PubMed Health⌕ Search

Biomedical subjects

W Malkusch

Publications and source records attributed to W Malkusch.

14 recordsLinked to original sources
PubMed2001

Digital light microscopy: prerequisite for optimum contrast enhancement and increase of resolution.

Since the reproducible production of microscope objectives was enabled by the lens calculations of Ernst Abbe in 1872, various attempts have been made to further increase the resolution of light microscopes. Apart from the improvements on the optical side, especially the introduction of fluorescence methods, the use of digital cameras connected to computers have brought us close to the theoretical limits of optical resolution. Due to improved speed and memory capacity of modern computers mathematical methods can be applied to stored three-dimensional (3D) sequences of digital images which, in addition to just contrast and edge enhancement, may result in the case of real 3D deconvolution, even in the visualisation of structures beyond the theoretical limitations of light optical resolution.

Animals↗
PubMed1999

Correlation of endoanal sonography with cross-sectional anatomy of the anal sphincter.

BACKGROUND: Anal endosonography has become an important imaging method in the diagnosis of anorectal disorders. However, little information exists as to whether anal endosonography reliably defines pelvic floor structures. The aim of this study was to correlate endoanal sonography with cross-sectional anatomy and histology. METHODS: Endosonographic tomograms were obtained from 9 human cadavers before fixation and cross-sectioning at identical levels. Muscular layers were defined by visual inspection, histology, immunohistology, and morphometry using three-dimensional sphincter reconstructions. RESULTS: Endosonography visualized only two muscular layers, whereas anatomic sections always revealed three. Comparisons revealed identical findings with regard to internal sphincter volumes and asymmetries. However, due to its failure to identify the longitudinal muscle, endosonography largely overestimated external sphincter volumes. In contrast to current beliefs, anatomic studies failed to detect striated muscle fibers within the longitudinal muscle and did not show an intersphincteric space. However, anatomic cross sections demonstrated "anterior bands" as newly described anchoring mechanisms for the anal sphincters. CONCLUSIONS: Anal endosonography supplies accurate information with regard to internal anal sphincter dimensions, but does not reliably outline deeper muscular layers. However, despite these drawbacks, comparisons of modern imaging techniques with cross-sectional anatomy may enhance our understanding of pelvic floor anatomy.

Aged↗
PubMed1999

Evidence for characteristic vascular patterns in solid tumours: quantitative studies using corrosion casts.

The vascular architecture of four different tumour cell lines (CaX, CaNT, SaS, HEC-1B) transplanted subcutaneously in mice was examined by means of microvascular corrosion casting in order to determine whether there is a characteristic vascular pattern for different tumour types and whether it differs significantly from two normal tissues, muscle and gut. Three-dimensional reconstructed scanning electron microscope images were used for quantitative measurements. Vessel diameters, intervessel and interbranch distances showed large differences between tumour types, whereas the branching angles were similar. In all tumours, the variability of the vessel diameters was significantly higher than in normal tissue. The quantitative data provide strong evidence for a characteristic vascular network determined by the tumour cells themselves.

Adenocarcinoma↗
PubMed1998

The vascular architecture of the chick chorioallantoic membrane: sequential quantitative evaluation using corrosion casting.

Microvascular corrosion casting was used for evaluating qualitatively and quantitatively angiogenesis in the chick chorioallantoic membrane (CAM). Series of CAMs from day 8 to 18 were examined. The density of plexus capillaries increases rapidly until day 10 and then remains constant. The vessels connected to the plexus (first order vessels) increase in number and length between days 10 and 12. The vessels initiating from first-order vessels (second order) also increase in number but remain nearly the same in lengths and diameters. Compared to previous studies using stereomicroscopy, significant differences in vessel numbers and lengths exist, which can be explained by the low resolution and magnification resulting in too low vascular densities of the pre- and post-capillaries. The third-order vessels increase in number until day 12 when they reach a plateau, whereas higher-order vessels increase in number. These results give an insight into the vascular development of this organ, and provide the basis for assessing the targets and effects of angiogenic or antiagiogenic agents.

Journal Article↗
PubMed1998

Impact of fibroblast growth factor-2 on tumor microvascular architecture. A tridimensional morphometric study.

Three cell clones originated by transfection of human endometrial adenocarcinoma HEC-1-B cells with fibroblast growth factor-2 (FGF-2) cDNA and characterized by a different capacity to produce and secrete the growth factor were transplanted subcutaneously in nude mice. Corrosion casting of the tumor microvasculature of xenografts produced by injection of 2 x 10(6) or 10 x 10(6) FGF-2-B9 cells (which produce and secrete significant amounts of FGF-2), 10 x 10(6) FGF-2-A8 cells (which produce comparable amounts of FGF-2 but do not secrete it), or 10 x 10(6) control FGF-2-B8 cells (which produce only trace amounts of FGF-2) was performed after 14 days of growth. Interbranching distances, intervascular distances, branching angles, and vessel diameters were then determined using tridimensional stereo pairs of the casted tumor vascularity. When transplanted at the same concentration, FGF-2-B9 cells grew faster in nude mice compared with FGF-2-A8 and FGF-2-B8 clones. The total amount of new vessel formation was far higher in FGF-2-B9 tumors than in FGF-2-B8 or FGF-2-A8 tumors. Also, vessel courses were more irregular and blind-ending vessels and evasates were more frequent in FGF-2-B9 tumors. Moreover, FGF-2-B9 tumor microvasculature was characterized by a wider average vascular diameter and by an extreme variability of the diameter of each individual vessel along its course between two ramifications. No statistical differences were observed when the distribution curves of the values of intervascular distances, interbranching distances, and branching angles of the microvessel network were compared among the different experimental groups. The distinctive features of the microvasculature of FGF-2-B9 tumors were retained, at least in part, in the smaller lesions produced by injection of a limited number of cells. The data indicate that FGF-2 production and release confer to FGF-2-B9 cells the ability to stimulate the formation of new blood vessels with distinctive architectural features. Neovascularization of FGF-2-B9 lesions parallels the faster rate of growth of the neoplastic parenchyma. This does not affect the overall architecture of the microvessel network that appears to be primed by characteristics of the HEC-1-B tumor cell line and/or by the microenvironment of the host. To our knowledge, this work represents the first attempt to define the influence of a single, defined growth factor on the tridimensional tumor vascular pattern.

Adenocarcinoma↗
PubMed1995

Does lung contusion affect both the traumatized and the noninjured lung parenchyma? A morphological and morphometric study in the pig.

Isolated unilateral lung contusion (LC) was induced in 12 pigs to determine the pathophysiological role of LC in the high mortality after multiple injury. The Horovitz quotient, pulmonary vascular resistance, mean pulmonary artery pressure, mixed venous oxygen consumption, inspiratory pressure and compliance were significantly decreased in the LC group as compared to controls. The number of polymorphonuclear granulocytes, the microvascular permeability of albumine and the Wilhelmy balance as determined by bronchoalveolar lavage were significantly increased after lung contusion. As indicators of a systemic reaction we found elevated plasma levels of the terminal complement complex and decreased levels of the complement factor 3a after LC. The morphological assessment revealed changes such as those encountered during the early phase of adult respiratory distress syndrome, with granulocyte sticking, endothelial cell adhesion and transendothelial diapedesis. Morphometric analysis demonstrated a significant decrease in alveolar diameter in both the injured and the contralateral lung due to impaired surfactant surface activity. A distinct increase in septal diameter, related to edema and caused by increased microvascular permeability, was found in the injured lungs. These findings emphasize that LC leads to a generalized impairment of the entire lung, which may lead to progressive lung failure.

Albumins↗
PubMed1995

Morphometry of experimental lung contusion: an improved quantitative method.

Alterations of lung tissue following pulmonary contusion are mainly assessed qualitatively. Quantitative examinations were limited up to now, to investigations in X-ray and computer tomography images, since morphometry of contused and normal biotic lung tissues seemed to be methodologically unfeasible. In order to overcome this shortcoming, the lungs of pigs were examined after unilateral lung contusion. In semithin sections, the thickness distribution of the interstitium and the volume distribution of the alveolar cavities were studied. Using an image analysis system a sequence of detection, erosion and skeletonisation steps were used to recognize the septal tissue correctly. The percent distributions were calculated from chord measurements after a sequence of erosion steps. It turned out that this technically simple procedure enabled highly reliable and valid results to be obtained, concerning the morphometric analysis of the alterations in the contused, as well as in the non-injured lungs.

Animals↗
PubMed1995

A simple and accurate method for 3-D measurements in microcorrosion casts illustrated with tumour vascularization.

Microvascular corrosion casting is an established method to investigate vascular patterns of nearly all organs. Trying to evaluate these specimens quantitatively using native scanning electron microscope (SEM) pictures always implied a big error, because the information of depth cannot be taken into account. However, SEM stereo pairs allow for exact measurements. Tumour microcorrosion casts were used to demonstrate the feasibility of this 3-D quantification method. The information of depth was calculated for each measuring point using the parallax. From the resulting coordinates the intervascular distances, the interbranching distances as well as the interbranching angles were determined. We found significant differences between all investigated tumours. Reproducibility tests and tests for the greatest error possibilities resulted in a maximum deviation of 2.5% to be expected. Consequently this method is suitable for all application ranges of microvascular corrosion casting as a quantitative determination method.

Animals↗
PubMed1993

Toxicological investigations on silicon carbide. 1. Inhalation studies.

The question of lung damage as a result of exposure to silicon carbide (SiC) was investigated by inhalation experiments to obtain information on the qualitative response of lung tissue to the test substance (SiC). For comparison, quartz, kaolinite, and tempered clay dusts were used. The indices for the effects of the dusts studied were organ weights, numbers of bronchoalveolar cells, lung surfactant phospholipid concentrations including subfractions, and lung clearance. Exposure to the test samples was carried out according to the Essen inhalation model in two independent series. The results of the two series were similar: Compared with sham controls, exposure to SiC did not affect the indices studied. Even at a low dose (a quarter of the SiC dose) quartz gave pronounced deviations in all indices. In particular, an increase in granulocytes indicated toxic properties of the dust. The long term elimination of quartz from the lung was worse than that of SiC. The kaolinite and tempered clay dusts were intermediate between SiC and quartz based on several of the indices studied. It is concluded that SiC is deposited practically inert in the lung.

Administration, Inhalation↗
PubMed1993

Toxicological investigations on silicon carbide. 2. In vitro cell tests and long term injection tests.

Silicon carbide (SiC) dust and other dusts for comparison were injected intratracheally at a high dose (50 mg) into rats and the response of the lungs and the lymph nodes was studied after an appropriate experimental period. The indices studied were: histological changes in the lung and lymph nodes, organ weights, the formation of collagenous fibres, and the appearance of quartz typical areas. According to several epidemiological investigations and previous experimental animal studies, SiC produces silicogenic (fibrogenic) effects. No changes in the tissues studied in terms of damaging fibrogenic effects could be found after eight months (first series) and three and 12 months (second series). In particular, the histological findings and the absence of quartz typical areas as well as the quantitative determination of collagen fibres show that SiC had no harmful effects on tissues. Based on these results, the extent to which other exposures during the production of SiC can be responsible for the established radiological alterations is discussed. Without doubt the following may be confounders: SiC fibres, crystalline SiO2 (quartz, cristobalite, tridymite), and possibly gaslike emissions (SO2). From the hygienic medical point of view the workplaces during SiC manufacture should be examined carefully. The substance SiC dust as such can be considered as inert from the experimental results based on qualitative and extremely sensitive procedures. A revision of the present threshold value for SiC in ther German MAK list is called for.

Animals↗
PubMed1979

[Recent developments of instrument assisted chromosome analysis with Quantimet 720 (author's transl)].

The system looks in a short time automatically for good metaphase spreadings. Two routines are described which evaluate the relocated metaphases in a semi-automatic way. One routine classifies human chromosomes, using the chromosome area and area ratio of the chromosome arms. The other routine classifies the chromosomes of the chinese hamster. In this routine statistical inputs for chromosome aberrations are possible.

Animals↗
PubMed1977

[Machine based chromosomes investigations with the Quantimet 720 (author's transl)].

A system is described, looking in a short time and automatically for metaphases qualified for further usings. Scanning time for 1 cm2 is about 8 minutes. The accepted metaphases are relocatable immediately. Chromosomes are classified in a further routine using chromosome area and area ratio of the chromosome arms. The characters are displayed on the screen near the single chromosomes. Furthermore there is the possibility to measure the banding of whole chromosomes or of single chromatides and display it in form of histograms on the screen.

Chromatids↗
PubMedDate not supplied

Advantages of Sirius Red staining for quantitative morphometric collagen measurements in lungs.

Sirius Red staining is presented as a method for collagen determination, enabling quantitative morphometric measurements to be performed in locally defined tissue areas. The advantage of this method is especially shown for alveolar lung tissue. By excluding the bronchial areas in the tissue sections, the differences in the degree of fibrosis proved to be more discrete after different loads of quartz dust than by any other method. The difference of 12 micrograms collagen measured colorimetrically represented a 1.2-fold increase. The collagen measured in the alveolar tissue by the morphometric method rose from 9.8 to 28.6%. This is a 2.9-fold increase, underlining the vast improvement in sensitivity. Thus, this method is specifically suitable for the evaluation of very small fibrotic lesions. The quartz doses given are particularly low compared to most other investigations. Histologic lung and lymph node sections from female Wistar rats injected intratracheally with differing quantities of quartz dust (0.03, 0.1, 0.5, 1.75 mg) were stained with Sirius Red, and the collagen fibers measured with a quantitative image analysis. The results for lymph nodes using different methods (wet weight determination, quantitative measurement of quartz typical areas, colorimetric and morphometric collagen determination) showed a high correlation at the different doses. This showed that the morphometric method is suitable for the quantitative measurement of collagen. Corresponding results were also found in the comparative lung tissue measurements (colorimetric and morphometric collagen determination). However, the morphometric method has the decisive advantage that measurements can be restricted to defined tissue areas and do not destroy the section.

Animals↗