Mapping 3D networks in human lung tissue using micro-computed tomography and immunofluorescence

Micro-computed tomography (µCT) is a non-destructive imaging technique that can reveal the 3D lung microstructure. 3D networks in µCT images are generally identified and segmented by manually tracing their outline, which is very time consuming and requires specialist knowledge of the tissue. We devised a new method to segment 3D networks and specific cell types semi-automatically by correlating µCT imaging with immunofluorescence microscopy. Using a prototype µCT system optimised for unstained soft tissues (Nikon Metrology, UK) we imaged unstained formalin-fixed paraffin-embedded human lung tissue at a voxel (3D pixel) size of 6-10 µm. The tissue was then sectioned and specific immunofluorescence staining performed at 20 µm intervals with primary antibodies for CK18 (airway epithelium) and CD68 (macrophages). Fluorescence microscopy images were digitised and registered to the µCT data. The blood vessel network was semi-automatically segmented using the µCT data and a region growing tool in the open source itk-SNAP software package (http://www.itksnap.org). Immunofluorescence staining was successfully distinguished from the background autofluorescence on paraffin-embedded lung tissue by using a far-red (>650 nm) emission secondary antibody. The autofluorescence was used to align the two-dimensional (2D) fluorescence microscopy to the three-dimensional (3D) µCT images using the BigWarp plugin in ImageJ (https://imagej.net/BigWarp). The aligned immunofluorescence images indicated the specific location of airway epithelium in the 3D lung volume and were used to semi-automatically segment the networks and cells in the µCT. Gaps in the 3D network between the immunofluorescently stained sections were filled by digital interpolation guided by the µCT data using itk-SNAP. The segmented 3D network of blood vessels and airways can then be further related to the location of immune cells (macrophages). In summary, correlation of 2D immunofluorescence and 3D µCT data permits localisation and segmentation of 3D lung networks and individual cell types in fixed human lung tissue. This novel correlative workflow allows for accurate, specific, and faster 3D network segmentation of human soft tissue

Sind härtere Strafen für Korruption erforderlich?

Der vorliegende Beitrag diskutiert die Frage, inwieweit härtere Sanktionen geeignet sind, zur Einschränkung von Korruption beizutragen. Da Strafen auf vielfältige Art und Weise das Entscheidungskalkül von Straftätern beeinflussen, ist nicht zweifelsfrei zu bestimmen, ob eine Strafverschärfung tatsächlich die erwünschten Wirkungen hervorbringt. Aus ökonomischer Sicht spricht eine Reihe von Gründen gegen die Überlegung, dass höhere Strafen zwangsläufig zu einem Absinken des Korruptionsniveaus führen. Unter Bezugnahme auf die zeitliche Dimension der Bestrafung wird ferner gezeigt, dass das Vorziehen von Zwangsmaßnahmen eine Alternative zur Strafverschärfung darstellt. Da Menschen weiter in der Zukunft liegende Auszahlungen geringer gewichten als unmittelbar bevorstehende Auszahlungen, zeigen Sanktionen umso mehr Wirkung, je früher sie auf das strafbare Verhalten erfolgen. Berücksichtigt man zudem Beobachtungen aus der empirischen Sozialforschung, wonach Personen weit in der Zukunft liegende Auszahlungen stark diskontieren, so ist zu vermuten, dass von einer Anhebung der Verurteilungswahrscheinlichkeit und einer frühzeitigen Bestrafung eine stärkere Präventivwirkung ausgeht als von einer Strafverschärfung. Abstract The article discusses the question, to what extent harder sanctions are suitable to reduce the amount of corruption. Punishments affect the decision of potential offenders in various ways. Therefore it seems doubtful if an aggravation of penalty really causes the desired effects. From economic view a set of reasons speaks against the consideration that higher punishments lead inevitably to dropping the corruption level. With reference to the temporal dimension of the punishment it is furthermore shown, that earlier punishment represents an alternative to the aggravation of penalty. Since humans weigh future payments lower than immediate payments, sanctions have more effect the sooner the sanctions take place. Considering the results of empirical investigations, which show that people devalue future payments relatively strong, it could be assumed, that an immediate punishment and an increased certainty of punishment causes a stronger deterrent effect than an increased severity of sanction