Exploring Bacterial Nanowires: From Properties to Functions and Implications

The discovery of electrically conductive bacterial nanowires from a broad range of microbes provides completely new insights into microbial physiology. Shewanella oneidensis strain MR-1, a dissimilatory metal-reducing bacterium, produces extracellular bacterial nanowires up to tens of micrometers long, with a lateral dimension of ~10 nm. The Shewanella bacterial nanowires are efficient electrical conductors as revealed by scanning probe techniques such as CP-AFM and STM. Direct electrical transport measurements along Shewanella nanowires reveal a measured nanowire resistivity on the order of 1 Ω∙cm. With electron transport rates up to 109/s at 100 mV, bacterial nanowires can serve as a viable microbial strategy for extracellular electron transport. By modulating the nanowire conductance in NW-FET configurations and CP-AFM measurements on nanowires coupled to different electrode materials, it has been found that Shewanella nanowires behave as a gateable p-type semiconductor with a Fermi level close to 5.3 eV. This finding further suggests that Shewanella nanowires may serve as electronic cables for efficient energy distribution and electronic signal exchange within microbial communities. Two separate AFM experiments, which are real-time elastic modulus mapping using torsional harmonic cantilevers and conventional AFM nanoindentation, mutually confirm that the elastic modulus of Shewanella nanowires is on the order of 1 GPa, with no significant variations in local elasticity along individual nanowires. With electrical properties comparable to those of moderately doped inorganic semiconductors and elasticity close to polymeric materials, bacterial nanowires may represent a new class of functional bionanomaterials that will potentially be building blocks for bionanoelectronics and flexible nanoelectronics

Effectiveness of a denture hygiene intervention programme among institutionalized elders

Objectives: To evaluate the effectiveness of a denture hygiene intervention programme in terms of improving denture cleanliness and denture stomatitis. Methods: Residents at seven elderly care homes were invited to participate in a denture hygiene programme. Clinical assessment of denture stomatitis was undertaken and denture cleanliness assessed: (i) qualitatively by the Denture Cleanliness Index ratings and (ii) quantitatively by planimetric assessments of plaque coverage from digital images using Adobe Photoshop®. Individual denture hygiene instruction was provided and denture cleanser (Polident®) supplied. Six weeks later assessments of denture stomatitis and denture cleanliness were undertaken. Results: Fifty-six participants were recruited; most had evidence of denture stomatitis (82.1%, 46) and 62.5% (35) of dentures were classified as ‘very poorly cleaned’. The mean percentage of plaque coverage was 28.11 (SD 19.64) and 37.5% (21) had evidence of plaque covering more than a third of the denture surface. Denture cleanliness was associated with denture stomatitis (P0.05).Conclusion: A 6-week denture hygiene intervention programme was effective at improving denture stomatitis and denture cleanliness among residents of elderly care homes. However, persistence of problems in denture cleanliness and denture stomatitis existed and this warrants further consideration.published_or_final_versio

Effectiveness of a denture hygiene intervention programme among institutionalized elders

Objectives: To evaluate the effectiveness of a denture hygiene intervention programme in terms of improving denture cleanliness and denture stomatitis. Methods: Residents at seven elderly care homes were invited to participate in a denture hygiene programme. Clinical assessment of denture stomatitis was undertaken and denture cleanliness assessed: (i) qualitatively by the Denture Cleanliness Index ratings and (ii) quantitatively by planimetric assessments of plaque coverage from digital images using Adobe Photoshop®. Individual denture hygiene instruction was provided and denture cleanser (Polident®) supplied. Six weeks later assessments of denture stomatitis and denture cleanliness were undertaken. Results: Fifty-six participants were recruited; most had evidence of denture stomatitis (82.1%, 46) and 62.5% (35) of dentures were classified as ‘very poorly cleaned’. The mean percentage of plaque coverage was 28.11 (SD 19.64) and 37.5% (21) had evidence of plaque covering more than a third of the denture surface. Denture cleanliness was associated with denture stomatitis (P0.05).Conclusion: A 6-week denture hygiene intervention programme was effective at improving denture stomatitis and denture cleanliness among residents of elderly care homes. However, persistence of problems in denture cleanliness and denture stomatitis existed and this warrants further consideration.published_or_final_versio

Ginsenoside-Rg1 mediates a hypoxia-independent upregulation of hypoxia-inducible factor-1α to promote angiogenesis

Hypoxia-inducible factor (HIF-1) is the key transcription regulator for multiple angiogenic factors and is an appealing target. Ginsenoside-Rg1, a nontoxic saponin isolated from the rhizome of Panax ginseng, exhibits potent proangiogenic activity and has the potential to be developed as a new angiotherapeutic agent. However, the mechanisms by which Rg1 promotes angiogenesis are not fully understood. Here, we show that Rg1 is an effective stimulator of HIF-1α under normal cellular oxygen conditions in human umbilical vein endothelial cells. HIF-1α steady-state mRNA was not affected by Rg1. Rather, HIF-1α protein synthesis was stimulated by Rg1. This effect was associated with constitutive activation of phosphatidylinositol 3-kinase (PI3K)/Akt and its effector p70 S6 kinase (p70S6K), but not extracellular-signal regulated kinase 1/2. We further revealed that HIF-1α induction triggered the expression of target genes, including vascular endothelial growth factor (VEGF). The use of small molecule inhibitors LY294002 or rapamycin to inhibit PI3K/Akt and p70S6K activities, respectively, resulted in diminished HIF-1α activation and subsequent VEGF expression. RNA interference-mediated knockdown of HIF-1α suppressed Rg1-induced VEGF synthesis and angiogenic tube formation, confirming that the effect was HIF-1α specific. Similarly, the angiogenic phenotype could be reversed by inhibition of PI3K/Akt and p70S6K. These results define a hypoxia-independent activation of HIF-1α, uncovering a novel mechanism for Rg1 that could play a major role in angiogenesis and vascular remodeling

Oxidative damages in tubular epithelial cells in IgA nephropathy: role of crosstalk between angiotensin II and aldosterone

<p>Abstract</p> <p>Background</p> <p>Inhibition of the renin-angiotensin-aldosterone system (RAAS) slows down the progression of chronic renal diseases (CKD) including IgA nephropathy (IgAN). Herein, we studied the pathogenetic roles of aldosterone (Aldo) in IgAN.</p> <p>Methods</p> <p>Human mesangial cells (HMC) was activated with polymeric IgA (pIgA) from IgAN patients and the effects on the expression of RAAS components and TGF-β synthesis examined. To study the roles of RAAS in the glomerulotubular communication, proximal tubular epithelial cells (PTEC) was cultured with conditioned medium from pIgA-activated HMC with eplerenone or PD123319, the associated apoptotic event was measured by the generation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and reactive oxygen species (ROS).</p> <p>Results</p> <p>Polymeric IgA up-regulated the Aldo synthesis and aldosterone synthase expression by HMC. The release of TGF-β by HMC was up-regulated synergistically by AngII and Aldo and this was inhibited by incubation of HMC with losartan plus eplerenone. Cultured PTEC express the mineralocorticoid receptor, but not synthesizing aldosterone. Apoptosis, demonstrated by cleaved PARP expression and caspase 3 activity, was induced in PTEC activated by conditioned medium prepared from HMC cultured with pIgA from IgAN patients. This apoptotic event was associated with increased generation of NADPH oxidase and ROS. Pre-incubation of PTEC with PD123319 and eplerenone achieved complete inhibition of PTEC apoptosis.</p> <p>Conclusions</p> <p>Our data suggest that AngII and Aldo, released by pIgA activated HMC, served as mediators for inducing apoptosis of PTEC in glomerulo-tubular communications. Crosstalk between AngII and Aldo could participate in determining the tubular pathology of IgAN.</p

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Masticatory performance and quality of life of HK older adults

Aim or Purpose: To examine the association between masticatory performance (MP) of older adults and their oral health-related (OHRQoL) and general health-related quality of life (HRQoL). Materials and Methods: 700 older adults aged ≥60 were recruited from outpatient clinics and community centers in Hong Kong(HK). Participant's objective MP was assessed through a* value of colour-changeable chewing gum, maximum anterior, and posterior bite force. Subjective MP was evaluated with a validated chewing function questionnaire(CFQ). The validated Cantonese version of the Geriatric Oral Health Assessment Index(GOHAI) and 12-item Short-Form Health Survey(SF-12) were used as the OHRQoL and HRQoL measures respectively. Other variables included socio-demographic characteristics, smoking habit, disease counts, handgrip strength, Clinical Frailty Scale(CFS), Katz Index of Independence in Activities of Daily Living(ADL), Lawton Instrumental ADL(C-IADL), Mini Nutritional Assessment-Short Form(MNA-SF), and HK 5min-Montreal Cognitive Assessment scores. Results: The mean GOHAI, PCS-12 and MCS-12 (physical and mental component summary of SF-12) scores were 51.5, 46.4 and 52.5 respectively. Multiple linear regression analysis revealed that participants who were older, had higher maximum posterior bite force, CFQ scores, Lawton C-IADL scores, and lower disease counts had higher GOHAI scores, indicating better OHRQoL. Regarding HRQoL, PCS-12 score had significant association with CFQ score, gender, disease counts, CFS and Lawton C-IADL score; whereas MCS-12 score was significantly related to CFQ score, age, disease counts, CFS, MNA status and handgrip strength. Conclusions: Better subjective MP as indicated by higher CFQ score was associated with better OHRQoL and HRQoL status among older adults in HK. Of the three measures of objective MP, only maximum posterior bite force had a significant association with OHRQoL