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Biomedical subjects

M C Habbersett

Publications and source records attributed to M C Habbersett.

8 recordsLinked to original sources
PubMed1984

Eimeria tenella: in vitro development in irradiated bovine kidney cells.

The initial infection and first-generation development of Eimeria tenella was quantified using a cloned MDBK (Madin-Darby Bovine Kidney) cell line, irradiated with gamma radiation prior to infection, as the host cell. Irradiated cell cultures were found to be more susceptible to infection and had a greater capacity to support parasite development than non-irradiated cultures. It was suggested that the larger proportion of cells in the G2 phase of the cell cycle, the larger individual cell size and the inhibition of cell division in the irradiated cultures were all factors contributing to the increased susceptibility to infection and capacity to support parasite growth and development. The application of this technique (host cell irradiation) to the cultivation of other intracellular, protozoan parasites is discussed.

Animals↗
PubMed1983

Trypanosoma cruzi: efficacy of the 2-substituted, 5-nitroimidazoles, MK-436 and L634,549, in tissue culture and mice.

Experimental studies were undertaken in tissue culture and mice infected with a cloned derivative of Trypanosoma cruzi, Y strain to determine the efficacy of two 2-substituted 5-nitroimidazole compounds, MK-436 and L634,549. The use of an X-irradiated myoblast culture system proved better than a conventional fibroblast culture for assaying the activity of compounds against intracellular parasite stages. MK-436 showed activity against amastigotes at a level of 25 micrograms/ml and L634,549 a dihydroxy metabolite of MK-436 showed activity 2 micrograms/ml. Neither compound caused morphological damage to the host cells at levels tested (250 micrograms/ml). By contrast, nifurtimox, which was active at 2 micrograms/ml, caused significant host cell damage at 100 micrograms/ml. In mice, studies in the chronic infection showed that MK-436 was curative at a level of 30 mg/kg if given daily for 20 days. Neither nifurtimox nor benznidazole were fully curative when given at a level of 100 mg/kg daily for 20 days. These studies showed that administration of MK-436 with a suitable solvent, PEG 400, enhanced its efficacy fourfold, and that efficacy was also enhanced by increasing the treatment interval. Since MK-436 showed better efficacy in chronic rodent infections than either nifurtimox or benznidazole, such compounds should be evaluated for efficacy in human Chagas' disease.

Animals↗
PubMed1981

Classification of gynecologic flow cytometry data: a comparison of methods.

Several discriminant function methods for automatically classifying flow cytometry data from human cervical material were developed and compared with previously published methods using a sample of 186 specimens. The misclassification rates (approximately 20%) were similar to those of other published techniques for classifying these data. The methods misclassify different cases, however. The apparent system performance appears to be limited by at least three factors: (1) use of too small a sample in constructing classification algorithms, (2) poor "visibility" of small numbers of abnormal cells in the flow histograms and (3) incorrect or inconsistent visual classification of the samples used to construct the classification algorithms. The third factor results in erroneously high estimates of the misclassification rate. Even so, the overall system performance appears to be comparable to that of many cytotechnologists.

Cervix Uteri↗
PubMed1980

Flow microfluorometric analysis of cellular DNA: Critical comparison of mithramycin and propidium iodide.

Mithramycin and propidium iodide were used to stain HeLa cells, human lymphoma cells, and phytohemagglutinin-stimulated lymphocytes for flow microfluorometric analysis of cellular DNA. The stains provided similar estimates for the proliferative fraction of the populations. However, significant differences in the relative fluorescent intensity were demonstrated in the three cell populations. Fluorescent intensity of HeLa and lymphoma cells stained with mithramycin was higher than matched propidium iodide-stained cells. Normal lymphocytes showed greater fluorescent intensity when stained with propidium iodide. Differences in the staining behavior of these two dyes may prove to be highly informative probes of chromatin structural differences.

Animals↗
PubMed1979

Quantitative analysis of flow microfluorometric data for screening gynecologic cytology specimens.

Gynecologic cytology specimens that included the entire spectrum of cervical cytology classification were stained with a combination of propidium iodide and fluorescein isothiocyanate, then analyzed using a flow microfluorometer to measure nucleic acid and protein content, respectively. Numerous descriptors of the resulting two parameter distribution (nucleic acid versus protein) were defined. These descriptors included assessment of the presence or absence of abnormal cells. They also included measures of the staining intensity and dispersion of the normal squamous cell population and the intensity of inflammatory response in the cell population. Relative percentages of inflammatory and epithelial cells were demonstrated to effect the screening performance of this system only in borderline lesions. Decision tree algorithms allowed optimization of the selected parameters for screening logic of normal-abnormal decisions on a specimen-by-specimen basis. In addition, quantitative definitions of specimen adequacy were determined. Appropriate controls for batch staining of specimens were evaluated. These results of applying pattern recognition techniques to flow microfluorometer multiparameter data demonstrate that considerably more information about cell populations and subpopulations can be extracted than heretofore possible.

Adolescent↗
PubMed1978

Drug-induced changes in DNA fluorescence intensity detected by flow microfluorometry and their implications for analysis of DNA content distributions.

Chicken erythrocytes, which contain less DNA than mammalian diploid cells, were used as an internal standard to control instrumental and staining variables during flow microfluorometric analysis. With the DNA stain, mithramycin, and with an EPICS II flow microfluorometer, ratios between the modal G1 fluorescence of experimental cells and that of chicken erythrocytes were determined. The results indicate that unperturbed cell populations of L1210 and HeLa cells in vitro and L1210 ascites cells in vivo have relatively stable fluorescence ratios, although there is a significant difference between the ratios of one L1210 cell line in vitro and another in vivo. In contrast, L1210 ascites treated in vivo with different schedules of cyclophosphamide and Adriamycin showed wide fluctuations in the fluorescence intensity ratios for 96 hr after treatment. Also, differences in the fluorescence ratios were observed between less advanced and more advanced L1210 ascites after treatment with the same schedule. These effects indicate an alteration in DNA staining with mithramycin, brought about by drug treatment that could seriously affect the interpretation of DNA histogram data. Nevertheless, changes in mithramycin staining may prove to be a very important probe to detect persistent drug effects.

Animals↗
PubMedDate not supplied

A pattern classification system for automated cervical cytologic screening based on flow microfluorometric analysis.

A data analytic technique is described for use in automated cervical cytology. The method entails the application of a two-dimensional Fourier transform to histogram data obtained by flow microfluorometry and the subsequent use of the Fourier coefficients as parameters for pattern classification. Analyses were performed on 186 samples including material from 62 positive and 124 negative cases. Cell suspensions were stained with propidium iodide and fluorescein isothiocyanate, and red and green cytofluoresence were measured simultaneously. The two-dimensional histogram data were normalized, the Fourier transform was applied, and a multivariate classifier based on 30 coefficients was assembled using a training set of half the original series. Performance was then assessed on the remaining cases. Overall accuracy was 79.6%, with a false-positive rate of 14.8% and a false-negative rate of 31.2%. The potential applicability of this approach as the basis of a practical screening system is discussed.

Adolescent↗