebsiella pneumoniae PmrA box motif. This prompted analysis of the putative A. baumannii PmrAB regulon which indicated that the A. baumannii PmrA consensus box is 5′- HTTAAD N5 HTTAAD. Additionally, we provide the first structural information for the A. baumannii PmrA N-terminal domain through X-ray crystallography, and we present a full-length model using molecular modeling. From these studies, we were able to infer the effects of two critical PmrA mutations, PmrA::I13M and PmrA::P102R, both of which confer increased colistin resistance. Based on these data, we suggest structural and dynamic reasons for how these mutations can affect PmrA function and hence encourage resistive traits. Understanding these mechanisms will aid in the development of new targeted antimicrobial therapies

A novel malaria vaccine candidate antigen expressed in Tetrahymena thermophila

Development of effective malaria vaccines is hampered by the problem of producing correctly folded Plasmodium proteins for use as vaccine components. We have investigated the use of a novel ciliate expression system, Tetrahymena thermophila, as a P. falciparum vaccine antigen platform. A synthetic vaccine antigen composed of N-terminal and C-terminal regions of merozoite surface protein-1 (MSP-1) was expressed in Tetrahymena thermophila. The recombinant antigen was secreted into the culture medium and purified by monoclonal antibody (mAb) affinity chromatography. The vaccine was immunogenic in MF1 mice, eliciting high antibody titers against both N- and C-terminal components. Sera from immunized animals reacted strongly with P. falciparum parasites from three antigenically different strains by immunofluorescence assays, confirming that the antibodies produced are able to recognize parasite antigens in their native form. Epitope mapping of serum reactivity with a peptide library derived from all three MSP-1 Block 2 serotypes confirmed that the MSP-1 Block 2 hybrid component of the vaccine had effectively targeted all three serotypes of this polymorphic region of MSP-1. This study has successfully demonstrated the use of Tetrahymena thermophila as a recombinant protein expression platform for the production of malaria vaccine antigens

Getting the right balance: insole design alters the static balance of people with diabetes and neuropathy

BACKGROUND: Over 1 in 3 older people with diabetes sustain a fall each year. Postural instability has been identified as independent risk factor for falls within people with Diabetic Peripheral Neuropathy (DPN). People with DPN, at increased risk of falls, are routinely required to wear offloading insoles, yet the impact of these insoles on postural stability and postural control is unknown. The aim of this study was to evaluate the effect of a standard offloading insole and its constituent parts on the balance in people with DPN. METHODS: A random sample of 50 patients with DPN were observed standing for 3 × 30 s, and stepping in response to a light, under five conditions presented in a random order; as defined by a computer program; 1) no insole, 2) standard diabetic: a standard offloading insole made from EVA/poron®, and three other insoles with one design component systematically altered 3) flat: diabetic offloading insole with arch fill removed, 4) low resilient memory: diabetic offloading insole with the cover substituted with low resilience memory V9, 5) textured: diabetic offloading insole with a textured PVC surface added (Algeos Ltd). After each condition participants self-rated perceived steadiness. RESULTS: Insole design effected static balance and balance perception, but not stepping reaction time in people with DPN. The diabetic and memory shaped insoles (with arch fill) significantly increased centre of pressure velocity (14 %, P = 0.006), (13 %, P = 0.001), and path length (14 %, P = 0.006), (13 %, P = 001), when compared to the no insole condition. The textured shaped and flat soft insole had no effect on static balance when compared to the no insole condition (P > 0.05). CONCLUSION: Insoles have an effect on static balance but not stepping reaction time. This effect is independent of neuropathy severity. The addition of a textured cover seems to counter the negative effect of an arch fill, even in participants with severe sensation loss. Static balance is unaffected by material softness or resilience. Current best practice of providing offloading insoles, with arch fill, to increase contact area and reduce peak pressure could be making people more unstable. Whilst flat, soft insoles maybe the preferable design option for those with poor balance. There is a need to develop an offloading insole that can reduce diabetic foot ulcer risk, without compromising balance

Fatores associados ao equilíbrio funcional e à mobilidade em idosos diabéticos ambulatoriais

OBJECTIVES: To characterize balance and mobility among diabetic elderly outpatients and to estimate the extent to which functional balance and mobility abnormalities can be influenced by sociodemographic, clinical and other functional factors in a cross-sectional study. METHODS: Ninety-one elderly (65+ years) outpatients were assessed. Mobility was evaluated by the Timed Up and Go Test (TUGT) and the balance, by the Berg Balance Scale (BS). RESULTS: TUGT mean score was 15.65 ± 5.9 seconds and BS mean score was 49.31 ± 7.3 points. Using linear regression analysis (α < 0.05), significant and independent positive relationships were obtained between TUGT and age, daily activities (ADL/IADL), step strategy, and proprioceptive sensitivity. Factors negatively associated with BS were: ADL/IADL, step strategy, proprioceptive sensitivity, orthostatic hypotension (OH) and conflictive sensory conditions. CONCLUSION: Elderly diabetic outpatients show abnormal balance and mobility related mainly to advanced age, disability, absence of step strategy, absence of proprioceptive sensitivity and presence of OH.OBJETIVOS: Caracterizar o equilíbrio e a mobilidade de idosos diabéticos ambulatoriais e estimar o quanto suas anormalidades podem ser influenciadas por fatores sociodemográficos, clínicos e funcionais globais em um estudo transversal. MÉTODOS: 91 idosos (65 + anos) ambulatoriais foram avaliados quanto à mobilidade pelo Timed Up and Go Test (TUGT) e ao equilíbrio, pela Berg Balance Scale (BS). RESULTADOS: A média dos escores do TUGT foi de 15,65 ± 5,9 segundos e da BS, de 49,31 ± 7,3 pontos. Empregando-se análise de regressão linear (α < 0,05), associações significantes positivas e independentes foram obtidas entre o TUGT e idade, atividades cotidianas, estratégia do passo atrás e sensibilidade proprioceptiva. Os fatores associados negativamente à BS foram: atividades cotidianas, estratégia do passo, sensibilidade proprioceptiva, hipotensão ortostática (HO) e condições sensoriais conflituosas. CONCLUSÃO: Idosos diabéticos ambulatoriais apresentam equilíbrio e mobilidade prejudicados, relacionados principalmente à idade avançada, limitação para atividades diárias, ausência de estratégia de equilíbrio, prejuízo na sensibilidade proprioceptiva e a presença de HO.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo (UNIFESP) Departamento de Medicina PreventivaUniversidade Cidade de São PauloUNIFESP Departamento de MedicinaUNIFESP, Depto. de Medicina PreventivaUNIFESP, Depto. de MedicinaSciEL

A whole-genome shotgun approach for assembling and anchoring the hexaploid bread wheat genome

Citation: Chapman, J. A., Mascher, M., Buluç, A., Barry, K., Georganas, E., Session, A., . . . Rokhsar, D. S. (2015). A whole-genome shotgun approach for assembling and anchoring the hexaploid bread wheat genome. Genome Biology, 16(1). doi:10.1186/s13059-015-0582-8Polyploid species have long been thought to be recalcitrant to whole-genome assembly. By combining high-throughput sequencing, recent developments in parallel computing, and genetic mapping, we derive, de novo, a sequence assembly representing 9.1 Gbp of the highly repetitive 16 Gbp genome of hexaploid wheat, Triticum aestivum, and assign 7.1 Gb of this assembly to chromosomal locations. The genome representation and accuracy of our assembly is comparable or even exceeds that of a chromosome-by-chromosome shotgun assembly. Our assembly and mapping strategy uses only short read sequencing technology and is applicable to any species where it is possible to construct a mapping population. © 2015 Chapman et al. licensee BioMed Central.Additional Authors: Muehlbauer, G. J.;Stein, N.;Rokhsar, D. S

The limited prosocial effects of meditation: A systematic review and meta-analysis

Many individuals believe that meditation has the capacity to not only alleviate mental-illness but to improve prosociality. This article systematically reviewed and meta-analysed the effects of meditation interventions on prosociality in randomized controlled trials of healthy adults. Five types of social behaviours were identified: compassion, empathy, aggression, connectedness and prejudice. Although we found a moderate increase in prosociality following meditation, further analysis indicated that this effect was qualified by two factors: type of prosociality and methodological quality. Meditation interventions had an effect on compassion and empathy, but not on aggression, connectedness or prejudice. We further found that compassion levels only increased under two conditions: when the teacher in the meditation intervention was a co-author in the published study; and when the study employed a passive (waiting list) control group but not an active one. Contrary to popular beliefs that meditation will lead to prosocial changes, the results of this meta-analysis showed that the effects of meditation on prosociality were qualified by the type of prosociality and methodological quality of the study. We conclude by highlighting a number of biases and theoretical problems that need addressing to improve quality of research in this area

DNA repair, genome stability and cancer: a historical perspective

The multistep process of cancer progresses over many years. The prevention of mutations by DNA repair pathways led to an early appreciation of a role for repair in cancer avoidance. However, the broader role of the DNA damage response (DDR) emerged more slowly. In this Timeline article, we reflect on how our understanding of the steps leading to cancer developed, focusing on the role of the DDR. We also consider how our current knowledge can be exploited for cancer therapy

What do the australian black summer fires signify for the global fire crisis?

The 2019–20 Australian fire season was heralded as emblematic of the catastrophic harm wrought by climate change. Similarly extreme wildfire seasons have occurred across the globe in recent years. Here, we apply a pyrogeographic lens to the recent Australian fires to examine the range of causes, impacts and responses. We find that the extensive area burnt was due to extreme climatic circumstances. However, antecedent hazard reduction burns (prescribed burns with the aim of reducing fuel loads) were effective in reducing fire severity and house loss, but their effectiveness declined under extreme weather conditions. Impacts were disproportionately borne by socially disadvantaged regional communities. Urban populations were also impacted through prolonged smoke exposure. The fires produced large carbon emissions, burnt fire-sensitive ecosystems and exposed large areas to the risk of biodiversity decline by being too frequently burnt in the future. We argue that the rate of change in fire risk delivered by climate change is outstripping the capacity of our ecological and social systems to adapt. A multi-lateral approach is required to mitigate future fire risk, with an emphasis on reducing the vulnerability of people through a reinvigoration of community-level capacity for targeted actions to complement mainstream fire management capacity

Clinical factors associated with a conservative gait pattern in older male veterans with diabetes

<p>Abstract</p> <p>Background</p> <p>Patients with diabetes and peripheral neuropathy are at higher risk for falls. People with diabetes sometimes adopt a more conservative gait pattern with decreased walking speed, widened base, and increased double support time. The purpose of this study was to use a multivariate approach to describe this conservative gait pattern.</p> <p>Methods</p> <p>Male veterans (mean age = 67 years; SD = 9.8; range 37–86) with diabetes (n = 152) participated in this study from July 2000 to May 2001 at the Veterans Affairs Medical Center, White River Junction, VT. Various demographic, clinical, static mobility, and plantar pressure measures were collected. Conservative gait pattern was defined by visual gait analysis as failure to demonstrate a heel-to-toe gait during the propulsive phase of gait.</p> <p>Results</p> <p>Patients with the conservative gait pattern had lower walking speed and decreased stride length compared to normal gait. (0.68 m/s v. 0.91 m/s, <it>p </it>< 0.001; 1.04 m v. 1.24 m, <it>p </it>< 0.001) Age, monofilament insensitivity, and Romberg's sign were significantly higher; and ankle dorsiflexion was significantly lower in the conservative gait pattern group. In the multivariate analysis, walking speed, age, ankle dorsiflexion, and callus were retained in the final model describing 36% of the variance. With the inclusion of ankle dorsiflexion in the model, monofilament insensitivity was no longer an independent predictor.</p> <p>Conclusion</p> <p>Our multivariate investigation of conservative gait in diabetes patients suggests that walking speed, advanced age, limited ankle dorsiflexion, and callus describe this condition more so than clinical measures of neuropathy.</p

Routine MRI findings of the asymptomatic foot in diabetic patients with unilateral Charcot foot

<p>Abstract</p> <p>Background</p> <p>Imaging studies of bones in patients with sensory deficits are scarce.</p> <p>Aim</p> <p>To investigate bone MR images of the lower limb in diabetic patients with severe sensory polyneuropathy, and in control subjects without sensory deficits.</p> <p>Methods</p> <p>Routine T1 weighted and T2-fat-suppressed-STIR-sequences without contrast media were performed of the asymptomatic foot in 10 diabetic patients with polyneuropathy and unilateral inactive Charcot foot, and in 10 matched and 10 younger, non-obese unmatched control subjects. Simultaneously, a Gadolinium containing phantom was also assessed for reference. T1 weighted signal intensity (SI) was recorded at representative regions of interest at the peritendineal soft tissue, the tibia, the calcaneus, and at the phantom. Any abnormal skeletal morphology was also recorded.</p> <p>Results</p> <p>Mean SI at the soft tissue, the calcaneus, and the tibia, respectively, was 105%, 105% and 84% of that at the phantom in the matched and unmatched control subjects, compared to 102% (soft tissue), 112% (calcaneus) and 64% (tibia) in the patients; differences of tibia vs. calcaneus or soft tissue were highly significant (p < 0.005). SI at the tibia was lower in the patients than in control subjects (p < 0.05). Occult traumatic skeletal lesions were found in 8 of the 10 asymptomatic diabetic feet (none in the control feet).</p> <p>Conclusion</p> <p>MR imaging did not reveal grossly abnormal bone marrow signalling in the limbs with severe sensory polyneuropathy, but occult sequelae of previous traumatic injuries.</p