Biomedical subjects

P Kube

Publications and source records attributed to P Kube.

6 recordsLinked to original sources

PubMed2003

Analysis and assessment of heavy metal pollution in suspended solids and sediments of the river Danube.

The Joint Danube Survey (JDS)--a comprehensive monitoring survey to assess the environmental pollution status of the river Danube--was carried out in 2001. Samples were taken at 74 positions along the river from Neu-Ulm (River-km 2589) down to the Danube Delta at the Black Sea (River-km 0) and in 24 main tributaries and anabranches. Besides other biological and chemical parameters, concentrations of Al, As, Cd, Cr, Cu, Fe, Pb, Mn, Hg, Ni, and Zn were determined in sediments and suspended solids. Lowest heavy metal concentrations were measured around River-km 1800. After an increase down to River-km 1000 (the Irongate Reservoir), a constant level or a slight decrease could be found down to and in the Danube Delta. Very high element concentrations were determined at only a few stations of the river Danube and in some tributaries. An evaluation of the pollution status of the river was carried out by enrichment factors (EFs) calculated using adapted background concentrations of heavy metals. Except single sampling sites and some tributaries, the pollution of the river Danube by As, Cr, Cu, Pb, Hg, Ni, and Zn can be regarded as rather low. However, elevated concentrations of Cd were found in both investigated matrices, particularly in the lower stretch of the river Danube beginning at the Irongate.

Environmental Monitoring↗

PubMed1998

Distribution, density and heterogeneity of canine mast cells and influence of fixation techniques.

The present study was carried out to determine the physiological distribution of mast cell numbers and types in the dog according to tissue location, staining and fixation methods. Tissue samples from stomach, duodenum, lung, lymph node, skin and uterus were evaluated. Samples were fixed in formalin as well as in Carnoy's fluid. The average number of mast cells was determined using a metachromatic staining method. Protease content of mast cells was examined with a double enzyme-immunohistochemical staining technique, using a histochemical reaction for chloroacetate esterase to detect chymase activity and an immunohistochemical staining method for the detection of tryptase. Canine mast cells can be subdivided into formalin-sensitive and -resistant mast cells. Three subtypes were identified according to their content of the mast cell-specific proteases tryptase (T) and chymase (C): T-, TC- and C-mast cells. Significant differences regarding the distribution of mast cell subtypes as well as the influence of the fixation method can be observed. This underlines the fact that data regarding mast cell heterogeneity from other species, obtained by different fixation methods, are not comparable. This fact has to be taken into consideration when evaluating mast cell subtypes under pathological conditions.

Animals↗

PubMed1998

Bovine mast cells: distribution, density, heterogeneity, and influence of fixation techniques.

Mast cells can be distinguished according to various characteristics: rodent mast cells have been subtyped by histochemical criteria, whereas canine and human mast cells have been classified according to their proteases. Comparisons of mast cells from different species have therefore resulted in contradictory and confusing opinions on mast cell heterogeneity. Thus, it is essential to obtain species-specific data on mast cell density and heterogeneity. The present study was carried out to determine the physiological distribution of mast cell numbers and types in bovines according to tissue location, staining, and fixation methods. Samples were fixed in formalin or Carnoy's fluid. The average number of mast cells was determined by using a metachromatic staining method. Protease content of mast cells was examined with a double-enzyme-immunohistochemical staining technique. Three mast cell subtypes were distinguished: T-, TC-, and C-mast cells. The T-mast cell was the predominant subtype in nearly all investigated organs and tissue locations. Only tryptase-positive mast cells could be demonstrated in bovine skin and uterus. No chymase activity was found in these organs, regardless of the fixation type. A larger number of mast cells was observed after fixation in Carnoy's fluid. The three different mast cell subtypes were only demonstrated in formalin-fixed tissue; chymase-positive mast cells were not found after fixation in Carnoy's fluid. Increasing experimental data suggest that mast cell subtypes have different functions in promoting and modulating inflammation and in remodeling the extracellular matrix. Since mast cell tryptase and chymase have different functional properties, these results may clarify the different reaction patterns observed in various organs and species.

Animals↗

PubMed1997

Automated measurement of retinal vascular tortuosity.

Automatic measurement of blood vessel tortuosity is a useful capability for automatic ophthalmological diagnostic tools. We describe a suite of automated tortuosity measures for blood vessel segments extracted from RGB retinal images. The tortuosity measures were evaluated in two classification tasks: (1) classifying the tortuosity of blood vessel segments and (2) classifying the tortuosity of blood vessel networks. These tortuosity measures were able to achieve a classification rate of 91% for the first problem and 95% on the second problem, which confirms that they capture much of the ophthalmologists' notion of tortuosity.

Fundus Oculi↗

PubMed1988

Reference frame effects on shape perception in two versus three dimensions.

Three experiments are reported in which it is tested whether the Gestalt effect of configural orientation on shape perception operates on two-dimensional (2-D) or three-dimensional (3-D) representations of space. It is known that gravitationally defined squares and diamonds take longer to discriminate in diagonal arrays than in horizontal or vertical arrays. In the first experiment it is shown that this interference effect decreases dramatically in magnitude when pictorial depth information is added so that subjects perceive the target shapes in different depth planes. In the second experiment this difference is shown not to be due to relative size of the target shapes or to occlusion of a background plane. It is also shown, in the final experiment, that this difference is not due to linear perspective information or merely to perception of the target figures in a 3-D scene. The overall pattern of results supports the position that this configural reference frame effect arises primarily when the elements of the configuration are coplanar, and that the principal organization underlying it is the structure of the perceived 3-D environment rather than that of the 2-D image. In all three experiments, however, there is also a small interference effect in the noncoplanar 3-D conditions. This might be due either to some aspect of reference frame selection operating on the 2-D image representation or to the failure of subjects to see depth in the 3-D stimuli on some proportion of the trials.

Attention↗

PubMedDate not supplied

Measurement and classification of retinal vascular tortuosity.

Diagnosis, Computer-Assisted↗