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Biomedical subjects

J R Barry

Publications and source records attributed to J R Barry.

18 recordsLinked to original sources
PubMed1998

Chondrogenesis in a cell-polymer-bioreactor system.

Chondrogenesis was studied under controlled in vitro conditions using a cell-polymer-bioreactor system. Bovine calf articular chondrocytes were seeded onto biodegradable polymer scaffolds and cultured in rotating bioreactor vessels. Concomitant increases in the amounts of glycosaminoglycan (GAG) and type II collagen resulted in cell-polymer constructs with continuous cartilaginous matrix over their entire cross sections (6.7 mm diameter x 5 mm thick) after 40 days of cultivation. As compared to natural calf cartilage, constructs had comparable cellularities, 68% as much GAG and 33% as much type II collagen per gram wet weight. The progression of chondrogenesis in chondrocyte-polymer constructs was similar to that suggested previously for precursor cells in vitro and developing limbs in vivo. In particular, the polymer scaffold provided a three-dimensional structure that could be seeded with chondrocytes at high cell densities in order to establish cell-to-cell contacts and initiate cartilage tissue development, whereas the bioreactor vessel provided a permissive microenvironment for chondrogenesis. This work demonstrates the promise of using tissue engineered constructs for in vitro studies of cell interactions and differentiation.

Animals↗
PubMed1998

Five-minute removal of soft lenses prevents most absorption of a topical ophthalmic solution.

PURPOSE: Patients who use topical ophthalmic medications and wear soft contact lenses must remove their lenses before drop instillation to prevent absorption of the medication into the lenses. No previous study has examined how long such a patient should wait before reinserting their lenses. This study was designed to test the hypothesis that waiting 5 minutes before reinsertion of lenses would be sufficient to reduce absorption to a level below what is needed to produce a physiological response. METHODS: Naphcon-A was used as the test solution and pupillary dilation was the physiological response measured. The amount of benzalkonium chloride (BAC) extracted from the lenses was also measured. Twenty-three subjects, none of whom had any significant ocular or systemic abnormalities nor showed pupillary dilation to directly applied Naphcon-A, completed this 3-week study. The study used a 2-period crossover design with a 1-week screening phase. Results were analyzed with a repeated-measure analysis of variance. RESULTS: The pupils averaged 0.316 mm larger when subjects instilled Naphcon-A with lenses in place as compared to when dosing with lenses removed for 5 minutes (P = 0.0008). Nine of 23 subjects showed pupillary dilation greater than 0.5 mm when dosing with lenses in place as compared to none when lenses were removed for 5 minutes. Significantly (P < 0.01) more BAC was extracted from lenses that had been worn during dosing than from lenses removed for 5 minutes (0.9 microgram/lens as compared to no detectible amount). CONCLUSION: Removing soft contact lenses for 5 minutes was sufficient to prevent absorption of clinically significant amounts of Naphcon-A into the lenses.

Absorption↗
PubMed1991

Cognitive advantage in sport: the nature of perceptual structures.

To extend and clarify the nature of the perceptual processes used by sport experts to perceive schematic sport information, two experiments used schematic football diagrams that varied in structure (structured vs. unstructured) and complexity (complex vs. easy). The primary objective was to examine and characterize the nature of the perceptual structures (chunks) that are initially encoded, stored, and subsequently retrieved. In Experiment 1, compared with nonexperts, experts recalled larger perceptual structures following the initial stimulus presentation of structured stimuli only, replicating the recall findings of previous research in other skill domains. Experiment 2 used a long-term memory recognition task and a sorting task. Experts had superior recall and recognition of structured stimuli only, along with more discriminating sorting criteria of perceptual structures within long-term memory. This suggests that experts possess a highly refined semantic network or organized, structured schematic information. This research extends and clarifies the similarities between the perceptual processes of experts in sport (i.e., football) and experts in skill domains that require obvious cognitive involvement (i.e., chess). The results are discussed with reference to the perceptual and conceptual chunking hypotheses. It is proposed that sport experts' knowledge of a conceptual category enables them to retrieve elements using a "generate-and-test process."

Attention↗
PubMed1990

Sport expertise: the cognitive advantage.

The purpose of this article is to illustrate the significance of the cognitive system in sport expertise. Consideration of visual-perceptual abilities, along with cognitive factors and their relationship with sport expertise, suggest that level of sport performance can be reliably differentiated on several cognitive dimensions. Information is given concerning the cognitive requirements of sports skills. It is argued that although visual-perceptual abilities are inherent in all levels of sport performance, cognitive factors are essential for sport expertise.

Cognition↗
PubMed1990

Endosomes can undergo an ATP-dependent density increase in the absence of dense lysosomes.

On the basis of evidence that lysosomal enzymes and membrane proteins are present in endosomes, we have previously suggested that the production of lysosomes involves maturation rather than vesicle fusion (Roederer, M., R. Bowser, R. F. Murphy, J. Cell. Physiol. 131, 200-209 (1987)). Since the appearance of endocytosed material in lysosomes is associated with an increase in buoyant density from that of endosomes, a prediction of the model is that endosomes should be capable of undergoing such an increase in vitro. We observe that under appropriate conditions, isolated endosomes containing [125I]EGF can undergo an increase in density in vitro to that of dense lysosomes, mimicking the density change which occurs in vivo. This occurs in the absence of dense lysosomes with which to fuse. The density increase requires ATP and can be efficiently inhibited in vitro by the presence of benzylamine, suggesting that vesicular acidification is required. Since low pH has previously been shown to induce formation of a matrix by lysosomal enzymes in vitro (Buckmaster, M. J., A. L. Ferris, B. Storrie, Biochem. J. 249, 921-923 (1988)), we propose that a mechanism by which endosomes and/or lysosomes increase their density is a low pH induced aggregation of vesicle contents which decreases the osmotic pressure inside the vesicle. Together with previous data, the results provide highly suggestive evidence that the pathway to lysosomes includes a maturation of the postsorting compartment into what has classically been termed a lysosome.

Adenosine Triphosphate↗
PubMed1978

A categorization system of crisis center telephone use: patterns of interaction.

Current investigations of telephone crisis intervention effectiveness have neglected the evaluation of broad patterns of interaction between the crisis center and the larger community. This study describes the development and implementation of a Caller Frequency Category System (CAFS) which is based upon the frequency and type of contacts between callers and the center. Data collected for 100 clients from a crisis intervention center suggest that the system can be applied reliably and does differentiate among clients by the type of interaction they have with the center. Two unexpected findings were that (a) longer-term callers tended to be older men or teenage girls, and (b) the greatest proportion of total telephone use involved calls initiated by the center itself to people other than crisis clients. Revisions to the CAFS are proposed which will clarify the role which a crisis center serves in the community-wide resolution of personal crises.

Community-Institutional Relations↗
PubMed1978

Problem-solving as a function of age, sex and the role appropriateness of the problem content.

The purpose of this study was to investigate problem-solving ability as a function of age, sex and problem content by using 20 problems chosen from the problem-solving literature. The problems were administered without time limits to 8 males and 8 females in each of three age groups: 20--30, 40--50, 60--70. Analysis revealed that only age influenced performance with the middle-age group scoring significantly higher than the other groups. Analysis of the time required by each age group to solve the problems showed the young group required significantly less time than the other groups. Finally, the young group was seen to make more errors of commission while the older group made more errors of omission.

Adult↗