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Gastrin and the ultrastructure of G cells after stimulation with acetylcholine (1978)

Mortensen, N. J. McC. ; Morris, J. F. ; Owens, C. J.

Springer

Cell & tissue research 192 (1978), S. 513-525

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ISSN: 1432-0878

Keywords: Gastrin cells (rat) ; Pyloric antrum ; Gastrin ; Hormone release ; Radioimmunoassay

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The effect of intragastric administration of acetylcholine on serum and antral gastrin concentrations of rats has been examined using a radio-immunoassay and quantitative electron microscopy. Exposure of the stomach of rats, previously fasted for 24 h, to 2% acetylcholine for either 0.5 or 2 h resulted in a significant 4–5 fold increase in serum gastrin concentrations to levels similar to those found in fed animals. Such treatment produced no detectable change in antral gastrin concentration or in the number or electron density of secretory granules in the G cells. This lack of detectable change in the G cells was not unexpected since our calculations suggest that less than 10 % of the total gastrin stored in the antrum is released over 2 h as a result of the stimulation with acetylcholine. The proportion of electron-lucent secretory granules was, however, markedly increased by prolonged fixation in aldehydes. The increase was similar in both ACh stimulated and control animals. These results indicate that the ultrastructural appearance of G cell secretory granules is influenced far more by the conditions of fixation than by the release of gastrin. They therefore cast considerable doubt on the hypothesis that gastrin is released by molecular dispersion from the granules.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00212330

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Flammability characteristics of fiber reinforced organic matrix composites (1978)

Silvergleit, M. ; Morris, J. G. ; Larosa, C. N.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 18 (1978), S. 97-106

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ISSN: 0032-3888

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: The effect of resin, fiber, and fire retardant additives on flammability characteristics of organic matrix composites was evaluated. Information is presented on the flame spread index, determined by the radiant panel test, the amount of smoke generated, and products of combustion, using the National Bureau of Standards Smoke Density Apparatus, and the amount of oxygen required to support combustion using the Oxygen Index method. These methods were effective in screening the flammability characteristics of organic matrix composites. Of the materials evaluated the polyimide composites were the most resistant to flame spread, exhibited the lowest evolution of smoke and toxic products and had the highest oxygen index. No differences in flame spread and oxygen index were observed for the polyester epoxy glass-cloth laminates. Addition of antimony trioxide and hydrated alumina to the polyester and epoxy resin systems significantly decreased the flame spread index and increased the oxygen index, but showed a marked increase in smoke evolution. Smoke properties depended on resin content whereas the type of reinforcement did not appear to affect flame spread index or smoke properties. The use of protective barriers in selected shipboard areas can reduce flame spread and lengthen the lime for generation of smoke.

Additional Material: 7 Ill.