Risk factors for recurrence of post-dural puncture headache following an epidural blood patch: a retrospective cohort study

INTRODUCTION

Post-dural puncture headache (PDPH) occurs in 0.38-6.3% of neuraxial procedures in obstetrics. Epidural blood patch (EBP) is the standard treatment but fails to provide full symptom relief in 4-29% of cases. Knowledge of the risk factors for EBP failure is limited and controversial. This study aimed to identify these risk factors.

METHODS

We performed a retrospective cohort study using electronic records of 47920 patients who underwent a neuraxial procedure between 2001 and 2018 in a large maternity hospital in Switzerland. The absence of full symptom relief and the need for further treatment was defined as an EBP failure. We performed univariate and multivariate analyses to compare patients with a successful or failed EBP.

RESULTS

We identified 212 patients requiring an EBP. Of these, 55 (25.9%) had a failed EBP. Signs and symptoms of PDPH did not differ between groups. While needle size and multiple pregnancies were risk factors in the univariate analysis, mostly those related to the performance of the EBP remained significant following adjustment. The risk of failure increased when the epidural space was deeper than 5.5 cm (OR 3.08, 95% CI 1.26 to 7.49) and decreased when the time interval between the initial dural puncture and the EBP was >48 h (OR 0.20, 95% CI 0.05 to 0.83).

CONCLUSION

Persistence of PDPH following a first EBP is not unusual. Close attention should be given to patients having their EBP performed <48 h following injury and having an epidural space located >5.5 cm depth, as these factors are associated with a failed EBP.

SLAC microresonator RF (SMuRF) electronics: A tone-tracking readout system for superconducting microwave resonator arrays

We describe the newest generation of the SLAC Microresonator RF (SMuRF) electronics, a warm digital control and readout system for microwave-frequency resonator-based cryogenic detector and multiplexer systems, such as microwave superconducting quantum interference device multiplexers (μmux) or microwave kinetic inductance detectors. Ultra-sensitive measurements in particle physics and astronomy increasingly rely on large arrays of cryogenic sensors, which in turn necessitate highly multiplexed readout and accompanying room-temperature electronics. Microwave-frequency resonators are a popular tool for cryogenic multiplexing, with the potential to multiplex thousands of detector channels on one readout line. The SMuRF system provides the capability for reading out up to 3328 channels across a 4-8 GHz bandwidth. Notably, the SMuRF system is unique in its implementation of a closed-loop tone-tracking algorithm that minimizes RF power transmitted to the cold amplifier, substantially relaxing system linearity requirements and effective noise from intermodulation products. Here, we present a description of the hardware, firmware, and software systems of the SMuRF electronics, comparing achieved performance with science-driven design requirements. In particular, we focus on the case of large-channel-count, low-bandwidth applications, but the system has been easily reconfigured for high-bandwidth applications. The system described here has been successfully deployed in lab settings and field sites around the world and is baselined for use on upcoming large-scale observatories.

Data-driven nonlinear model reduction to spectral submanifolds in mechanical systems

While data-driven model reduction techniques are well-established for linearizable mechanical systems, general approaches to reducing nonlinearizable systems with multiple coexisting steady states have been unavailable. In this paper, we review such a data-driven nonlinear model reduction methodology based on spectral submanifolds. As input, this approach takes observations of unforced nonlinear oscillations to construct normal forms of the dynamics reduced to very low-dimensional invariant manifolds. These normal forms capture amplitude-dependent properties and are accurate enough to provide predictions for nonlinearizable system response under the additions of external forcing. We illustrate these results on examples from structural vibrations, featuring both synthetic and experimental data. This article is part of the theme issue 'Data-driven prediction in dynamical systems'.

The ePix10k 2-megapixel hard X-ray detector at LCLS

The ePix10ka2M (ePix10k) is a new large area detector specifically developed for X-ray free-electron laser (XFEL) applications. The hybrid pixel detector was developed at SLAC to provide a hard X-ray area detector with a high dynamic range, running at the 120 Hz repetition rate of the Linac Coherent Light Source (LCLS). The ePix10k consists of 16 modules, each with 352 × 384 pixels of 100 µm × 100 µm distributed on four ASICs, resulting in a 2.16 megapixel detector, with a 16.5 cm × 16.5 cm active area and ∼80% coverage. The high dynamic range is achieved with three distinct gain settings (low, medium, high) as well as two auto-ranging modes (high-to-low and medium-to-low). Here the three fixed gain modes are evaluated. The resulting dynamic range (from single photon counting to 10000 photons pixel-1 pulse-1 at 8 keV) makes it suitable for a large number of different XFEL experiments. The ePix10k replaces the large CSPAD in operation since 2011. The dimensions of the two detectors are similar, making the upgrade from CSPAD to ePix10k straightforward for most setups, with the ePix10k improving on experimental performance. The SLAC-developed ePix cameras all utilize a similar platform, are tailored to target different experimental conditions and are designed to provide an upgrade path for future high-repetition-rate XFELs. Here the first measurements on this new ePix10k detector are presented and the performance under typical XFEL conditions evaluated during an LCLS X-ray diffuse scattering experiment measuring the 9.5 keV X-ray photons scattered from a thin liquid jet.

Coherent Lagrangian swirls among submesoscale motions

The emergence of coherent Lagrangian swirls (CLSs) among submesoscale motions in the ocean is illustrated. This is done by applying recent nonlinear dynamics tools for Lagrangian coherence detection on a surface flow realization produced by a data-assimilative submesoscale-permitting ocean general circulation model simulation of the Gulf of Mexico. Both mesoscale and submesoscale CLSs are extracted. These extractions prove the relevance of coherent Lagrangian eddies detected in satellite-altimetry-based geostrophic flow data for the arguably more realistic ageostrophic multiscale flow.

Risk factors for peripheral nerve injuries following neuraxial labour analgesia: a nested case-control study

BACKGROUND

Post-partum lower extremity motor and sensory dysfunctions occur in 0.1-9.2‰ of deliveries. While macrosomia, lithotomy position and forceps use are well-identified causes of peripheral nerve injuries, additional contributors such as patient condition and anaesthesia care may also have to be considered.

METHODS

We performed a case-control study nested in a cohort of 19,840 patients having neuraxial anaesthesia for childbirth. Cases were all patients who developed motor or sensory dysfunction of lower extremities in the post-partum period. These were compared, using Chi-square, Fisher's exact test, logistic regression and time series, to a random sample of controls without any neurological symptoms or injury.

RESULTS

We identified 19 (0.96‰) patients with peripheral nerve injuries of which 15 (0.76‰) were likely associated with obstetrical care. In four additional cases (0.20‰), a nerve root injury due to the Tuohy needle was suspected. Univariate risk factors were: a gestational age ≥ 41 weeks, Odds Ratio (OR) 3.8; 95% CI: 1.1-13.1, late initiation of neuraxial anaesthesia OR 8.2; 95% CI: 1.8-37.9, a repeated anaesthetic procedure OR 2.8; 95% CI: 1.0-7.8, assisted delivery with forceps OR 9.8; 95% CI: 1.2-114.1 and newborn birth weight > 3.5 kg with an OR 6.8; 95% CI: 2.0-22.5.

CONCLUSION

Obstetrical related factors are the most prominent risk associated with peripheral nerve injuries. This study highlights however that patient and anaesthesia-related factors may also contribute to peripheral nerve injuries.

Intrathecal clonidine as an adjuvant for neuraxial anaesthesia during caesarean delivery: a systematic review and meta-analysis of randomised trials

BACKGROUND

Clonidine is used as adjuvant to local anaesthetics for spinal anaesthesia. Its potential harm and benefits have not been systematically reviewed in obstetrics, and medical regulatory authorities do not recommend its intrathecal administration. The aim of this study was to assess the safety and efficacy of intrathecal clonidine for caesarean delivery.

METHODS

We conducted a systematic literature search in Medline, Embase, the Cochrane Library databases and trial registries for randomised trials assessing intrathecal clonidine as an adjuvant to local anaesthetics in patients undergoing caesarean delivery. Studies were assessed for quality, and data were extracted on study characteristics, safety and efficacy. Pooled data analysis using random-effects models was performed. Relative risk (RR) or mean difference with 95% confidence intervals (CI) were used to analyse outcomes.

RESULTS

Of 201 reports screened, 12 relevant clinical trials were included. Clonidine prolonged the duration of sensory block by 128.2min (95% CI 81.7 to 174.8) and motor block by 44.7min (95% CI 8.7 to 80.7). Clonidine increased sedation, RR 3.92 (95% CI 1.17 to 13.14), but did not increase the risk of hypotension, pruritus or postoperative nausea and vomiting. Apgar scores at 1 or 5min were not influenced by the addition of intrathecal clonidine.

CONCLUSION

Clonidine is an effective and safe adjuvant to local anaesthetics for spinal anaesthesia for caesarean delivery. This opens the debate as to whether intrathecal clonidine as an "off label" prescription should be reconsidered by medical regulatory authorities.

Post-traumatic stress disorder in parturients delivering by caesarean section and the implication of anaesthesia: a prospective cohort study

Background

Post-traumatic stress disorder (PTSD) occurs in 1–7% of women following childbirth. While having a caesarean section (C-section) is known to be a significant risk factor for postpartum PTSD, it is currently unknown whether coexisting anaesthesia-related factors are also associated to the disorder. The aim of this study was to assess anaesthesia-linked factors in the development of acute postpartum PTSD.

Methods

We performed a prospective cohort study on women having a C-section in a tertiary hospital in Switzerland. Patients were followed up six weeks postpartum. Patient and procedure characteristics, past morbidity or traumatic events, psychosocial status and stressful perinatal events were measured. Outcome was divided into two categories: full PTSD disease and PTSD profile. This was based on the number of DSM-IV criteria of the Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV) present. The PTSD Checklist Scale and the Clinician Administered PTSD Scale were used for measurement.

Results

Of the 280 patients included, 217 (77.5%) answered the questionnaires and 175 (62.5%) answered to an additional phone interview. Twenty (9.2%) had a PTSD profile and six (2.7%) a PTSD. When a full predictive model of risk factors for PTSD profile was built using logistic regression, maternal prepartum and intrapartum complications, anaesthetic complications and dissociative experiences during C-section were found to be the significant predictors for PTSD profile.

Conclusion

This is the first study to show in parturients having a C-section that an anaesthesia complication is an independent risk factor for postpartum PTSD and PTSD profile development, in addition to known perinatal and maternal risk factors.

Quantitative flow analysis of swimming dynamics with coherent Lagrangian vortices

Undulatory swimmers flex their bodies to displace water, and in turn, the flow feeds back into the dynamics of the swimmer. At moderate Reynolds number, the resulting flow structures are characterized by unsteady separation and alternating vortices in the wake. We use the flow field from simulations of a two-dimensional, incompressible viscous flow of an undulatory, self-propelled swimmer and detect the coherent Lagrangian vortices in the wake to dissect the driving momentum transfer mechanisms. The detected material vortex boundary encloses a Lagrangian control volume that serves to track back the vortex fluid and record its circulation and momentum history. We consider two swimming modes: the C-start escape and steady anguilliform swimming. The backward advection of the coherent Lagrangian vortices elucidates the geometry of the vorticity field and allows for monitoring the gain and decay of circulation and momentum transfer in the flow field. For steady swimming, momentum oscillations of the fish can largely be attributed to the momentum exchange with the vortex fluid. For the C-start, an additionally defined jet fluid region turns out to balance the high momentum change of the fish during the rapid start.

X-ray detectors at the Linac Coherent Light Source

Free-electron lasers (FELs) present new challenges for camera development compared with conventional light sources. At SLAC a variety of technologies are being used to match the demands of the Linac Coherent Light Source (LCLS) and to support a wide range of scientific applications. In this paper an overview of X-ray detector design requirements at FELs is presented and the various cameras in use at SLAC are described for the benefit of users planning experiments or analysts looking at data. Features and operation of the CSPAD camera, which is currently deployed at LCLS, are discussed, and the ePix family, a new generation of cameras under development at SLAC, is introduced.

Detector program for the LCLS complex

Over five years of operation the Linac Coherent Light Source has helped established free-electron lasers as a radically new paradigm for x-ray-based science. Part of this has been the demonstration of novel experimental techniques and the qualification of established methods in the LCLS environment. To take full advantage of this machine, a complimentary suite of detectors must be made available to scientists. Progress towards this goal will be described along with experience gained from operating within the LCLS environment. The status of currently installed detectors as well as future plans will be presented.

[Quality improvement initiatives in hospitals: which one to choose]

The number of quality improvement initiatives in hospitals has been steadily increasing in the last decades. Most of these initiatives are inspired by three quality control and improvement models developed in the manufacturing industry: the final inspection, the quality assurance and the total quality management. The purpose of this review is to describe how these methods have been implemented in healthcare organizations and to assess their effectiveness and acceptability by healthcare professionals. This review should help quality managers and healthcare professionals to choose a model that is best adapted to their needs and expected goals.

Meta-analysis of two-arm studies: Modeling the intervention effect from survival probabilities

Pooling the hazard ratios is not always feasible in meta-analyses of two-arm survival studies, because the measure of the intervention effect is not systematically reported. An alternative approach proposed by Moodie et al. is to use the survival probabilities of the included studies, all collected at a single point in time: the intervention effect is then summarised as the pooled ratio of the logarithm of survival probabilities (which is an estimator of the hazard ratios when hazards are proportional). In this article, we propose a generalization of this method. By using survival probabilities at several points in time, this generalization allows a flexible modeling of the intervention over time. The method is applicable to partially proportional hazards models, with the advantage of not requiring the specification of the baseline survival. As in Moodie et al.'s method, the study-level factors modifying the survival functions can be ignored as long as they do not modify the intervention effect. The procedures of estimation are presented for fixed and random effects models. Two illustrative examples are presented.

High-resolution protein structure determination by serial femtosecond crystallography

Structure determination of proteins and other macromolecules has historically required the growth of high-quality crystals sufficiently large to diffract x-rays efficiently while withstanding radiation damage. We applied serial femtosecond crystallography (SFX) using an x-ray free-electron laser (XFEL) to obtain high-resolution structural information from microcrystals (less than 1 micrometer by 1 micrometer by 3 micrometers) of the well-characterized model protein lysozyme. The agreement with synchrotron data demonstrates the immediate relevance of SFX for analyzing the structure of the large group of difficult-to-crystallize molecules.

[Patient information and informed consent in orthopaedic surgery: is it possible?]

Informed consent of the patient is a prerequisite for all surgical intervention. However, there is no consensus as to the quantity, manner and type of information that must be transmitted to the patient before an operation. Traditionally the patient receives information orally, but it is estimated that half of the information given by the physician is forgotten after 6 weeks. More and more complementary written documents have been proposed, but often they are beyond the understanding of the patient. Thus, other approaches are necessary. The models of communication that favor the partnership offer the best compromise between the principles of patient autonomy and that which benefits the treatment, allowing the patient to make the best decision.

Observation of two-neutrino double-beta decay in 136Xe with the EXO-200 detector

We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.

Swiss healthcare cost containment policies and their impact on anaesthetists' density and satisfaction

INTRODUCTION

To control healthcare costs, Federal and Cantonal states have introduced policies to limit expenses and the number of practising physicians. It is unclear to date whether these policies have had a real impact on anaesthetists in Switzerland. The aim of the current study was to assess the density, characteristics and satisfaction of anaesthetists in Latin Switzerland and to compare the results with data collected before the introduction of cost containment policies in 2002.

METHOD

We performed a cross-sectional study between March and July 2009 and included all practicing anaesthetists in Latin Switzerland. A questionnaire consisting of 103 items analysing demographics, activity and job satisfaction was used. The results were analysed and compared to a previous survey conducted in 2002.

RESULTS

Compared to 2002, there was an overall 12% increase in the number of practising anaesthetists who were older and more often females (42% versus 35% in 2002 (p = 0.06)). The number of non-Swiss anaesthetists significantly increased to 19% compared to 11% in 2002 (p <0.05). In contrast, working hours in public hospitals decreased from 59 to 53 hours/week (p <0.001). The majority of anaesthetists considered that their overall personal situation was better than in the previous 10 years and 87.7% considered that these measures had no impact on their future plans.

CONCLUSIONS

Implicit rationing policies introduced in Switzerland to limit healthcare costs and the number of physicians has had no impact on anaesthetists' workforce density, working conditions and overall satisfaction in Latin Switzerland. This opens the question of the real usefulness of these policies, at least for anaesthetists.

Clinical factors associated with the non-utilization of an anaesthesia incident reporting system

BACKGROUND

Incident reporting is a widely recommended method to measure undesirable events in anaesthesia. Under-utilization is a major weakness of voluntary incident reporting systems. Little is known about factors influencing reporting practices, particularly the clinical environment, anaesthesia team composition, severity of the incident, and perceived risk of litigation. The purpose of this study was to assess each of these, using an existing anaesthesia database.

METHODS

We performed a retrospective cohort study and analysed 46 207 surgical patients. We used multivariate analysis to identify factors associated with the non-utilization of the reporting system.

RESULTS

We found that in 7022 (15.1%) of the procedures performed, the incident reporting system was not used. Factors associated with the non-use of the system were regional anaesthesia/local anaesthesia, odds ratio (OR) 1.64 [95% confidence interval (CI) 1.03-2.62], emergency procedures OR 1.15 (95% CI: 1.05-1.27), and a consultant anaesthetist working without a trainee, OR 1.71 (95% CI: 1.03-2.82). In contrast, factors such as longer duration of surgery, OR 0.85 (95% CI: 0.76-0.94), the presence of a senior anaesthesia trainee, OR 0.86 (95% CI: 0.81-0.92), and the occurrence of severe complications with a high risk of litigation (i.e. death, nerve injuries) were less associated with a non-use of the reporting system, OR 0.65 (95% CI: 0.44-0.97). Team composition and time of day had no measurable impact on reporting practices.

CONCLUSIONS

Clinical factors play a significant role in the utilization of an anaesthesia incident reporting system and more particularly, severity of complications and higher liability risks which appear more as incentives than barriers to incident reporting.

[From aviation to surgery: the challenge of safety]

Medical errors result in 44,000 to 98,000 deaths per year in the United States of America. Within the surgical specialties, half of these errors occur in the operating room. The origin of these errors is multifactorial, and is generally associated with problems in communication and teamwork. In order to improve safety in the operating room, many hospitals now propose to the medical staff "crew resource management" (CRM) training programs inspired by the aviation industry. This approach favors a better utilization of surgical checklists, improves efficiency during chirurgical interventions, and reduces patient mortality. In October 2009 we introduced a CRM course within the department of surgery at the Geneva University Hospitals. We are presenting this program as well as the first results following its application.

Meta-analysis of binary outcomes from two-by-two tables when the length of follow-up varies and hazards are proportional

Odds ratios (ORs) and relative risks (RRs) are sensitive to the length of follow-up. In meta-analyses, pooling such results from studies with different lengths of follow-up may lead to an artificial heterogeneity and discrepancy caused by the choice of the summary index. In this article, we explore the utility of a meta-analysis method that uses the ratio of logarithms of survival probability as the measure of association, and that avoids the problems mentioned above when hazards are proportional. Meta-analyses of ORs, RRs and ratios of logarithms of survival probability are compared through a simulation study, in which data are simulated from a proportional hazard model and the length of follow-up varies across studies using realistic patterns of variability. Results show that the heterogeneity increases with the variability of length of follow-up for OR and RR, but not for the ratio of the logarithms of survival probability. A published meta-analysis is used to illustrate the method.

Assessment of an unplanned admission to the intensive care unit as a global safety indicator in surgical patients

An unplanned intensive care unit admission within 24 hours of a procedure with an anaesthetist in attendance (UIA) is a recommended clinical indicator It is designed to identify preventable iatrogenic complications. Often understood as a specific anaesthetic outcome, its value has been repeatedly questioned. Iatrogenic complications however often result from successive mishaps. In the specific context of an UIA these complications can be related both to anaesthesia and surgery. UIA is therefore probably more a global indicator of the safety of surgical care (anaesthetic and surgical) rather than a specific anaesthetic outcome. Its utility as such is however unknown. The purpose of this study was to assess the value of UIA as a global measure of avoidable iatrogenic complications in surgical patients. Using computerised patient records and medical charts, all patients with an UIA over a study period of five years were identified. The proportion, cause and preventability of iatrogenic complications amongst these patients were assessed. A total of 188 UIA patients were identified by peer reviewers. Of these, 87% to 92% had a complication caused by anaesthesia and/or surgery. Anaesthesia was found to be responsible for 24% to 31% of iatrogenic complications. All other cases related to the combination of anaesthesia and surgery or surgery alone. Of these, 74% to 92% of complications were found to be preventable. Despite intrinsic limitations of the retrospective chart review method, UIA can be considered as a valuable tool to detect avoidable iatrogenic complications related to both surgical and anaesthetic care.

Intra-operative awareness in children: the value of an interview adapted to their cognitive abilities

Intra-operative awareness in paediatric patients has been little studied for many years because of the difficulties in relying on children's testimony. Earlier questionnaires used to detect this complication were not adapted to children's language and memory capacities. By using a qualitative method, a semi-structured in-depth interview adapted to their cognitive abilities, we have now conducted a prospective evaluation of the incidence and risk factors for intra-operative awareness in children undergoing general anaesthesia. Data were obtained from interviews with 410 children (aged 6-16 years) which were conducted within 36 h of general anaesthesia for elective or emergency surgery. One month after surgery, 293 of these patients were interviewed again. Three independent adjudicators classified each potential case of awareness. We considered awareness to include both the 'confirmed awareness' and the 'possible awareness' cases. The accuracy of the children's recall was calculated. The relationship between their awareness and the anaesthesia management was examined. There were five cases of confirmed awareness, and six cases of possible awareness. The incidence of confirmed awareness was 1.2%, but when the possible cases were also considered, the overall incidence of this complication was as high as 2.7% (95% confidence interval, 1.4-5.0%). The only predictive factor identified was the multiple manoeuvres with which the airways were secured (odds ratio, 8.4; 95% confidence interval, 2.4-29.07%). The present study confirms the existence of intra-operative awareness in the paediatric population. The application of a semi-structured in-depth interview adapted to the cognitive capacities of the children appears to enhance the detection of awareness in this population.

Direct Lyapunov exponent analysis enables parametric study of transient signalling governing cell behaviour

Computational models aid in the quantitative understanding of cell signalling networks. One important goal is to ascertain how multiple network components work together to govern cellular responses, that is, to determine cell 'signal-response' relationships. Several methods exist to study steady-state signals in the context of differential equation-based models. However, many biological networks influence cell behaviour through time-varying signals operating during a transient activated state that ultimately returns to a basal steady-state. A computational approach adapted from dynamical systems analysis to discern how diverse transient signals relate to alternative cell fates is described. Direct finite-time Lyapunov exponents (DLEs) are employed to identify phase-space domains of high sensitivity to initial conditions. These domains delineate regions exhibiting qualitatively different transient activities that would be indistinguishable using steady-state analysis but which correspond to different outcomes. These methods are applied to a physicochemical model of molecular interactions among caspase-3, caspase-8 and X-linked inhibitor of apoptosis--proteins whose transient activation determines cell death against survival fates. DLE analysis enabled identification of a separatrix that quantitatively characterises network behaviour by defining initial conditions leading to apoptotic cell death. It is anticipated that DLE analysis will facilitate theoretical investigation of phenotypic outcomes in larger models of signalling networks.

Stretching, alignment, and shear in slowly varying velocity fields

We derive criteria that locate intense material stretching and shear in two-dimensional flows with slow time dependence. Our derivation makes use of the near integrability of the equation of variations along trajectories of the slowly varying flow. The criteria yield two diagnostic scalar fields for use in real-time Lagrangian predictions in geophysical flows.

Trail-induced apoptosis and interaction with cytotoxic agents in soft tissue sarcoma cell lines

Five human soft tissue sarcoma (STS) cell lines (HTB-82 rhabdomyosarcoma, HTB-91 fibrosarcoma, HTB-92 liposarcoma, HTB-93 synovial sarcoma and HTB-94 chondrosarcoma) were analysed for their sensitivity to tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and the function of the TRAIL apoptotic pathway in these cells. TRAIL induced significant apoptosis (>90%) in HTB-92 and HTB-93 cells, whereas no effect was observed in HTB-82, HTB-91 and HTB-94 cells. TRAIL-Receptor 1 (TRAIL-R1) was expressed in TRAIL-sensitive HTB-92 and HTB-93 cell lines, but not in TRAIL-resistant HTB-91 and HTB-94 cells. HTB-82 cells, which expressed the long (c-FLIP(L)) and short (c-FLIP(S)) splice variants of the FLICE-like inhibitory protein (FLIP), were resistant to TRAIL in spite of the presence of TRAIL-R1. TRAIL-R2,-R3,-R4 and osteoprotegerin (OPG) expression did not correlate with TRAIL sensitivity. Coincubation of TRAIL and doxorubicin led to the overexpression of TRAIL-R2 resulting in a synergistic effect of doxorubicin and TRAIL in TRAIL-sensitive cell lines and in the overcoming of TRAIL-resistance in all of the TRAIL-resistant cell lines, except HTB-91, which lacked caspase 8 expression. These data suggest that TRAIL, either as a single agent or in combination with cytotoxic agents, might represent a new treatment option for advanced STS, which constitutes a largely chemotherapy-resistant disease.

Experimental measurements of stretching fields in fluid mixing

Using precision measurements of tracer particle trajectories in a two-dimensional fluid flow producing chaotic mixing, we directly measure the time-dependent stretching field. This quantity, previously available only numerically, attains local maxima along lines that coincide with the stable and unstable manifolds of hyperbolic fixed points of Poincaré maps. Contours of a passive impurity field are found at each instant to be oriented parallel to the lines that have recently experienced large stretching. The local stretching varies by 12 orders of magnitude.

Oxygen embolism after hydrogen peroxide irrigation of a vulvar abscess

We report a case of venous oxygen embolism in a 33-yr-old healthy woman after irrigation of a vulvar abscess with 25 ml of 3% hydrogen peroxide. Venous oxygen embolism was diagnosed by the development of sudden hypoxia associated with a decrease in end-tidal carbon dioxide concentration from 5.3 kPa to 3.2 kPa, and a 'mill-wheel' sound on cardiac auscultation soon after injection of the solution. The patient responded to corrective treatment including the Trendelenburg position and 100% oxygen. She made an uneventful recovery. We discuss the possible causative mechanism of this embolism, the different diagnostic methods, and the controversial aspects of available treatments. We emphasize that hydrogen peroxide is a dangerous and unsuitable agent for routine wound irrigation and debridement.

Response to "Comment on 'Finding finite-time invariant manifolds in two-dimensional velocity fields' " [Chaos 11, 427 (2001)]

Lapeyre, Hua, and Legras have recently suggested that the detection of finite-time invariant manifolds in two-dimensional fluid flows, as described by Haller and Haller and Yuan, can be substantially improved. In particular, they suggested (a) a change of coordinates to strain basis before the application of Theorem 1 of Haller and (b) the use of a nondimensionalized time computed from Theorem 1. Here we discuss why these proposed steps will not result in a significant overall improvement. We verify our arguments in a more detailed computation of the example analyzed in Lapeyre, Hau, and Legras (the Kida ellipse), as well as in a two-dimensional barotropic turbulence simulation. While in both of these examples the techniques suggested by Lapeyre, Hau, and Legras reveal additional thin regions of hyperbolicity near vortex cores, they also lead to an overall loss of detail in the global computation of finite-time invariant manifolds. (c) 2001 American Institute of Physics.

Measurement of CP-violating asymmetries in B0 decays to CP eigenstates

We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23x10(6) Upsilon(4S)-->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events in which one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta = 0.34+/-0.20 (stat)+/-0.05 (syst).

Tolerance to solid organ transplants through transfer of MHC class II genes

Donor/recipient MHC class II matching permits survival of experimental allografts without permanent immunosuppression, but is not clinically applicable due to the extensive polymorphism of this locus. As an alternative, we have tested a gene therapy approach in a preclinical animal model to determine whether expression of allogeneic class II transgenes (Tg's) in recipient bone marrow cells would allow survival of subsequent Tg-matched renal allografts. Somatic matching between donor kidney class II and the recipient Tg's, in combination with a short treatment of cyclosporine A, prolonged graft survival with DR and promoted tolerance with DQ. Class II Tg expression in the lymphoid lineage and the graft itself were sequentially implicated in this tolerance induction. These results demonstrate the potential of MHC class II gene transfer to permit tolerance to solid organ allografts.