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Biomedical subjects

A Liljeborg

Publications and source records attributed to A Liljeborg.

6 recordsLinked to original sources
PubMed1989

Native fibrin gel networks observed by 3D microscopy, permeation and turbidity.

Native fully hydrated fibrin gels formed at different fibrinogen and thrombin concentrations and at different ionic strengths were studied by confocal laser 3D microscopy, liquid permeation and turbidity. The gels were found to be composed of straight rod-like fiber elements that often came together at denser nodes. In gels formed at high fibrinogen concentrations, or with high amounts of thrombin, the spaces between the fibers decreased, indicating a decrease of gel porosity. The fiber strands were also shorter. Gel porosity decreased dramatically in gels formed at the high ionic strengths. Shorter fibers were observed and fiber swelling occurred at ionic strengths above 0.24. Quantitative parameters for gel porosity, fiber mass/length ratio and diameter were also derived by liquid permeation and turbidometric analyses of the gels. Permeation analysis showed that gel porosity (measured as Ks) decreased in gels formed at higher fibrin and thrombin concentrations in agreement with the porosity observed by microscopy. The turbidometric analysis showed good agreement with the permeation data for gels formed at various thrombin concentrations, but supported the permeation data more poorly in gels formed at different fibrinogen concentrations, especially above 2.5 mg/ml. Turbidometric analysis showed that the fiber mass/length ratio and diameter decreased in gels formed at ionic strength up to 0.24, as was seen in the permeation study. However, at higher ionic strengths swelling of the fibers was suggested from the gel turbidity data and this was also indicated by microscopy. These findings are discussed in relation to previous hydrodynamic and electron microscopic studies of fibrin gels.

Fibrinogen↗
PubMed1989

A confocal laser microscope scanner for digital recording of optical serial sections.

A confocal laser microscope scanner developed at our institute is described. Since an ordinary microscope is used, it is easy to view the specimen prior to scanning. Confocal imaging is obtained by laser spot illuminatin, and by focusing the reflected or fluorescent light from the specimen onto a pinhole aperture in front of the detector (a photomultiplier tube). Two rotating mirrors are used to scan the laser beam in a raster pattern. The scanner is controlled by a microprocessor which coordinated scanning, data display, and data transfer to a host computer equipped with an array processor. Digital images with up to 1024x1024 pixels and 256 grey levels can be recorded. The optical sectioning property of confocal scanning is used to record thin (about 1 microm) sections of a specimen without the need for mechanical sectioning. By using computer-control to adjust the focus of the microscope, a stack of consecutive sections can be automatically recorded. A computer is then used to display the 3-D structure of the specimen. It is also possible to obtain quantitative information, both geometric and photometric. In addition to confocal laser scanning, it is easy to perform non-confocal laser scanning, or to use conventional microscopic illumination techniques for (non-confocal) scanning. The design has proved reliable and stable, requiring very few adjustments and realignments. Results obtained with this scanner are reported, and some limitations of the technique are discussed.

Animals↗
PubMed1988

Three-dimensional reconstruction of neurons in the lamprey spinal cord in whole-mount, using a confocal laser scanning microscope.

When investigating the detailed morphology of nerve cells, three-dimensional structural information is often of great value. We present here a technique by which 'optical sectioning' and three-dimensional reconstruction of fluorescence-labelled neurons in the lamprey spinal cord has been performed by means of a confocal microscope scanner with a laser beam as the light source. In confocal microscopy only a small spot of the specimen is being illuminated at any one time, and only light from the illuminated spot is detected. This gives several advantages compared with traditional microscopy: (1) Lateral resolution is improved, and any 'halo' effects occurring around structures with intense fluorescence are drastically reduced. In addition (2), a unique depth resolution is obtained due to the strong attenuation of structures that are out of focus. This allows the system presented here to (3) perform a detailed three-dimensional computer reconstruction of the neuron, without any need for physical sectioning of the tissue. The volume of data points sampled can subsequently be treated in various ways, including selection of different viewing angles, enhancement of contours, and background suppression.

Animals↗
PubMed1985

Autoradiographic changes of 3H-alpha-bungarotoxin binding in rat hind limb muscles after a cryoinjury of the sciatic nerve and in acrylamide intoxication.

The morphological distribution of acetylcholine receptors in rat tibialis anterior and soleus muscles after a cryoinjury of the sciatic nerve was studied by in vitro autoradiography with 3H-alpha-bungarotoxin (3H-alpha-Btx). Tibialis anterior from rats intoxicated with acrylamide was also investigated by this technique. A computer system was used for densitometry and colour coding of the autoradiographs. In normal muscle, 3H-alpha-Btx binding was observed only at the motor endplates. From the second day after the nerve lesion the area of binding spread from the motor endplate region towards the muscle-tendon regions and on the 16th day almost all parts of the muscles showed increased binding. The binding had begun to decrease in the middle parts of the muscles on the 20th day and on the 30th day binding was observed only in the motor endplate area. Tibialis anterior from rats intoxicated with acrylamide (total dose 1100 mg X kg-1) showed 3H-alpha-Btx binding over the entire muscle.

Acrylamide↗
PubMed1985

The laser reflection method. Computerized analysis of speckle pattern.

The laser reflection method of remote measurements permits registration of small tooth movements. Its precision was investigated by studying the errors associated with patient repositioning in the apparatus using the computer controlled image scanner OSIRIS. Fifty repositionings of healthy subjects were evaluated. The results show that the mean error of repositioning is 2.8 micron laterally and 9.2 micron sagittally. This agrees with earlier manual-visual measurements but the higher precision due to computer evaluation of the speckle patterns gives much more reliable estimate of the repositioning error. The study confirms the fact that the laser reflection method permits accurate measurements of tooth movements.

Adult↗