Search PubMed⌕ Search

Biomedical subjects

E Burke

Publications and source records attributed to E Burke.

At least 55 records · Page 3Linked to original sources
PubMed1988

On-line sample cleanup in the liquid chromatographic analysis of pharmaceuticals for citrate content.

Matrix interferents are removed from pharmaceutical samples via an on-line, automated column switching process in which the difference in hydrophobicity between the analyte and the interferents allows these species to be isolated in different parts of the chromatographic system. In this case, the interferents are trapped on a cleanup column and are flushed to waste as the analyte undergoes additional separation on an analytical column. The utility of this approach is demonstrated by the quantitation of citrate in pharmaceutical samples by ion suppression, reversed-phase liquid chromatography. The performance of this system is statistically equivalent to that of a manual pretreatment method employing disposable, solid-phase extraction cartridges.

Chromatography, Liquid↗
PubMed1987

Tubular lysosomes accompany stimulated pinocytosis in macrophages.

A network of tubular lysosomes extends through the cytoplasm of J774.2 macrophages and phorbol ester-treated mouse peritoneal macrophages. The presence of this network is dependent upon the integrity of cytoplasmic microtubules and correlates with high cellular rates of accumulation of Lucifer Yellow (LY), a marker of fluid phase pinocytosis. We tested the hypothesis that the efficiency of LY transfer between the pinosomal and lysosomal compartments is increased in the presence of tubular lysosomes by asking how conditions that deplete the tubular lysosome network affect pinocytic accumulation of LY. Tubular lysosomes were disassembled in cells treated with microtubule-depolymerizing drugs or in cells that had phagocytosed latex beads. In unstimulated peritoneal macrophages, which normally contain few tubular lysosomes and which exhibit relatively inefficient transfer of pinocytosed LY to lysosomes, such treatments had little effect on pinocytosis. However, in J774 macrophages and phorbol ester-stimulated peritoneal macrophages, these treatments markedly reduced the efficiency of pinocytic accumulation of LY. We conclude that a basal level of solute accumulation via pinocytosis proceeds independently of the tubular lysosomes, and that an extended tubular lysosomal network contributes to the elevated rates of solute accumulation that accompany macrophage stimulation. Moreover, we suggest that the transformed mouse macrophage cell line J774 exhibits this stimulated pinocytosis constitutively.

Animals↗
PubMed1986

Effect of alterations in the size of the vacuolar compartment on pinocytosis in J774.2 macrophages.

J774.2 macrophages cultured in medium containing 10 mg/ml sucrose accumulate the sugar by pinocytosis and become highly vacuolated, due to the sugar's osmotic effect within the vacuolar compartment. When such cells are incubated in medium containing 0.5 mg/ml invertase, the enzyme reaches the sucrose vacuoles by pinocytosis, then cleaves the sugar to more permeant monosaccharides. Within 4 hours, the vacuoles shrink to smaller, phase-dense organelles (Cohn and Ehrenreich, 1969, J. Exp. Med., 129:201). We have used this reversible expansion of the lysosomal compartment to address two questions: (1) Does the increased size of the lysosomal compartment affect pinocytic accumulation of solute, and (2) what is the fate of the vacuolar membrane and its soluble content during invertase-induced vacuole shrinkage? Using lucifer yellow (LY) as a probe for pinocytic fluid influx and efflux, we found that vacuolated cells accumulated 30-50% less LY than controls and returned to higher rates of pinocytosis after invertase-induced vacuole shrinkage. A similar reduction in LY accumulation was achieved after feeding cells latex beads to increase the size of the lysosomal compartment. Thus, treatments that increased the size of the lysosomal compartment reduced solute accumulation via pinocytosis. A dramatic shrinkage of LY-containing sucrose vacuoles followed pinocytosis of invertase. Despite this reduction in size of the LY-containing vacuoles, the overall rate of LY efflux did not increase significantly during invertase-induced vacuole collapse. Electron microscopy revealed that during shrinkage, the excess vacuolar membrane was compressed into whorled membranous organelles (residual bodies), with fluid markers (colloidal gold and, by inference, LY) trapped inside. The trapping of LY inside lysosomes as J774.2 macrophages returned to their normal dimensions indicates that nearly all of the surplus membrane contents were removed from circulation as well.

Cells, Cultured↗
PubMed1983

Dry bed training without a urine alarm: lack of effect of setting and therapist contact with child.

Three variations in the mode of delivery of Dry Bed Training as a treatment for nocturnal enuresis were investigated. Twenty-three children, ranging in age from 4 to 14, received dry bed training without the additional use of a urine alarm. Treatment variations included: (a) in-home training of parents and child, (b) office based training of parents and child, and (c) office based training of parents only. An additional 7 children served as a waiting list control during the first 8 weeks of the study. A wide variety of outcome measures showed improvement for the entire sample regardless of specific mode of delivery. Implications for the treatment of enuresis using dry bed training and a number of critical methodological issues are discussed.

Adolescent↗
PubMed1983

Laser trabeculoplasty in the pseudo-exfoliation syndrome.

Because of the high incidence of pseudo-exfoliation in Ireland and because of the difficult problem this group poses regarding control it was decided to treat a group of these patients with the Argon Laser. This paper is a preliminary report of our experience.

Glaucoma↗
PubMed1981

Alternatives in the handling, processing and storage of electrocardiograms.

Physicians and administrators are becoming aware that computer technology can play a significant role in the electrocardiology department. Problems related to the large number of requests for electrocardiograms, the production and communication of electrocardiographic tracings and reports, the access to stored tracings and the overall cost of providing effective services have led administrators to look for assistance through automation. Before expensive equipment and new procedures are introduced, a survey of the electrocardiology department's functions and procedures can lead to important insights. Automation can be achieved in stages, and problems can be solved by separate steps. Options range from basic word-processing support to completely automated electrocardiographic interpretation and computerized storage of records. Choosing the appropriate equipment and programs requires knowledge of the present system, awareness of the options and analysis of the costs and savings.

Computers↗