Computer-assisted diagnosis based on computer-based image interpretation and 3D-visualization

PURPOSE: To survey methods for 3D data visualization and image analysis which can be used for computer based diagnostics. MATERIAL AND METHODS: The methods available are explained in short terms and links to the literature are presented. Methods which allow basic manipulation of 3D data are windowing, rotation and clipping. More complex methods for visualization of 3D data are multiplanar reformation, volume projections (MIP, semi-transparent projections) and surface projections. Methods for image analysis comprise local data transformation (e.g. filtering) and definition and application of complex models (e.g. deformable models). RESULTS: Volume projections produce an impression of the 3D data set without reducing the data amount. This supports the interpretation of the 3D data set and saves time in comparison to any investigation which requires examination of all slice images. More advanced techniques for visualization, e.g. surface projections and hybrid rendering visualize anatomical information to a very detailed extent, but both techniques require the segmentation of the structures of interest. Image analysis methods can be used to extract these structures (e.g. an organ) from the image data. DISCUSSION: At the present time volume projections are robust and fast enough to be used routinely. Surface projections can be used to visualize complex and presegmented anatomical features.     

Effect of a glycerol-containing hypotonic medium on erythrocyte phospholipid asymmetry and aminophospholipid transport during storage

Previous studies from our laboratory have shown that under blood bank storage conditions red blood cell (RBC) ATP and lipid content were better maintained in a glycerol-containing hypotonic experimental additive solution (EAS 25) than in the conventional storage medium Adsol. The objective of this study was to determine the mechanism of the protective effect of EAS 25, by measuring transmembrane phospholipid asymmetry and the membrane integrity of stored RBCs. Split units of packed RBCs were stored in either EAS 25 or Adsol. RBCs were analyzed after 0, 42, and 84 days and vesicles shed from stored RBCs were analyzed after 84 days of storage. Phospholipid asymmetry was measured by phospholipase A2 digestion (RBCs) and activation of the prothrombinase complex (RBCs, vesicles). RBC membrane exhibited a significantly greater (P < 0.01) amount of phosphatidylethanolamine externalized after storage in Adsol than in EAS 25 (44.3% +/- 11.7 vs. 25.3% +/- 5.7, respectively). Prothrombin converting activities in RBCs were significantly lower than in shed vesicles (P < 0.001) suggesting the presence of phosphatidylserine in the outer monolayer of vesicle, but not in RBC membranes. The rates of inwardly-directed aminophospholipid transport in RBCs decreased by 50% and glutathione levels decreased by approximately 50% in both media. RBC cholesterol and phospholipid content of stored RBCs remained significantly greater (P < 0.01) in EAS 25 than in Adsol. The results indicate that despite comparable reduction in the rate of aminophospholipid transport and reduced GSH concentrations, RBC phospholipid asymmetry was better maintained during storage in EAS 25 than in Adsol. The data suggest that glycerol in the hypotonic EAS helps preserve RBC lipid organization and membrane integrity during storage.     

Chaos and fractals in dynamical models of transport and reaction

This paper contains a discussion of dynamical randomness among the different methods of simulation of a fluid and its characterization by the concept of Kolmogorov-Sinai entropy per unit time. Moreover, a renormalization-group method is presented in order to construct the hydrodynamic and reactive modes of relaxation in chaotic models. The renormalization-group construction allows us to obtain the dispersion relation of these modes, i.e. their damping rate versus the wavenumber. Besides, these modes are characterized by a fractal dimension given in terms of a diffusion coefficient and a Lyapunov exponent.     

Phenylhydrazones as new good substrates for the dioxygenase and peroxidase reactions of prostaglandin synthase: formation of iron(III)-sigma-phenyl complexes

Phenylhydrazones of various aromatic and aliphatic aldehydes or ketones act as good substrates of the dioxygenase reaction of prostaglandin synthase (PGHS). Corresponding alpha-azo hydroperoxides are formed as intermediates with maximum initial rates of O2 consumption between 8 and 230 mol (mol of PGHS)-1 s-1 for benzophenone and hexanal phenylhydrazone, respectively. The Km values for these reactions vary from 100 to 300 microM. These alpha-azo hydroperoxides are then converted to the corresponding alpha-azo alcohols by the peroxidase reaction of PGHS. During such oxidations of phenylhydrazones by PGHS, a new complex of this hemeprotein characterized by peaks at 438 and 556 nm is formed. This complex was obtained both by direct reaction of PGHS Fe(III) with phenyldiazene and by reaction of PGHS Fe(III) with phenylhydrazine in the presence of O2. By analogy to results previously reported for hemoglobin, myoglobin, catalase, and cytochrome P450, this species should be a sigma-phenyl PGHS FeIII-Ph complex. The PGHS FeIII-Ph complex should derive from an oxidation of the intermediate alpha-azo alcohol by PGHS Fe(III), cleavage of the resulting alkoxy radical with formation of a ketone (or aldehyde) and Ph*, and combination of PGHS Fe(II) with Ph*. Such an oxidation of alpha-azo alcohols by lipoxygenase-FeIII with formation of Ph* was reported previously. The formation of Ph* and of PGHS FeIII-Ph is likely the cause of the inhibitory effects previously reported for arylhydrazones toward PGHS.