Both EUCAST and CLSI recommend broth microdilution (BMD) for antimicrobial susceptibility testing of colistin, but BMD is rarely used in routine microbiology laboratories. The objective of this study ...was to evaluate five commercially available BMD products and two brands of gradient tests for colistin MIC determination using BMD according to ISO standard 20776-1 as reference.
Colistin MIC determination was performed according to the manufacturer's instructions on five commercially available BMD products (Sensititre, MICRONAUT-S, MICRONAUT MIC-Strip, SensiTest, and UMIC) and two gradient tests (Etest and MIC Test Strip). Colistin reference MICs were determined using frozen panels according to ISO standard 20776-1. An international collection of Gram-negative bacteria (n=75) with varying levels of colistin susceptibility was tested.
The colistin BMD products correlated well with reference tests, in particular for Sensititre and the two MICRONAUT products (essential agreement ≥96%: 66/69 (96%, CI 88–99%), 72/75 (96%, CI 88–99%) and 74/75 (99%, CI 92–100%)). The results were somewhat poorer for the BMD products SensiTest and UMIC: EA 88% (51/58, CI 77–95%) and 82% (61/74, CI 72–89%), respectively), and considerably poorer for the gradient tests (EA 43–71% depending on gradient test and Mueller-Hinton agar manufacturer). The gradient tests generally underestimated colistin MICs, resulting in a significant number of false susceptible results (9–18 of total 75 tests, compared with 1–3 for the BMD products).
Based on the results of this study, we advise laboratories not to trust gradient tests for colistin susceptibility testing and to use broth microdilution methods for this purpose. There are several commercial broth microdilution tests available and in principle they perform well.
The thermal stability and flame retardancy of polyurethanes is reviewed. Polyurethanes (PUs) are an important class of polymers that have wide application in a number of different industrial sectors. ...More than 70% of the literature that deals with PUs evaluates their thermal stability or flame retardancy and attempts to provide a structure–property correlation. The importance of studying thermal degradation, understanding the processes occurring during thermal stress as well as the parameters affecting the thermal stability of PUs are essential in order to effectively design polyurethanes having tailor-made properties suitable for the particular environment where they are to be used. A detailed description of TGA, TGA-MS and TGA-FTIR methods for studying the decomposition mechanism and kinetics is also a part of this review. In general, thermal decomposition of PUs begins with the hard segment (HS) and a number of parameters govern a polyurethane's thermal stability. Detailed description of the parameters such as HS, soft segment (SS) and chain extender (CE) structure and molecular weight, NCO:OH ratio, catalyst nature and crosslink density that affect the nature of PU degradation is given. Descriptions of approaches to improve the thermal stability in PUs such as formation of poly(urethane-isocyanurate), poly(urethane-oxazolidone) and poly(urethane-imide) in addition to other methods such as PUs with an s-triazine ring or increased aromatic ring concentration, azomethane linkages as well as use of hyperbranched polyols as crosslinking agents is given. A part of the review is also concentrated on the improvement of thermal stability via hybrid formation such as the incorporation of appropriate amounts of fillers, e.g., nano-silica; Fe
2O
3; TiO
2; silica grafting; nanocomposite formation using organically modified layered silicates; incorporation of Si–O–Si crosslinked structures via sol–gel processes; and the incorporation of polyhedral oligomeric silsesquioxane (POSS) structures into the PU backbone or side chain. Incorporation of carbon nanotubes (CNT) into PUs and the use of functionalized fullerenes in PUs are also described as these are the newest tools to obtain good thermal stability and flame retardancy. Part of the review also concentrates on the process that occurs during burning of PUs, flame retardant mechanisms and different additives or reactive type flame retardants used in the PU industry. The use and working function of expandable graphite and melamine as additive type flame retardants are shown. Description of the use of different reactive type organophosphorus compounds, cyclotriphosphazenes, aziridinyl curing agents in aqueous polyurethane dispersions (PUDs), organoboron compounds and organosilicon compounds for improving flame retardancy is also given.
Summary The definition and classification of chronic kidney disease (CKD) have evolved over time, but current international guidelines define this condition as decreased kidney function shown by ...glomerular filtration rate (GFR) of less than 60 mL/min per 1·73 m2 , or markers of kidney damage, or both, of at least 3 months duration, regardless of the underlying cause. Diabetes and hypertension are the main causes of CKD in all high-income and middle-income countries, and also in many low-income countries. Incidence, prevalence, and progression of CKD also vary within countries by ethnicity and social determinants of health, possibly through epigenetic influence. Many people are asymptomatic or have non-specific symptoms such as lethargy, itch, or loss of appetite. Diagnosis is commonly made after chance findings from screening tests (urinary dipstick or blood tests), or when symptoms become severe. The best available indicator of overall kidney function is GFR, which is measured either via exogenous markers (eg, DTPA, iohexol), or estimated using equations. Presence of proteinuria is associated with increased risk of progression of CKD and death. Kidney biopsy samples can show definitive evidence of CKD, through common changes such as glomerular sclerosis, tubular atrophy, and interstitial fibrosis. Complications include anaemia due to reduced production of erythropoietin by the kidney; reduced red blood cell survival and iron deficiency; and mineral bone disease caused by disturbed vitamin D, calcium, and phosphate metabolism. People with CKD are five to ten times more likely to die prematurely than they are to progress to end stage kidney disease. This increased risk of death rises exponentially as kidney function worsens and is largely attributable to death from cardiovascular disease, although cancer incidence and mortality are also increased. Health-related quality of life is substantially lower for people with CKD than for the general population, and falls as GFR declines. Interventions targeting specific symptoms, or aimed at supporting educational or lifestyle considerations, make a positive difference to people living with CKD. Inequity in access to services for this disease disproportionally affects disadvantaged populations, and health service provision to incentivise early intervention over provision of care only for advanced CKD is still evolving in many countries.
In the context of comprehensive and coordinated approaches to school health, academic classrooms have gained attention as a promising setting for increasing physical activity and reducing sedentary ...time among children. The aims of this paper are to review the rationale and knowledge base related to movement integration in academic classrooms, consider the practical applications of current knowledge to interventions and teacher education, and suggest directions for future research. Specifically, this paper (i) situates movement integration amid policy and research related to children's health and the school as a health‐promoting environment; (ii) highlights the benefits of movement integration; (iii) summarizes movement integration programs and interventions; (iv) examines factors associated with classroom teachers’ movement integration; (v) offers strategies for translating research to practice and (vi) forwards recommendations for future inquiry related to the effectiveness and sustainability of efforts to integrate movement into classroom routines. This paper provides a comprehensive resource for developing state‐of‐the‐art initiatives to maximize children's movement in academic classrooms as a key strategy for important goals in both education and public health.
People with chronic kidney disease (CKD) have an increased risk of stroke but the magnitude of increased risk and the independent effects of glomerular filtration rate (GFR) and albuminuria are ...unclear. We aimed to quantify the association between the independent and combined effects of GFR and albuminuria on stroke risk.
We searched MEDLINE and EMBASE (February 2014) for cohort studies or randomized controlled trials (RCTs) which reported stroke incidence in adults with a baseline measurement of GFR and/or albuminuria. We extracted study and participant characteristics, risk of bias and relative risks (RR, with confidence interval; CI) of stroke associated with GFR and/or quantity of albuminuria, synthesized data using random effects meta-analysis and explored heterogeneity using meta-regression.
We identified 83 studies; 63 cohort studies (2 085 225 participants) and 20 RCTs (168 516 participants) reporting 30 392 strokes. There was an inverse linear relationship between GFR and risk of stroke, with risk of stroke increasing 7% (RR: 1.07, CI: 1.04-1.09) for every 10 mL/min/1.73 m(2) decrease in GFR. A 25 mg/mmol increase in albumin-creatinine ratio was associated with a 10% increased risk of stroke (RR: 1.10, 95% CI: 1.01-1.20). The effect of albuminuria was independent of GFR. Results were not different across subtypes of stroke, sex and varying prevalence of cardiovascular risk factors.
Stroke risk increases linearly and additively with declining GFR and increasing albuminuria. CKD staging may also be a useful clinical tool for identifying people who may benefit most from interventions to reduce cardiovascular risk.
Novel highly functional biobased epoxy compounds, epoxidized sucrose esters of fatty acids (ESEFAs), were cross-linked with a liquid cycloaliphatic anhydride to prepare polyester thermosets. The ...degree of cure or conversion was studied using differential scanning calorimetry (DSC), and the sol content of the thermosets was determined using solvent extraction. The mechanical properties were studied using tensile testing to determine Young’s modulus, tensile stress, and elongation at break. Dynamic mechanical analysis (DMA) was used to determine glass-transition temperature, storage modulus, and cross-link density. The nanomechanical properties of the surfaces were studied using nanoindentation to determine reduced modulus and indentation hardness. The properties of coatings on steel substrates were studied to determine coating hardness, adhesion, solvent resistance, and mechanical durability. Compared with the control, epoxidized soybean oil, the anhydride-cured ESEFAs have high modulus and are hard and ductile, high-performance thermoset materials while maintaining a high biobased content (71–77% in theory). The exceptional performance of the ESEFAs is attributed to the unique structure of these macromolecules: well-defined compact structures with high epoxide functionality. These biobased thermosets have potential uses in applications such as composites, adhesives, and coatings.
Steroid-sparing strategies have been attempted in recent decades to avoid morbidity from long-term steroid intake among kidney transplant recipients. Previous systematic reviews of steroid withdrawal ...after kidney transplantation have shown a significant increase in acute rejection. There are various protocols to withdraw steroids after kidney transplantation and their possible benefits or harms are subject to systematic review. This is an update of a review first published in 2009.
To evaluate the benefits and harms of steroid withdrawal or avoidance for kidney transplant recipients.
We searched the Cochrane Kidney and Transplant Specialised Register to 15 February 2016 through contact with the Information Specialist using search terms relevant to this review.
All randomised and quasi-randomised controlled trials (RCTs) in which steroids were avoided or withdrawn at any time point after kidney transplantation were included.
Assessment of risk of bias and data extraction was performed by two authors independently and disagreement resolved by discussion. Statistical analyses were performed using the random-effects model and dichotomous outcomes were reported as relative risk (RR) and continuous outcomes as mean difference (MD) with 95% confidence intervals.
We included 48 studies (224 reports) that involved 7803 randomised participants. Of these, three studies were conducted in children (346 participants). The 2009 review included 30 studies (94 reports, 5949 participants). Risk of bias was assessed as low for sequence generation in 19 studies and allocation concealment in 14 studies. Incomplete outcome data were adequately addressed in 22 studies and 37 were free of selective reporting.The 48 included studies evaluated three different comparisons: steroid avoidance or withdrawal compared with steroid maintenance, and steroid avoidance compared with steroid withdrawal. For the adult studies there was no significant difference in patient mortality either in studies comparing steroid withdrawal versus steroid maintenance (10 studies, 1913 participants, death at one year post transplantation: RR 0.68, 95% CI 0.36 to 1.30) or in studies comparing steroid avoidance versus steroid maintenance (10 studies, 1462 participants, death at one year after transplantation: RR 0.96, 95% CI 0.52 to 1.80). Similarly no significant difference in graft loss was found comparing steroid withdrawal versus steroid maintenance (8 studies, 1817 participants, graft loss excluding death with functioning graft at one year after transplantation: RR 1.17, 95% CI 0.72 to 1.92) and comparing steroid avoidance versus steroid maintenance (7 studies, 1211 participants, graft loss excluding death with functioning graft at one year after transplantation: RR 1.09, 95% CI 0.64 to 1.86). The risk of acute rejection significantly increased in patients treated with steroids for less than 14 days after transplantation (7 studies, 835 participants: RR 1.58, 95% CI 1.08 to 2.30) and in patients who were withdrawn from steroids at a later time point after transplantation (10 studies, 1913 participants, RR 1.77, 95% CI 1.20 to 2.61). There was no evidence to suggest a difference in harmful events, such as infection and malignancy, in adult kidney transplant recipients. The effect of steroid withdrawal in children is unclear.
This updated review increases the evidence that steroid avoidance and withdrawal after kidney transplantation significantly increase the risk of acute rejection. There was no evidence to suggest a difference in patient mortality or graft loss up to five year after transplantation, but long-term consequences of steroid avoidance and withdrawal remain unclear until today, because prospective long-term studies have not been conducted.
The emergence of Big Data has added a new aspect to conceptualizing the use of digital technologies in the delivery of public services and for realizing digital governance. This article explores, via ...the ‘value-chain’ approach, the evolution of digital governance research, and aligns it with current developments associated with data analytics, often referred to as ‘Big Data’. In many ways, the current discourse around Big Data reiterates and repeats established commentaries within the eGovernment research community. This body of knowledge provides an opportunity to reflect on the ‘promise’ of Big Data, both in relation to service delivery and policy formulation. This includes, issues associated with the quality and reliability of data, from mixing public and private sector data, issues associated with the ownership of raw and manipulated data, and ethical issues concerning surveillance and privacy. These insights and the issues raised help assess the value of Big Data in government and smart city environments.
This work proposes and analyzes a Smolyak-type sparse grid stochastic collocation method for the approximation of statistical quantities related to the solution of partial differential equations with ...random coefficients and forcing terms (input data of the model). To compute solution statistics, the sparse grid stochastic collocation method uses approximate solutions, produced here by finite elements, corresponding to a deterministic set of points in the random input space. This naturally requires solving uncoupled deterministic problems as in the Monte Carlo method. If the number of random variables needed to describe the input data is moderately large, full tensor product spaces are computationally expensive to use due to the curse of dimensionality. In this case the sparse grid approach is still expected to be competitive with the classical Monte Carlo method. Therefore, it is of major practical relevance to understand in which situations the sparse grid stochastic collocation method is more efficient than Monte Carlo. This work provides error estimates for the fully discrete solution using L q norms and analyzes the computational efficiency of the proposed method. In particular, it demonstrates algebraic convergence with respect to the total number of collocation points and quantifies the effect of the dimension of the problem (number of input random variables) in the final estimates. The derived estimates are then used to compare the method with Monte Carlo, indicating for which problems the former is more efficient than the latter. Computational evidence complements the present theory and shows the effectiveness of the sparse grid stochastic collocation method compared to full tensor and Monte Carlo approaches.
PDF
