Andres Kriete

Ultraviolet confocal fluorescence microscopy of the in vitro cornea: redox metabolic imaging

A laser scanning microscope was fitted with two argon-ion lasers that provided wavelengths in the regions of 364, 488, and 514 nm. A Zeiss water objective of 25 x , with a numerical aperture of 0.8, corrected for the UV, was used to measure the fluorescence from optical sections of freshly enucleated rabbit eyes. The confocal microscope was used in both the reflected and fluorescent modes to image in situ epithelial and endothelial cells. An excitation wavelength of 364 nm and emission at 400-500 nm were used to image the fluorescence from reduced pyridine nucleotides. We demonstrate the feasibility of two-dimensional fluorescent confocal imaging of reduced pyridine nucleotides in corneal epithelial and endothelial cells.

Dental anatomy portrayed with microscopic volume investigations

The clinical treatment of the root canal of teeth--called endodontics--assumes a precise idea of the spatial arrangement of the anatomy of teeth and their inner structure. By using computer-assisted data acquisition from filmed sequences of histologic serial sections and a special kind of magnetic resonance microscope--the Stray Field Imaging (STRAFI)--volume investigations were carried out using special functions of a newly developed 3D software. Possible applications and future perspectives are discussed.

Computerized three-dimensional reconstructions of serial sections in electron microscopy

To improve reconstructive 3D electron microscopy novel methods are discussed to represent and process serial section images in a cuberille environment. This includes the analysis of the transfer characteristics of the image detection system, the use of laser-induced fiducials for deformation correction and alignment, the control of section thickness by EELS and the use of ESI to image thick sections.

Methodical aspects of 3-D reconstruction of chromatin architecture in mouse trophoblast giant nuclei

Precise 3‐D reconstruction of the spatial organization of murine trophoblast giant‐cell chromatin is a prerequisite for detailed investigations on the fine structural changes in chromatin‐fibre organization during the trophoblast endomitotic cell cycle. It appears very likely that sequential fine structural changes in the chromatin arrangement are concomitant with the changes in the gene expression pattern of these cells during the early phase of murine gestation.

A method for spatio-temporal (4-D) data representation in confocal microscopy : application to neuroanatomical plasticity

This paper describes a new method for data representation and visualization in four dimensions (three dimensions plus time). Sequential volumes, exhibiting morphological activity, are acquired non‐invasively with a confocal scanning laser microscope, where each data set corresponds to a time sample. A pipelined processing includes packing of volumes and specific volume rendering techniques. Subsequent processing in HIS (hue, intensity, saturation) colour space combines functional, packed images with shaded three‐dimensional views. As a result, even subtle changes in morphology become visible and computational time is saved. Experimental findings obtained from investigations of synaptic plasticity in cultured retinal tissue are reported.

3D imaging of lung tissue by confocal microscopy and micro-CT

Two complementary techniques for the imaging of tissue subunits are discussed. A computer guided light microscopic imaging technique is described first, which confocally resolves thick serial sections axially. The lateral area of interest is increased by scanning a mosaic of images in each plane. Subsequently, all images are fused digitally to form a highly resolved volume exhibiting the fine structure of complete respiratory units of lung. A different technique described is based on microtomography. This method allows to image volumes up to 3x3x3 cm at a resolution of up to 7 microns. Due to the lack of strong density differences, a contrast enhancement procedure is introduced which makes this technique applicable for the imaging of lung tissue. Imaging, visualization and analysis described here are parts of an ongoing project to model structure and to simulate function of tissue subunits and complete organs.

Methodological basis of three-dimensional imaging and visualization in biomedical sciences: a review

This review gives an inventory of methodologies used in three-dimensional imaging and visualization in biomedical sciences. It mainly addresses multislice data acquisition in microscopy and clinical scanners. Subjects treated for visual ization of volume data sets are three-dimensional reconstruction representation editing animation techniques and special hardware solutions. 1

Segmentbestimmung im Computertomogramm der Lunge In-vitro Validierung

Fur die radiologische Diagnostik ist die Kenntnis der Lungenlappensegmente zur segmentgenauen Berechnung von CT-Funktionsparametern und zur Tumorlokalisation ein Gewinn. Nach Vorverarbeitung der computertomographischen Bilddaten der Lunge wird der Bronchialbaum mit einem speziellen Bereichswachstumsverfahren segmentiert und automatisch in seine Unterbaume zerlegt. Ein auf Wachstumsmodellen basierender Algorithmus approximiert daraus die Grenzen der Lungenlappensegmente. Die Validierung mit zwei in-vitro Praparaten der Lunge ergab fur klinische HRCT-Daten eine Genauigkeit der Segmentapproximation von ca. 70%.

Data representation and visualization in 4-D microscopy

Computer representation in biological microscopy is progressing from the well established modeling of three-dimensional (3-D) structural information towards the visualization of spatio- temporal (4-D) information. This paper describes two new methods to process sequential volumes, where each data set corresponds to a time sample. The first technique is based on surface rendering to study organ and tissue development. Contour stacks are rendered and in- between stages are interpolated. This technique allows the analysis and simulation of growth following different mathematical models and relates them with experimental findings. The second technique got appreciation for volume rendering of morphogenesis in living tissue. Sequences scanned with a confocal microscope are packed. The combination of ray-casting reconstructions within a color model allows for a rendering of morphogenetic activity.

3-D visualization of mammalian intranuclear chromatin using computer-assisted confocal laser scan microscopy

In this study we describe three different approaches for the 3-D reconstruction of the spatial arrangement of iniranuclear chromatin. Using a Zeiss confocal laser scanning microscope (CLSM) image acquisition of optical sections was achieved in the fluorescence mode either using isolated nuclei stained with ethidiumbromide (EthBr) or on Feulgen stained tissue whole mounts. Different methods were applied for 3-D reconstruction: (i) contours of interesting structures were outlined by interactive cursor movement on a digitizer tablet (ii) digitized optical sections were transformed into image stacks by a software implemented on the microscope system and finally processed for a 3-D display and (iii) a ray-tracing method was used to provide a 3-D display of reconstructed surfaces from serial CLSM images after extensive image preprocessing. The characteristics of the different methods are discussed with respect to the biological system used.