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S J Morris

Publications and source records attributed to S J Morris.

At least 127 records · Page 7Linked to original sources
PubMed1977

Correlation of physical and morphological parameters with release of catecholamines, ATP, and protein from adrenal medulla chromaffin granules.

Exchanging 0.3 M sucrose for 0.3 M glycerol as the bathing medium for isolated bovine adrenal chromaffin granules at 0 degrees C or raising the temperature of granules suspended in 0.3 M sucrose to 37 degrees C causes the release of catecholamines, ATP and soluble protein stored in the granules. These treatments also reduce the turbidity (absorbance at a non-absorbing wavelength) of the same suspensions. The glycerol-induced release is shown by morphology and morphometry to be due to lysis of the granules. Advantage is taken of the difference in density of the intact granules and the granule ghosts to confirm this result by centrifugation of glycerol-incubated samples on continuous gradients of sucrose and metrizamide. Similar centrifugation experiments performed on the granules incubated in sucrose at 37 degrees C show that lysis also accounts for the fast phase of release of granule contents, and not graded selective release of material from otherwise intact granules.

Adenosine Triphosphate↗
PubMed1977

An osmometer model for changes in the buoyant density of chromaffin granules.

We present a model for the structure of isolated bovine adrenal medulla chromaffin granules derived from the dependence of granule density on the osmotic pressure of the suspension medium at 2 degrees C. The granule consists of a flexible, inelastic membrane bounding an osmotically active core. The core consists of a solution space and a separate, nonosmotic phase. Since the granule behaves like a "perfect" osmometer over a wide range of osmolarities, we conclude that (a) within these limits, the core consists of a constant amount of condensed material and a constant number of particles in solution, (b) from the constraints of the osmometer model, the osmolality inside the granule must equal the osmolality outside. Therefore the high concentrations of catecholamines (greater than 0.7 M) and ATP (greater than 0.18 M) measured biochemically cannot be dissolved in the core solution as separate molecules, but must be condensed into larger aggregates. These results are supported by electron micrographic examination of the effect of osmotic pressure changes on granule morphology.

Adenosine Triphosphate↗
PubMed1977

Allergic laryngospasm on initiating oral propranolol therapy.

A 29-year-old woman suffered acute laryngospasm on taking the initial dose of propranolol hydrocholoride for the treatment of hypertension associated with a hyperdynamic circulatory state. Hypersensitivity to the tartrazine additive used as a stabilizing agent in oral propranolol appeared the likely cause of anaphylaxis, although a direct hypersensitivity to propranolol itself could not be excluded.

Administration, Oral↗
PubMed1976

The preparation and characterization of synaptic vesicles of high purity.

Very pure preparations of synaptic vesicles have been obtained from guinea pig cerebral cortex and from the electromotor synapses of Torpedo marmorata by density gradient centrifugation in a zonal rotor followed by chromatography on columns of glass beads of controlled pore size. Markers for soluble cytoplasm (lactate dehydrogenase), plasma and endoplasmic membranes membranes (Na-K-ATPase; acetylcholinesterase, NADPH-cytochrome c reductase], mitochondrial membranes [cytochrome oxidase] and lysosomes [acid phosphatase] were used to assess contamination and were undetectable. The only enzymes detected in the highly purified preparations from guinea pig cerebral cortex were Mg- and Ca-activated ATPases, but their content relative to acetylcholine fell on chromatography suggesting that they may be constituents of non-cholinergic vesicles. Lipids analyses of the highly purified vesicles confirmed earlier results and showed that glycolipids and lysolecithin are present in negligible amounts; this suggests that lysolecithin is not required for exocytosis of synaptic vesicles. A discussion of the probable limiting concentration of acetycholine in cerebral cortical vesicles derived solely from cholinergic terminals suggests that from 13 to 56% of the vesicles isolated are cholinergic, depending on the assumptions made.

Acetylcholine↗
PubMedDate not supplied

The influenza haemagglutinin-induced fusion cascade: effects of target membrane permeability changes.

To define the stages in influenza haemagglutinin (HA)-mediated fusion the kinetics of fusion between cell pairs consisting of single influenza HA-expressing cells and single erythrocytes (RBC) which had been labelled with both a fluorescent lipid (Dil) in the membrane and a fluorescent solute (calcein) in the aqueous space have been monitored. It is shown that release of solute from the target cell occurs, following the formation of the hemi-fusion diaphragm. These results are discussed in terms of a model in which fusion peptide insertion into the target membrane induces lipid stalks, which results in the formation of a hemifusion diaphragm and a fusion pore. Bilayer expansion due to overproduction of these stalks can give rise to collateral damage of target membranes.

3T3 Cells↗