Stress and the acute gastric mucosal lesion.
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Acute Disease↗
Biomedical subjects
M A Simons
Publications and source records attributed to M A Simons.
Effects of carbenoxolone on gastric mucosal permeability and blood flow in the dog.
The effects of topical application of carbenoxolone at neutral and acidic pH were compared in exteriorized, chambered segments of canine gastric corpus. When dissolved in saline at pH 7.5 to 8.0, 0.25% carbenoxolone caused a rapid drop in gastric potential difference of 56 +/- 2 mv and greatly increased permeability to H+ ions. Blood flow, as measured by radioactive microspheres, was not changed by carbenoxolone treatment, but subsequent exposure to isotonic HC1 caused an abrupt rise in flow. Application of 0.25% carbenoxolone suspension in isotonic HC1 caused no change in potential difference, permeability, or blood flow. Neither carbenoxolone preparation had a significant effect on aspirin-induced H+ back-diffusion or injury.
Animals↗
A health service for horses.
The current position of the horse in the United Kingdom is discussed and the attitudes of the horse-owning public are examined. It is suggested that there are welfare, economic and practical advantages to owners and the veterinary profession in a veterinary health scheme for horses. A scheme which has been tried successfully in the field is discussed.
Animals↗
Effects of p-chloromercuribenzene sulfonate upon ultrastructure of canine gastric surface cells.
Exposure of the mucosal surface of exteriorized chambered fundic segments of dog stomach to p-chloromercuribenzene sulfonate (PCMBS) resulted in predictable gross and microscopic structural changes. The first visible response after PCMBS (10 mM) in isosmotic HCl was an intense release of periodic acid-Schiff-stainable mucus. Within 2 min, radioactive PCMBS was found within cells along the entire depth of the gastric glands. Surface cells at 15 min revealed vacuolization of the cell cytoplasm, dilation of the perinuclear and intercellular spaces, mitochondrial swelling, loss of microvilli, and plasmalemma irregularities. Tight junctions, Golgi, and mucous granules appeared unaltered. However, in advanced injury, mucous granules became less dense and their membranes, which were usually smooth, became fragmented and convoluted at this point. Necrotic parietal cells were extruded into the lumen. Damage, however, only rarely extended into the deeper glandular and connective tissue areas.
4-Chloromercuribenzenesulfonate↗
Comparison of gastric mucosal blood flow as determined by aminopyrine clearance and gamma-labeled microspheres.
Gastric mucosal blood flow was simultaneously determined by aminopyrine clearance and gamma-labeled microspheres (15 +/- 5 mu in diameter) in anesthetized dogs prepared with a chambered segment of stomach greater curvature. Paired flow measurements were made in 11 dogs (n = 28) secreting in response to intravenous histamine (1mug per kg per min), in 11 (n = 21) nonsecreting dogs given intravenous isoproterenol (0.5 or 1.0 mug per kg per min), and in 9 (n = 10) dogs given no drugs to stimulate secretion or blood flow (resting dogs). Eight additional injections were done in dogs receiving various combinations of isoproterenol and histamine. Isotonic HCl was maintained on the mucosal surface during all experiments. Regression analysis demonstrated a highly significant linear correlation between clearance and microsphere-measured flow in the histamine (P less than 0.001, r = 0.96) and isoproterenol (P less than 0.001, r = 0.78) experiments, with clearance averaging 83% of microsphere flow during histamine stimulation but only 25% during isoproterenol. The relationship between clearance and microsphere flow was not significantly different for the resting and isoproterenol experiments. Mucosal perfusion measured by microspheres was about 5 times the resting value for both histamine and isoproterenol-stimulated dogs. Perfusion calculated from aminopyrine clearance averaged 46, 38, and 90% of the microsphere value in the resting, isoproterenol, and histamine experiments, respectively. Pooled data from secreting dogs demonstrated a fairly constant ratio of microsphere-measured flow to clearance (1.25 +/- 0.06 mean +/- SEM), regardless of the secretory rate. Our results indicate that aminopyrine clearance reflects only a small fraction of mucosal blood flow in the nonsecreting stomach, even in the presence of exogenous acid.
Aminopyrine↗
Some aspects of the examination of horses for insurance.
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Animal Population Groups↗
A mathematical model for signal from spins flowing during the application of spin echo pulse sequences.
Models are presented for both laminar and plug flow that predict the signal from spins flowing during the application of slice-selective spin echo pulse sequences. The models permit calculation of the total signal from a cylindrical vessel lying perpendicular to the slice and incorporate the effect of the physical displacement of the spins between successive excitations. This time-of-flight effect gives a signal which is composed of contributions from a finite number of spin populations, with each population signal weighted by the fractional volume of that spin population within the cylindrical vessel segment. The signal and fractional volume from each spin population are derived analytically for ten different spin echo pulse sequences. The models for plug and laminar flow have important application for predicting and interpreting flow effects observed in clinical images. They are shown to be useful for selecting pairs of pulse sequences that can be used to obtain digitally subtracted MR images which provide optimum contrast for flowing blood with essentially complete suppression of stationary anatomy. These models provide a means for quantitatively comparing the expected signal from flowing spins for the many techniques presently being investigated for MR angiography.
Blood Circulation↗