Biomedical subjects

K Rodenacker

Publications and source records attributed to K Rodenacker.

24 records · Page 2Linked to original sources

PubMed1990

Quantitative evaluation of radiation-induced changes in sperm morphology and chromatin distribution.

Sperm head cytometry provides a useful assay for the detection of radiation-induced damage in mouse germ cells. Exposure of the gonads to radiation is known to lead to an increase of diploid and higher polyploid sperm and of sperm with head shape abnormalities. In the pilot studies reported here quantitative analysis of the total DNA content, the morphology, and the chromatin distribution of mouse sperm was performed. The goal was to evaluate the discriminative power of features derived by high resolution image cytometry in distinguishing sperm of control and irradiated mice. Our results suggest that besides the induction of the above mentioned variations in DNA content and shape of sperm head, changes of the nonhomogeneous chromatin distribution within the sperm may also be used to quantify the radiation effect on sperm cells. Whereas the chromatin distribution features show larger variations for sperm 21 days after exposure (dpr), the shape parameters seem to be more important to discriminate sperm 35 dpr. This may be explained by differentiation processes, which take place in different stages during mouse spermatogenesis.

Animals↗

PubMed1989

Computer-assisted imaging cytometry of nuclear chromatin reveals bone tumor virus infection and neoplastic transformation of adherent osteoblast-like cells.

Established osteoblast-like (OB) cells infected with the bone tumor-inducing C-type retrovirus OA MuLV remained nontumorigenic over 104 cell culture passages. DNA histograms revealed a new cell population with a stem line peak at 5c. A second OA MuLV-infected OB cell line underwent neoplastic transformation with increasing passage level. These cells showed diffuse aneuploidy. Stepwise linear discriminant analysis of the chromatin structure of control, OA MuLV-infected, and FBR osteosarcoma virus-transformed cell lines resulted in various levels of discrimination ranging between 79.6% for control cells versus nontumorigenic OA MuLV-infected cells, and 96.6% for nontumorigenic OA MuLV-infected cells versus FBR osteosarcoma virus-transformed cells. OA MuLV-infected tumorigenic cells and FBR osteosarcoma virus-transformed cells were discriminated at a 93.6% level.

Animals↗

PubMed1988

Interval-coded texture features for artifact rejection in automated cervical cytology.

In order to improve the separation between abnormal cells and noncellular artifacts in the CERVIFIP automated cervical cytology prescreening system, 22 different object texture features were investigated. The features were all statistical parameters of the pixel density histograms or one-dimensional filtered values of central and border regions of the object images. The features were calculated for 231 images (100 cells and 131 artifacts) detected as Suspect Cells by the current CERVIFIP and were then tested in hierarchical and linear discriminant classifiers. After selecting the two best features for use in a hierarchical classifier, 83% correct classification was achieved. One of these features was specifically designed to remove poorly focused objects. With maximum likelihood discrimination using all 22 features, an overall correct classification rate of 90% was obtained.

Cell Division↗

PubMed1983

Correlation between chromatin morphology as derived by digital image analysis and autoradiographic labeling pattern.

In order to interpret the Feulgen-dependent chromatin morphology on a functional basis, we performed model experiments in which labeling with 14C-thymidine and 14C-uridine was used as a functional parameter. Using a relocation facility, information on either DNA or RNA, labeling intensity of a cell was added to the parameters of image analysis by measuring the same cell by scanning photometry after Feulgen staining. The Feulgen-stained nuclei were interactively sampled and automatically segmented. Most of the textural information was gained from a flat texture image obtained by subtracting the original image from a median-filtered image. In addition to the autoradiographic features, visually recognizable differences in nuclear morphology, such as the number of nucleoli and the level of condensed (inactive) and diffuse (active) regions of the chromatin, were also correlated with textural parameters. Using the supervised cluster analysis method, an attempt was made to establish a correlation between visual nuclear morphology and autoradiographic labeling intensity that improved the functional understanding of the Feulgen features. Our results further clarify the supramolecular chromatin structure and its dynamics during specific transitions in the cell cycle, namely the G0-G1, G1-S and S-G2 transitions; this information may become useful in diagnostic procedures.

Animals↗

PubMed1981

Changes in benign cell populations in cases of cervical cancer and its precursors.

In two totally independent experiments, typical intermediate cells were visually selected by experienced cytotechnicians trained in the analysis of monodisperse Papanicolaou-stained ectocervical smears. The smears were carefully diagnosed per se and in correlation with routine smears from the same patients. For specimens of classes exhibiting tumor cells, the diagnosis was histologically verified. About 20 cells per specimen were selected from at least ten specimens per Papanicolaou class, amounting to total sample sizes of about 1,000 cells. In the first experiment, only cell nuclei were SMP scanned; in the second experiment, the whole cells were TV scanned. Correlation and classification analyses were performed; these resulted in the clear demonstration that intermediate cell populations in ectocervical smears are different in patients with different neoplastic gradings.

Female↗

PubMed1980

Estimation of the performance of an array-processor oriented system for automatic Pap smear analysis.

The rapid progress in computer technology makes possible the automatic analysis of thousands of cells on a slide in the field of automatic uterine cancer cytology. Our approach starts with the high-resolution scanning of visually selected and classified single cells determining the training set for discriminant analysis. On the basis of more than 15 morphologic and textural features measured, correct classification results of 95% are reached. Our aim is to speed up our image processing system by means of an Array-Processor, the model AP 120 B from Floating Point Systems. In this study a realistic time estimation of the scanning, segmentation, feature extraction and classification of about 40,000 cells on a slide is performed.

Computers↗