Biomedical subjects
S Cooney
Publications and source records attributed to S Cooney.
Effect of somatic cell count and polymorphonuclear leucocyte content of milk on composition and proteolysis during ripening of Swiss-type cheese.
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A protein farnesyl transferase involved in abscisic acid signal transduction in Arabidopsis.
The hormone abscisic acid (ABA) modulates a variety of developmental processes and responses to environmental stress in higher plants. A collection of mutations, designated era, in Arabidopsis thaliana that confer an enhanced response to exogenous ABA includes mutations in the Era1 gene, which encodes the beta subunit of a protein farnesyl transferase. In yeast and mammalian systems, farnesyl transferases modify several signal transduction proteins for membrane localization. The era1 mutants suggest that a negative regulator of ABA sensitivity must be acted on by a farnesyl transferase to function.
In vitro growth of neonatal rat islet cells is stimulated by adhesion to matrix.
We examined DNA synthesis in non-enzymatically isolated neonatal rat pancreatic islets sub-cultured to eliminate fibroblast contamination, which was excluded both by demonstrating no effect of fibroblast growth factor (FGF) on 3H-thymidine incorporation and by immunofluorescence of attached islets using a mouse anti-fibroblast monoclonal antibody. 3H-thymidine incorporation in islets increased with increasing glucose up to a concentration of 21.1 mM in both free-floating islets (11,789 cpm/micrograms DNA +/- 1,610 SEM) and islets attached to fibronectin coated plastic (43,043 cpm/micrograms DNA +/- 9,203 SEM). These values were significantly higher when compared to 3H-thymidine incorporation in medium containing 11.1 mM glucose (p < 0.007, and p < 0.0001 for free-floating and attached islets respectively). 3H-thymidine incorporation was significantly higher in attached islets than in free-floating islets at all glucose concentrations tested (p < 0.005 at 11.1 mM, 16.1 mM, and 21.1 mM; and p < 0.01 at 26.1 mM). 5-bromo-2'-deoxyuridine (BrDU) staining of islets showed an increased number of positive nuclei in cells localised within attached islets (37.6 nuclei per islet +/- 5.1 SEM) compared to free-floating islets (7.62 nuclei per islet +/- 1.04 SEM, p < 0.001), indicating that attachment influenced proliferation of islet cells not physically in contact with the matrix. No difference in glucose-stimulated insulin release was observed between attached and free-floating islets. In conclusion, a fibroblast free islet culture was used to document the stimulatory effect of islet attachment on DNA synthesis, which was greater than the stimulation exerted by glucose alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Insulin secretion and DNA synthesis of cultured islets of Langerhans are influenced by the matrix.
To compare the effect of matrix on glucose-stimulated insulin release, we cultured neonatal (3- to 5-day-old) rat islets of Langerhans, devoid of mesenchymal cell, on fibronectin, Cell-Tak, or endothelial basement membranes, free-floating, or dispersed into single cells. We also examined the rate of DNA synthesis during the culture period. Compared to free-floating islets [0.386 +/- 0.03 (SEM) ng per 24 h/ng total], single-cell cultures had the lowest basal insulin release (0.159 +/- 0.03 ng per 24 h/ng total; p < 0.0001), which was also low in islets attached to endothelial basement membrane (0.294 +/- 0.02 ng per 24 h/ng total; p = 0.01). The spontaneous insulin release (1 h in medium with 2.7 mM glucose) was lowest in islets attached to endothelial basement membrane (0.003 +/- 0.00023 ng per h/ng total; p < 0.0001 vs. free-floating) and highest in single-cell cultures (0.01153 +/- 0.00259 ng per h/ng total; p = 0.039 vs. free-floating). The ability to increase insulin release following a glucose challenge (16.1 mM for 1 h) was highest in islets grown on endothelial basement membranes (16.4-fold) and fibronectin (12.6-fold) compared to free-floating islets (8.7-fold), Cell-Tak (7.9-fold), and single-cell cultures (5.4-fold).(ABSTRACT TRUNCATED AT 250 WORDS)
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Rectal aminophylline gel in treatment of apnoea in premature newborn babies.
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