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Biomedical subjects

B Palcic

Publications and source records attributed to B Palcic.

At least 55 records · Page 3Linked to original sources
PubMed1994

Probabilistic inference in computer-aided screening for cervical cancer: an event covering approach to information extraction and decision rule formulation.

A pattern analysis approach called event covering is introduced and applied to the problem of determining the significance of measured morphological attributes of cervical cells in an automated screening process. The approach is shown to be effective in deciding which characteristics at the event (outcome) level are of little or no diagnostic value, and in formulating sets of predictive rules using the most pertinent ones.

Adult↗
PubMed1993

Quantitative evaluation of malignant potential of early breast cancer using high resolution image cytometry.

We have been testing two independent hypotheses which postulate that the malignant potential of early breast cancer can be objectively assessed by measuring nuclear features of the diagnostic-malignant cells (hypothesis I) and/or normal-appearing epithelial cells found in the vicinity of the carcinoma (hypothesis II). In preliminary experiments, we tested some of these hypotheses using historical samples and a high resolution image cytometry apparatus. Tissue sections were stained with our stoichiometric stain and over 60 nuclear features, primarily texture features describing the DNA distribution in the nuclei, were employed in the multivariate analyses. Data derived from measurements of ductal carcinoma in situ (DCIS) with and without the invasive component indicated that the malignant potential of these lesions can be estimated with a sensitivity and specificity of at least 80%. The analysis of the tissue surrounding an invasive breast carcinoma showed that the existing malignancy can be predicted solely from the measurements of normal nuclei (normal-appearing breast lobules) in more than 85% of patients. This result indicates that the analysis of benign tissues also could give prognostically valid information. These results can be greatly improved using larger sample sizes and other improvements, including technical improvements of the cytometry device. We believe that this approach can be developed into a practical diagnostic and prognostic tool for better management of early breast cancer.

Breast Diseases↗
PubMed1993

Time lapse video recordings of highly purified human hematopoietic progenitor cells in culture.

Major hurdles in studies of stem cell biology include the low frequency and heterogeneity of human hematopoietic precursor cells in bone marrow and the difficulty of directly studying the effect of various culture conditions and growth factors on such cells. We have adapted the cell analyzer imaging system for monitoring and recording the morphology of limited numbers of cells under various culture conditions. Hematopoietic progenitor cells with a CD34+ CD45RAlo CD71lo phenotype were purified from previously frozen organ donor bone marrow by fluorescence activated cell sorting. Cultures of such cells were analyzed with the imaging system composed of an inverted microscope contained in an incubator, a video camera, an optical memory disk recorder and a computer-controlled motorized microscope XYZ precision stage. Fully computer-controlled video images at defined XYZ positions were captured at selected time intervals and recorded at a predetermined sequence on an optical memory disk. In this study, the cell analyzer system was used to obtain descriptions and measurements of hematopoietic cell behavior, like cell motility, cell interactions, cell shape, cell division, cell cycle time and cell size changes under different culture conditions.

Cell Communication↗
PubMed1993

A computerized system for morphometric analysis of digitized images of histologically prepared arterial cross sections.

A method is described for computerized, operator-assisted, morphometric measurement of histologically prepared arterial cross sections. The system is composed of an image cytometer equipped with a one power lens and a digitizing camera interfaced with an imaging board residing in a PC computer. Algorithms were developed for automated segmentation of the areas of interest. The method is rapid, objective, accurate and requires minimum operator intervention. It gives reliable and reproducible results in the measurement of all elements of the cross section including circumference, area of the media, circumference of the internal elastic lamina, area of the lumen and percent occlusion of the lumen by the intimal thickening. While manual measurements using computerized planimetric methods give similar results, this method is an order of magnitude faster (1-2 min vs. 10-20 min per cross section) thus facilitating the study of large numbers of specimens. A blinded re-measurement of 284 sections of artery for reproducibility yielded r values of 0.86-0.97.

Adult↗
PubMed1993

Cell survival measurements at low doses using an automated image cytometry device.

The statistical precision of cell survival data measured at low doses can be greatly improved if the number of cells assayed at each dose point is known exactly. This paper describes an image cytometry technique that has been developed for this purpose. Treated cells are plated into tissue culture flasks, and after attachment their locations are determined with 98% accuracy by automated scanning procedures. These locations are revisited after an appropriate incubation period to assay for colony formation. Colonies may be scored either manually or using image data collected by the device. Additional information, such as heterogeneity of colony size, can also be obtained.

Animals↗
PubMed1993

A computerized autofluorescence and diffuse reflectance spectroanalyser system for in vivo skin studies.

A microcomputer-controlled spectroanalyser system has been set up to study optical properties of normal and abnormal human skin in vivo. The system can measure both tissue autofluorescence and diffuse reflectance at selected skin locations. The sample holder allows adjustment of the incident angle of the illumination light and the pick-up angle of the collected light providing the means to examine different depths of skin tissue. Using this system, we detected measurable skin autofluorescence with a maximum at about 470 nm when excited with 380 nm UV radiation. In this work, we also show that the absorption and scattering properties of the skin tissue (which can be determined from the measured diffuse reflectance spectrum) affect the shape of the autofluorescence spectrum. We believe that the combination of autofluorescence and diffuse reflectance measurements will lead to better understanding of the optical properties of normal and abnormal skin tissue.

Computer Systems↗
PubMed1993

Detection and localization of early lung cancer by imaging techniques.

Two new technologic developments may have a significant impact on the detection and localization of early lung cancer. These two developments work together in a complementary way. The first is a solid-state microscope that can be applied in the prescreening of sputum cytology specimens. The finding that malignancy-associated changes (MACs) are present in ostensibly normal bronchial epithelial cells may be used to improve the sensitivity of sputum cytology to detect cancer. Once abnormal or MAC cells are found, a second device, a fluorescence bronchoscope, can be employed to localize the source of the abnormal cells. Fluorescence bronchoscopy is also a potentially useful tool for procuring premalignant tissue for molecular biology studies and for monitoring the progress of patients in chemoprevention studies.

Bronchoscopy↗
PubMed1993

[Assessment of anti-proliferative and anti-inflammatory drugs for treatment of ocular fibroblast proliferation using dynamic microscope image processing scanner].

Controlling ocular fibroblast proliferation may significantly improve the effectiveness of glaucoma filtration surgery. Drugs for the inhibition of fibroblast growth are currently in clinical use. However, systemic studies of drugs with different mechanisms of action have not been performed on human ocular fibroblasts. We have developed a method to evaluate the effect of chemotherapeutic agents on fibroblast proliferation, motility, and dynamic morphology. This involves the use of an automated microscope system designed for quantitative measurement of movement and morphology of live cells in tissue culture. This technique was tested on an established tissue culture fibroblast (3T3 cells) and then applied to secondary culture of human scleral and subconjunctival fibroblasts. 5-fluorouracil and colchicine were tested for their effect on fibroblast behaviour. Our data indicated that colchicine was more effective than 5-fluorouracil in inhibiting fibroblast proliferation and movement, and in changing morphology. Using this system, fundamental biological effects of various pharmacological manipulations could be studied in vitro prior to in vivo applications.

3T3 Cells↗
PubMed1993

Detection of dysplasia and carcinoma in situ with a lung imaging fluorescence endoscope device.

The performance of a novel bronchoscopic fluorescence imaging system was compared with conventional white light bronchoscopy with a data base of 328 biopsy-confirmed sites from 53 patients and 41 volunteers. The two methods were found to have the same specificity (94%); however, the sensitivity of the fluorescence system (72.5%) was found to be 50% greater than that of the white light bronchoscopy (48.4%) in detecting dysplasia and carcinoma in situ. The fluorescence system uses a nonlinear discriminant function combining the red and green image intensity values to form a pseudoimage that, when displayed on an RGB monitor, allows the detection and delineation of abnormal areas. In 15% of the patients with lung cancer, synchronous carcinoma in situ was found in addition to the large invasive cancer. Of the current smokers in this study, 40% had moderate dysplasia and 12% had severe dysplasia. For the ex-smokers 25% had moderate dysplasia, 6% had severe dysplasia, and 13% had carcinoma in situ. Fluorescence imaging may become an important adjunct to conventional bronchoscopic examination to improve our ability to diagnose and stage lung cancer more accurately.

Aged↗
PubMed1992

Automated image detection and segmentation in blood smears.

A simple technique which automatically detects and then segments nucleated cells in Wright's giemsa-stained blood smears is presented. Our method differs from others in 1) the simplicity of our algorithms; 2) inclusion of touching (as well as nontouching) cells; and 3) use of these algorithms to segment as well as to detect nucleated cells employing conventionally prepared smears. Our method involves: 1) acquisition of spectral images; 2) preprocessing the acquired images; 3) detection of single and touching cells in the scene; 4) segmentation of the cells into nuclear and cytoplasmic regions; and 5) postprocessing of the segmented regions. The first two steps of this algorithm are employed to obtain high-quality images, to remove random noise, and to correct aberration and shading effects. Spectral information of the image is used in step 3 to segment the nucleated cells from the rest of the scene. Using the initial cell masks, nucleated cells which are just touching are detected and separated. Simple features are then extracted and conditions applied such that single nucleated cells are finally selected. In step 4, the intensity variations of the cells are then used to segment the nucleus from the cytoplasm. The success rate in segmenting the nucleated cells is between 81 and 93%. The major errors in segmentation of the nucleus and the cytoplasm in the recognized nucleated cells are 3.5% and 2.2%, respectively.

Algorithms↗
PubMed1992

Detection of squamous cell cancer and pre-cancerous lesions by imaging of tissue autofluorescence in the hamster cheek pouch model.

Early detection of invasive and pre-invasive neoplasms of the aerodigestive tract will ultimately improve the management of patients with these lesions. This paper describes the use of quantitative fluorescence imaging of early squamous cell carcinomas in an animal model. Dysplasia, carcinoma in situ and invasive cancers were imaged exploiting tumour autofluorescence. Mapped biopsies were obtained from areas imaged determining a sensitivity of 100% and specificity of 80%. Autofluorescence imaging is an excellent method of detecting neoplasms of the aerodigestive tract.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

The relative biological effectiveness of 60Co gamma-rays, 55 kVp X-rays, 250 kVp X-rays, and 11 MeV electrons at low doses.

The relative biological effectiveness (RBE) of selected low-LET radiation modalities (55 kVp X-rays, 250 kVp X-rays, 60Co gamma-rays, and 11 MeV electrons) was investigated for survival of two cell lines (V79 and CHO). Detailed measurements were made in the low (0 to 3 Gy) dose range using an image cytometry device to accurately determine the number of cells assayed at each dose point. Data were also collected in the high dose range (0 to 10 Gy) using conventional counting and plating techniques. RBE values (+/- 1 SE) varied from 1.0 +/- 0.07 (V79 cells) and 1.2 +/- 0.05 (CHO cells) at high doses to 1.3 +/- 0.07 (V79) and 1.4 +/- 0.1 (CHO) at low doses for 55 kVp X-rays, from 1.1 +/- 0.05 (V79) and 1.1 +/- 0.04 (CHO) at high doses to 1.1 +/- 0.06 (V79) and 1.2 +/- 0.2 (CHO) at low doses for 250 kVp X-rays, and from 1.1 +/- 0.08 (V79) and 1.0 +/- 0.04 (CHO) at high doses to 1.0 +/- 0.06 (V79) and 0.9 +/- 0.1 (CHO) at low doses for 11 MeV electrons. Only the low and high dose RBEs for 55 kVp X-rays relative to 60Co gamma-rays were significantly different.

Animals↗
PubMed1992

Detection of dysplasia and carcinoma in situ by ratio fluorometry.

Fluorescence bronchoscopy was performed in 82 volunteers recruited from occupational groups at risk of exposure to asbestos and/or diesel fumes to determine whether differences in tissue autofluorescence between normal and malignant bronchial tissues can be used to improve the sensitivity of standard fiberoptic bronchoscopy in detecting dysplasic and carcinoma in situ (CIS). This study consisted of 25 nonsmokers, 40 exsmokers, and 17 current smokers with mean ages of 52, 55, and 49 yr, respectively. Tissue autofluorescence was induced by a blue light from an He-Cd laser coupled to the illumination channel of the bronchoscope and analyzed by a ratiofluorometer. One or more sites of moderate or severe dysplasia were found in 12% of the exsmokers and current smokers but in none of the nonsmoker volunteers. CIS was found in two of the exsmokers. The sensitivity of fluorescence bronchoscopy (86%) was found to be 50% better than that of conventional white-light bronchoscopy (52%) in detecting dysplasia and CIS. Pre- and post-bronchoscopy sputum cytology failed to detect these precancerous lesions. Our results suggest that fluorescence bronchoscopy may be an important new method that can improve the ability to detect and localize precancerous and/or CIS lesions.

Asbestos↗
PubMed1992

Comparison of three different methods for automated classification of cervical cells.

Over 4600 exfoliated squamous cervical cells taken from appropriate Papanicolaou samples were classified as normal, mildly dysplastic, moderately dysplastic and severely dysplastic by an experienced cytopathologist. The slides were de-stained and subsequently re-stained with Feulgen Thionin-SO2 stain. Images of the nuclei were then captured, recorded and processed employing an image cytometry device. Automated classification of the cells was carried out using three different methods--discriminant function analysis, a decision tree classifier and a neutral network classifier. The discriminant function analysis method, which combined all dysplastic cells into an abnormal group, achieved a combined error rate of less than 0.4% for moderate and severe dysplastic cells, and less than 40% for mildly dysplastic cells. All three methods yielded comparable results, which approached those of human performance.

Cell Nucleus↗
PubMed1992

Determination of DNA ploidy in archival tissue from non-Hodgkin's lymphoma using flow and image cytometry.

Paraffin-embedded tissue from a series of 40 cases of diffuse, large cell lymphoma was analyzed by both flow and image cytometry to compare the ability of these techniques to detect DNA aneuploid populations. Image cytometry (ICM) was performed both on nuclear suspensions and tissue sections. Twenty cases (50%) were non-diploid by at least one method of analysis. Twenty-five percent of the cases were aneuploid by flow cytometry (FCM) alone. The majority of these cases were near-diploid tumors which could not be resolved by ICM. Peri-tetraploid peaks were identified by ICM of tissue sections alone in 15% of the cases. There was an apparent loss of these peri-tetraploid cells during the preparation of the nuclear suspensions. The remaining cases showed a good correlation between all three methods in the determination of DNA ploidy. Flow and image cytometry are complimentary techniques when applied to archival tissue, however aneuploid populations may be missed if ICM is not performed on tissue sections.

Aneuploidy↗
PubMed1991

Autofluorescence of normal and malignant bronchial tissue.

In vivo autofluorescence spectra were obtained in 5 patients with carcinoma in situ, 26 patients with invasive tumors, and 1 patient with severe dysplasia. Significant spectral differences were observed between pre-cancerous, cancerous, and normal bronchial tissues. This difference may afford a method to image and/or detect early lung cancer by using tissue autofluorescence alone.

Bronchi↗
PubMed1991

Computer automation in measurement and analysis of cell motility in vitro.

The application of computerized techniques to the study of cell motility has allowed direct examination and quantitation of individual cell movement and morphology. This has stimulated interest in theoretical models of cell motility, and has prompted the need for increasingly sophisticated approaches to analyze and present cell motility data. In this article we review some of the microscope systems currently used to study cell motility, and give more details on such a system developed in our own laboratory, the DMIPS Cell Analyzer. Brief examples of its application to the field of cell motility are provided. Some areas of further research in the field of automated microscopy are also discussed.

Animals↗