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G Wassilew

Publications and source records attributed to G Wassilew.

At least 19 recordsLinked to original sources
PubMed1989

Comparison of conventional morphometry and image analysis for the solution of histomorphometric problems.

The main differences between conventional morphometry and image analysis for their application in histopathology are pointed out. Conventional morphometry allows the use of contextural informations and a priori knowledge in a convenient manner. This is the most complicated thing in image analysis. The solution of this problem lies on the field of artificial intelligence. On the other hand, image analysis is able to measure densitometrical and textural features, to determine arbitrary quantiles and moments of feature distributions, to match scenes. Therefore the descriptive power of image analysis is much higher than the power of conventional morphometry.

Humans↗
PubMed1989

[The use of small and large computers for setting up data banks for morphometry].

The organization and structure of data masses including results of scientific research is presented on the base of the morphometric method. The data massif is realized on ESER-1056 large scale computer. Currently, all the results of the universally scientific programme "Statist", designed for mathematical and statistical morphometric data processing, are collected in this data massif. A personal computer is linked with a large-scale computer by a cable for data transfer by telecommunication, the whole system accomplishes distributed ata processing. This enables the scientist to use the data massif directly from his working site.

Computers↗
PubMed1989

[Ultrastructural morphometric studies of myocardial cells of rats after 3 hour autolysis with and without preliminary short term physical exertion].

The influence of a period of 3 h of autolysis on the ultrastructure of the heart muscle cells of 2 groups of rats was examined. One group was undergone 5 h of swimming training and the other remains without such training. The results indicate that some ultrastructural changes caused by the exercise are the same even after 3 h of autolysis. On the other hand, swimming training before autolysis affects the process of autolysis.

Animals↗
PubMed1988

[Relations between vascular, interstitial and tubular changes in the transplanted kidney].

To determine the question of the extent of fibrous intimal swelling in chronic transplant vasculopathy, of fibrous interstitial broadening and of tubular atrophy, we performed semi-quantitative histological examinations on 139 biopsy specimens, 70 removed kidney allografts and 35 allografts after autopsy, respectively. A positive correlation was found between vascular and interstitial changes. Morphometric analyses were done in 9 removed transplants and 2 normal kidneys, at which in each case 4 cortical regions including the supplying middle-sized and small arteries are examined. It was shown, that the extent of intimal swelling was variable and in the same sense also the degree of interstitial proliferation. Thus, the correlation as mentioned above is confirmed. Therefore, it is presumed that the extent of chronic transplant vasculopathy with reduction of the blood supply is most important to the formation of interstitial broadening and tubular atrophy. On principle other causes are possible and must be excluded by histological and/or angiographic investigations.

Atrophy↗
PubMed1987

Morphometric and densitometric investigations of protoplasmic astrocytes and neurons in human hepatic encephalopathy.

Morphometric and densitometric evaluations were made of nuclei of astrocytes and nerve cells of 49 cases with chronic liver diseases and of 9 control cases. The data measured from Nissl-stained specimens of putamen were compared with clinical degrees of encephalopathy and with blood ammonia levels. The parameters measured included nuclear area and optical density of nuclei. The nuclear area of astrocytes (AAREA), on average, was found to grow significantly along with aggravation of encephalopathy, that growth being from 39 micron 2 in the control group to about 60 micron 2 in cases of severe encephalopathy. Furthermore the proportion of astrocyte nuclei with an area above 70 micron 2 (ALRG) and the proportion of the optical light area of the total nuclear area (AHOLE) rises. Mean compactness (ACEXT) and mean extinction of astrocyte nuclei (AMEXT) dropped along with growing severity of encephalopathy. Mean blood ammonia levels rose from 42 mumol/l in cases with no microscopically detectable signs of encephalopathy to about six times higher values in cases with severe encephalopathy. Optical density of astrocyte nuclei was negatively correlated and mean nuclear area positively correlated to blood ammonia levels. No characteristic morphometric and densitometric changes of nerve cell nuclei were recordable from the putamen.

Adolescent↗
PubMed1987

[Age-related structural changes in the stimuli-conducting system of the human heart].

The cardionectors of 32 patients who had died at different ages without clinical or morphological indications of heart disease were examined. The autopsy was performed 8 to 24 h after death. Histochemical and histomorphometric tests were used to detect age-related changes in the conduction system (sino-auricular and AV nodes). The proportion of connective tissue increases in the cardionector and diminishes in the muscle tissue with increasing age, the changes being more pronounced in the sino-auricular than in the AV node. In the age group over 60, for instance, the proportion of connective tissue by volume is over 120% higher, in the sino -auricular node and 90% higher in the AV node than in the age group under 10. The correlation coefficient between age and proportion of connective tissue is also higher in the sino-auricular node (0.65) than in the AV node (0.53).

Adolescent↗
PubMed1983

[Histomorphometry and karyometry studies of variably differentiated rectal cancers in humans before and after radiotherapy].

Histo-morphometrical and karyometric examinations were carried out on biopsy and surgical samples from patients with cancer of the rectum. The aim of the examination was, to work out the structural morphometric characteristics of the differentiated cancer of the rectum high- and middle level and to list the quantitative morphological changes of the cancer caused irradiation with different total doses. The results of the histo-morphometric and karyometric examinations demonstrate, that both of the examined differential grades of the cancer differ less in their nucleus morphology but more in their composition of the parenchyma and stroma. Of the three total doses of irradiation the two doses using 2,500 and 4,000 rad proved to be effective as regards the structural changes of the tumor.

Adenocarcinoma↗
PubMed1981

[Electron microscopic findings during hypothermic storage preservation of the liver. II. (author's transl)].

Porcine livers were preserved by simple hypothermic storage for 6 h using plasma-protein-fraction 5%, albumin 5%, Collins C2, and Ringer-lactate followed by a morphometric evaluation of the electron-microscopic changes. The morphometric parameters reflecting swelling of mitochondriae showed the most pronounced changes and were suited best for reproduction. The best result was achieved by using Collins C2-storage. The endoplasmic reticulum was found to be only slightly swollen in all preservation solutions investigated here, at the same time a degranulation of granular endoplasmic reticulum could be demonstrated. The increase in volume of lysosomes per unit-volume was not significant.

Animals↗
PubMed1980

[Ultrastructural-morphometric characterization of adaptive and compensatory myocardial changes using heart enlargement as an example].

A morphometric analysis of the heart muscle cell shows significant differences in the reaction of different cellular structures in different experimental stress models of the myocardium (swimming exercise and ligature infarction) in the rat. For instance, the number of mitochondria is 44% higher only 2 days after infarction than after 45 h of swimming exercise over a period of 4 weeks. The mitochondria/myofibrils ratio is higher than in the case of training. But later on in the course of the experiment the number of mitochondria and their membrane surface density diminishes compared with training. The differences in the rate of formation and in the kind and intensity of the changes are probably attributable to different adaptive mechanisms by means of which the heart reacts to acute and chronic loads.

Adaptation, Physiological↗
PubMed1980

[Comparative quantitative-cytochemical and ultrastructura-morphometric studies for the characterization of the rat heart in experimental myocardial infarct].

Some oxidative enzymes of undamaged sites of the left ventricle were examined with the aid of ultrastructural morphometric and quantified cytochemical methods 1, 2, 7 and 14 days after the ligature of the descending branch of the left coronary artery. A comparison of the ultrastrastructural morphometric data with the densitometric data showed that increases in the activities of some oxidative enzymes are accompanied by enlargements of the mitochondria.

Animals↗
PubMed1980

[Multivariable EDV-program for light and electron microscopic morphometry].

A computer program for morphometry and stereology in which conventional morphometric and stereological data acquisition (direct linear measurement, point counting technique) is used and which is designed for variable application of conventional and electron microscopy is presented. There are several program variants and magnification stages each designed for a different structural level. There is fixed number of essential subcellular, cellular and extracellular structures for different kinds of tissue (myocardial, liver and connective tissue), but this number can be enlarged with each stage of magnification and for each measured parameter by reserving free places for evaluating additional structures. Thanks to the extended program and to the fact that these free places are interchangeable, the program can be used independently of the kind of tissue examined and of the kind of morphological information sought. The program structure is realized by means of a master control and 4 external subprograms. The statistical analysis of the morphometric stereological parameters is calculated by image, case by case or group by group. The mean values of the calculated primary and secondary parameters, the standard errors and the standard error/mean value ratio are printed out. All common stereological parameters and the essential cellular and extracellular structures of different kinds of tissue are described in quantitative terms with the aid of the program.

Computers↗
PubMed1980

[Methods for the determination of the surface density of myocardial cell membranes with special regard to the mitochondrial cristae].

The possibility of using modified formulas for determining the surface density of cellular membranes of the heart muscle cell was discussed, sarcoplasmic reticulum and particularly mitochondrial cristae being used as examples. By using modified formulas and different stages of magnification it could be possible to determine the surface density of critae also in such experimental conditions in which the mitochondrial cristae appear to be densely packed.

Animals↗