One of the major causes of ecological and environmental problems comes from the enormous number of discarded waste tires, which is directly connected to the exponential growth of the world’s population. In this paper, previous works carried out on the effects of partial or full replacement of aggregate in concrete with waste rubber on some properties of concrete were investigated. A database containing 457 mixtures with partial or full replacement of natural aggregate with waste rubber in concrete provided by different researchers was formed. This database served as the basis for investigating the influence of partial or full replacement of natural aggregate with waste rubber in concrete on compressive strength. With the aid of the database, the possibility of achieving reliable prediction of the compressive strength of concrete with tire rubber is explored using neural network modelling. Globally, 1.5 billion tires are produced annually, of which 300 million are produced in the USA [Waste tires represent a potential for re-entry into the market through new materials and new products. Recently, tire waste found its use in the cement industry as a substitute source for the production of playground matt, and for various coverings. This material found its application in various fields, from different kinds of barriers and posts, as well as in asphalt pavement mixtures . GovernmThe long lifetime of waste tire rubber was one of the factors which aroused the interest of the research community in the replacement of natural river aggregate with rubber products in concrete mixtures. This was with the goal of producing environmentally-friendly concrete . The ducGood characteristics of recycled tire rubber, low elastic modulus and highly ductile-engineered cementitious composites repair material were used to alleviate repair failure induced by restrained drying shrinkage . Higher Rubber aggregates in concrete have the greatest impact on concrete compressive strength . El-GammIn recent years, interest and application of artificial neural networks (ANNs) has increased due to their simplicity and efficiency in creating input-output black box models. ANNs have been applied in diverse areas such as medicine, business, physics, geology, engineering, and environmental engineering in particular ,16,17. Although the prediction of concrete properties with natural aggregates using artificial neural network (ANN) modeling has been widely researched ,19,20,21Prediction of the compressive strength of rubberized concrete based on test measurements by utilizing an ANN was reported by Abdollahzade et al. . CompareApplication of an ANN was reported by Diaconescu et al.  in the dGesoglu et al.  proposedFrom the literature review, it can be stated that not a lot of research has been carried out using ANNs to predict the compressive strength of concrete with tire rubber. None of them involved a large enough database needed to attain a more reliable estimation of compressive strength. The first contribution of this study is to compile a suitably large database with enough experimental results . Irrespective of the experimental studies on concrete with tire rubber, no algorithm exists for defining concrete compressive strength. The second contribution of this study is to use the data in the generated database to create an ANN model capable of predicting compressive strength to a suitable degree of accuracy.A methodical search of published papers, using sources such as Springer, Scopus and Google, dealing with cement-based rubber concrete properties up to January 2018 was conducted. To focus on the study of the compressive strength of rubber concrete, rubber mixtures such as asphalt rubber concrete or rubber mortar were not considered. In addition, publications written in a non-English language, or ones of local rather than international affiliation, were also excluded. To ensure that there were no omissions, broad keywords such as concrete, rubber, rubber concrete, rubberized concrete, and rubcrete were used.The collected experimental database contains data from 457 published tests . SelectiAmong the first studies considered was that from Toutanji in 1996 , who useMore researches were provided in order to investigate mechanical properties of rubberized concrete. The largest database of performed tests was done in , where tIn , apart fIn Paine , the expThe authors in  concludeThere are, mainly, two ways of adding rubber aggregate to concrete: (i) adding rubber aggregate relative to the weight or volume of concrete directly; or (ii) substituting aggregates of concrete by weight and by volume. Due to the fact that the density of natural aggregate in concrete is approximately 2.5 times that of rubber, it means that if weight substitution is used to replace rubber in the aggregates, the volume of the resulting mixture would be much higher than the original one. From a practical viewpoint, substituting natural aggregate of concrete with rubber aggregate by volume is more suitable.Those researches were taken into consideration in order to investigate various characteristics of concrete with rubber waste. As previously stated, in this paper, only the influence of partial or full replacement of natural aggregate with waste rubber in concrete on the compressive strength of rubberized concrete is investigated. The first conclusion that can be obtained from Thus, when natural aggregate is replaced by rubber aggregate, the load carrying material in the mixture is reduced, resulting in a decrease of compressive strength.In addition, rubber particles, which are less stiff than natural aggregate, can be considered as gaps in the concrete mixture.Rubber aggregate is significantly softer than natural aggregate.At the boundary between the rubber particles and concrete matrix, stress concentration usually arises. Due to the elastic mismatch, during loading, cracks are initialized around the rubber aggregate and quickly develop around the rubber particles, expanding rapidly throughout the matrix causing increased rupture in the concrete.Due to their non-polar nature, air is captured on the surface of rubber particles, and causes great inconsistency between rubber aggregate and the surrounding cement.The reasoning behind this could be: Since, according to the The following equation defines the total aggregate ratio:fc,28 in MPa). This performance indicator represents the output parameter. The general distribution of input and output data with the minimum, maximum and average values are presented in The experimental database consists of six input parameters: cement (kg); w/c ratio; fine natural aggregate (NA-F) (%); coarse natural aggregate (NA-C) (%); fine rubber (RB-F) (%); and coarse rubber (RB-C) (%). For structural applications, one of the most important mechanical properties of concrete is the compressive strength. Thus, in order to evaluate the performance of aggregate substitution with rubbers, it is necessary to estimate the compressive strength of concrete at the age of 28 days (The histogram of the percentage of RB-F compared to the fine aggregate (NA-F) is presented in When coarse rubber aggregate replacement is being considered, the situation is slightly different b. Most oThe weight of the cement in the database is in the range of 250 to 650 kg c. ThirtyThe w/c ratio of the database is presented in Artificial neural networks (ANNs) are often used for modelling complex nonlinear functions determined from observations. ANN has proven to be an efficient tool for engineering applications due to its powerful data processing and learning capabilities ,16. Therpurelin (2), and non-linear sigmoid functions logsig (3) and tansig (4) which are defined as follows: The basic structure of the most popular multi-layer feedforward ANN generally consists of three distinctive layers, each of which is made up of nodes or neurons: the input layer, one or more hidden layers, and the output layer. In such a network, data only travels forward through the layers. The input layer is used for the introduction of data to the model. The hidden layers are used for data processing while the output layer is used to obtain the model output. The neurons of a given layer are linked to other neurons in the following layer. Apart from the neurons in the input layer, which only passes data through, all the other neurons are made up of several components: weights, an offset or bias and an activation function . Common ANN training involves determining the set of optimal values of weights. This is achieved by determining the model errors, i.e., the difference between the obtained model outputs and the measured or desired output values. The optimal values of the weights are then determined by minimizing a cost function which is basically the mean squared error (MSE). This training process is performed iteratively for a given number of cycles until a suitable network output accuracy is obtained. In this study, the Levenberg-Marquardt method is used, in combination with Bayesian regularization, to determine the optimal values of the weights. This optimization procedure minimizes a combination of squared errors and weights, and then determines the suitable combination in order to enhance the generalization properties of the network. In order to improve the generalization properties of ANN, the experimental data needs to be divided into three subsets: training, validation, and testing datasets. In this study, 70% of the original experimental data was randomly selected as the training dataset, 15% as the validation dataset and 15% as the test dataset. The training dataset is used to determine the model ANN weights (or parameters) i.e., for model calibration, the validation dataset is used during training to prevent overfitting, i.e., to improve the generalization capabilities of the model, while the test dataset is used to evaluate or validate the model.The number of neurons in the hidden layers greatly affects the stability of the ANN. Randomly selecting the number of hidden neurons may cause either underfitting or overfitting of the models . UnderfiIn this paper, the optimal number of neurons for the ANN model was determined by carrying out a 5-fold cross validation using the training dataset. Since the number of neurons in the input and output layers are determined by the number of input and output parameters respectively, cross validation was used to determine the number of neurons in the hidden layer. ANN models containing one, two and three hidden layers were analyzed. All possible combinations were considered using 2 to 20 neurons for the models with one hidden layer, 2 to 20 neurons per layer for the models with two hidden layers and 2 to 10 neurons per layer for the models with three hidden layers. A flow chart of the model selection procedure is given in Using the previously described procedure, the most suitable ANN model obtained consisted of three hidden layers with nine, three and two hidden neurons respectively , with siR), the root mean square error (RMSE) and mean absolute percentage error (MAPE), defined as follows:EVi is the measured or experimental value of compressive strength, PVi is the predicted value or model output (compressive strength), EVmean is the average measured or experimental value of compressive strength, PVmean is the average model output value representing the compressive strength and n is the number of data samples.In order to evaluate the effectiveness and predictive accuracy of each, three statistical performance measures were used: the coefficient of correlation . The maximum absolute error obtained on the train data is about 20, while a maximum value of about 26 was obtained on test data. The results were obtained without any additional experiments in a fairly short period of time and with relatively acceptable errors. The application of an ANN multilayer backpropagation network in the field of predicting the compressive strength of concrete with tire rubber is appropriate and can be seen as an alternative and suitable approach.A database containing 457 mixtures with partial or full replacement of natural aggregate with waste rubber in concrete provided by different researchers was formed. This database served as the basis for neural network modelling in order to achieve a suitably accurate prediction of the compressive strength of concrete with tire rubber. Artificial neutral networks have shown to be able predict results from examples and observations. This makes them a powerful tool for solving complex problems in various fields and specifically in civil engineering. Various artificial neural network models for determining the compressive strength of concrete at the age of 28 days with tire rubber were considered. Models having one, two and three hidden layers and various numbers of neurons were analyzed. The model with three hidden layers, with nine, three and two neurons respectively, gave the best results with respect to prediction accuracy. This model had the highest


Static contact angle results showed a significant increment of 49.8° and 53.4° for the respective surface hydrophobicity and lipophilicity measurements. More importantly, both storage modulus (G’) and loss modulus (G’’) are improved in the hybrid POSS PUs and these parameters can be further adjusted by varying POSS content in the copolymer. As a biodegradable hybrid filler, the as-synthesized POSS PUs also demonstrated a remarkable effect in toughening commercial polyesters, indicating a simple yet useful strategy in developing high-performance polyester for advanced biomedical applications.A series of hybrid thermoplastic polyurethanes (PUs) were synthesized from bi-functional polyhedral oligomeric silsesquioxane (B-POSS) and polycaprolactone (PCL) using 1,6-hexamethylene diisocyanate (HDI) as a coupling agent for the first time. The newly synthesized hybrid materials were fully characterized in terms of structure, morphology, thermal and mechanical performance, as well as their toughening effect toward polyesters. Thermal gravimeter analysis (TGA) and differential scanning calorimetry (DSC) showed enhanced thermal stability by 76 °C higher in decomposition temperature (T Polyurethane (PU) is a kind of thermoplastic elastomeric polymer, consisting of both hard and soft segments. The soft segments are usually composed of flexible polyester or polyether and the hard segments are usually composed of diisocyanates with benzyl structure . Such al1.5)n , where R could be a hydrogen atom/organic group, such as alkyl, aryl, vinyl, acrylate, epoxide group, to name a few , 0.30 , 0.71 , 1.62  and 3.44 .3,13-di(trimethylsilyl)oxypropyloctaphenyl B-POSS was synthesized as per Wei et al.’s study . 3,13-di2Cl2 (90 mL) in a flask were stirred and purged with nitrogen. Methyltrichlorosilane  in anhydrous methanol (10 mL) was added dropwise to the solution within 30 min. The reaction was carried out at room temperature for 5 h, and then solvents were removed by rotary evaporation. Finally, 2.25 g powder was collected with yield of 93 wt % through washing the product with a mixture of THF and hexane (50/50 vol/vol) and dried in a vacuum oven. 1H-NMR : 0.31 , 0.74 , 1.63 , 3.47 ; MALDI-TOFMASS (product + Na+): 1292.1 Da .3,13-dihydroxypropyloctaphenyl B-POSS (B-POSS) was synthesized as per Wei et al.’s study . 3,13-di2 (375 μL) and anhydrous toluene (150 mL), vigorously stirred at room temperature for 5 min and then reacted at 110 °C for another 20 h under dry nitrogen. After that, the solvent was eliminated via rotary evaporation and the mixture was precipitated by adding an excessive amount of methanol. Then, the precipitate was obtained through centrifugation and washed with methanol three times. The product was dried in a vacuum oven at 40 °C for 24 h and then 8.13 g product of O-8000 was obtained with a yield of 85%. 1H-NMR : 1.4–1.6 , 2.3 , 4.1 , 7.14–7.50 . FTIR : 1536 (–NH–), 1730 (–COO–). GPC : Mw = 10,100, Mw/Mn = 1.35. O-4000, O-10000, O-12000 and O-14000 were prepared using the same manner, simply varying the ε-CL feed content.The B-POSS incorporated oligomers of polycarprolactone (PCL) were synthesized with B-POSS and ε-CL by varying ε-CL content as shown in 2  was added into solution and HDI  in anhydrous toluene (10 mL) was added dropwise to the solution. The reaction was allowed to proceed at 70 °C for another 3 h under nitrogen. After that, the solvent was removed by rotary evaporation and PU-8000 was collected by precipitation with a large amount of ethyl ether. Finally, the product was obtained after drying at 40 °C for 24 h in a vacuum oven, and 5.65 g product was obtained with a yield of 83%. PU-4000, PU-10000, PU-12000 and PU-14000 were prepared through the same synthetic route with yields of 84%, 81%, 85% and 86%, respectively. Neat PU was obtained using PCL and HDI in the same way.To synthesize the designed linear PUs, the POSS-PCL oligomers are further reacted with HDI through stoichiometric and temperature control to produce five types of PUs with various physical properties as shown in Mw/Mn) for these hybrid polyurethanes was slightly higher than that of the control polyurethane. The increased values of the polydispersity index could be attributed to the high steric hindrance of B-POSS. It is possible that the nanoscale size of B-POSS restricted the motion of the POSS macromer during the polymerization and that this effect was increasingly pronounced while its concentration was sufficiently high.All the polyurethanes with B-POSS in the main chains were subjected to gel permeation chromatography (GPC) to measure their molecular weights. In all cases, high-molecular-weight products were obtained. It is noted that the polydispersity index  using tetramethylsilane  as the internal standard. Chemical shifts were reported in parts per million (ppm) and CDCl3 was used as solvent for all the samples.Matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS)  with gentisic acid  as the matrix and THF as the solvent was used to measure the molecular weight of B-POSS.−1 with scan number of 32.FTIR spectra were tested at room temperature via an IR Prestige-21 spectrometer  operated at a resolution of 4 cmThermogravimetric analysis was carried out using a thermogravimetric analyzer  at room temperature to 800 ° C at 10 °C/min under an air atmosphere.The thermal behavior test of the polymer was measured using a DSC (Q10) differential scanning calorimeter . The polymer was heated from room temperature to 150 °C at a heating rate of 15 °C/min under air atmosphere.The molecular weight and molecular weight distribution of the polymer were determined using THF as the eluent and polystyrene as the standard gel permeation chromatography .Scanning electron microscopy was used to characterize the surface morphology using SEM .The rheological measurements of the polymer were carried out using a TA DHR-2 rheometer  on parallel plates of 20 mm diameter.−1 and 25 °C.The tensile test was carried out using a microcomputer-controlled electronic universal testing machine  at a crosshead speed of 10 mm/min1H-NMR spectra of 3,13-dihydroxypropyloctaphenyl B-POSS (B-POSS), 3,13-di(trimethylsilyl) oxypropyloctaphenyl B-POSS and 3,13-dihydrooctaphenyl B-POSS is shown in 3, –CH2–OH and phenyl groups, respectively. The integration area ratio between b, e and f is 3.01: 2.04: 20.03, which is close to the theoretical ratios calculated from the structural formula. In 3, –CH2, –CH2O and benzene rings, respectively. In addition, the peaks of Si–H protons at 4.98 ppm disappeared completely, indicating the successful hydrosilylation reaction. For B-POSS, the methyl protons peak of trimethylsilyloxypropyl at 0.02 ppm also completely disappeared after the deprotection reaction of 3,13-di(trimethylsilyl)oxypropyloctaphenyl B-POSS. Moreover, the successful synthesis of B-POSS was further confirmed by MALDI-TOF mass spectroscopy, where the molecular weight of B-POSS was determined to be 1292.1 (B-POSS + Na+), which is in good agreement with the calculated value (1269.1) from the molecular structure , 1.2 ppm  was assigned to the protons of CH2 in the coupling regent HDI. The phenyl groups of B-POSS moieties were detected at 7.14–7.50 ppm in the spectrum, suggesting that B-POSS have been successfully incorporated into the main chain of PUs.The typical −1 disappeared after chain extension through urethane reaction  are determined as 207, 238, 246, 266, 280 and 283 °C for neat PU, PU-4000, PU-8000, PU-10000, PU-12000 and PU-14000, respectively  of the polymer drastically [Thermal stability and transitions of polymers were characterized by TGA and DSC analyses. TGA curves of PU, PU-4000, PU-8000 and PU-12000 are shown in ectively . Accordistically , and thestically ,26,27,29stically . The silg) are 47, 54, 60, 64, 67 and 69 °C for PU, PU-4000, PU-8000, PU-10000, PU-12000 and PU-14000  (PLGA) was selected as target polymer. As it is well-known, PLGA is a biodegradable functional polymer with good biocompatibility, non-toxicity and film-forming properties. It has been widely used in pharmaceutical, medical engineering materials and modern industrial fields . HoweverIn summary, a series of hybrid thermoplastic polyurethanes (PUs) incorporated with bi-functional polyhedral oligomeric silsesquioxane in the polymer backbone were successfully synthesized and fully characterized. With the introduction of B-POSS into the main chain, the surface hydrophobicity and thermal and mechanical stability of the hybrid PUs were significantly increased. The structure-property correlations were instigated by comparing with neat PU. As a new kind of thermoplastic filler, the hybrid PUs can also be used to improve the mechanical strength of PLGA, exhibiting promising application in biomedical devices.


Concrete compressive strength is an important parameter of material properties for assessing seismic performance of reinforced concrete (RC) structures, which has a certain level of uncertainty due to its inherent variability. In this paper, the method of concrete strength validation of finite element model using smart aggregate (SA)-based stress monitoring is proposed. The FE model was established using Open System for Earthquake Engineering Simulation (OpenSEES) platform. The concrete strengths obtained from the material test, peak stress of SA, and estimated concrete strength based on SA stress were employed in FE models. The lateral displacement monitored by Liner variable differential transformer and vertical axial load monitored by load cell in the experiment are applied in the model. By comparing the global response , local response  and corresponding root-mean-square error obtained from experiment and numerical analysis, the capabilities of validation of FE model using SA-based stress monitoring method were demonstrated. The assessment of seismic performance of the existing infrastructures is a matter of high priority in earthquake prone areas. Quantifying the material properties of these structures is critical due to the impact that it has on the subsequent application of assessment methods. For reinforced concrete (RC) buildings, concrete compressive strength has emerged as an important material property that requires careful consideration because it directly relates to durability and strength of RC structure.crf) obtained from the material test must be higher than the specified compressive strength, cf, to guarantee the safety of structures. A similar requirement also can be found in Chinese concrete design code [crf depends significantly on workmanship including mix, casting and curing operations [crf being lower than cf. It has been proven that the coefficient of variation (CV) of concrete compressive strength often exceeds 20% [crf of existing structures to establish the suitable FE model for evaluating the seismic performance of RC structure in advance in case of earthquake.According to American concrete design code , the aveign code . Concretign code . In pracerations ,5,6. Furerations , chemicaerations  and fireerations , may reseeds 20% . Therefocrf prediction because many NDT parameters are sensitive to concrete strength variations. Two major NDT methods are mostly considered: hardness tests [Non-destructive evaluation (NDT) provides a promising way towards ss tests ,12,13,14ss tests ,16,17. Tss tests . Howeverss tests . Besidesss tests . The expss tests . Howeverss tests . Additioss tests . To avoiss tests ,23,24,25Smart aggregate (SA), as a piezoelectric-based embeddable transducer, is made of a waterproof material packaged PZT patch between concrete or granite blocks to protect it from moisture and fragile broken ,26. SA iIn this paper, we report on a feasibility study of concrete compressive strength validation of FE model using SA-based stress monitoring method. The FE model was established through the platform of Open System for Earthquake Engineering Simulation (OpenSEES). The global and local response, and corresponding root-mean-square error were compared.The SA was fabricated by sandwiching a PZT patch between a pair of granite blocks with epoxy, as illustrated in The two-dimensional FE model was established. The layout of nodes and elements of the FE model is shown in The division of the cross-section at the integration point (140 mm away from Node 2) is presented in uσ is the ultimate strength of the rebar, which is 1.3 times of yield strength yσ. ys and us are loaded-end slips corresponding to the bar stresses of yσ and uσ, respectively. ys can be calculated using Equation (1) [α is the parameter used in the local bond-slip relation, which is taken as 0.4 in this paper in accordance with provision 6.1 of CEB-FIP Model code 2010 [bd is the diameter of the longitudinal steel bar, which is 22 mm in this paper. yσ is the yield strength of the rebar, which is tested to be 460 MPa. us = 30–40 ys, which is set to be 35. As shown in b’ = 0.3 in this study. To employ the model for capturing the pinching characteristic effect of reinforcement in flexural members subjected to reversed cyclic loading, the coefficient cR, which defines the pinching characteristic, is set to 0.6 according to the literature [The material property of the reinforcement fibers in the zero-length section element proposed in the literature  is showntion (1) (1)sy=2.ode 2010 . db is t0E, is 210 GPa. The yield strength of the rebar σy is tested to be 460 MPa, corresponding to the yield strain yε of 2190 με. The strain-hardening ratio b is 0.02. The parameter 0R, which controls the curvature of the transition from the elastic to plastic-hardening branch, is 20 [As shown in h, is 20 .uf is the ultimate residual strength, 0ε is the strain at peak strength, uε is the strain when the residual strength is reached, and E is the Young’s modulus of the concrete.To further improve the efficiency of simulation and adequately capture the major behavior of concrete in compression rather than tension, the constitutive relationship for the concrete is modeled using the Kent–Scott–Park model  with no cf is a statistical parameter, which is a variable for the concrete structures. To identify the average concrete compressive strength, four typical parameters, namely lower limit and average value of concrete compressive strength of concrete cube, the peak stress monitored by SA, and the estimated strength based on concrete stress distribution assumption, were selected as the potential concrete compressive strength in the models and denoted FEA-1–4, respectively.It should be noted that ccf is the confined concrete compressive strength induced by stirrups. κ is the ratio between ccf and cf, which can be expressed as [The average strength of the concrete cube specimen cast with the column was 33.5 MPa with a coefficient of variation of 0.13. The unconfined concrete strength of the RC column is considered to be 0.79 times smaller than that of the concrete cube due to end friction effects , which iessed as :(3)κ=1+sρ, is 0.0092. The yield strength of stirrup, yhf, is 300 MPa.In this paper, the stirrup is plain bars at 100 mm spacing with a diameter of 10 mm. The volume–stirrup ratio, The lower limit and average value of concrete compressive strength of concrete cube are considered as the candidates of the unconfined concrete compressive strength of RC column, which were 23.0 and 26.5 MPa, respectively. The corresponding lower limit and average value of the confined concrete compressive strength can be calculated using Equation (2), which are 26.0 and 29.7 MPa, respectively.The monitored peak compressive stress of SA in experiment is 39.4 MPa , which i3k/α, where 3k is 0.925 and α is 0.85 for normal strength concrete [3k/α, which is 42.9 MPa for confined concrete. Utilizing Equation (2), the estimated unconfined concrete can be obtained, which is 40.0 MPa.The stress monitored by SA can be recognized as the average compressive stress of limited zone. Based on the stress distribution assumption, as illustrated in concrete . The estuf is 0.2 and 0.8 times cf for unconfined and confined concrete, respectively. In accordance with Chinese code for design of concrete structures [0uε and the ratio of the peak strain to ultimate stain of the unconfined concrete, ε0u/uuε, can be obtained. The ratio of peak strain of confined concrete to that of unconfined concrete, ε0c/0uε, is equal to ε as well, which can be obtained using Equation (3). The confined ultimate strain, εuc, is a constant, 0.02 in this study.The detailed of the concrete constitutive parameters are shown in The loading scheme for FE analysis was the same as that of the experiment in . The disThe global response including lateral load and hysteretic loop were used to evaluate the effectiveness of strength prediction by comparing the results of experiment with that of FE analysis.As shown in The lateral load-displacement hysteretic loops are shown cf, which is reasonable based on the relationship between Young’s modulus and cf, as illustrated in Generally, the global response rather than the local response  was used for evaluating the difference between experimental and FE results, due to the lack of effective local stress and strain monitoring methods, especially in large deformation stage. In this study, utilizing the SAs combined with strain gauge, the local response including concrete stress, rebar strain, and cross-section moment were obtained, providing a new index to evaluate the performance of strength prediction.The stress-histories of five typical locations, as presented in The strain time-histories of rebar derived from FE models and experiment are compared in cf. The results of FEA-3 and FEA-4 agree better with experimental moment than those of FEA-1 and FEA-2.To further validate the feasibility of SA-based concrete strength monitoring method, the typical moment time-history of cross-section A-A obtained from experiment and FE analysis was compared, as illustrated in expx and anax are the amplitude of each cycle during cyclic loading for experimental and analytical curve, respectively.To quantify the difference between the experimental and analytical result, a specific form of root-mean-square (RMS) error was adopted, as expressed in Equation (4)The RMS error of concrete stress at five typical locations (Points I–V) is shown in The RMS error of cross-section moment is shown in This paper proposes the concrete strength validation of FE model using smart aggregate-based stress monitoring method. The concrete strengths obtained from material test, peak stress of SA, and estimated concrete strength based on SA stress were employed. The FE models were established, considering the load-end slip of rebar. To verify the proposed method, the global and local responses of the RC column and corresponding root-mean-square (RMS) error obtained from the experimental and numerical analysis were compared. The conclusions are summarized as follows.The concrete stress of local response is a more sensitive index than global response and other local responses (rebar strain and cross-section moment) to identify the difference between experiment and FE simulation. The concrete compressive strength of the plastic hinge zone of RC structure obtained from standard specimens cast simultaneously provides a conservative estimate. The compressive strength in FE model can be validated using SA-based seismic stress monitoring method.


HR) = 2.19, 95% confidence interval (CI) = 1.55–3.10). c-Met immunohistochemical staining positivity was also associated with worse relapse-free survival  and presence of regional lymph node metastases (odds ratio (OR) = 1.76, 95% CI = 1.26–2.45). High levels of c-Met expression in HNSCC predict unfavorable prognosis associated with common clinicopathological features.This meta-analysis aims to evaluate the effects of high c-Met levels in head and neck squamous cell carcinomas (HNSCC) on survival and clinicopathological features. Publications concerned with the clinical significance of c-Met protein expression in HNSCC were identified from the Scopus and Web of Science database searches. To elucidate the relationship between c-Met expression and clinical outcomes, a meta-analysis of the selected articles was conducted. Seventeen publications involving a total of 1724 patients met the inclusion criteria. c-Met overexpression was significantly correlated with poor overall survival (hazard ratio ( By hijacking these pathways through c-Met activation, tumors increase their potential for invasive growth and metastasis2.c-Met is a transmembrane tyrosine kinase receptor for hepatocyte growth factor (HGF) also named scatter factor (SF). Its physiological function is connected to key processes in tissue embryogenesis and wound healing such as the ability of migratory cells to detach from the extracellular matrix, to elude anoikis and finally to settle in newly forming or damaged tissue3. The currently most used prognostic system is the TNM classification which relies on gross pathological features of the tumor and has inherent limitations in its ability to predict the aggressiveness of the neoplasm4.Head and neck squamous cell carcinoma (HNSCC) is the prominent histological type of head and neck cancer causing more than 200,000 deaths each year5. c-Met has recently gained significant attention due to it is being associated with the cancer stem cell population6 and also acting as a key component of resistance mechanism against epidermal growth factor receptor (EGFR) inhibition by novel therapeutics such as cetuximab7.To address these issues, several biomarkers are currently under investigation as potential prognostic factors in HNSCCMET gene mutations and copy number alterations or by assessing c-Met overexpression8. While some studies have linked c-Met dysregulation to worse prognosis in HNSCC patients11, others have not found any significant correlation13. The aim of this meta-analysis is, therefore, to aid investigators and physicians in evaluating the role of c-Met as a robust prognostic factor in head and neck squamous cell carcinoma.Owing to its importance in cancer progression, aberrant c-Met signalling has been studied specifically in the context of HNSCC mainly by identifying MET gene amplification status as a prognostic factor but the scarcity and heterogeneity of the data prevented a reasonable statistical analysis14. Only studies explicitly including squamous cell cancer were included. While 4 studies in total have explored c-Met expression levels in all various sites of the head and neck, 9 studies have focused only on the oral cavity, 3 only on oropharyngeal tumors and lastly, a single study included solely hypopharyngeal lesions. A subgroup analysis dissecting differences among these locations was not feasible due to lack of data on the association between clinical outcomes and the tumor site.The literature selection process of the eligible studies is presented in Fig. 15. Specifically, 12 articles evaluated N tumor staging, 10 also assessed T tumor staging and/or prognostic clinical staging, 9 studied tumor differentiation level , 6 investigated the presence of distant metastases, 4 articles measured locoregional failure occurrences and finally, 2 papers provided p16 positivity values in high and low c-Met expression groups. Supplementary information presents all the studies included in the meta-analysis in detail.Fourteen studies explored the prognostic significance of c-Met in overall survival, while only 11 investigated relapse-free survival . Association of several clinicopathological parameters with c-Met expression level was also studied by some of the selected papers. A single study only analyzed c-Met staining positivity and clinicopathological parameters but not patient survivalHR = 2.19, 95% CI = 1.55–3.10; Fig. 24. A moderate measure of heterogeneity was observed among these studies . Combined data from a total of 11 studies also demonstrated a relationship between positive c-Met staining and poor RFS 26.Meta-analysis of 14 applicable studies showed that positive staining for c-Met was associated with lower OS . Seven of these studies also evaluated the impact of c-Met overexpression on worse RFS. Statistically significant association was found after combining the data , sample size  and the ratio of c-Met positive to c-Met negative samples . In all studied subgroups, c-Met staining positivity was associated with both poorer OS and RFS, except for the “Asian” subgroup which had a significant relationship only between c-Met staining positivity and worse OS but not between c-Met staining positivity and poorer RFS , presence of distant metastasis , locoregional failure , poor tumor differentiation  or condensed TNM stage . Also, no correlation was found between high levels of c-Met and p16 positivity , albeit only 2 studies investigated this parameter. Results of this analysis are presented in Table c-Met staining positivity was significantly correlated with regional lymph nodes metastasis . Further investigation by Egger’s test also did not provide evidence for publication bias in any of the aforementioned parameters Table  and 3.Identification of prognostic markers enables stratification of patients into high-risk groups for whom a specific therapy could be necessary. In this meta-analysis, a significant relationship between high c-Met expression level and poor overall survival in the context of head and neck squamous cell carcinoma has been demonstrated.Even though immunohistochemistry was used in all the included studies, a primary obstacle in interpreting and combining the outcome data was the diversity of cutoff definitions for the high and low expression patient groups used by the authors. In some studies, the chosen criteria have taken into account all the possible immunohistochemical factors and at the same time have been strict enough to warrant the usage of the term high/low c-Met expression. In other included articles, the criteria have not been clear or stringent enough and thus the separated patient groups can only be recognized as c-Met staining positive or negative, while the c-Met staining positive group could have expression levels ranging from fairly low, through moderate to high. To improve the interpretability of the results, overall and relapse-free survival values were calculated for all of the studies taken together and then separately for the high/low expression studies with stricter criteria. With all the studies combined, c-Met staining positivity was associated with poorer overall and relapse-free survival. When considering only the subset of studies with stricter cutoff criteria, high c-Met expression was correlated with worse overall survival but not with poorer relapse-free survival. This discrepancy could have arisen due to reduced statistical power when analyzing only a subset of all the possible studies. A unified method of scoring tissue samples for c-Met overexpression would greatly improve the comparability of future studies. A possible candidate for this role is a scoring method used in three of the eight high/low expression studies, the only one employed by more than a single group of authors.Subgroup analysis showed that neither sample size, c-Met positive to c-Met negative ratio, nor the stratification of patients by Asian and Western countries have influenced the statistical significance of the association of c-Met staining positivity with poor overall survival. This was also true for the relationship between c-Met staining positivity and relapse-free survival, except for the Asian subgroup, where an insignificant hazard ratio was calculated, perhaps due to a higher measure of survival data extraction from Kaplan-Meier curves and therefore introduced error in the Asian subgroup.28. Indeed, in the present meta-analysis, a relationship between c-Met positivity and regional lymph node metastases was observed. Furthermore, a previously published study has shown c-Met-positive head and neck cancer cells to possess cancer stem cell properties and to contribute to chemo- and radiotherapy resistance6. HPV positivity of head and neck tumors is usually accompanied by p16 positivity and can have very different outcomes when compared to HPV negative cancers29. A relationship between c-Met positivity and p16 positivity could be in part responsible for these varying outcomes. However, no statistically significant correlation was found in our study.The biological role of c-Met provides a possible explanation for its association with poor prognosis. Aberrant HGF/c-Met signalling has been previously shown to suppress E-cadherin expression and on the other hand, increase expression of matrix metalloproteinases thus inducing a migratory phenotype in the affected cellsThere are several limitations which must be kept in mind when interpreting the results of this meta-analysis. First, usage of different antibodies against c-Met among studies contributes to ambiguity. Second, the number of patients in each study is generally small, thus reducing the power and precision of subgroup analyses. Lastly, only manuscripts published in English were considered for inclusion in this study, ignoring potential high-quality articles in other languages.In summary, this meta-analysis shows that c-Met overexpression is an indicator of poor overall survival in head and neck squamous cancer patients, while c-Met immunohistochemical staining positivity is associated with worse overall and relapse-free survival as well as higher rates of regional lymph node metastases. These findings can help expand the application of c-Met as a prognostic marker in the clinical setting.A systematic search of the published literature was conducted in the Scopus and Web of Science databases using the following terms: (c-met OR “kinase MET” OR “MET kinase” OR HGFR OR SFR OR “scatter factor receptor” OR “hepatocyte growth factor receptor”) AND (hnscc OR (“head and neck” AND cancer) OR  AND (cancer OR tumo* OR carcinoma*))). Titles and abstracts of the resulting studies were reviewed to remove unrelated papers. The remaining part of the studies was read in full with the reference lists scanned for relevant articles.In order to be selected, a study had to meet the following inclusion criteria: (1) was published in English; (2) measures c-Met protein level in human head and neck tumors; (3) provides survival data such as hazard ratio (HR) of overall survival (OS) or relapse-free survival (RFS) or corresponding Kaplan-Meier curves or provides data correlating c-Met protein level and clinicopathological features such as tumor TNM staging. When multiple articles included the same population of patients, only the most recently published paper was considered. The eligibility of the studies for meta-analysis was evaluated by two authors (V.V. and J.G.).et al.30. Extracted data are available at Supplementary dataset The following characteristics were extracted from each eligible study: 1) age and sex of the patient population; (2) follow-up length; (3) number of cases in c-Met positive and negative groups; (4) TNM staging, clinical staging, histological grades and anatomical site of the tumor samples; (5) c-Met positivity definition and cutoff values; (6) HRs with 95% CIs for OS and RFS or corresponding Kaplan-Meier curves. Preferentially, values calculated with multivariate (i.e. multivariable) Cox proportional hazard model were used in the meta-analysis. If these were not available, results from univariate Cox regression or estimates from Kaplan-Meier survival curves were utilized instead. Calculation of HR from Kaplan-Meier curves was conducted according to Tierney  age and 23. Of these 9 articles, three have used a completely identical cutoff definition31. The 8 remaining papers have based their cutoff values only on either weak staining intensity or a relatively small proportion of stained cells without explicitly mentioning any consideration was given to the strength of the staining26.Due to no clear and standardized criteria for stratification of patients into high- and low-expression groups based on c-Met IHC results, authors of the included studies employed a wide variety of scoring algorithms to distinguish these two patient groups. Of the 17 included studies, only 9 have evaluated both staining intensity along with the relative number of cells stained and also had stringent enough cutoff criteria to truly separate patients into high- and low-expression groupsBased on this, the 9 selected studies with stricter cutoff criteria have also been analyzed separately as c-Met high expression studies while all articles taken together are further termed c-Met positivity studies (Supplementary information).The expression of c-Met was determined as high or low, according to the definition and cutoff values of each study. To evaluate the effect of association between c-Met expression and OS or RFS, the hazard ratio of patients with low c-Met expression vs. patients with high c-Met expression was used. HR > 1 implied worse prognosis for the patients with high levels of c-Met expression.https://CRAN.R-project.org/package = meta) and metafor . Because each included study was done on a different population and using varying c-Met expression cutoff values, a random effects model was used to combine the data. Heterogeneity among studies was evaluated by the restricted maximum-likelihood (REML) method. Publication bias was first assessed graphically by Begg’s funnel plot analysis and consequently using Egger’s test with significant publication bias defined as p < 0.05. Only parameters with at least 5 applicable studies were analyzed for publication bias.All analyses were carried out using the R packages meta (version 4.8–4, Supplementary informationSupplementary dataset


Preparing an antibiotic stewardship program requires detailed information on overall antibiotic use, prescription indication and ecology. However, longitudinal data of this kind are scarce. Computerization of the patient chart has offered the potential to collect complete data of high resolution. To gain insight in our global antibiotic use, we aimed to explore antibiotic prescription in our intensive care unit (ICU) from various angles over a prolonged time period.We studied all adult patients admitted to Ghent University Hospital ICU from 1 January 2013 until 31 December 2016. Antibiotic prescription data were prospectively merged with diagnostic  and microbiology data by ICU physicians during daily workflow through dedicated software. Definite focus of infection and probability of infection (classified as high/moderate/low) were reassessed by dedicated ICU physicians at patient discharge.During the study period, 8763 patients were admitted and overall antibiotic consumption amounted to 1232 days of therapy (DOT)/1000 patient days. Antibacterial DOT  were linked with infection in 80%; the predominant foci were the respiratory tract (49%) and the abdomen (19%). A microbial cause was identified in 56% (3169/5686). Moderate/low probability infections accounted for 42% of antibacterial DOT prescribed for respiratory tract infections; for abdominal infections, this figure was 15%. The median treatment duration of moderate/low probability respiratory infections was 4 days (IQR 3–7). Antifungal DOT  were linked with infection in 47% of total antifungal DOT. Antifungal prophylaxis was primarily administered in the surgical ICU (76%), with a median duration of 4 DOT (IQR 2–9).By prospectively combining antibiotic, microbiology and clinical data we were able to construct a longitudinal, multifaceted dataset on antibiotic use and infection diagnosis. A complete overview of this kind may allow the identification of antibiotic prescription patterns that require future antibiotic stewardship attention.The online version of this article (10.1186/s13054-018-2178-7) contains supplementary material, which is available to authorized users. Antibiotics are among the most prescribed drugs in the intensive care unit (ICU) , 2. The Surveillance of antibiotic prescription is a first and essential step to measure antibiotic expenditure, to document physicians’ incentives to prescribe antibiotics and to identify areas of potential overuse or misuse which could then be a target for antimicrobial stewardship interventions , 13–15. In this manuscript, we present a complete and in-depth analysis of global antibiotic prescription and infection diagnosis in a university hospital ICU over a 4-year period. These data were collected with the help of a locally developed software program, which has been designed to link pharmaceutical, clinical and microbiological data together with diagnostic interpretation while performing daily bedside clinical work. As such, we were able to get a bird’s eye view of our local antibiotic prescribing practices, which can then serve as a starting point for the future construction of an antibiotic stewardship program (ASP).This study was conducted from 1 January 2013 until 31 December 2016 at the medical (14 beds) and surgical (22 beds) ICU of Ghent University Hospital (1054 beds). The Ghent University Hospital Ethics Committee approved the study (registration number B670201628197) and waived informed consent based on the non-interventional nature of this study and the complete anonymization of patient data. Patients aged 16 years or older were included.An Intensive Care Information System  integrating computerized physician order entry for medication prescriptions, computerized medication administration recording and clinical patient monitoring data has been available at the bedside since 2003. Patients are managed in a closed ICU model. Antibiotic prescriptions are at the discretion of the attending senior ICU physician, without the use of stringent protocols or antibiotic restrictions. As a rule, postoperative prophylactic treatment is not prolonged for more than 24 h following the procedure. Empirical antibiotic choices are guided by systematically collected surveillance cultures whenever available. Direct microscopic examination is performed on all diagnostic respiratory and per-operative samples. Pathogen identification is routinely performed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Microbiology results are reported electronically. Interdisciplinary staff meetings with medical microbiologists reviewing all antibiotic prescriptions take place once weekly in the medical ICU and three times weekly in the surgical ICU; these staff also include the presence of infectious diseases specialists in the surgical ICU. In addition, daily advice and follow up by these specialties is possible on a demand basis. Treatment duration and opportunities for antibiotic de-escalation are evaluated daily by the attending ICU physician and during the interdisciplinary discussions.2O), a semi-recumbent position (30–45°) and daily assessment of sedation.A ventilation-associated pneumonia (VAP) prevention bundle was used during the entire study period and involved the use of strict hand hygiene, oral care with chlorhexidine, endotracheal tube cuff pressure control  was developed by a consortium of the Ghent University Hospital ICU and the Department of Information Technology (INTEC) of the Faculty of Engineering of Ghent University . The proPrescription indication and antimicrobial utilization were described for all patients that were admitted during this study period. In microbiologically confirmed infections, the timing of appropriate antibiotic therapy was defined as the point in time at which all pathogens involved in the infection were covered by at least one component of the treatment.Antimicrobial days of therapy (DOT) per admission and per patient days is recommended as utilization metric by the STEWARDS panel and others , 14, 22.Subgroup analyses were performed in the patient populations with an ICU length of stay (LOS) equal to or more than 48 h versus less than 48 h, respectively, as this latter subgroup consists mainly of the less severely ill patients in our setting . In addition, patients with an ICU LOS of 48 h or more constitute the population at risk of developing ICU-acquired infection, which was defined as an infection emerging after more than 48 h of ICU admission.p < 0.05. For outcome analysis, we only included the last ICU episode of patients with consecutive ICU admissions. Statistical analysis was performed using R Statistical Software (version 3.4.2).Categorical variables were expressed as frequencies (percentages) and continuous variables were described as medians with the interquartile range . Differences in categorical variables were calculated using the Pearson chi-square test. The Mann–Whitney U test was used to compare continuous variables. Statistical significance was defined as A total of 10,743 ICU admissions were recorded in 8763 patients, resulting in a total of 47,403 patient days from 1 January 2013 until 31 December 2016. ICU and hospital mortality were 10.7% and 15%, respectively. Median Acute Physiology and Chronic Health Evaluation (APACHE) II score at admission was 18 (IQR 13–25). Mechanical ventilation was provided in 3958 admissions (36.8%) with a median duration of 2 days (IQR 1–6), resulting in 20,897 ventilation days. Vasopressor therapy was administered in 3639 admissions (33.9%) with a median duration of 2 days (IQR 2–4). Detailed information on patient characteristics is presented in Additional file Staphylococcus aureus isolates in our ICU population. Vancomycin resistance was present in 1.9% of the Enterococcus species isolates. Extended spectrum beta-lactamase production (ESBL) was present in 33% of Enterobacteriaceae isolates, whereas carbapenemase production was present in 1.2%.Methicillin resistance was present in 23% of the Patients were exposed to at least one antibiotic class in 66% 7051/10743) of ICU admissions. An infection was present within the first 48 h of ICU admission in 35% (3804/10743) of admissions. An ICU-acquired infection was diagnosed in 23% (1096/4851) of admissions with an ICU length of stay of more than 48 h. Detailed information on antibiotic exposure per ICU episode is provided in Fig. /10743 ofA total number of 10,731 treatment courses (infection bars) was recorded during the study period. Respectively 4525 (42.2%) and 6206 (57.8%) of these courses were prescribed for prophylaxis and for infection. Fungal infections represented 8% (520/6206) of the infectious episodes. Infections were microbiologically confirmed in 56% (3169/5686) and 63% (327/520) of bacterial and fungal infections, respectively. Antibiotic treatment initiated in the ICU was considered appropriate within 12 h and 24 h, respectively, following treatment initiation in 83% and 87% of microbiologically confirmed infections. Infections were ICU-acquired in 28% of cases (1767/6206). The focus of the bacterial infections was predominantly respiratory and abdominal . The crude ICU mortality rate in patients with respiratory and abdominal infections was 22.1% and 19.2%, respectively. Infection probability was classified as high, moderate or low in 50%, 34% and 16%, respectively, of the respiratory infections compared to 76%, 16% and 8%, respectively, of the abdominal infections. The median treatment duration of high, moderate and low probability respiratory infections for which the course was completed on the ICU was 7 days (IQR 5–10), 6 days (IQR 4–8)] and 4 days (IQR 2–6), respectively. Only 19% of the respiratory infections were classified as ventilator-associated. A total of 345 cases of VAP and 182 cases of ventilator-associated tracheobronchitis (VAT) were diagnosed, resulting in VAP and VAT incidences of 16.5/1000 ventilation days and 8.7/1000 ventilation days, respectively. Respectively, 52%, 37% and 11% of VAP were classified as having a high, moderate or low probability of infection, translating into VAP incidences of 8.6, 6.1 and 1.8/1000 ventilation days, respectively. VAP incidence was 17.0/1000 ventilation days in the medical ICU and 16.1/1000 ventilation days in the surgical ICU. The median treatment duration of VAP and VAT episodes in the ICU was 7 days (IQR 5–9) and 6 days (IQR 4–7), respectively. The crude ICU mortality rate in patients with VAP and VAT was 32.6% and 21.1%, respectively  were administered, resulting in 58,413 DOT (1232 DOT/1000 patient days). Detailed utilization analysis per antibiotic agent and infection probability is presented in Table Prophylactic therapy accounted for 25% of the total antimicrobial DOT; first-generation cephalosporins, folate pathway inhibitors, monobactams and azoles were predominantly used in this setting. Antibacterial prophylaxis mainly comprised perioperative prophylaxis (46%) and prolonged prophylaxis in the immunosuppressed patient (19%). The median duration of perioperative prophylaxis was 8 h (IQR 8–17). In addition, 9% and 11%, respectively, of antibacterial prophylaxis was initiated in the setting of trauma and following aspiration with respective durations of 3 DOT (IQR 2–4) in trauma patients and 3 DOT (IQR 2–5) in the setting of aspiration. Antifungal prophylaxis accounted for 53% of the total antifungal DOT and was primarily administered in the surgical ICU (76%), with a median duration of 4 DOT (IQR 2–9).Seventy-five percent of the total antimicrobial DOT was used to treat infections. Of the total amount of DOT used to treat bacterial respiratory infections, 42% was used to treat infections with a moderate and low probability; for bacterial abdominal infections, this figure was 15%.Enterobacteriaceae were the predominant bacterial species that were designated as causative pathogens in both respiratory and abdominal infections . Amoxicillin/clavulanic acid resistance and cefuroxime resistance was present in 48% and 39% of the Enterobacteriaceae isolates, respectively. Non-fermenting Gram-negative bacilli were the second most prevalent pathogens associated with respiratory infections (15%), and mainly consisted of Pseudomonas aeruginosa. Piperacillin-tazobactam, ceftazidime and meropenem resistance was present in 27%, 20% and 20%, respectively, of the Pseudomonas isolates. Enterococci were the second most prevalent pathogens that were linked as causative in the abdominal infections (20%) and ampicillin resistance was present in 44% of the isolates  and timespan covered (4 years).Our study confirms that the antibiotic burden in the ICU is very high. Respectively, 66% of all admitted patients and 84% of patients with an ICU stay of more than 48 h were exposed to at least one class of antibiotic. These figures are consistent with the results of the one-year prospective surveillance study of Bergmans et al. and with the EPIC II point-prevalence study, which reported antibiotic prescription in 61% and 71% of admitted patients, respectively .Clostridium difficile infection, rates of antibiotic-resistant pathogens, days of antibiotic therapy/number of admissions, days of antibiotic therapy/patient days and redundant therapy events. All of these metrics may be derived from separate electronic data sources  and a connection between the different elements is not mandatory; however, these metrics are crude and unable to provide insight into antibiotic prescription. By linking these sources, a deeper understanding of the different factors driving antimicrobial use can be obtained, as illustrated by this study.The need for detailed antibiotic prescription surveillance and feedback to the clinician was already acknowledged in the very early stages of antimicrobial stewardship, but there is disagreement about which appropriate measures to select , 23, 24.For example, the respiratory system accounted for half of identified sources of bacterial infection and more than one third of the total antibacterial DOT. Compared to abdominal infections, which represented the second largest group of bacterial infections and destination for antibiotic consumption, respiratory infections were less frequently categorized as highly probable , which also reflected the amount of DOT that was designated to treat these highly probable infections . One quarter of the infections that were diagnosed in our ICU were ICU-acquired, which is in contrast with the study of Bergmans et al. where half of the infections were ICU-acquired and almost exclusively occurred in ventilated patients. Whereas the authors of the previous study concluded that stewardship should be focused on the prevention of ventilator-associated respiratory infections, this statement may apply less to our ICU population. In addition, restricting duration of antibiotic therapy in VAP of high probability will offer little gain, as the median treatment duration was only 7 days. In contrast, more restrictive use of antibiotics in suspected respiratory tract infections with cultures remaining negative and/or a swift clinical resolution, could result in a more profound reduction of antibiotic consumption. In addition, we observed that prophylactic treatment accounted for one fourth of the total DOT. Although this figure seems extremely high, more in-depth evaluation showed that two thirds of the antibacterial prophylactic treatment consisted of perioperative prophylaxis and prophylaxis in the immunocompromised patient, which conformed to guidelines with regard to treatment duration in the ICU. Whether aspiration and trauma justify antibiotic prophylaxis, and for what duration, is still a matter of debate; more recent studies promote restrictive use of antibiotics in this setting –29. We bDespite the recognition of the importance of high-quality surveillance data to support antibiotic stewardship, few studies have provided detailed data on ICU global antibiotic consumption and infection diagnosis over an extended period of time , 19, 31.Our study has limitations. First, building the database starting from computerized physician order entry depends on adequate filling in of the “pop-up” questions that are triggered by it, and by the persistent commitment of attending physicians or infection control personnel in linking the various information sources and finalizing infection diagnosis. Second, as stated before, the lack of adherence to strict criteria in labeling infection diagnosis in the current design hampers multicenter application . ProbablWe were able to obtain a unique bird’s eye view on global antibiotic use and infection diagnosis in our ICU over a 4-year time period by analysis of a multifaceted dataset, which was collected during the daily clinical workflow of ICU physicians with the help of information technology. In doing so, we revealed antibiotic prescription patterns that merit the attention of antibiotic stewardship.Additional file 1:2)/fractional inspired oxygen (FiO2) ratio, sequential organ failure assessment score (SOFA)). For every antibiotic prescription that is entered via computerized physician order entry, a horizontal bar is created that runs just above the timeline and lengthens upon duration of the prescription (antibiotic bar). This bar is accompanied by a second bar running in parallel below the timeline and describing the indication for this antibiotic . The infection bar is created in a two-step fashion. A preliminary version is fed by data from a short questionnaire that “pops up” in real time after any antibiotic prescription and inquires the prescriber about indication, likely focus, severity and probability of infection and presence of microbiological data guiding antibiotic choice. This preliminary bar can be altered manually when more data on the origin and clinical evolution of the infection become available. Multiple antibiotic prescriptions can thus be linked with the same infection bar; in addition, the same antibiotic bar can be linked with multiple infection bars . For each infectious episode, focus, severity and probability of infection is selected from a drop-down menu. More detailed information on prescription and infection are revealed on the base of the screen by hovering over the bars. All positive microbial culture results and matching susceptibility patterns are automatically indicated above the timeline using small symbols, whereas selected microbiological isolates that are linked to an infection are displayed underneath the timeline. (JPG 479 kb)Screenshot of COSARA central infection dashboard view. Time-graphs at the top of the page show the evolution of selected clinical (e.g. fever) and laboratory ) variables and indicators of severity-of-illness Additional file 3:Staphylococcus aureus promoting glycopeptide prescription in suspected pneumonia with negative sputum cultures). (JPG 298 kb)Screenshot of COSARA antibiotic-infection combinations linked to microbiology data overview. The coupled antibiotic-infection bars can be linked to microbiological culture results; pathogens may be designated as causative pathogens or as non-causative pathogens influencing antibiotic prescription Additional file 5:Patient characteristics. (DOC 36 kb)Additional file 6:Treatment duration per focus of infection. (DOC 41 kb)Additional file 7:Antimicrobial use per antimicrobial class and per year. (DOC 61 kb)


Genome instability often arises at common fragile sites (CFSs) leading to cancer-associated chromosomal rearrangements. However, the underlying mechanisms of how CFS protection is achieved is not well understood. We demonstrate that BLM plays an important role in the maintenance of genome stability of structure-forming AT-rich sequences derived from CFSs (CFS-AT). BLM deficiency leads to increased DSB formation and hyper mitotic recombination at CFS-AT and induces instability of the plasmids containing CFS-AT. We further showed that BLM is required for suppression of CFS breakage upon oncogene expression. Both helicase activity and ATR-mediated phosphorylation of BLM are important for preventing genetic instability at CFS-AT sequences. Furthermore, the role of BLM in protecting CFS-AT is not epistatic to that of FANCM, a translocase that is involved in preserving CFS stability. Loss of BLM helicase activity leads to drastic decrease of cell viability in FANCM deficient cells. We propose that BLM and FANCM utilize different mechanisms to remove DNA secondary structures forming at CFS-AT on replication forks, thereby preventing DSB formation and maintaining CFS stability. Common fragile sites (CFSs) are large chromosomal regions which are more prone to breakage than other places in the genome. They are a part of normal chromosome structure and are present in all human beings, but are also hotspots for chromosomal rearrangement during oncogenesis. Understanding how CFSs are protected to prevent genome instability is thus extremely important for revealing the mechanism underlying cancer development. We found that Bloom syndrome protein BLM is involved in resolving DNA secondary structures that arise at AT-rich sequences in CFSs, suggesting a critical function of BLM in protecting CFSs. We also found that this BLM function is distinct from the role of Fanconi anemia protein FANCM in protecting CFSs, and loss of both BLM and FANCM activities leads to cell death. These studies reveal important mechanisms of the maintenance of CFS stability in mammalian cells. Genome instability is a hallmark of cancer cells . Certainin vitro [in vivo at the AT-rich sequences derived from FRA16D when they are present in yeast, and also at the AT-rich sites in FRA16C and FRA16B in mammalian cells [Multiple mechanisms have been proposed to elucidate replication stress-induced CFS breakage (often termed as CFS expression) . CFSs tein vitro , 17. Impan cells –20. We oan cells . TherefoFANCM is an ATP-dependent branch-point translocase, which is mutated in Fanconi anemia (FA) patients . We prevBloom’s syndrome (BS) is a genetic disorder that is associated with a wide range of abnormalities including growth retardation, immunodeficiency, genome instability and predisposition to cancer , 26. TheIn this study, we identified a new role of BLM in preventing DSB formation at CFS-AT sequences in a manner dependent on BLM helicase activity and ATR-mediated phosphorylation of BLM. This BLM function is non-overlapping with the role of Fanconi anemia (FA) protein FANCM in the maintenance of CFS stability identified in our previous study . We propAs described previously, insertion of Flex1, the AT-rich sequence derived from FRA16D, into the EGFP-based HR reporter (HR-Flex) significantly increases mitotic recombination when comparing with the HR-Luc reporter which contains a luciferase sequence insertion of similar size  Fig 1A)Fig 1A). In addition to Flex1, AT-rich sequences derived from other CFSs also induce mitotic recombination . When BLTo examine whether BLM is recruited to CFS-derived AT rich sequences, we performed chromatin immunoprecipitation (ChIP) of Flag-BLM to the Flex1 surrounding regions in the HR-Flex reporter which is stably integrated in the genome using two sets of primers P1 and P2 . Flag-BLTo examine whether BLM prevents DSB formation at CFS-derived AT-rich sequences upon replication stress, we performed ChIP analysis of γH2AX at Flex1 present on pCEP4-Flex1 plasmids with or without BLM depletion. γH2AX is significantly increased at Flex1 after exposure to HU when BLM is inactivated by shRNAs . We alsoWhen we placed Flex1 in the Epstein-Barr virus (EBV) replication origin-containing plasmids (pCEP4-Flex1) that are propagated as episomes in mammalian cells, plasmid instability is increased comparing to the plasmids containing the luciferase control sequence (pCEP4-Luc) . PlasmidBLM unwinds DNA secondary structures, such as G4 DNA . We hypoTo examine whether DSB formation is increased at Flex1 when BLM helicase activity is inhibited, we performed ChIP of γH2AX at Flex1 in U2OS (pCEP4-Flex1) cells expressing BLM-WT or BLM-KD helicase mutant. Indeed, loss of BLM helicase activity increases DSB formation at Flex1 . Loss ofBLM is phosphorylated by ATR at Thr99 and Thr122 sites upon replication stress . To showFlex1-induced mitotic recombination is increased upon HU treatment , which iIt has been shown that oncogene expression induces CFS expression . We showWe showed previously that FANCM is important for maintaining Flex1 stability and its translocase activity is required for such activity . Since BWe also monitored DSB formation at Flex1 when BLM or FANCM is inactivated. ChIP analysis of γH2AX at Flex1 showed that inactivation of both BLM and FANCM causes more DSB formation than when either of them is inactivated after HU treatment . This stIt was described that FANCM and BLM are recruited to telomeres in cells which specifically use the alternative lengthening of telomeres (ALT) mechanism to maintain telomere integrity, and depletion of BLM and FANCM leads to synthetic lethality in ALT cells . These sWe tested further whether the helicase activity of BLM is important for cell viability of FANCM deficient cells. We expressed BLM-WT or BLM-KD helicase mutant in FANCM WT or FANCM KO HCT116 cells, followed by inactivation of endogenous BLM by shRNAs. Loss of BLM helicase activity drastically reduces cell viability of FANCM KO HCT116 cells while having minimal effect on FANCM WT cells , suggestCFSs are hotspots for chromosomal rearrangement and are often mapped to breakpoints in cancer cells , 44. We CFS instability is caused by multiple mechanisms and the presence of AT-rich sequences which are prone to forming secondary structures is one of the causes for CFS expression . Upon reIn the HR-Flex reporter, if DSBs are generated at Flex1 and are repaired by HR, EGFP open reading frame would be restored to produce green cells . Our resBLM is a 3’ to 5’ helicase . BiochemWe showed that FANCM is important for maintaining stability of CFS-AT sequences in a manner dependent on its translocase activity . FANCM iFANCM contains ATP-dependent branch point translocase activity and promotes replication fork regression , 48. We Loss of FANCM or BLM activity both increases mitotic recombination at Flex1, suggesting that HR is used to repair DSBs accumulated at CFS-derived AT-rich sequences when either FANCM or BLM branch is deficient. In support of this, we showed that CtIP and BRCA1 are required for mediating increased mitotic recombination not only when FANCM is defective , but alsIt has been described that FANCM and BLM are synthetic lethal in ALT cells, which is caused by impaired telomere replication due to FANCM deficiency, combined with impaired HR function when BLM is defective . We showin vitro [in vivo. Meanwhile, we also acknowledge that the role of BLM in HR may additionally contribute to the synthetic lethality interaction of BLM and FANCM. Fork collapse at DNA secondary structures would require HR-mediated repair and replication restart that involve BLM for end resection.Our study demonstrates that both FANCM and BLM are important for maintaining stability of structure-forming AT-rich sequences derived from CFSs. We propose that the non-overlapping functions of BLM and FANCM to resolve DNA secondary sequences at replication forks could be one of the important causes for their synthetic lethality interactions . DNA secin vitro , 49, it We showed that ATR-mediated phosphorylation of BLM is important for maintaining Flex1 stability. It is possible that ATR-dependent phosphorylation of BLM stimulates BLM helicase activity, thereby contributing to Flex1 protection. Alternatively, phosphorylation of BLM by ATR may modulate the way of BLM binding to Flex1, and thus influence Flex1 unwinding by BLM. In this aspect, ChIP analysis showed that the recruitment of the ATR phosphorylation mutant BLM-T99A/T122A to Flex1 is largely unchanged. However, it is still possible that ATR-mediated phosphorylation of BLM may influence the affinity of BLM for direct Flex1 binding after its recruitment or modulate the conformation of BLM in complex with Flex1 resulting in change of unwinding activity.It was shown that the BLM helicase activity and ATR-mediated phosphorylation of BLM are both required for replication restart upon replication stress, but the underlying mechanisms are not clear . We founBLM is a multifunctional protein which couples recombinational repair with replication fork protection. Our study reveals its new function in conjugation with FANCM to protect stability of AT-rich sequences in CFSs to maintain CFS stability. This role along with its function in end resection at early steps of HR and dissolution to prevent crossover at late steps of HR , may undHuman U2OS, 293T and HCT116 cells were cultured at 37°C in a humidified atmosphere of 5% CO2 in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin. FANCM knockout HCT116 cells were previously described .BLM wild-type and indicated mutants were generated by PCR and subcloned into Babe-puro vectors containing 1x N-terminal Flag-tag or NBLV0051 (Novo Bio) vector containing a 3x N-terminal Flag-tag. FANCM wild-type and FANCM-MM2 mutants were also subcloned into NBLV0051 (Novo Bio) vector containing a 3x N-terminal Flag-tag. Point mutations, small hairpin RNA (shRNA) target site-resistant mutations were generated using the QuikChange Site-directed Mutagenesis Kit (Stratagene). The EGFP-based HR-Flex reporter and HR-Luc reporter containing the 0.34 kb Flex1 and luciferase-derived fragment (Luc), respectively, and pCEP4-Flex1 and pCEP4-Luc plasmids were described previously . EGFP-baSilencing of endogenous BLM and FANCM was achieved by retroviral or lentiviral infection using pMKO or pLKO vectors to express corresponding shRNAs , 59. shRWestern blot analysis was performed as described . Cells wCommercial antibodies used include anti-BLM , anti-H2AX-S139p , anti-Ras , anti-FLAG , anti-Ku70 , anti-β-actin . Antibodies against FANCM was kindly provided by Dr. Weidong Wang [Spontaneous mitotic recombination assay was described before . BrieflyPlasmid stability assay was performed as described . BrieflyCell proliferation was determined by counting cells every 24 hours using hemocytometer and normalized to the first day. Cell viability was shown by colony formation. HCT116 and its derivative cell lines were plated at 5000 cells per 10 cm plate and were grown in complete media for two weeks. Cell colonies were fixed with cold methanol and stained with 1% crystal violet.3), and cross-linking was reversed by adding in 4 μl of 5 M NaCl and incubating at 65°C for 6 hr, followed by proteinase K digestion for 2 hr at 42°C. DNA was extracted by QIAquick kit (QIAGEN) according to the manufacture instructions.ChIP assays were performed as described previously . BrieflyFor ChIP at Flex1 in the HR reporter stably integrated in the genome or at AT-rich sequences in the endogenous FRA3B locus, recovered DNA was analyzed by quantitative PCR (qPCR) and the readout was normalized to the vector control which is set as 1. GAPDH locus was used as a control to show the specificity of protein binding to Flex1. The primers used for ChIP at Flex1 in HR reporter: P1F 5’CTCCAATTCGCCCTATAGTGAGTCGTATTA, P1R 5’TTACTTGTACAGCTCGTCCATGC, P2F 5’GGCAGTACATCAATGGGCGTG, and P2R 5'CCTTTAGTGAGGGTTAATTGCGCG; at AT-rich sequences in FRA3B: 3B-P1F 5’TTAGCCTACTTCAGGGTTTCT and 3B-P1R 5’TGGAGAGGTTACTACTGGCA; and at GAPDH: GAPDH-F 5’CCCTCTGGTGGTGGCCCCTT and GAPDH-R 5’GGCGCCCAGACA CCCAATCC.For γH2AX ChIP at Flex1 or Luc surrounding regions on the pCEP4-Flex1 or pCEP4-Luc plasmids, recovered DNA was amplified by regular PCR or qPCR with primers 5’TCAGGGGGAGGTGTGGGAGG and 5’GCAGTCCACAGACTGCAAAG. Regular PCR was programmed as preheat at 95°C for 3 min followed by 35 cycles of 95°C 15 sec, 50°C 15 sec, 70°C 30sec. Regular PCR products were resolved by 1.5% agarose DNA gel . AlternaFragile site analysis using fluorescence in situ hybridization (FISH) was performed as described . BrieflyAll the statistical data are the results of at least three independent experiments and presented as mean±SD. Numerical data for all figures are included in S1 FigChIP analysis of γH2AX at Flex1 in pCEP4-Flex1 or Luc in pCEP4-Luc was performed by qPCR using samples described in (TIF)Click here for additional data file.S2 FigAnti-γH2AX ChIP analysis at endogenous FRA3B locus was performed by qPCR in U2OS cells expressing BLM shRNA or vector (Ctrl) upon APH treatment  using indicated primers (left). ChIP value in Ctrl is set as 1 for normalization. BLM expression is indicated by Western analysis (right).(TIF)Click here for additional data file.S3 FigFlag-FANCM-WT or Flag-FANCM-MM2 was expressed in 293T cells, and the interaction of Flag-FANCM and Flag-FANCM-MM2 with endogenous BLM was examined by IP of Flag followed by anti-BLM Western.(TIF)Click here for additional data file.S4 Fighttp://unafold.rna.albany.edu/?q=mfold, Nucleic Acids Res. 2003; 31(13): 3406–3415).Prediction of DNA secondary structures of Flex1, 16C/AT1 and 16C/AT3 with highest stability was performed by the Mfold Program ((TIF)Click here for additional data file.S5 FigU2OS (HR-Flex) cells expressing shRNAs for CtIP or BRCA1, or control vector (Ctrl), were infected with lentiviruses encoding shRNAs for BLM. Spontaneous mitotic recombination was examined 8 days after infection with a control without expressing shRNAs. Western blots are shown for indicated proteins.(TIF)Click here for additional data file.S1 Data(XLSX)Click here for additional data file.