974 research outputs found
Antibodies to Lipopolysaccharides after Immunization of Humans with the Rough Mutant Escherichia coli J5
To investigate whether immunization with Escherichia coli J5 boiled cells induces antibodies directed at deep core structures, antibodies against JS lipopolysaccharide (LPS), Re LPSt and Iipid A were measured in the serum of 70 volunteers before and 2 weeks after immunization. To improve the sensitivity and the specificity ofELISAt complexes of core LPS with high-density lipoproteins were used instead of free core LPS as antigens. A median three-fold increase in antibodies directed against J5 LPS was observed, but no significant increase in the antibodies against Re LPS or lipid A was found. Since JS antiserum did not react with several smooth LPS or with Re LPS and lipid At cross-reactivity could not be demonstrated. Thus, immunization of volunteers with E. coli J5 produced a modest specific antibody response against J5 LPS. The mechanism of protection previously observed with J5 antiserum remains unclea
Clinical experience with Timentin in severe hospital infections
Sixty-four severe infections in hospitalized patients were treated with intravenous Timentin. Most patients (mean age: 50-5 years, range 18-85) had serious underlying conditions such as agranulocytosis, heart failure, cancer, diabetes mellitus, chronic alcoholism or other functional or anatomical abnormalities. Forty-three episodes were bacteriologically proved, and bacteraemia was diagnosed in 18. The sites of infection were: lower respiratory tract (10), upper respiratory tract (10), soft tissues(9), urinary tract (7), bones (6), peritoneal cavity (3), meninges (1) and pelvis (1). Inaddition, 13 episodes of fever and four of septicaemia in patients with agranulocytosis were treated with Timentin plus amilcacin. Overall, 59% of the episodes were cured, 14% improved and 17% failed to respond. In 9% of cases the efficacy of the Timentin was unassessable mainly because of concurrent administration of other antimicrobials. Failure appeared to be more frequent in soft tissue and intra-abdominal infections, in patients infected with bacteria susceptibleto Timentin but resistant to ticarcillin and in patients superinfected with Timentin-resistant strains. Major side effects were haemorrhagic diathesis with platelet dysfunction (1), severe water sodium overload (1), and possibly pancreatitis (1).Other side effects were mild: catheter-related phlebitis, and abnormal but clinically insignificant laboratory test results. Timentin appears to be an effective and safebroad-spectrum combination which compares favourably with third-generation cephalosporins in the treatment of severe hospital infections. More experience is needed to decide whether the some what lower response rate in patients infected with ticarcillin-resistant strains is significan
Cefepime monotherapy for the empirical treatment of fever in granulocytopenic cancer patients
In a pilot study, we evaluated the efficacy and the safety of cefepime, a new cephalosporin with extended-spectrum activity against both Gram-positive and Gram-negative bacteria, as empirical monotherapy for 108 febrile episodes in 84 granulocytopenic cancer patients. Cefepime (2 g tds) was given for a minimum of 7 days or until resolution of infection. Of the 108 episodes, 91 were evaluable. Microbiologically documented infections occurred in 25 patients (27%) (18 Gram-positive, 7 Gram-negative), of whom 18 had bacteraemia. Infection was clinically documented in 47 patients (52%) and fever was unexplained in 19 (21%). Overall, 71% (65/91) of the infections resolved. Response rates were 86% (6/7) for Gram-negative infections, 44% (8/18) for Gram-positive infections (57%%for cefepime-susceptible Gram-positive bacteria), 77% (36/47) for clinically documented infections and 79% (15/19) for unexplained fevers. Of the 26 patients (29%) whose primary infections did not improve with cefepime monotherapy, 23 responded after the addition of other antibiotics. Sixteen patients (18%) developed secondary infections of which 13 were microbiologically documented; Gram-positive bacteria were isolated from seven patients, Gram-negative bacteria from two, fungi from three and a virus from one. Adverse effects were mild and did not require premature discontinuation of therapy except for one patient who developed an immediate allergic reaction after the first dose of cefepime from which he recovered fully. The survival rate after resolution of granulocytopenia was 96%; three patients died of primary bacterial infection and one from secondary disseminated candidiasis. In this pilot study, cefepime monotherapy appeared safe and effective as empirical therapy for fever in cancer patients with granulocytopenia. Whether cefepime is superior to other advanced-generation cephalosporins for the treatment of Gram-positive infections will require evaluation in a larger comparative stud
Demonstration of Cross-Reactive Antibodies to Smooth Gram-Negative Bacteria in Antiserum to Escherichia coli J5
We investigated the discrepancy between the broad cross-protection against gram-negative infections afforded by antiserum to Escherichia coli J5 and its apparently narrow cross-reactivity in vitro. Rabbits immunized with J5 bacteria produced antibodies to both the J5 lipopolysaccharide (LPS; titer by ELISA, 1:60,000) and LPS from the Re mutant of Salmonella minnesota (i.e., to the ketodeoxyoctonate [KDO] and lipid A determinants; titer, 1:3,200). In highly diluted antiserum, titers of antibody to J5 LPS were reduced by 28%-41% after adsorption with seven strains of smooth gram-negative bacteria and by only 4% after adsorption with the Re mutant. Smooth gram-negative bacteria adsorbed virtually all antibody to Re LPS. Therefore, rabbit antiserum to J5 contains type-specific antibodies to core determinants distal to KDO that can obscure highly cross-reactive antibodies to lipid A-KDO in vitro. Cross-reactive antibodies are demonstrable by adsorption with whole bacteria at limiting concentrations of antibod
Laboratory Experiments of Model-based Reinforcement Learning for Adaptive Optics Control
Direct imaging of Earth-like exoplanets is one of the most prominent
scientific drivers of the next generation of ground-based telescopes.
Typically, Earth-like exoplanets are located at small angular separations from
their host stars, making their detection difficult. Consequently, the adaptive
optics (AO) system's control algorithm must be carefully designed to
distinguish the exoplanet from the residual light produced by the host star.
A new promising avenue of research to improve AO control builds on
data-driven control methods such as Reinforcement Learning (RL). RL is an
active branch of the machine learning research field, where control of a system
is learned through interaction with the environment. Thus, RL can be seen as an
automated approach to AO control, where its usage is entirely a turnkey
operation. In particular, model-based reinforcement learning (MBRL) has been
shown to cope with both temporal and misregistration errors. Similarly, it has
been demonstrated to adapt to non-linear wavefront sensing while being
efficient in training and execution.
In this work, we implement and adapt an RL method called Policy Optimization
for AO (PO4AO) to the GHOST test bench at ESO headquarters, where we
demonstrate a strong performance of the method in a laboratory environment. Our
implementation allows the training to be performed parallel to inference, which
is crucial for on-sky operation. In particular, we study the predictive and
self-calibrating aspects of the method. The new implementation on GHOST running
PyTorch introduces only around 700 microseconds in addition to hardware,
pipeline, and Python interface latency. We open-source well-documented code for
the implementation and specify the requirements for the RTC pipeline. We also
discuss the important hyperparameters of the method, the source of the latency,
and the possible paths for a lower latency implementation.Comment: Accepted for publication in JATI
Treatment of gram-negative septic shock with human IgG antibody to Escherichia coli J5: a prospective, double-blind, randomized trial
In a randomized, double-blind, multicenter trial we compared the efficacy of a preparation of human IgG antibody to Escherichia coli J5 (J5-IVIG) with that of a standard IgG preparation (IVIG) for the treatment of gram-negative septic shock. At study entry, patients received a single intravenous dose of 200 mg/kg of body weight (maximal dose, 12 g) of either J5-IVIG or IVIG. Of the 100 patients randomized, 71 (30 receiving J5-IVIG and 41 receiving IVIG) had a documented gram-negative infection. Mortality from gram-negative septic shock was 50% (15 of 30) in J5-IVIG recipients and 49% (20 of 41) in IVIG recipients. In addition, treatment with J5-IVIG did not reduce the number of systemic complications of shock and did not delay the occurrence of death due to septic shock. Thus we conclude that J5-IVIG was not superior to IVIG in reducing mortality or in reversing gram-negative septic shock
Cefepime monotherapy for the empirical treatment of fever in granulocytopenic cancer patients.
In a pilot study, we evaluated the efficacy and the safety of cefepime, a new cephalosporin with extended-spectrum activity against both Gram-positive and Gram-negative bacteria, as empirical monotherapy for 108 febrile episodes in 84 granulocytopenic cancer patients. Cefepime (2 g tds) was given for a minimum of 7 days or until resolution of infection. Of the 108 episodes, 91 were evaluable. Microbiologically documented infections occurred in 25 patients (27%) (18 Gram-positive, 7 Gram-negative), of whom 18 had bacteraemia. Infection was clinically documented in 47 patients (52%) and fever was unexplained in 19 (21%). Overall, 71% (65/91) of the infections resolved. Response rates were 86% (6/7) for Gram-negative infections, 44% (8/18) for Gram-positive infections (57% for cefepime-susceptible Gram-positive bacteria), 77% (36/47) for clinically documented infections and 79% (15/19) for unexplained fevers. Of the 26 patients (29%) whose primary infections did not improve with cefepime monotherapy, 23 responded after the addition of other antibiotics. Sixteen patients (18%) developed secondary infections of which 13 were microbiologically documented; Gram-positive bacteria were isolated from seven patients, Gram-negative bacteria from two, fungi from three and a virus from one. Adverse effects were mild and did not require premature discontinuation of therapy except for one patient who developed an immediate allergic reaction after the first dose of cefepime from which he recovered fully. The survival rate after resolution of granulocytopenia was 96%; three patients died of primary bacterial infection and one from secondary disseminated candidiasis. In this pilot study, cefepime monotherapy appeared safe and effective as empirical therapy for fever in cancer patients with granulocytopenia. Whether cefepime is superior to other advanced-generation cephalosporins for the treatment of Gram-positive infections will require evaluation in a larger comparative study
Antibodies to lipopolysaccharides after immunization of humans with the rough mutant Escherichia coli J5
To investigate whether immunization with Escherichia coli J5 boiled cells induces antibodies directed at deep core structures, antibodies against J5 lipopolysaccharide (LPS), Re LPS, and lipid A were measured in the serum of 70 volunteers before and 2 weeks after immunization. To improve the sensitivity and the specificity of ELISA, complexes of core LPS with high-density lipoproteins were used instead of free core LPS as antigens. A median three-fold increase in antibodies directed against J5 LPS was observed, but no significant increase in the antibodies against Re LPS or lipid A was found. Since J5 antiserum did not react with several smooth LPS or with Re LPS and lipid A, cross-reactivity could not be demonstrated. Thus, immunization of volunteers with E. coli J5 produced a modest specific antibody response against J5 LPS. The mechanism of protection previously observed with J5 antiserum remains unclear
Benchmark problems for continuum radiative transfer. High optical depths, anisotropic scattering, and polarisation
Solving the continuum radiative transfer equation in high opacity media
requires sophisticated numerical tools. In order to test the reliability of
such tools, we present a benchmark of radiative transfer codes in a 2D disc
configuration. We test the accuracy of seven independently developed radiative
transfer codes by comparing the temperature structures, spectral energy
distributions, scattered light images, and linear polarisation maps that each
model predicts for a variety of disc opacities and viewing angles. The test
cases have been chosen to be numerically challenging, with midplane optical
depths up 10^6, a sharp density transition at the inner edge and complex
scattering matrices. We also review recent progress in the implementation of
the Monte Carlo method that allow an efficient solution to these kinds of
problems and discuss the advantages and limitations of Monte Carlo codes
compared to those of discrete ordinate codes. For each of the test cases, the
predicted results from the radiative transfer codes are within good agreement.
The results indicate that these codes can be confidently used to interpret
present and future observations of protoplanetary discs.Comment: 15 pages, 10 figures, accepted for publication in A&
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