Characterising information gains and losses when collecting multiple epidemic model outputs

BACKGROUND

Collaborative comparisons and combinations of epidemic models are used as policy-relevant evidence during epidemic outbreaks. In the process of collecting multiple model projections, such collaborations may gain or lose relevant information. Typically, modellers contribute a probabilistic summary at each time-step. We compared this to directly collecting simulated trajectories. We aimed to explore information on key epidemic quantities; ensemble uncertainty; and performance against data, investigating potential to continuously gain information from a single cross-sectional collection of model results.

METHODS

We compared projections from the European COVID-19 Scenario Modelling Hub. Five teams modelled incidence in Belgium, the Netherlands, and Spain. We compared July 2022 projections by incidence, peaks, and cumulative totals. We created a probabilistic ensemble drawn from all trajectories, and compared to ensembles from a median across each model's quantiles, or a linear opinion pool. We measured the predictive accuracy of individual trajectories against observations, using this in a weighted ensemble. We repeated this sequentially against increasing weeks of observed data. We evaluated these ensembles to reflect performance with varying observed data.

RESULTS

By collecting modelled trajectories, we showed policy-relevant epidemic characteristics. Trajectories contained a right-skewed distribution well represented by an ensemble of trajectories or a linear opinion pool, but not models' quantile intervals. Ensembles weighted by performance typically retained the range of plausible incidence over time, and in some cases narrowed this by excluding some epidemic shapes.

CONCLUSIONS

We observed several information gains from collecting modelled trajectories rather than quantile distributions, including potential for continuously updated information from a single model collection. The value of information gains and losses may vary with each collaborative effort's aims, depending on the needs of projection users. Understanding the differing information potential of methods to collect model projections can support the accuracy, sustainability, and communication of collaborative infectious disease modelling efforts.

A case for ongoing structural support to maximise infectious disease modelling efficiency for future public health emergencies: A modelling perspective

This short communication reflects upon the challenges and recommendations of multiple COVID-19 modelling and data analytic groups that provided quantitative evidence to support health policy discussions in Switzerland and Germany during the SARS-CoV-2 pandemic. Capacity strengthening outside infectious disease emergencies will be required to enable an environment for a timely, efficient, and data-driven response to support decisions during any future infectious disease emergency. This will require 1) a critical mass of trained experts who continuously advance state-of-the-art methodological tools, 2) the establishment of structural liaisons amongst scientists and decision-makers, and 3) the foundation and management of data-sharing frameworks.

Explicit modeling of antibody levels for infectious disease simulations in the context of SARS-CoV-2

Measurable levels of immunoglobulin G antibodies develop after infections with and vaccinations against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These antibody levels are dynamic: due to waning, antibody levels will drop over time. During the COVID-19 pandemic, multiple models predicting infection dynamics were used by policymakers to support the planning of public health policies. Explicitly integrating antibody and waning effects into the models is crucial for reliable calculations of individual infection risk. However, only few approaches have been suggested that explicitly treat these effects. This paper presents a methodology that explicitly models antibody levels and the resulting protection against infection for individuals within an agent-based model. The model was developed in response to the complexity of different immunization sequences and types and is based on neutralization titer studies. This approach allows complex population studies with explicit antibody and waning effects. We demonstrate the usefulness of our model in two use cases.

Predicting the effects of COVID-19 related interventions in urban settings by combining activity-based modelling, agent-based simulation, and mobile phone data

Epidemiological simulations as a method are used to better understand and predict the spreading of infectious diseases, for example of COVID-19. This paper presents an approach that combines a well-established approach from transportation modelling that uses person-centric data-driven human mobility modelling with a mechanistic infection model and a person-centric disease progression model. The model includes the consequences of different room sizes, air exchange rates, disease import, changed activity participation rates over time (coming from mobility data), masks, indoors vs. outdoors leisure activities, and of contact tracing. It is validated against the infection dynamics in Berlin (Germany). The model can be used to understand the contributions of different activity types to the infection dynamics over time. It predicts the effects of contact reductions, school closures/vacations, masks, or the effect of moving leisure activities from outdoors to indoors in fall, and is thus able to quantitatively predict the consequences of interventions. It is shown that these effects are best given as additive changes of the reproduction number R. The model also explains why contact reductions have decreasing marginal returns, i.e. the first 50% of contact reductions have considerably more effect than the second 50%. Our work shows that is is possible to build detailed epidemiological simulations from microscopic mobility models relatively quickly. They can be used to investigate mechanical aspects of the dynamics, such as the transmission from political decisions via human behavior to infections, consequences of different lockdown measures, or consequences of wearing masks in certain situations. The results can be used to inform political decisions.

Predicting the effects of COVID-19 related interventions in urban settings by combining activity-based modelling, agent-based simulation, and mobile phone data

Epidemiological simulations as a method are used to better understand and predict the spreading of infectious diseases, for example of COVID-19. This paper presents an approach that combines a well-established approach from transportation modelling that uses person-centric data-driven human mobility modelling with a mechanistic infection model and a person-centric disease progression model. The model includes the consequences of different room sizes, air exchange rates, disease import, changed activity participation rates over time (coming from mobility data), masks, indoors vs. outdoors leisure activities, and of contact tracing. It is validated against the infection dynamics in Berlin (Germany). The model can be used to understand the contributions of different activity types to the infection dynamics over time. It predicts the effects of contact reductions, school closures/vacations, masks, or the effect of moving leisure activities from outdoors to indoors in fall, and is thus able to quantitatively predict the consequences of interventions. It is shown that these effects are best given as additive changes of the reproduction number R. The model also explains why contact reductions have decreasing marginal returns, i.e. the first 50% of contact reductions have considerably more effect than the second 50%. Our work shows that is is possible to build detailed epidemiological simulations from microscopic mobility models relatively quickly. They can be used to investigate mechanical aspects of the dynamics, such as the transmission from political decisions via human behavior to infections, consequences of different lockdown measures, or consequences of wearing masks in certain situations. The results can be used to inform political decisions.

Prediction of Covid-19 spreading and optimal coordination of counter-measures: From microscopic to macroscopic models to Pareto fronts

The Covid-19 disease has caused a world-wide pandemic with more than 60 million positive cases and more than 1.4 million deaths by the end of November 2020. As long as effective medical treatment and vaccination are not available, non-pharmaceutical interventions such as social distancing, self-isolation and quarantine as well as far-reaching shutdowns of economic activity and public life are the only available strategies to prevent the virus from spreading. These interventions must meet conflicting requirements where some objectives, like the minimization of disease-related deaths or the impact on health systems, demand for stronger counter-measures, while others, such as social and economic costs, call for weaker counter-measures. Therefore, finding the optimal compromise of counter-measures requires the solution of a multi-objective optimization problem that is based on accurate prediction of future infection spreading for all combinations of counter-measures under consideration. We present a strategy for construction and solution of such a multi-objective optimization problem with real-world applicability. The strategy is based on a micro-model allowing for accurate prediction via a realistic combination of person-centric data-driven human mobility and behavior, stochastic infection models and disease progression models including micro-level inclusion of governmental intervention strategies. For this micro-model, a surrogate macro-model is constructed and validated that is much less computationally expensive and can therefore be used in the core of a numerical solver for the multi-objective optimization problem. The resulting set of optimal compromises between counter-measures (Pareto front) is discussed and its meaning for policy decisions is outlined.

Design of nanostructured hybrid materials: twin polymerization of urethane-based twin prepolymers

Organic–inorganic hybrid materials with urethane functionalities were obtained by simultaneous twin polymerization of twin prepolymers in combination with the ideal twin monomer 2,2′-spirobi[4H-1,3,2-benzodioxasiline]. The twin prepolymers consist of a urethane-based prepolymer with reactive terminal groups which can react during the twin polymerization process. Nanostructured hybrid materials with integrated dialkylsiloxane crosslinked urethane structures, phenolic resin and SiO₂ are obtained in a one pot process. The effects of the polymerization temperature as well as those of various catalysts and reagent ratios on the polymerization behavior were investigated. The molecular structures of the obtained materials were determined by ¹³C- and ²⁹Si-{¹H}-CP-MAS NMR spectroscopies. HAADF-STEM-measurements were performed to prove the distribution of silicon in the hybrid material.

Organic–inorganic hybrid materials with urethane functionalities were obtained by simultaneous twin polymerization of twin prepolymers in combination with the twin monomer 2,2′-spirobi[4H-1,3,2-benzodioxasiline].

Ternary composites by an in situ hydrolytic polymerization process

Polyamide 6/modified silica composite materials have been prepared by a coupled polymerization procedure. For this purpose, the three-component-system we presented in a previous publication, consisting of ε-aminocaproic acid (ε-ACA), ε-caprolactam (ε-CL), and 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one) (Si(ε-CL)₄), has been combined with other silicon monomers with one or two methyl groups (MeSi(ε-CL)₃ and Me₂Si(ε-CL)₂). The simultaneous polymerization of ε-CL and silicon monomers leads to the in situ formation of silica/polysiloxane particles and the surrounding polyamide 6 matrix in one step. Moreover, 3-aminopropyltriethoxysilane has been added to the three-component-system to achieve covalent bonding between organic and inorganic phases and to inhibit agglomeration of the silica particles. Chemical structures and morphologies of the composites have been investigated by solid-state NMR and FTIR spectroscopy as well as electron microscopy and SEC measurements. Structural effects on thermal properties have been studied by DSC and TGA measurements.

Polyamide 6/silica/polysiloxane composites have been prepared in a one-step process using lactam-substituted silicon monomers.

Polyamide 6/silica hybrid materials by a coupled polymerization reaction

Polyamide 6/SiO₂hybrid materials with an adjustable SiO₂amount were produced by the coupled polymerisation of three monomeric components namely 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one), 6-aminocaproic acid and ε-caprolactam within one process.

Large outbreak of Salmonella Thompson related to smoked salmon in the Netherlands, August to December 2012

Binary file ES_Abstracts_Final_ECDC.txt matches

MATSim-T

Micro-simulations for transport planning are becoming increasingly important in traffic simulation, traffic analysis, and traffic forecasting. In the last decades the shift from using typically aggregated data to more detailed, individual based, complex data (e.g. GPS tracking) andthe continuously growing computer performance on fixed price level leads to the possibility of using microscopic models for large scale planning regions. This chapter presents such a micro-simulation. The work is part of the research project MATSim (Multi Agent Transport Simulation, http://matsim.org). In the chapter here the focus lies on design and implementation issues as well as on computational performance of different parts of the system. Based on a study of Swiss daily traffic – ca. 2.3 million individuals using motorized individual transport producing about 7.1 million trips, assigned to a Swiss network model with about 60,000 links, simulated and optimized completely time-dynamic for a complete workday – it is shown that the system is able to generate those traffic patterns in about 36 hours computation time.

A computational study of routing algorithms for realistic transportation networks

We carry out an experimental analysis of a number of shortest-path (routing) algorithms investigated in the context of the TRANSIMS (TRansportation ANalysis and SIMulation System) project. The main focus of the paper is to study how various heuristic as well as exact solutions and associated data structures affect the computational performance of the software developed for realistic transportation networks. For this purpose we have used a road network representing, with high degree of resolution, the Dallas Fort-Worth urban area.We discuss and experimentally analyze various one-to-one shortest-path algorithms. These include classical exact algorithms studied in the literature as well as heuristic solutions that are designed to take into account the geometric structure of the input instances.Computational results are provided to compare empirically the efficiency of various algorithms. Our studies indicate that a modified Dijkstra's algorithm is computationally fast and an excellent candidate for use in various transportation planning applications as well as ITS related technologies.

Supporting perception in the service of dynamic decision making

Skilled performers in complex environments rely heavily on heuristic strategies to cope with the time pressure and complexity of dynamic tasks. We suggest that the use of task simplification strategies based largely on perception and pattern recognition is fundamental to the novice-expert shift in dynamic decision making. We therefore suggest that interface training interventions should support the development of highly effective and robust heuristic strategies, rather than the development of more abstract, cognitively intensive strategies. A pair of empirical studies are presented that investigated the benefits of training interventions aimed at supporting perceptual and pattern-recognitional activities in dynamic environments. Results suggest that the acquisition of skilled performance in dynamic environments can be accelerated by supporting perceptual activities in the service of dynamic decision making. Implications of these results for training, aiding, and interface design are discussed.

Regulation of the uncoupled GTPase activity of elongation factor G (EF-G) by the conformations of the ribosomal subunits

The elongation factor G (EF-G) GTPase activity is induced by either 70S ribosomes or 50S ribosomal subunits. The GTPase activity induced by 50S ribosomal subunits is predominant at low concentrations of monovalent cations and decreases with increasing concentrations of K+ or NH4+. Double-logarithmic plots of the data reveal straight lines with different slopes for low and high concentrations of monovalent cations, respectively, intersecting at the same concentration of monovalent cations where maximal EF-G GTPase activity is measured in the presence of both ribosomal subunits. Substantially the same curves are obtained when 50S ribosomal subunits are substituted by 50S CsCl-core particles partially reconstituted by addition of purified 50S split proteins L7/L12. Intact 30S ribosomal subunits, but not 30S CsCl-core particles are able to associate with 50S ribosomal subunits and to modulate ribosome-dependent EF-G GTPase activity. Therefore, our data clearly show that the biphasic courses of the NH4+ and K+ curves of EF-G GTPase activity induced by 50S ribosomal subunits are not due to contaminations with 30S ribosomal subunits but result from different conformations of EF-G/50S ribosomal-subunit complexes at low and high concentrations of monovalent cations, respectively. CD spectra of 50S ribosomal subunits measured under different salt conditions have shown that the conformation of the 50S ribosomal subunits is strongly dependent on the concentration of monovalent cations. The conformation of 30S ribosomal subunits is, however, considerably stronger influenced by the Mg2+ than by the concentration of monovalent cations. The salt effects on the conformation of the 30S ribosomal subunits correspond to the salt effects on the association of ribosomal subunits and the modulation of EF-G GTPase activity by 30S ribosomal subunits. Since, in the presence of both ribosomal subunits, EF-G GTPase activity is maximal at the same concentration of monovalent cations where obviously a spontaneous conformation change of 50S ribosomal subunits takes place, we postulate that EF-G GTPase primarily acts on the ribosomes by changing the conformation of 50S ribosomal subunits. The resulting model is based on the assumption that EF-G GTPase activity is considerably more strongly induced by the 'substrate conformation' ('state I') than by the 'product conformation' of the 50S ribosomal subunits ('state II'). A spontaneous transformation of 'state II' to 'state I' is expected to occur in the absence of mRNA, aminoacyl-tRNA and EF-T especially under salt conditions favouring state I.

Regulation of elongation factor G GTPase activity by the ribosomal state. The effects of initiation factors and differentially bound tRNA, aminoacyl-tRNA, and peptidyl-tRNA

The elongation factor G (EF-G) is responsible for the translocation of the ribosome along the mRNA chain. Under in vitro conditions, EF-G exhibits a very active uncoupled GTPase activity which is dependent on the presence of ribosomes and is modulated by mRNA-dependent binding of tRNA. In the absence of tRNA, uncoupled EF-G GTPase is inhibited by initiation factors IF1 and IF3, but not by initiation factor IF2. In the presence of N-fMet-tRNAfMet and poly(A,U,G) or in the presence of N-acetyl-Phe-tRNAPhe and poly(U), initiation factor IF2 causes an additional decrease of the uncoupled EF-G GTPase activity. This effect, however, is dependent on the presence of IF1 and IF3 and is obviously due to the mRNA- and initiation factor-dependent binding of N-fMet-tRNAfMet and N-acetyl-Phe-tRNAPhe, respectively, to the ribosomal P-site. Non-enzymatic binding of N-fMet-tRNAfMet and N-acetyl-Phe-tRNAPhe, however, causes a stimulation of uncoupled EF-G GTPase activity. The same effects are observed for Met-tRNA, Phe-tRNAPhe and uncharged tRNA. These findings are discussed in the light of the three-site model of the ribosome and the mechanism of translocation.

[Late results following implantation of aortic bifurcation prosthesis]

From January 1976 to December 1986 181 patients with chronic arterial occlusive disease were provided with an Y-prosthesis of the aorta. In a retrospective study we reviewed the history of these patients. From 130 (72%) patients we obtained information about the further course of the disease, 83 (46%) patients were reexamined. Depending on the preoperative stage (Fontaine-Ratschow classification) of the chronic arterial occlusive disease, patients in higher stages had a greater benefit from the implantation by shifting into a more satisfactory stage. The majority of patients without any postoperative complaints (48%) belonged to the group, preoperatively classified into stage II B. Depending on the type of occlusion the best results were obtained in unique occlusions of the aorto-iliac vascular segment. 50% of the reexamined patients had no complaints although in 61% of these cases the superficial femoral artery was occluded in the mean time. 47 patients deceased during the interval of observation. In most cases death was caused by other manifestations of the basic disease (e.g. cardiac infarction or cerebral apoplexy). The 10-year-survival rate was 59%. The majority of patients with chronic occlusive disease of the pelvic arteries profited from the implantation of an aortal Y-prosthesis. The long-term success of this operation with its low lethality depends on the preoperative stage and the extent of the occlusive process.

An inhibitor of elongation factor G (EF-G) GTPase present in the ribosome wash of Escherichia coli: a complex of initiation factors IF1 and IF3?

An inhibitor of elongation factor G (EF-G) GTPase isolated from the ribosome wash of Escherichia coli was shown to stimulate the poly(A,U,G)- and initiation factor 2 (IF2)-dependent binding of N-formyl-[35S]Met-tRNAfMet to ribosomes. In the presence of saturating amounts of the EF-G GTPase inhibitor, neither addition of initiation factor 1 (IF1) nor addition of initiation factor 3 (IF3) caused a further stimulation of the formation of N-formyl-[35S]Met-tRNAfMET/poly(A,U,G)/ribosome complexes. Both IF1 and IF3 were shown to inhibit ribosome-dependent EF-G GTPase, especially when both initiation factors were added either in absence or in the presence of initiation factor 2 (IF2), poly(A,U,G) and N-formyl-Met-tRNAfMet. Therefore, we conclude that the EF-G GTPase inhibitor consisting of two polypeptide subunits with apparent molecular masses of 23,000 and 10,000 Da is a complex of initiation factors IF1 and IF3. The inhibition of EF-G GTPAse by IF3, but not the effects of IF1 in the presence or absence of IF3 could be reversed by increasing the Mg(2+)-concentration as already shown for the EF-G GTPase inhibitor. Therefore, IF1 as well as the EF-G GTPase inhibitor do not influence the ribosome-dependent EF-G GTPase by affecting the association of ribosomal subunits.

Lithium carbonate and mood disorder in recently detoxified alcoholics: a double-blind, placebo-controlled pilot study

The effects of lithium carbonate were assessed in a double-blind, placebo-controlled study of a small group of recently detoxified alcoholics. The patients were treated during their 2nd and 3rd week of abstinence. A previous study demonstrated the existence in these patients of a syndrome of mildly elevated psychomotor rate, including irritability, grandiosity, an increased need for social contact, loquaciousness, and sexual preoccupation. The intensity of this syndrome was significantly decreased by treatment with low dose lithium carbonate, with no effect of placebo treatment.

[Results of endoscopic perforating vein dissection]

The subfascial discision of insufficient perforating veins is considered the most effective therapeutic principle for the treatment of postthrombotic disturbances of the skin as well as for trophic disturbances caused by varicose. A new endoscopic technique allows to be sectioned them under direct view control with little trauma. In the period from November 1986 to April 1990 61 patients underwent an endoscopic sectioning of perforating veins. Perforating veins have most frequently been separated in the area of the Cockett group (153), the 24 cm perforating vein (74) and in the area of the Boyd group (63). Two patients (3.3%) with trophic disturbances of the skin in the area of the shank showed disturbances of wound healing after the operation. First results of the follow-up examination 3-37 months postoperative have proved good (45%) to very good (40%) results. Criteria, which were observed, were pains in the leg, disturbances of sensibility, swellings and relapsed varices. Only two patients proved a bad result. Insufficient perforating veins in the area of the shank were not found by one of the 61 operated patients. Referring to a staging of chronic venous insufficiency it can be said that with the exception of the two patients above mentioned there is a ranging to a more favourable stage or to a complete treating.

Isolation and characterization of an inhibitor of ribosome-dependent GTP hydrolysis by elongation factor G

Two inhibitors of ribosome-dependent GTP hydrolysis by elongation factor (EF)G were found in the ribosome wash of Escherichia coli strain B. One of these inhibitors was purified to homogeneity and characterized. The isolated inhibitor was found to consist of two polypeptide subunits with apparent molecular masses of 23 kDa and 10 kDa. Inhibition of EF-G GTPase could not be overcome by increasing amounts of the elongation factor or high concentrations of GTP, but was reversed by large amounts of ribosomes. The effect of the inhibitor was reduced by increasing concentrations of either 30S or 50S ribosomal subunits. EF-G-dependent GTPase of 50S ribosomal subunits was not affected by the inhibitor. These findings clearly show that the inhibitor interferes with the modulation of EF-G GTPase activity by the interactions between 30S and 50S ribosomal subunits. Under conditions, where 30S CsCl core particles are able to associate with 50S subunits and to stimulate EF-G GTPase, the effect of the inhibitor was considerably reduced when intact 30S ribosomal subunits were substituted by 30S CsCl core particles. This finding indicates that 30S CsCl split proteins are important for the action of the inhibitor and that the inhibitor does not affect the EF-G GTPase merely by interfering with the association of ribosomal subunits. Furthermore, poly(U)-dependent poly(phenylalanine) synthesis was considerably less sensitive to the inhibitor than EF-G GTPase. When ribosomes were preincubated with poly(U) and Phe-tRNA(Phe), poly(phenylalanine) synthesis was considerably less affected by the inhibitor, whereas EF-G GTPase was still sensitive.

[Quantification of changes in the skeletal muscle blood circulation following revascularization using a 99m technetium-labeled tracer]

A new 99mTc-labelled tracer (99mTc-Sestamibi) was used for the first time to demonstrate the perfusion of the skeletal muscle. In 16 patients with obstructive atherosclerosis of the lower limbs the change of perfusion of thigh and lower leg was studied with SPECT before and after vascular surgery (n = 11) or percutaneous transluminal angioplasty (n = 5). Comparative results of scintigraphic measurements and clinical observations (ankle-arm pressure, treadmill test) in 10 surgical patients (14 operated legs) showed correct positive or negative results in 86% (12/14).

Untersuchungen zur Quantifizierung der Änderung der Skelettmuskeldurchblutung nach Gefäßrevaskularisationen mit einem 99mTechnetiummarkierten Tracer

A new 99mTc-labelled tracer (99mTc-Sestanriibi) was used for the first time to demonstrate the perfusion of the skeletal muscle. In 16 patients with obstructive atherosclerosis of the lower limbs the change of perfusion of thigh and lower leg was studied with SPECT before and after vascular surgery (n = 11) or percutaneous transluminal angioplasty (n = 5). Comparative results of scintigraphic measurements and clinical observations (ancle-arm pressure, treadmill test) in 10 surgical patients (14 operated legs) showed correct positive or negative results in 86% (12/14).

Effects of light and acetate on the liberation of zoospores by a mutant strain ofChlamydomonas reinhardtii

In light-dark-synchronized cultures of the unicellular green algaChlamydomonas reinhardtii, release of zoospores from the wall of the mother cell normally takes place during the second half of the dark period. The recently isolated mutant 'ls', however, needs light for the liberation of zoospores when grown photoautotrophically under a 12 h light-12 h dark regime. The light-induced release of zoospores was found to be prevented by addition of the photosystem-II inhibitor 3-(3',4'-dichlorophenyl)-1,1-dimethylurea. Furthermore, light dependence of this process was shown to be abolished when the mutant 'ls' was grown either photoautotrophically under a 14 h light-10 h dark regime or in the presence of acetate. Our findings indicate that the light-dependency of zoospore liberation observed in cultures of this particular mutant during photoautotrophic growth under a 12 h light-12 h dark regime might be attributed to an altered energy metabolism. The light-induced release of zoospores was found to be prevented by addition of cycloheximide or chloramphenicol, antibiotics which inhibit protein biosynthesis by cytoplasmic and organellar ribosomes, respectively. Actinomycin D, an inhibitor of RNA synthesis, however, did not affect the light-induced liberation of zoospores.Sporangia accumulate in stationary cultures of the mutant 'ls'. Release of zoospores was observed when these sporangia were collected by centrifugation and incubated in the light after resuspension in fresh culture medium. Since liberation of zoospores was not observed after dilution of the stationary cultures with fresh culture medium, we suppose that components which interfere with the action of the sporangial autolysin are accumulated in the culture medium of the mutant 'ls'.

[The results and complications of 616 percutaneous transhepatic biliary drainages]

During nine years, percutaneous transhepatic biliary drainage was carried out 616 times on 563 patients in the Department of Radiology, University of Mainz Medical School. 50.3% were pre-operative and 39% were palliative. More than 80% were necessitated by malignant lesions. Subsequent improvements in biochemical measurements were observed in 82.4% of patients. Complications of the procedure led to the death of five patients (0.8%) and required surgery in nine patients (1.5%). The following complications were observed: biliary peritonitis in 0.6%, sepsis in 1.9%, bleeding in 1.9% and fever higher than 38 degrees C in 16.2%.

In Vitro Evolution and Preliminary Characterization of a Cadmium-Resistant Population of Chlamydomonas reinhardtii

A cadmium-tolerant population of Chlamydomonas reinhardtii was derived from a Cd-sensitive cell wall-deficient strain by long-term selection in liquid culture. A comparison of Cd-sensitive and Cd-tolerant cells revealed that Cd tolerance was due to genetically determined alterations of metabolism rather than to increased efficiency of a detoxification system.