Phospholipase-C sensitive GPI-anchored proteins of goat sperm: possible role in sperm protection.

The role of glycosylphosphatidylinositol (GPI)-anchored sperm proteins in reproduction has been investigated. SDS-polyacrylamide gels (PAGE) analysis of goat sperm (Capra indica) indicated that several GPI-anchored proteins were released by phosphatidylinositol-specific phospholipase-C (PI-PLC) treatment. The distribution of this category of PI-PLC-sensitive GPI-anchored proteins on the surface of sperm was examined by indirect immunofluorescence. The fluorescence microscopic study clearly demonstrated that the PI-PLC-sensitive GPI-anchored proteins are confined predominantly to the head region of goat sperm. Further experiments were conducted on intact and PI-PLC treated sperm in order to decipher the function of GPI proteins. Co-incubation of sperm with peritoneal macrophages led to the enhanced phagocytosis of PI-PLC treated sperm by macrophages compared with the untreated intact sperm. Transmission electron micrographs of the macrophages acquired from the phagocytosis assay are provided to corroborate the same. From the results obtained it is inferred that one or more of the PI-PLC-sensitive GPI-anchored proteins on the sperm surface could act as protection factor(s) that shield the sperm from macrophages.

Unobtrusive evaluation of mammographer's eye movements during diagnosis of mammograms.

The authors sought to evaluate the visual search patterns of mammographers to better understand the process by which a diagnosis is reached when mammographic images are viewed. An unobtrusive gaze tracking system was applied to track gaze direction and pupil size. Data were collected at 60 Hz and analyzed to evaluate how visual search patterns (location and duration of gaze dwells and pupil size changes) altered when mammograms were repeatedly displayed. Two tests were performed. In the first test, a mammographer was shown the same mammogram on two occasions, separated by a 1-year interval. The second test evaluated the visual search patterns of four mammographers during a 30-minute display period, in which four mammograms were shown a variable number of times. Analysis of the gaze dwell data demonstrated that, although general recognition of a mammogram can occur within 1 second, even though 1 year separated the two occasions when the image was shown, repeated display of a mammogram may result in changes in (a) the time taken to reach a diagnosis, (b) the length of gaze dwell, (c) the total number of correct and incorrect diagnoses, and (d) pupillary constriction. Results from these tests may yield important information about how mammographers view images and how this process can affect diagnostic accuracy.

Unobtrusively tracking eye gaze direction and pupil diameter of mammographers.

RATIONALE AND OBJECTIVES: The visual process that radiologists use for diagnosis is incompletely understood. This study developed techniques to unobtrusively track direction and pupil diameter of radiologists reading a wide variety of films. We evaluated the eye gaze patterns of mammographic experts to gain knowledge that might improve the rate of early detection of breast cancer. METHODS: A video camera with a near-infrared light filter is pointed at the mammographic expert who is reading mammograms. The video images are analyzed in real time on a personal computer to detect eye gaze direction and pupil diameter. Two separate trials were used: 1) to demonstrate the system's speed and ability to work with mammograms (a brief test with one mammographer was used) and 2) four mammographic experts evaluated 14 mammograms. RESULTS: In the first trial, the system successfully tracked the eye gaze of a mammographer who quickly recognized the patient case, with the pupil diameter briefly increasing 40%, and then the gaze direction dwelling in an area of microcalcifications. In the second trial, 66% of the false-positive results for films with masses were associated with long eye gaze dwells, whereas 33% of the prolonged dwells for films with microcalcifications were associated with true-positive diagnoses. CONCLUSIONS: This near-infrared light system successfully tracked the eye gaze direction and pupil diameter of mammographic experts evaluating films. The association of long eye gaze dwells with diagnostic accuracy varied with the type of object being viewed. In films with masses, false-positive diagnoses were associated with long dwells. In films with microcalcifications, true-positive diagnoses were associated with long dwells.

Instrumentation for direct observation of frozen hydrated specimens in the electron microscope.

Instrumentation and techniques are described for the transfer and observation of frozen hydrated specimens in the transmission electron microscope. The transfer is accomplished without the complexity of a vacuum transfer device but also without significant sublimation of specimen ice or frosting. Examples are given of the transfer and observation of thin sections of rapidly frozen muscle and of rapidly frozen thin film preparations of isolated cells.