Biomedical subjects

T T DeVaney

Publications and source records attributed to T T DeVaney.

4 recordsLinked to original sources

PubMed2001

Fractal dimension of K1735 mouse melanoma clones and spheroid invasion in vitro.

An in vitro tumour-host confrontation method to investigate the invasion behaviour of cancer has been applied to K1735 mouse melanomas. Fluorescently labelled spheroids of cancer cells and host cells were confronted and the temporal course of cancer invasion into the host was investigated using confocal laser scanning microscopy. To improve the quantitative data of this method, the boundary images of the fluorescently labelled confrontation pairs were treated as fractals. The physical and mathematical framework for determination of the fractal capacity dimension is widely used in biology and medicine and has proved to be a very useful tool for describing the cancer invasion process. The fractal capacity dimension determination was carried out by dilation of the binary boundaries of the objects, which were treated as an estimate of the Minkowski-Bouligand dimension. The fractal dimension correlated well with the degree of invasion of the K1735-M2 clone. Control experiments, with host-host confrontations and various K1735 clones with reduced invasiveness, support these results.

Animals↗

PubMed2001

[Technical errors in the application of Graf's hip sonography method].

AIM: The aim of the study is to point out possible examination errors because of a titled transducer, and to analyse their sources. METHODS: The results obtained by experienced examiners using the correct examination technique were compared to results obtained under defined deviations from the standard. With the use of a computer model the course taken by the ultrasound waves in the neonatal hip was simulated and the sonographic image reconstructed. RESULTS: Twisted as well as tilted positions of the transducer lead to significant errors in alpha, the acetabular roof angle. This is in accordance with the computer model predictions. Caudo-cranially tilted probes lead to false-positive, therapeutically relevant incorrect diagnoses. CONCLUSION: The computer simulation predicts a high degree of accuracy of hip sonography in Graf's technique under standard conditions. The effectiveness of sonographic infant hip screening largely depends on the ability to adhere to the standardized approach, minimizing possible errors. A mechanical transducer guide prevents tilting errors by reducing the degrees of variability in positioning the transducer.

Artifacts↗

PubMed2001

Carcinoma of the larynx: predictors of diagnostic delay.

OBJECTIVES: In tumors of the upper aerodigestive tract a dose-response relationship between tumor stage and its prognosis raises the chance of a reduction in the diagnostic delay. The interval between the first symptom and the start of tumor-specific therapy and the influencing factors is not well known. The goals of this study were to investigate the diagnostic delay and the influencing factors and to predict the factors that prolong the diagnostic process. STUDY DESIGN: Prospective, nonrandomized study. METHODS: The intervals between first symptom and first consultation of a physician (patient delay) and between first consultation and first tumor-specific therapy (doctor delay) were investigated. Predictors for increased patient or doctor delay were evaluated, and a multiple logistic regression model for increased doctor delay was developed. RESULTS: The total diagnostic delay (sum of patient and doctor delays) was 3 to 4 months. A multifactorial model for the ratio of odds revealed that for women and glottic cancers (1.73) the chance was twice as high for a doctor delay greater than 30 days, whereas subjects with an increased patient delay (>30 d) had reduced odds of being delayed by the physician. CONCLUSIONS: The higher chance of extended doctor delay for glottic tumors compared with supraglottic tumors should be reflected in differential therapeutic strategies. Even unspecific lesions of the vocal folds should be followed up at the end of the therapy, at least. Therapies of glottic lesions without final control have the chance of resulting in delays in treatment. Women, especially, should be included in a follow-up examination. On the other hand, patients with increased patient delay have lower odds of longer doctor delay, which may be the result of tumor growth and, consequently, easier diagnosis.

Carcinoma, Squamous Cell↗

PubMed1999

Cross-talk reduction in confocal images of dual fluorescence labelled cell spheroids.

Dual fluorescence labelling is an advanced method to separate two individual specimens in a biological system using confocal microscopy. An inherent problem of this method is fluorescence channel cross-talk, which causes problems for the exact spatial determination and separation of the specimens. Using a parallel fluorescence detection and an image processing technique, based on an image subtraction method, we have developed a very straight forward method for correcting the dual channel fluorescence images. We successfully applied this method to a 3-dimensional cancer spheroid invasion assay and controlled the cross-talk compensation efficiency by a quality parameter.

Animals↗