Biomedical subjects

Jennifer Gillis

Publications and source records attributed to Jennifer Gillis.

3 recordsLinked to original sources

PubMed2002

Measurement of hydrophobic interactions of mammalian cells grown in culture.

An assay was developed to measure the hydrophobic interactions of commonly used mammalian cell lines grown in culture. The assay depends on the loss of cells from an aqueous suspension following vortexing with a hydrophobic oil phase. This allowed the determination of a hydrophobicity index, which was significantly higher for Chinese Hamster Ovary (CHO) cells than either a murine hybridoma (CC9C10) or a myeloma (SP2/0). This suggests that CHO cells may have a higher intrinsic cell surface hydrophobicity. The assay was also used to study the effect of different additives on the hydrophobic interactions of the cells. A dose-dependent effect was shown for the non-ionic surfactant, Pluronic F68, in reducing the hydrophobic interaction of the CHO cells. However, the pattern of the decrease due to Pluronic F68 was different for each cell line. A higher concentration of Pluronic F68 (0.2%) was required to eliminate the hydrophobic interactions of CHO cells compared to either myelomas or hybridomas, where only 0.05% was required to reduce these interactions to a similar level. Several oils were found suitable for this assay although canola oil maximized the sensitivity of the measured changes. The assay may be useful in monitoring changes in the hydrophobic interactions of mammalian cells during growth in bioreactors. This may be important in optimizing the concentration of cell protectants such as Pluronic F68 in agitated cultures.

Animals↗

PubMed2002

Visual search for high-level configural differences as well as low-level critical features is highly efficient early in childhood.

Visual search, or the ability to locate a single target from a field of distractors, is used as a means of assessing the capacity of the visual system with regard to the detection of low-level stimulus dimensions such as color, line orientation, and other specific perceptual features and higher level characteristics such as three-dimensional (3-D) orientation implied by pictorial cues to depth or occlusion. Target-distractor differences of importance to the visual system result in rapid (and possibly preattentive) target location while differences of lesser importance (or differences that are less salient) tend to elicit slower, less efficient search performance (search in this latter case may require attentional resources.) Adult abilities in this type of task have been tested extensively, but comparatively little is known about the development of these abilities. The present investigation was conducted to test, across a range of ages in childhood, the ability to detect visual search targets defined by a low-level critical feature (a texton; B. Julesz, 1981) and by static (pictorial) cues to depth. Children 2 to 9 years of age and adults were tested with each type of target. Previous data from infant studies predicted that the texton-defined differences would elicit highly efficient search performance, and this proved to be the case. When no texton difference was present, however, children's search was highly inefficient. Children between 4 to 9 years of age also proved to be quite efficient at locating a target, differing only by a pictorially rendered 3-D orientation from the distractors, but were much less efficient when the static cues to 3-D orientation were removed. These findings confirm previous reports that the basic processes underlying visual search are functional early in development, but suggest that children's search is less efficient than adult search when attention is required for object localization.

Child↗

PubMed2002

Backpack use in children.

PURPOSE: This article describes backpack use and incidence of back pain in children. METHODS: A convenience sample of 345 children, grades five through eight, served as subjects. A written questionnaire was developed to gather information on demographics, leisure activity level, bag type, locker use, students' perceptions of bag weight and comfort, and students' reports of history of back pain. Scales were provided for students to weigh themselves with and without backpacks. RESULTS: Younger children carried proportionally greater backpack loads. Percentage of body weight by grade was as follows: fifth grade = 19%, sixth grade = 21%, seventh grade = 14%, and eighth grade = 15% body weight. Fifty-five percent of all subjects carried a load greater than 15% of their body weight, and one third of students reported a history of back pain. Percentage of body weight carried, however, was not significantly related to history of back pain. CONCLUSION: Concerns raised by parents and professionals that children are carrying heavy loads are justified; however, the relationship between heavy carrying load and back pain needs further elucidation. Recommendations for physical therapy, backpack safety, and injury prevention are provided.

Journal Article↗