Improving the Prediction of Spontaneous and Post-thrombolytic Recanalization in Ischemic Stroke Patients.

BACKGROUND: Endovascular treatment for acute ischemic stroke patients was recently shown to improve recanalization rates and clinical outcome in a well-defined study population. Intravenous thrombolysis (IVT) alone is insufficiently effective to recanalize in certain patients or of little value in others. Accordingly, we aimed at identifying predictors of recanalization in patients treated with or without IVT. METHODS: In the observational Acute Stroke Registry and Analysis of Lausanne (ASTRAL) registry, we selected those stroke patients (1) with an arterial occlusion on computed tomography angiography (CTA) imaging, (2) who had an arterial patency assessment at 24 hours (CTA/magnetic resonance angiography/transcranial Doppler), and (3) who were treated with IVT or had no revascularization treatment. Based on 2 separate logistic regression analyses, predictors of spontaneous and post-thrombolytic recanalization were generated. RESULTS: Partial or complete recanalization was achieved in 121 of 210 (58%) thrombolyzed patients. Recanalization was associated with atrial fibrillation (odds ratio , 1.6; 95% confidence interval, 1.2-3.0) and absence of early ischemic changes on CT (1.1, 1.1-1.2) and inversely correlated with the presence of a significant extracranial (EC) stenosis or occlusion (.6, .3-.9). In nonthrombolyzed patients, partial or complete recanalization was significantly less frequent (37%, P < .01). The recanalization was independently associated with a history of hypercholesterolemia (2.6, 1.2-5.6) and the proximal site of the intracranial occlusion (2.5, 1.2-5.4), and inversely correlated with a decreased level of consciousness (.3, .1-.8), and EC (.3, .1-.6) and basilar artery pathology (.1, .0-.6). CONCLUSIONS: Various clinical findings, cardiovascular risk factors, and arterial pathology on acute CTA-based imaging are moderately associated with spontaneous and post-thrombolytic arterial recanalization at 24 hours. If confirmed in other studies, this information may influence patient selection toward the most appropriate revascularization strategy.

Application of contrast media in post-mortem imaging (CT and MRI).

The application of contrast media in post-mortem radiology differs from clinical approaches in living patients. Post-mortem changes in the vascular system and the absence of blood flow lead to specific problems that have to be considered for the performance of post-mortem angiography. In addition, interpreting the images is challenging due to technique-related and post-mortem artefacts that have to be known and that are specific for each applied technique. Although the idea of injecting contrast media is old, classic methods are not simply transferable to modern radiological techniques in forensic medicine, as they are mostly dedicated to single-organ studies or applicable only shortly after death. With the introduction of modern imaging techniques, such as post-mortem computed tomography (PMCT) and post-mortem magnetic resonance (PMMR), to forensic death investigations, intensive research started to explore their advantages and limitations compared to conventional autopsy. PMCT has already become a routine investigation in several centres, and different techniques have been developed to better visualise the vascular system and organ parenchyma in PMCT. In contrast, the use of PMMR is still limited due to practical issues, and research is now starting in the field of PMMR angiography. This article gives an overview of the problems in post-mortem contrast media application, the various classic and modern techniques, and the issues to consider by using different media.

Eye-tracking of nodule detection in lung CT volumetric data.

PURPOSE: Signal detection on 3D medical images depends on many factors, such as foveal and peripheral vision, the type of signal, and background complexity, and the speed at which the frames are displayed. In this paper, the authors focus on the speed with which radiologists and naïve observers search through medical images. Prior to the study, the authors asked the radiologists to estimate the speed at which they scrolled through CT sets. They gave a subjective estimate of 5 frames per second (fps). The aim of this paper is to measure and analyze the speed with which humans scroll through image stacks, showing a method to visually display the behavior of observers as the search is made as well as measuring the accuracy of the decisions. This information will be useful in the development of model observers, mathematical algorithms that can be used to evaluate diagnostic imaging systems. METHODS: The authors performed a series of 3D 4-alternative forced-choice lung nodule detection tasks on volumetric stacks of chest CT images iteratively reconstructed in lung algorithm. The strategy used by three radiologists and three naïve observers was assessed using an eye-tracker in order to establish where their gaze was fixed during the experiment and to verify that when a decision was made, a correct answer was not due only to chance. In a first set of experiments, the observers were restricted to read the images at three fixed speeds of image scrolling and were allowed to see each alternative once. In the second set of experiments, the subjects were allowed to scroll through the image stacks at will with no time or gaze limits. In both static-speed and free-scrolling conditions, the four image stacks were displayed simultaneously. All trials were shown at two different image contrasts. RESULTS: The authors were able to determine a histogram of scrolling speeds in frames per second. The scrolling speed of the naïve observers and the radiologists at the moment the signal was detected was measured at 25-30 fps. For the task chosen, the performance of the observers was not affected by the contrast or experience of the observer. However, the naïve observers exhibited a different pattern of scrolling than the radiologists, which included a tendency toward higher number of direction changes and number of slices viewed. CONCLUSIONS: The authors have determined a distribution of speeds for volumetric detection tasks. The speed at detection was higher than that subjectively estimated by the radiologists before the experiment. The speed information that was measured will be useful in the development of 3D model observers, especially anthropomorphic model observers which try to mimic human behavior.

Chest CT at a dose below 0.3 mSv : impact of iterative reconstruction on image quality and lung analysis

Le nombre d'examens tomodensitométriques (Computed Tomography, CT) effectués chaque année étant en constante augmentation, différentes techniques d'optimisation, dont les algorithmes de reconstruction itérative permettant de réduire le bruit tout en maintenant la résolution spatiale, ont étés développées afin de réduire les doses délivrées. Le but de cette étude était d'évaluer l'impact des algorithmes de reconstruction itérative sur la qualité image à des doses effectives inférieures à 0.3 mSv, comparables à celle d'une radiographie thoracique. Vingt CT thoraciques effectués à cette dose effective ont été reconstruits en variant trois paramètres: l'algorithme de reconstruction, rétroprojection filtrée versus reconstruction itérative iDose4; la matrice, 5122 versus 7682; et le filtre de résolution en densité (mou) versus spatiale (dur). Ainsi, 8 séries ont été reconstruites pour chacun des 20 CT thoraciques. La qualité d'image de ces 8 séries a d'abord été évaluée qualitativement par deux radiologues expérimentés en aveugle en se basant sur la netteté des parois bronchiques et de l'interface entre le parenchyme pulmonaire et les vaisseaux, puis quantitativement en utilisant une formule de merit, fréquemment utilisée dans le développement de nouveaux algorithmes et filtres de reconstruction. La performance diagnostique de la meilleure série acquise à une dose effective inférieure à 0.3 mSv a été comparée à celle d'un CT de référence effectué à doses standards en relevant les anomalies du parenchyme pulmonaire. Les résultats montrent que la meilleure qualité d'image, tant qualitativement que quantitativement a été obtenue en utilisant iDose4, la matrice 5122 et le filtre mou, avec une concordance parfaite entre les classements quantitatif et qualitatif des 8 séries. D'autre part, la détection des nodules pulmonaires de plus de 4mm étaient similaire sur la meilleure série acquise à une dose effective inférieure à 0.3 mSv et le CT de référence. En conclusion, les CT thoraciques effectués à une dose effective inférieure à 0.3 mSv reconstruits avec iDose4, la matrice 5122 et le filtre mou peuvent être utilisés avec confiance pour diagnostiquer les nodules pulmonaires de plus de 4mm.

State of Logistics and Operations Management in Finnish and Swedish Companies – Survey Research Findings

In this research we are examining what is the status of logistics and operations management in Finnish and Swedish companies. Empirical data is based on the web based questionnaire, which was completed in the end of 2007 and early 2008. Our examination consists of roughly 30 answers from largest manufacturing (highest representation in our sample), trade and logistics/distribution companies. Generally it could be argued that these companies operate in complex environment, where number of products, raw materials/components and suppliers is high. However, usually companies rely on small amount of suppliers per raw material/component (highest frequency is 2), and this was especially the case among Swedish companies, and among those companies, which favoured overseas sourcing. Sample consisted of companies which mostly are operating in an international environment, and are quite often multinationals. Our survey findings reveal that companies in general have taken logistics and information technology as part of their strategy process; utilization of performance measures as well as system implementations have followed the strategy decisions. In the transportation mode side we identify that road transports dominate all transport flow classes (inbound, internal and outbound), followed by sea and air. Surprisingly small amount of companies use railways, but in general we could argue that Swedish companies prefer this mode over Finnish counterparts. With respect of operations outsourcing, we found that more traditional areas of logistics outsourcing are driving factors in company's performance measurement priority. In contrary to previous research, our results indicate that the scope of outsourcing is not that wide in logistics/operations management area, and companies are not planning to outsource more in the near future. Some support is found for more international operations and increased outsourcing activity. From the increased time pressure of companies, we find evidence that local as well as overseas customers expect deliveries within days or weeks, but suppliers usually supply within weeks or months. So, basically this leads into considerable inventory holding. Interestingly local and overseas sourcing strategy does not have that great influence on lead time performance of these particular sourcing areas - local strategy is anyway considerably better in responding on market changes due to shorter supply lead times. In the end of our research work we have completed correlation analysis concerning items asked with Likert scale. Our analysis shows that seeing logistics more like a process rather than function, applying time based management, favouring partnerships and measuring logistics within different performance dimensions results on preferred features and performance found in logistics literature.

Molecular basis and regulation of insect pathogenicity in plant-beneficial pseudomonads

Les bactéries du genre Pseudomonas ont la capacité étonnante de s'adapter à différents habitats et d'y survivre, ce qui leur a permis de conquérir un large éventail de niches écologiques et d'interagir avec différents organismes hôte. Les espèces du groupe Pseudomonas fluorescens peuvent être facilement isolées de la rhizosphère et sont communément connues comme des Pseudomonas bénéfiques pour les plantes. Elles sont capables d'induire la résistance systémique des plantes, d'induire leur croissance et de contrer des phytopathogènes du sol. Un sous-groupe de ces Pseudomonas a de plus développé la capacité d'infecter et de tuer certaines espèces d'insectes. Approfondir les connaissances sur l'interaction de ces bactéries avec les insectes pourraient conduire au développement de nouveaux biopesticides pour la protection des cultures. Le but de cette thèse est donc de mieux comprendre la base moléculaire, l'évolution et la régulation de la pathogénicité des Pseudomonas plante-bénéfiques envers les insectes. Plus spécifiquement, ce travail a été orienté sur l'étude de la production de la toxine insecticide appelée Fit et sur l'indentification d'autres facteurs de virulence participant à la toxicité de la bactérie envers les insectes. Dans la première partie de ce travail, la régulation de la production de la toxine Fit a été évaluée par microscopie à épifluorescence en utilisant des souches rapportrices de Pseudomonas protegens CHA0 qui expriment la toxine insecticide fusionnée à une protéine fluorescente rouge, au site natif du gène de la toxine. Celle-ci a été détectée uniquement dans l'hémolymphe des insectes et pas sur les racines des plantes, ni dans les milieux de laboratoire standards, indiquant une production dépendante de l'hôte. L'activation de la production de la toxine est contrôlée par trois protéines régulatrices dont l'histidine kinase FitF, essentielle pour un contrôle précis de l'expression et possédant un domaine "senseur" similaire à celui de la kinase DctB qui régule l'absorption de carbone chez les Protéobactéries. Il est donc probable que, durant l'évolution de FitF, un réarrangement de ce domaine "senseur" largement répandu ait contribué à une production hôte-spécifique de la toxine. Les résultats de cette étude suggèrent aussi que l'expression de la toxine Fit est plutôt réprimée en présence de composés dérivés des plantes qu'induite par la perception d'un signal d'insecte spécifique. Dans la deuxième partie de ce travail, des souches mutantes ciblant des facteurs de virulence importants identifiés dans des pathogènes connus ont été générées, dans le but d'identifier ceux avec une virulence envers les insectes atténuée. Les résultats ont suggéré que l'antigène O du lipopolysaccharide (LPS) et le système régulateur à deux composantes PhoP/PhoQ contribuent significativement à la virulence de P. protegens CHA0. La base génétique de la biosynthèse de l'antigène O dans les Pseudomonas plante-bénéfiques et avec une activité insecticide a été élucidée et a révélé des différences considérables entre les lignées suite à des pertes de gènes ou des acquisitions de gènes par transfert horizontal durant l'évolution de certaines souches. Les chaînes latérales du LPS ont été montrées comme vitales pour une infection des insectes réussie par la souche CHA0, après ingestion ou injection. Les Pseudomonas plante-bénéfiques, avec une activité insecticide sont naturellement résistants à la polymyxine B, un peptide antimicrobien modèle. La protection contre ce composé antimicrobien particulier dépend de la présence de l'antigène O et de la modification du lipide A, une partie du LPS, avec du 4-aminoarabinose. Comme les peptides antimicrobiens cationiques jouent un rôle important dans le système immunitaire des insectes, l'antigène O pourrait être important chez les Pseudomonas insecticides pour surmonter les mécanismes de défense de l'hôte. Le système PhoP/PhoQ, connu pour contrôler les modifications du lipide A chez plusieurs bactéries pathogènes, a été identifié chez Pseudomonas chlororaphis PCL1391 et P. protegens CHA0. Pour l'instant, il n'y a pas d'évidence que des modifications du lipide A contribuent à la pathogénicité de cette bactérie envers les insectes. Cependant, le senseur-kinase PhoQ est requis pour une virulence optimale de la souche CHA0, ce qui suggère qu'il régule aussi l'expression des facteurs de virulence de cette bactérie. Les découvertes de cette thèse démontrent que certains Pseudomonas associés aux plantes sont de véritables pathogènes d'insectes et donnent quelques indices sur l'évolution de ces microbes pour survivre dans l'insecte-hôte et éventuellement le tuer. Les résultats suggèrent également qu'une recherche plus approfondie est nécessaire pour comprendre comment ces bactéries sont capables de contourner ou surmonter la réponse immunitaire de l'hôte et de briser les barrières physiques pour envahir l'insecte lors d'une infection orale. Pour cela, les futures études ne devraient pas uniquement se concentrer sur le côté bactérien de l'interaction hôte-microbe, mais aussi étudier l'infection du point de vue de l'hôte. Les connaissances gagnées sur la pathogénicité envers les insectes des Pseudomonas plante-bénéfiques donnent un espoir pour une future application en agriculture, pour protéger les plantes, non seulement contre les maladies, mais aussi contre les insectes ravageurs. -- Pseudomonas bacteria have the astonishing ability to survive within and adapt to different habitats, which has allowed them to conquer a wide range of ecological niches and to interact with different host organisms. Species of the Pseudomonas fluorescens group can readily be isolated from plant roots and are commonly known as plant-beneficial pseudomonads. They are capable of promoting plant growth, inducing systemic resistance in the plant host and antagonizing soil-borne phytopathogens. A defined subgroup of these pseudomonads evolved in addition the ability to infect and kill certain insect species. Profound knowledge about the interaction of these particular bacteria with insects could lead to the development of novel biopesticides for crop protection. This thesis thus aimed at a better understanding of the molecular basis, evolution and regulation of insect pathogenicity in plant-beneficial pseudomonads. More specifically, it was outlined to investigate the production of an insecticidal toxin termed Fit and to identify additional factors contributing to the entomopathogenicity of the bacteria. In the first part of this work, the regulation of Fit toxin production was probed by epifluorescence microscopy using reporter strains of Pseudomonas protegens CHAO that express a fusion between the insecticidal toxin and a red fluorescent protein in place of the native toxin gene. The bacterium was found to express its insecticidal toxin only in insect hemolymph but not on plant roots or in common laboratory media. The host-dependent activation of Fit toxin production is controlled by three local regulatory proteins. The histidine kinase of this regulatory system, FitF, is essential for the tight control of toxin expression and shares a sensing domain with DctB, a sensor kinase regulating carbon uptake in Proteobacteria. It is therefore likely that shuffling of a ubiquitous sensor domain during the evolution of FitF contributed to host- specific production of the Fit toxin. Findings of this study additionally suggest that host-specific expression of the Fit toxin is mainly achieved by repression in the presence of plant-derived compounds rather than by induction upon perceiving an insect-specific signal molecule. In the second part of this thesis, mutant strains were generated that lack factors previously shown to be important for virulence in prominent pathogens. A screening for attenuation in insect virulence suggested that lipopolysaccharide (LPS) O-antigen and the PhoP-PhoQ two-component regulatory system significantly contribute to virulence of P. protegens CHAO. The genetic basis of O-antigen biosynthesis in plant-beneficial pseudomonads displaying insect pathogenicity was elucidated and revealed extensive differences between lineages due to reduction and horizontal acquisition of gene clusters during the evolution of several strains. Specific 0 side chains of LPS were found to be vital for strain CHAO to successfully infect insects by ingestion or upon injection. Insecticidal pseudomonads with plant-beneficial properties were observed to be naturally resistant to polymyxin B, a model antimicrobial peptide. Protection against this particular antimicrobial compound was dependent on the presence of O-antigen and modification of the lipid A portion of LPS with 4-aminoarabinose. Since cationic antimicrobial peptides play a major role in the immune system of insects, O-antigenic polysaccharides could be important for insecticidal pseudomonads to overcome host defense mechanisms. The PhoP-PhoQ system, which is well-known to control lipid A modifications in several pathogenic bacteria, was identified in Pseudomonas chlororaphis PCL1391 and P. protegens CHAO. No evidence was found so far that lipid A modifications contribute to insect pathogenicity in this bacterium. However, the sensor kinase PhoQ was required for full virulence of strain CHAO suggesting that it additionally regulates the expression of virulence factors in this bacterium. The findings of this thesis demonstrate that certain plant-associated pseudomonads are true insect pathogens and give some insights into how these microbes evolved to survive within and eventually kill the insect host. Results however also point out that more in-depth research is needed to know how exactly these fascinating bacteria manage to bypass or overcome host immune responses and to breach physical barriers to invade insects upon oral infection. To achieve this, future studies should not only focus on the bacterial side of the microbe-host interactions but also investigate the infection from a host-oriented view. The knowledge gained about the entomopathogenicity of plant-beneficial pseudomonads gives hope for their future application in agriculture to protect plants not only against plant diseases but also against insect pests.

CT attenuation values of blood and myocardium: rationale for accurate coronary artery calcifications detection with multi-detector CT.

OBJECTIVES: To determine inter-session and intra/inter-individual variations of the attenuations of aortic blood/myocardium with MDCT in the context of calcium scoring. To evaluate whether these variations are dependent on patients' characteristics. METHODS: Fifty-four volunteers were evaluated with calcium scoring non-enhanced CT. We measured attenuations (inter-individual variation) and standard deviations (SD, intra-individual variation) of the blood in the ascending aorta and of the myocardium of left ventricle. Every volunteer was examined twice to study the inter-session variation. The fat pad thickness at the sternum and noise (SD of air) were measured too. These values were correlated with the measured aortic/ventricular attenuations and their SDs (Pearson). Historically fixed thresholds (90 and 130 HU) were tested against different models based on attenuations of blood/ventricle. RESULTS: The mean attenuation was 46 HU (range, 17-84 HU) with mean SD 23 HU for the blood, and 39 HU (10-82 HU) with mean SD 18 HU for the myocardium. The attenuation/SD of the blood were significantly higher than those of the myocardium (p < 0.01). The inter-session variation was not significant. There was a poor correlation between SD of aortic blood/ventricle with fat thickness/noise. Based on existing models, 90 HU threshold offers a confidence interval of approximately 95% and 130 HU more than 99%. CONCLUSIONS: Historical thresholds offer high confidence intervals for exclusion of aortic blood/myocardium and by the way for detecting calcifications. Nevertheless, considering the large variations of blood/myocardium CT values and the influence of patient's characteristics, a better approach might be an adaptive threshold.

The Swiss cohort study on substance use risk factors : findings of two waves

Aim: To summarize published findings in peer-reviewed journals of the first two waves of the Swiss Cohort Study on Substance Use Risk Factors (C-SURF), a longitudinal study assessing risk and protective factors of 5,987 young men during the phase of emerging adulthood (20 years at baseline, followed-up 15 months later). Methods: Included were 33 studies published until November 2014 focusing on substance use. Results: Substance use in early adulthood is a prevalent and stable behavior. The 12-month prevalence of nonmedical use of prescription drugs (10.6%) lies between that of cannabis (36.4%) and other illicit drugs such as ecstasy (3.7%) and cocaine (3.2%). Although peer pressure in the form of misconduct is associated with increased substance use, other aspects such as peer involvement in social activities may have beneficial effects. Regular sport activities are associated with reduced substance use, with the exception of alcohol use. Young men are susceptible to structural conditions such as the price of alcohol beverages or the density of on-premise alcohol outlets. Particularly alcohol use in public settings such as bars, discos or in parks (compared with private settings such as the home) is associated with alcohol-related harm, including injuries or violence. Being a single parent versus nuclear family has no effect on alcohol use, but active parenting does. Besides parenting, religiousness is an important protective factor for both legal and illegal substance use. Merely informing young men about the risks of substance use may not be an effective preventive measure. At-risk users of licit and illicit substances are more health literate, e. g., for example, they seek out more information on the internet than non-at-risk-users or abstainers. Discussion: There are a number of risk and protective substance use factors, but their associations with substance use do not necessarily agree with those found outside Europe. In the United States, for example, heavy alcohol use in this age group commonly takes place in private settings, whereas in Switzerland it more often takes place in public settings. Other behaviors, such as the nonmedical use of prescription drugs, appear to be similar to those found overseas, which may show the need for targeted preventive actions. C-SURF findings point to the necessity of establishing European studies to identify factors for designing specific preventive actions.