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Piperaquine (PQ) is an antimalarial drug that is highly protein-bound. Variation in plasma protein contents may affect the pharmacokinetic (PK) exposure of unbound drug, leading to alteration of clinical outcomes. All published methods for determination of PQ in human plasma measure the total PQ including both bound and unbound PQ to plasma proteins. There is no published method for unbound PQ determination. Here we report an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for determination of PQ in human plasma filtrate prepared by filtering human plasma through Millipore Microcon® centrifugal filters (10k NMWL). The filter cup had to be treated with 5% benzalkonium chloride to reduce non-specific binding to the filter devices before filtration of plasma samples. Multiple reactions monitoring (MRM) of the ion pairs m/z 535/288 for PQ and m/z 541/294 for the internal standard (IS) was selected for quantification. When electrospray ionization (ESI+) was used, paradoxical matrix effect was observed despite the structure similarity of the deuterated IS: Ion suppression for PQ versus ion enhancement for the PQ-d6, even though they were closely eluted: 0.62 min versus 0.61 min. Separation was achieved on Evo C18 column (50 × 2.1 mm, 1.7 μm, Phenomenex Inc.) eluted with 10 mM NH4OH and MeCN. When atmospheric pressure chemical ionization in positive mode (APCI+) was used for ion source, matrix effect diminished. Separation was achieved on a PFP column (30 × 2.1 mm, 1.7 μm, Waters, Corp.) eluted with aqueous 20 mM ammonium formate 0.14% trifluoroacetic acid (A) and methanol-acetonitrile (4:1, v/v) containing 0.1% trifluoroacetic acid (B) at 0.8 mL/min flow rate in a gradient mode: 30-30-80-80-30-30%B (0-0.1-1.0-1.40-1.41-1.50 min). The retention time was 0.67 min for both PQ and the IS. The method was validated with a linear calibration range from 20 to 5,000 pg/mL and applied to clinical samples.

This paper addresses a central issue linked to research conducted on an eclectic conglomeration of people connected in various ways to the principal European site of the Japanese new religion of Tenrikyō. Although the center itself is in a Parisian suburb and the majority of its key actors are Japanese, the people connected to this center and its associated social world span beyond the Paris region and include various nationalities, countries of residence, and even religious identities. Moreover, the people connected to this center and the presence of the Tenrikyō religion in Europe are largely one and the same, but not entirely. A question commonly posed to the researcher by "outsiders" is how many Tenrikyō "members" there are in Paris, France, and/or Europe, and if they are Japanese or the nationality of the local country (French, German, etc.) The complexities of answering such questions are the focus of this discussion. [ABSTRACT FROM AUTHOR]

Piperaquine (PQ) is an antimalarial drug that is highly protein-bound. Variation in plasma protein contents may affect the pharmacokinetic (PK) exposure of unbound drug, leading to alteration of clinical outcomes. All published methods for determination of PQ in human plasma measure the total PQ including both bound and unbound PQ to plasma proteins. There is no published method for unbound PQ determination. Here we report an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for determination of PQ in human plasma filtrate prepared by filtering human plasma through Millipore Microcon® centrifugal filters (10k NMWL). The filter cup had to be treated with 5% benzalkonium chloride to reduce non-specific binding to the filter devices before filtration of plasma samples. Multiple reactions monitoring (MRM) of the ion pairs m/z 535/288 for PQ and m/z 541/294 for the internal standard (IS) was selected for quantification. When electrospray ionization (ESI+) was used, paradoxical matrix effect was observed despite the structure similarity of the deuterated IS: Ion suppression for PQ versus ion enhancement for the PQ-d6, even though they were closely eluted: 0.62 min versus 0.61 min. Separation was achieved on Evo C18 column (50 × 2.1 mm, 1.7 μm, Phenomenex Inc.) eluted with 10 mM NH4OH and MeCN. When atmospheric pressure chemical ionization in positive mode (APCI+) was used for ion source, matrix effect diminished. Separation was achieved on a PFP column (30 × 2.1 mm, 1.7 μm, Waters, Corp.) eluted with aqueous 20 mM ammonium formate 0.14% trifluoroacetic acid (A) and methanol-acetonitrile (4:1, v/v) containing 0.1% trifluoroacetic acid (B) at 0.8 mL/min flow rate in a gradient mode: 30–30–80–80–30–30%B (0–0.1–1.0–1.40–1.41–1.50 min). The retention time was 0.67 min for both PQ and the IS. The method was validated with a linear calibration range from 20 to 5,000 pg/mL and applied to clinical samples.

We determined total and unbound concentrations of doravirine (DOR) in cerebrospinal fluid and blood plasma. Total and unbound DOR concentrations in cerebrospinal fluid exceeded the half-maximal effective concentration against wild-type virus (5.1 ng/mL) in all patients, suggesting that DOR may contribute to inhibit viral replication in this compartment. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the population pharmacokinetics of total and unbound concentrations of prophylactic cefazolin (CFZ) in patients with prostatectomy or nephrectomy. We also aimed to calculate a pharmacodynamics target unbound concentration that exceeded the minimum inhibitory concentration (MIC), to design an effective dosing regimen. Briefly, 614 total concentration and 610 unbound concentration samples from 152 individuals were evaluated, using a nonlinear mixed-effects model. The obtained pharmacodynamics index target value reflected the probability of maintaining CFZ unbound trough concentrations exceeding MIC 90 , 0.5 mg/L, and MIC 50 , and 1.0 mg/L, to account for methicillin-susceptible Staphylococcus aureus (MSSA) or Escherichia coli . Population pharmacokinetics were estimated using a two-compartment model with nonlinear protein binding. Unbound systemic clearance (CL) was significantly associated with creatinine clearance, while the maximum protein-binding constant was significantly associated with albumin levels. The probability of achieving an unbound concentration exceeding the MIC 50 for E. coli or MIC 90 for MSSA in a patient with normal renal function following a 1 g CFZ infusion over 15 min was above 90% at 3 h after the initial dose. Our findings indicated that population pharmacokinetic parameters are useful for determining unbound CFZ pharmacokinetics and evaluating intraoperative CFZ redosing intervals., Competing Interests: The authors declare no conflict of interest.

Sequence-programmable transcription activator-like effector (TALE) proteins have emerged as a highly efficient tool for genome engineering. Recent crystal structures depict a transition between an open unbound solenoid and more compact DNA-bound solenoid formed by the 34 amino acid repeats. How TALEs switch conformation between these two forms without substantial energetic compensation, and how the repeat-variable di-residues (RVDs) discriminate between the cognate base and other bases still remain unclear. Computational analysis on these two aspects of TALE-DNA interaction mechanism has been conducted in order to achieve a better understanding of the energetics. High elasticity was observed in the molecular dynamics simulations of DNA-free TALE structure that started from the bound conformation where it sampled a wide range of conformations including the experimentally determined apo and bound conformations. This elastic feature was also observed in the simulations starting from the apo form which suggests low free energy barrier between the two conformations and small compensation required upon binding. To analyze binding specificity, we performed free energy calculations of various combinations of RVDs and bases using Poisson-Boltzmann surface area (PBSA) and other approaches. The PBSA calculations indicated that the native RVD-base structures had lower binding free energy than mismatched structures for most of the RVDs examined. Our theoretical analyses provided new insight on the dynamics and energetics of TALE-DNA binding mechanism.

Sequence-programmable transcription activator-like effector (TALE) proteins have emerged as a highly efficient tool for genome engineering. Recent crystal structures depict a transition between an open unbound solenoid and more compact DNA-bound solenoid formed by the 34 amino acid repeats. How TALEs switch conformation between these two forms without substantial energetic compensation, and how the repeat-variable di-residues (RVDs) discriminate between the cognate base and other bases still remain unclear. Computational analysis on these two aspects of TALE-DNA interaction mechanism has been conducted in order to achieve a better understanding of the energetics. High elasticity was observed in the molecular dynamics simulations of DNA-free TALE structure that started from the bound conformation where it sampled a wide range of conformations including the experimentally determined apo and bound conformations. This elastic feature was also observed in the simulations starting from the apo form which suggests low free energy barrier between the two conformations and small compensation required upon binding. To analyze binding specificity, we performed free energy calculations of various combinations of RVDs and bases using Poisson-Boltzmann surface area (PBSA) and other approaches. The PBSA calculations indicated that the native RVD-base structures had lower binding free energy than mismatched structures for most of the RVDs examined. Our theoretical analyses provided new insight on the dynamics and energetics of TALE-DNA binding mechanism.

For several centuries, the most common Western painting format was a stretched (and primed) canvas. From the end of the sixteenth century until the middle of the twentieth, the canvas by and large remained attached to a wooden frame and preparatory layers were applied. In this article, I examine some of the consequences and possibilities that arise from the absence of one these two components: the stretcher. I look at uses of raw and unbound canvas during the painting process, particularly at the way they changed the position of the artist's body with regard to the canvas support and tools. The shift between stretched and unstretched modified the painter's stance (from parallel to the support, to perpendicular or crossed, inducing a downward view) and introduced an awareness of the body and of the support. It modified the relationship between the painter and the canvas, so that the handling of the canvas became a component in painting techniques. I also emphasize that the removal of the stretcher opened up possibilities that continue to foster artistic inquiry. [ABSTRACT FROM AUTHOR]

We determined total and unbound concentrations of bictegravir (BIC) in cerebrospinal fluid (CSF) in 15 asymptomatic, virologically suppressed patients. The median plasma and CSF total BIC concentrations were 1837.1 ng/mL (interquartile range [IQR], 1237.2-2586.7) and 6.9 (IQR, 4.8-10.9), respectively. Median unbound BIC concentration was 2.48 ng/mL (IQR, 1.6-3.7). Total and unbound BIC CSF concentrations were above the half-maximal effective concentration value in all patients, and all subjects had human immunodeficiency virus viral suppression in plasma and CSF. Bictegravir may contribute to inhibit viral replication in this compartment. [ABSTRACT FROM AUTHOR]

Darunavir (DRV) is an HIV protease inhibitor commonly used as part of antiretroviral treatment regimens globally for children and adolescents. It requires a pharmacological booster, such as ritonavir (RTV) or cobicistat. To better understand the pharmacokinetics (PK) of DRV in this younger population and the importance of the RTV boosting effect, a population PK substudy was conducted within SMILE trial, where the maintenance of HIV suppression with once daily integrate inhibitor + darunavir/ritonavir in children and adolescents is evaluated. A joint population PK model that simultaneously used total DRV, unbound DRV, and total RTV concentrations was developed. Competitive and non-competitive models were examined to define RTV's influence on DRV pharmacokinetics. Linear and non-linear equations were tested to assess DRV protein binding. A total of 443 plasma samples from 152 adolescents were included in this analysis. Darunavir PK was best described by a one-compartment model first-order absorption and elimination. The influence of RTV on DRV pharmacokinetics was best characterized by ritonavir area under the curve on DRV clearance using a power function. The association of non-linear and linear equations was used to describe DRV protein binding to alpha-1 glycoprotein and albumin, respectively. In our population, simulations indicate that 86.8% of total and unbound DRV trough concentrations were above 0.55 mg/L [10 times protein binding-adjusted EC 50 for wild-type (WT) HIV-1] and 0.0243 mg/L (10 times EC 90 for WT HIV-1) targets, respectively. Predictions were also in agreement with observed outcomes from adults receiving 800/100 mg DRV/r once a day. Administration of 800/100 mg of DRV/r once daily provides satisfactory concentrations and exposures for adolescents aged 12 years and older., Competing Interests: The authors declare no conflict of interest.

The purpose of this article is to present an outlook on current publishing models and the way they relate to each other. The first part offers an overview of the traditional trade model in its present form and looks at the main alternatives, with a particular emphasis on crowdfunding. Can examples of subscription models be found from the past? Particular attention is given to the crowdfunding publisher Unbound in order to analyse how its hybrid business model fits into the field of contemporary cultural production. The final part looks at the dynamics between traditional trade publishers, Unbound, and the wider cultural ecosystem, exploring how different models can operate beyond direct competition, benefiting from each other’s presence in the market in the common quest to keep books alive. [ABSTRACT FROM AUTHOR]

The number and scale of crowdfunding platforms has increased dramatically in recent years, arguably more so than any other open phenomenon. This increase has allowed several crowdfunding websites to capture significant public attention, e.g. Kickstarter, Indiegogo. Yet, the growth of these specialist websites is only one aspect of the increasing popularity of crowdfunding technologies. Another, less-commonly discussed development is the propagation and integration of crowdfunding technologies into novel hybrid or proprietary production contexts, such as t-shirts (e.g. Threadless) or video games (e.g. Star Citizen). Such integrations are to be expected as crowdfunding technologies grow and evolve. However, they also present new challenges for managers and system designers, as the manner in which different features of crowdfunding technologies are enacted becomes decreasingly predictable the more their application domains diverge. This study performs a socio-material case study of Unbound, an innovative book publisher based in the UK. Unbound uses crowdfunding technologies to help authors raise the funding necessary to publish their books. However, once this funding has been reached, Unbound assumes more typical publisher responsibilities, such as editing, printing, binding, shipping, and promoting these books. Findings from Unbound identify four categories of socio-material practices in this hybrid model, each of which contains multiple sub-practices enacting different material features. This includes practices for fundraising, practices for maintaining traditional publishing standards, practices for creative contribution by backers, and practices for motivations. Further, tensions are observed for each of these categories of practices, due to the conflicting demands for inclusivity and selectivity associated with crowdfunding and publishing, respectively. [ABSTRACT FROM AUTHOR]

Micro-deval test provides a measure of resistance and durability of aggregates submerged in water through the actions of aggregate particles and abrasion from steel balls. The presence of water in the test chamber provides a more realistic assessment of field conditions when compared with Los Angeles (LA) abrasion test. Currently there is only one testing procedure in the United States (U.S.) to evaluate the coarse aggregates using micro-deval tests. Previous studies indicate that there has been significant interest in utilizing micro-deval test to assess the suitability coarse aggregates to be used in asphalt concrete and their field performance. However the studies related to evaluating coarse aggregates with micro-deval test for base course applications are very limited. This study attempts to address how the micro-deval testing procedure may be revised to better assess the performance of aggregates considered for the base course. Aggregates with seven different geological compositions were used in the study. Total of 250 micro-deval tests were performed and the results confirmed the repeatability and the suitability of the proposed method to all of the tested aggregates. As part of this study, a threshold is determined for the optimum amount of abrasive charge that should be used in the tests to obtain maximum material loss regardless of the geological make-up of the aggregate. If this approach is followed, a strong relationship between the number of revolutions and percent material loss is achieved. This relationship provides an opportunity to shorten the micro-deval tests and also an approach to assess durability of aggregates at number of revolutions significantly larger than what is prescribed in the existing micro-deval testing procedure. This ability may be used in the future to more realistically relate the long-term durability prediction of aggregates as it relates to field performance of base course. [ABSTRACT FROM AUTHOR]

Alkyl ketene dimer (AKD) is the reactive synthetic sizing agent that is used in alkaline or neutral papermaking conditions to provide certain level of hydrophobicity to the paper and board. The sizing mechanism of AKD involves its reaction with the hydroxyl groups on cellulose. However, all of AKD does not chemically react with fibers; some of it may undergo hydrolysis in water to form unstable β-keto acids, which decarboxylate to the corresponding ketone. This portion of AKD remains non-reacted (unbound) and adsorbs onto fibers. The sizing effect depends mainly on the quantity of chemically reacted (bound) AKD in paper, while the role of unbound forms, that is ketone and oligomer, is still not clear. Both bound and unbound portions of AKD have their own effect on paper. It is important to know the proportion of bound and unbound form of AKD in paper. The different techniques have been adopted for the separation and analysis of bound and unbound AKD present in paper. The aim of this paper is to review and summarize the various techniques provided by the researchers to separate the different forms of AKD and highlight the most important aspects for their separation.

For the quantification of propofol total and unbound drug concentrations a sensitive and specific liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated. To separate unbound propofol an ultrafiltration step before sample preparation was performed. Both the ultrafiltrate and plasma samples were extracted with solid-phase extraction and substituted with deuterated propofol as an internal standard. Separation was performed by gradient elution using UPLC-like system and analyzed by MS/MS consisting of an electrospray ionization source. To detect low and high concentration levels of propofol two calibration curves were identified and showed linearity within the range of 1–50 ng/ml and 50–20000 ng/ml. The lower limit of quantification was 1 ng/ml. Intra- and interassay precision and accuracy did not exceed ±15%. The method was applied to a clinical study during intensive care treatment of patients after coronary artery bypass grafting. [ABSTRACT FROM AUTHOR]

In some patient groups, including critically ill patients, the pharmacokinetics of β-lactam antibiotics may be profoundly disturbed due to pathophysiological changes in distribution and elimination. Therapeutic drug monitoring (TDM) is a strategy that may help to optimise dosing. The aim of this review was to identify and analyse the published literature on the methods used for β-lactam quantification in TDM programmes. Sixteen reports described methods for the simultaneous determination of three or more β-lactam antibiotics in plasma/serum. Measurement of these antibiotics, due to low frequency of usage relative to some other tests, is generally limited to in-house chromatographic methods coupled to ultraviolet or mass spectrometric detection. Although many published methods state they are fit for TDM, they are inconvenient because of intensive sample preparation and/or long run times. Ideally, methods used for routine TDM should have a short turnaround time (fast run-time and fast sample preparation), a low limit of quantification and a sufficiently high upper limit of quantification. The published assays included a median of 6 analytes [interquartile range (IQR) 4-10], with meropenem and piperacillin being the most frequently measured β-lactam antibiotics. The median run time was 8 min (IQR 5.9-21.3 min). There is also a growing number of methods measuring free concentrations. An assay that measures antibiotics without any sample preparation would be the next step towards real-time monitoring; no such method is currently available. [ABSTRACT FROM AUTHOR]

Piperaquine (PQ) is an antimalarial drug that is highly protein-bound. Variation in plasma protein contents may affect the pharmacokinetic (PK) exposure of unbound drug, leading to alteration of clinical outcomes. All published methods for determination of PQ in human plasma measure the total PQ including both bound and unbound PQ to plasma proteins. There is no published method for unbound PQ determination. Here we report an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for determination of PQ in human plasma filtrate prepared by filtering human plasma through Millipore Microcon® centrifugal filters (10k NMWL). The filter cup had to be treated with 5% benzalkonium chloride to reduce non-specific binding to the filter devices before filtration of plasma samples. Multiple reactions monitoring (MRM) of the ion pairs m/z 535/288 for PQ and m/z 541/294 for the internal standard (IS) was selected for quantification. When electrospray ionization (ESI + ) was used, paradoxical matrix effect was observed despite the structure similarity of the deuterated IS: Ion suppression for PQ versus ion enhancement for the PQ-d 6 , even though they were closely eluted: 0.62 min versus 0.61 min. Separation was achieved on Evo C 18 column (50 × 2.1 mm, 1.7 μ m, Phenomenex Inc.) eluted with 10 mM NH 4 OH and MeCN. When atmospheric pressure chemical ionization in positive mode (APCI + ) was used for ion source, matrix effect diminished. Separation was achieved on a PFP column (30 × 2.1 mm, 1.7 μ m, Waters, Corp.) eluted with aqueous 20 mM ammonium formate 0.14% trifluoroacetic acid (A) and methanol-acetonitrile (4:1, v/v) containing 0.1% trifluoroacetic acid (B) at 0.8 mL/min flow rate in a gradient mode: 30-30-80-80-30-30%B (0-0.1-1.0-1.40-1.41-1.50 min). The retention time was 0.67 min for both PQ and the IS. The method was validated with a linear calibration range from 20 to 5,000 pg/mL and applied to clinical samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Abstract: A method for a sensitive and specific analysis of hydromorphone total and unbound drug concentrations in human plasma was developed and validated. Sample preparation was preceded with an ultrafiltration step to separate the unbound drug from the protein bound fraction of hydromorphone. Both the ultrafiltrate and plasma samples were extracted with solid-phase extraction and substituted with stable isotope-labeled hydromorphone that was used as internal standard. Chromatographic separation was performed by gradient elution with UPLC-like system and eluates were analyzed by tandem mass spectrometry equipped with an electrospray ionization source. Sample preparation was optimized for good recovery of hydromorphone and the results were consistent. Calibration curves demonstrated linearity in the concentration range of 78–5000pg/ml for analysis of both total and unbound concentrations of hydromorphone. The limit of detection was 1pg and the lower limit of quantification was 78pg/ml for both total and unbound hydromorphone plasma drug concentrations. Intra- and interassay reproducibility and inaccuracy did not exceed 10%. Hydromorphone was on the average 14% bound to plasma proteins, supporting the previously published unreferenced statements that the protein binding of hydromorphone is low. Method was applied to a clinical trial in patients undergoing open heart surgery to generate a target controlled infusion model for the postoperative patient controlled analgesia with hydromorphone. [Copyright &y& Elsevier]

Abstract: With the clinical imperative to further research in the area of optimising antibiotic dosing in the intensive care setting, a simple high performance liquid chromatography method was developed and validated for routinely determining the free (unbound) concentration of ten beta-lactam antibiotics in 200μL of human plasma. Antibiotics determined include three cephalosporins (ceftriaxone, cephazolin and cephalotin); two carbapenems (meropenem and ertapenem); and five penicillins (ampicillin, piperacillin, benzylpenicillin, flucloxacillin and dicloxacillin). There was a single common sample preparation method involving ultracentrifugation and stabilisation. Chromatography was performed on a Waters XBridge C18 column with, depending on analytes, one of four acetonitrile-phosphate buffered mobile phases. Peaks of interest were detected via ultraviolet absorbance at 210, 260 and 304nm. The method has been validated and used in a pathology laboratory for therapeutic drug monitoring in critically ill patients. The significant variability in the level of protein binding that is common with antibiotics traditionally considered to have high protein binding (e.g. ceftriaxone, cephazolin, ertapenem, flucloxacillin and dicloxacillin) suggests that this assay should be preferred for measuring the pharmacologically active concentration of beta-lactam antibiotics in a therapeutic drug monitoring programme. [Copyright &y& Elsevier]

Abstract: A sensitive and specific liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the quantification of sufentanil total and unbound drug concentrations. Unbound drug was separated by an ultrafiltration step before sample preparation. Both the ultrafiltrate and plasma samples were extracted with solid-phase extraction and substituted with deuterated sufentanil used as an internal standard. Separation was performed by gradient elution using UPLC-like system and analysed by MS/MS consisting of an electrospray ionization source. Calibration curves showed linearity in the concentration range of 5–2500pg/ml for analysis of both total and unbound concentrations of sufentanil. The lower limit of quantification was 5pg/ml for both total and unbound sufentanil plasma drug concentrations. Intra- and interassay precision and accuracy did not exceed 15%. Method was applied to pharmacokinetic study in patients undergoing coronary artery bypass grafting. [Copyright &y& Elsevier]

Laser ultrasonics is a well known and mature non-destructive technique for inspecting polymer matrix composites used in aerospace. This technique uses a pulse echo interrogation mode, in which ultrasound is first generated by a pulsed laser and then detected by a second laser coupled to an optical interferometer. While very successful to find delaminations in laminates, difficulties are found for reliably detecting disbonds in honeycomb and foam core structures, particularly when the detachment occurs at the back skin. For this purpose, a novel technique called laser tapping is proposed. Laser tapping is based on the thermoelastic excitation by a pulsed laser of the top skin which bulges and is driven into vibration if it is detached from the material underneath. Laser tapping uses essentially the same hardware as laser ultrasonics but probes in a lower ultrasonic frequency range. Laser ultrasonics and laser tapping can then be advantageously used concurrently. This paper presents examples of applications of a combined laser ultrasonic laser tapping system to honeycomb structures with defects, including delaminations in the skin and skin detachments at the front side and the back side. [ABSTRACT FROM AUTHOR]

Background: Ceftriaxone is recommended for empiric antimicrobial therapy in patients with sepsis. Therapeutic Drug Monitoring (TDM) guided dose optimisation could elucidate pharmacokinetic variabilities, improving treatment efficacy. However, detailed data on Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) for unbound ceftriaxone quantification in serum are scarce., Objective: The authors aimed to develop a reliable UPLC-MS/MS method for serum ceftriaxone quantification and exhibit its application potential in routine hospital settings., Methods: In this observational, single centre study, UPLC-MS/MS method validation included specificity, carry-over, linearity, repeatability, intermediate precision, accuracy, the limit of quantification, and plasma protein binding. Unbound and total ceftriaxone were quantified in the serum of 5 critically ill patients. Pharmacokinetic/Pharmacodynamic (PK/PD) target attainment calculations were performed for both unbound and total ceftriaxone. The PK/PD target for unbound ceftriaxone in serum was set at 4 times the non-species related minimum inhibitory concentration breakpoint of 1 mg/L for at least 60% of the dosing interval., Results: The UPLC-MS/MS method revealed acceptable limits for clinical samples, with coefficients of variation < 15.0% for concentrations between 0.2 - 400.0 mg/L. Ceftriaxone eluted at 1.94 min and ceftazidime, as internal standard, eluted at 1.42 min. Patients demonstrated a median unbound ceftriaxone fraction of 29.1% (IQR: 15.2 - 52.2). Day 1 of ceftriaxone treatment presented a median PK/PD target attainment of 100.0% (IQR: 81.1 - 100.0) for unbound ceftriaxone in serum, while for calculations based on total concentrations, this figure was 23.9% (IQR: 10.5 - 80.6)., Conclusion: The described UPLC-MS/MS method enables reliable and rapid ceftriaxone quantification in the serum of critically ill patients. Method feasibility was exhibited for TDM purposes in routine clinical practice., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Alkyl ketene dimer (AKD) is the reactive synthetic sizing agent that is used in alkaline or neutral papermaking conditions to provide certain level of hydrophobicity to the paper and board. The sizing mechanism of AKD involves its reaction with the hydroxyl groups on cellulose. However, all of AKD does not chemically react with fibers; some of it may undergo hydrolysis in water to form unstable β-keto acids, which decarboxylate to the corresponding ketone. This portion of AKD remains non-reacted (unbound) and adsorbs onto fibers. The sizing effect depends mainly on the quantity of chemically reacted (bound) AKD in paper, while the role of unbound forms, that is ketone and oligomer, is still not clear. Both bound and unbound portions of AKD have their own effect on paper. It is important to know the proportion of bound and unbound form of AKD in paper. The different techniques have been adopted for the separation and analysis of bound and unbound AKD present in paper. The aim of this paper is to review and summarize the various techniques provided by the researchers to separate the different forms of AKD and highlight the most important aspects for their separation. [ABSTRACT FROM AUTHOR]

Sequence-programmable transcription activator-like effector (TALE) proteins have emerged as a highly efficient tool for genome engineering. Recent crystal structures depict a transition between an open unbound solenoid and more compact DNA-bound solenoid formed by the 34 amino acid repeats. How TALEs switch conformation between these two forms without substantial energetic compensation, and how the repeat-variable di-residues (RVDs) discriminate between the cognate base and other bases still remain unclear. Computational analysis on these two aspects of TALE-DNA interaction mechanism has been conducted in order to achieve a better understanding of the energetics. High elasticity was observed in the molecular dynamics simulations of DNA-free TALE structure that started from the bound conformation where it sampled a wide range of conformations including the experimentally determined apo and bound conformations. This elastic feature was also observed in the simulations starting from the apo form which suggests low free energy barrier between the two conformations and small compensation required upon binding. To analyze binding specificity, we performed free energy calculations of various combinations of RVDs and bases using Poisson-Boltzmann surface area (PBSA) and other approaches. The PBSA calculations indicated that the native RVD-base structures had lower binding free energy than mismatched structures for most of the RVDs examined. Our theoretical analyses provided new insight on the dynamics and energetics of TALE-DNA binding mechanism., (© 2014 Elsevier Inc. All rights reserved.)