Innate resistance to Listeria monocytogenes in tumor-bearing mice.

We have previously described the isolation, cloning, and characterization of a tumorigenic murine fibrosarcoma, designated JBS. Growth of JBS tumors in syngeneic mice initiates an anti-tumor immune response that initially manifests as progressive splenic hyperplasia and an increased proliferative ability in cultured splenocytes. In animals with tumors progressing beyond the 2 cm stage there is a reduction in spleen size and a gradual decrease in splenocyte proliferative abilities, leading to anergy at heavy tumor burdens (>3.5 cm). During the phase of immune hyperresponsiveness in tumor-bearing mice clearance of Listeria monocytogenes by components of the innate immune system is increased. This heightened resistance to infection is most likely macrophage-mediated because these mice demonstrate an increased ability to recruit macrophages to the peritoneal cavity during Listeria infection. In addition, these macrophages are highly activated in vivo as evidenced by an elevated capacity to express class II MHC (Ia) molecules. This increase in macrophage activation status is coincident with an increased capacity of splenocytes from tumor-bearing mice to secrete IFN-gamma. In mice with much heavier tumor burdens (>3.5 cm), down-regulation of the immune response leads to a reduction in peritoneal macrophage numbers, decreased macrophage Ia expression, and diminished splenic clearance of L. monocytogenes. Our data demonstrate that activation of macrophages distal to the tumor site occurs as an initial consequence of tumor growth. It is only in mice with very heavy tumor burdens that functionality of macrophages is sufficiently suppressed to allow increased splenic growth of L. monocytogenes.

Chronic estrogen treatment in male rats reveals mammosomatotropes and allows inhibition of prolactin secretion by somatostatin.

Previous in vivo studies demonstrated that estrogen treatment of male rats allows somatostatin (SRIF) to inhibit PRL release. The objective of this study was to determine whether chronic estrogen (E2) treatment of male rats can induce the conversion of somatotropes to mammosomatotropes. In situ hybridization and reverse hemolytic plaque assay were used to evaluate the effects of E2 treatment on GH and PRL messenger RNA (mRNA) content and hormone secretion in individual pituitary cells. Male rats were implanted for 2-6 weeks with placebo or estradiol-containing pellets (5mg/90-day release). Pituitaries were removed and prepared for reverse haemolytic plaque assay to determine PRL and GH secretion. This was followed by in situ hybridization using 35S-labeled riboprobes for PRL and GH mRNA. Chronic E2 treatment increased both the percentage of pituitary cells that secreted PRL and the amount of PRL secreted per cell. Concomitantly, there was a decrease in both the percentage of GH-secreting cells and that amount of GH secreted per cell. In situ hybridization demonstrated that E2 treatment increased PRL mRNA while decreasing GH mRNA in single pituitary cells. Significantly, in control male rat pituitary cell cultures, no PRL-secreting cells were positive for GH mRNA. In contrast, after chronic E2 treatment, 10% of PRL-secreting cells contained GH mRNA. In the control pituitary cell cultures, SRIF had no effect on PRL release, but SRIF significantly inhibited PRL release from pituitary cell cultures prepared from E2-treated male rats. These studies demonstrate that the adult pituitary preserves plasticity and, under the appropriate steroid milieu, allows conversion of somatotropes to mammosomatotropes.

Relactation by mothers of sick and premature infants.

Relactation, the induction of lactation at any time beyond the immediate postpartum period, has received minimal scientific investigation. In this study, one adoptive mother and six mothers ten to 150 days postpartum, who for a variety of reasons did not initiate or maintain lactation after delivery, attempted relactation. Each suckled her infant at regular feeding intervals. Prior to milk production, formula was provided during suckling through an artificial device. Serum prolactin responses to thyrotropin-releasing hormone infusion and to suckling were measured at the start of the study and to suckling at approximately weekly intervals thereafter. All mothers produced milk; three completely nourished their infants and two others provided at least half of their infants' nutritional needs. The adoptive mother and one other failed to provide significant quantities of milk. Mothers reached their maximum potential for milk production in varying periods of time (eight to 58 days). Shorter postpartum interval and less postpartum breast involution correlated with the likelihood of successful relactation and the rapidity of the onset of lactation. Basal prolactin levels and stimulation tests were of no additional predictive value. Each mother, regardless of milk production, expressed positive feelings about nurturing her infants in this manner. We conclude that relactation frequently is possible and may offer the mother of a sick or premature infant who desires to breast-feed an alternative if she does not maintain lactation in the immediate postpartum period.

Contrast-detail detectability analysis: comparison of a digital spot mammography system and an analog screen-film mammography system.

RATIONALE AND OBJECTIVES: The authors compared the contrast-detail detectability properties of an optically coupled charge-coupled device (CCD) digital mammography system with those of a conventional analog screen-film mammography system. METHODS: A proprietary contrast-detail phantom was imaged with both systems. Twelve observers viewed analog and digital images obtained at seven different mean glandular doses. Contrast-detail-dose curves were generated on the basis of the readers' visual perceptions. Interobserver errors were also calculated. In addition, the authors applied a theoretical model for lesion detectability to calculate and compare the digital and analog mammography systems. RESULTS: The readers' contrast-detail detectability was significantly superior with the digital system in the detail and contrast ranges evaluated (P < .001). CONCLUSION: The performance of the readers paralleled the performance predicted by the theoretical model for the two imaging systems. The following features account for the superior performance of the digital mammography system: (a) higher quantum efficiency of the phosphor, (b) wider dynamic range, (c) better contrast transfer characteristics, and, most important, (d) greater photon flux at the phosphor entrance.

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.

High- versus low-top shoes for the prevention of ankle sprains in basketball players. A prospective randomized study.

Using a prospective, randomized experimental design, 622 college intramural basketball players were stratified by a previous history of ankle sprains to wear a new pair of either high-top, high-top with inflatable air chambers, or low-top basketball shoes during all games for a complete season. Subjects were asked to complete a history questionnaire and were given a complete ankle examination. They were allowed to wear these shoes only during basketball competition. Followed over the course of a 2-month intramural season, 15 ankle injuries occurred during 39,302 minutes of player-time: 7 in high-top shoes, 4 in low-top shoes, and 4 in high-top shoes with inflatable air chambers. The injury rates (injuries per player-minute) were 4.80 x 10(-4) in high-top shoes, 4.06 x 10(-4) in low-top shoes, and 2.69 x 10(-4) in high-top shoes with inflatable air chambers. There was no significant difference among these 3 groups, leading to the conclusion that there is no strong relationship between shoe type and ankle sprains.

Neutron radiography inspection of investment castings.

Investment casting, also known as the lost wax process, is a manufacturing method employed to produce near net shape metal articles. Traditionally, investment casting has been used to produce structural titanium castings for aero-engine applications with wall thickness less than 1 in (2.54 cm). Recently, airframe manufacturers have been exploring the use of titanium investment casting to replace components traditionally produced from forgings. Use of titanium investment castings for these applications reduces weight, cost, lead time, and part count. Recently, the investment casting process has been selected to produce fracture critical structural titanium airframe components. These airframe components have pushed the traditional inspection techniques to their physical limits due to cross sections on the order of 3 in (7.6 cm). To overcome these inspection limitations, a process incorporating neutron radiography (n-ray) has been developed. In this process, the facecoat of the investment casting mold material contains a cocalcined mixture of yttrium oxide and gadolinium oxide. The presence of the gadolinium oxide, allows for neutron radiographic imaging (and eventual removal and repair) of mold facecoat inclusions that remain within these thick cross sectional castings. Probability of detection (POD) studies have shown a 3 x improvement of detecting a 0.050 x 0.007 in2 (1.270 x 0.178 mm2) inclusion of this cocalcined material using n-ray techniques when compared to the POD using traditional X-ray techniques. Further, it has been shown that this n-ray compatible mold facecoat material produces titanium castings of equal metallurgical quality when compared to the traditional materials. Since investment castings can be very large and heavy, the neutron radiography facilities at the University of California, Davis McClellan Nuclear Radiation Center (UCD/MNRC) were used to develop the inspection techniques. The UCD/MNRC has very unique facilities that can handle large parts up to 39 ft (12 m) in length and 13 ft (4 m) high weighing up to 5000 lbs (2300 kg). These handling systems are robotically driven. The neutron radiographic system consists of a highly thermalized neutron beam. The neutron beam has an intensity of 5.6 x 10(6) n/cm2 s, with a L/D = 200 at a power of 2 MW. A divergent beam collimator is used which provides a beam of approximately 22 in (56 cm) in diameter at the film plane. A vacuum cassette with a gadolinium vapor deposited screen is used to collect the image. Exposure times can be as short as 3 min, or up to 30 min.

Health Heritage© a web-based tool for the collection and assessment of family health history: initial user experience and analytic validity.

A detailed family health history is currently the most potentially useful tool for diagnosis and risk assessment in clinical genetics. We developed and evaluated the usability and analytic validity of a patient-driven web-based family health history collection and analysis tool. Health Heritage(©) guides users through the collection of their family health history by relative, generates a pedigree, completes risk assessment, stratification, and recommendations for 89 conditions. We compared the performance of Health Heritage to that of Usual Care using a nonrandomized cohort trial of 109 volunteers. We contrasted the completeness and sensitivity of family health history collection and risk assessments derived from Health Heritage and Usual Care to those obtained by genetic counselors and genetic assessment teams. Nearly half (42%) of the Health Heritage participants reported discovery of health risks; 63% found the information easy to understand and 56% indicated it would change their health behavior. Health Heritage consistently outperformed Usual Care in the completeness and accuracy of family health history collection, identifying 60% of the elevated risk conditions specified by the genetic team versus 24% identified by Usual Care. Health Heritage also had greater sensitivity than Usual Care when comparing the identification of risks. These results suggest a strong role for automated family health history collection and risk assessment and underscore the potential of these data to serve as the foundation for comprehensive, cost-effective personalized genomic medicine.

Eye movements can control localized image enhancement and analysis.

The eye movements of a reader during interpretation of digital chest radiographs can provide valuable information for lesion detection. Measures of eye movements (e.g., the locations and durations of gaze dwells) are associated with detection accuracy. During image interpretation, the reader's eye movements are tracked unobtrusively with a video camera mounted below the monitor displaying the images. The eye movement information is used to identify regions of prolonged dwell, which are associated with false-positive detection of pulmonary nodules. Based on the locations of the dwell regions, a small, circular region of interest is created within the image. Real-time digital processing can then be performed within this region of interest. Such processing can be performed as the reader is looking at the image or after the image has been interpreted. Readers' eye movements can be used to direct localized image enhancement and analysis during interpretation of digital chest radiographs.