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Biomedical subjects

S H Norris

Publications and source records attributed to S H Norris.

At least 55 records · Page 3Linked to original sources
PubMed1985

The comparative properties of plaster of Paris and plaster of Paris substitutes.

Modern casting materials are becoming available in an increasing and bewildering variety. A series of tests has been devised to investigate the properties of these materials. They have been tested for strength, flexibility, lamination, fatigue life and radiolucency. Their properties have been compared with those of plaster of Paris in order that the role of the newer materials can be defined. It is suggested that the tests described might form the basis of a standard from which user trials could be designed to appraise the value of these materials in clinical practice.

Calcium Sulfate↗
PubMed1985

Transport of sodium and chloride across rat gastric mucosa in vitro.

The effects of ion substitution, inhibitors and variations in transmural p.d. on the movements of sodium and chloride across an in vitro preparation of rat gastric mucosa have been studied. The tissue maintained net steady-state transport of sodium in the mucosal-to-serosal direction in the absence of transmural gradients of electrochemical potential. Sodium transport was independent of the presence of chloride, and was abolished by 1 X 10(-5) M-amiloride. The inhibitor produced a decrease in short-circuit current equivalent to the depression of sodium transport, indicating that the sodium transport process was electrogenic. Variations in transmural p.d. showed that the sodium transport process included two components: one that varied with p.d. and one that was independent of it. These findings have been interpreted in terms of a system for sodium transport composed of three components: two rate-limiting entry mechanisms at the apical membrane, one of which can be represented as a conductive channel for sodium diffusion and the other as a neutral process possibly a sodium-hydrogen exchanger, and a voltage-independent pump at the basolateral membrane analogous to the constant-current pump models described in some other epithelia. The tissue maintained a net secretory movement of chloride in the short-circuited condition. The process responsible for net transport of chloride could be resolved into two components: one that was sodium dependent, electrogenic, and abolished by 8 X 10(-3) M-acetazolamide, and one that was independent of the presence of sodium, electrically silent and abolished by 5 X 10(-4) M-SITS (4-acetamido-4'-isothiocyano-2,2'-disulphonic acid stilbene). Both components of the chloride transport process varied with p.d. These findings were interpreted in terms of a system of three components: two entry mechanisms at the basolateral membrane including a coupled sodium-chloride influx process and a chloride-bicarbonate exchanger in parallel, and a rate-limiting conductive channel at the apical membrane. In addition, the studies on the effects of variations in transmural p.d. on chloride fluxes revealed a symmetrical voltage-independent component, dependent on the presence of chloride in the trans compartment, and it was suggested that this component may reflect the presence of a chloride-chloride exchange mechanism.

Acetazolamide↗
PubMed1985

Stimulation of pepsinogen secretion in permeable isolated gastric glands.

Rabbit isolated gastric glands were treated with digitonin so that stimulation of pepsinogen secretion could be studied in a permeable system. Criteria for permeabilization were the release of lactate dehydrogenase in response to digitonin as well as the finding that calcium stimulation and spermine inhibition required the presence of digitonin. Other evidence confirmed that digitonin directly permeabilized chief cells. Pepsinogen secretion was elicited from digitonin-treated gastric glands by a number of agents, including calcium, vanadate, cholecystokinin octapeptide (CCK-OP), 8-bromo-adenosine 3',5'-cyclic monophosphate, and forskolin. Spermine was found to inhibit secretion stimulated by each of these agents only in the presence of digitonin, suggesting an intracellular site of spermine action. We concluded that spermine inhibition of secretion could be used as a marker of secretion elicited from permeable chief cells. The ability to stimulate pepsinogen secretion by such agents as CCK-OP and forskolin suggests that stimulus-secretion coupling is virtually intact even in permeable chief cells. We felt that this preparation should offer unusual opportunities for investigating the mechanisms involved in the intracellular regulation and activation of pepsinogen secretion.

Animals↗
PubMed1984

Inhibition of pepsinogen secretion in isolated gastric glands by amphotericin B is secretagogue specific.

Pepsinogen secretion from isolated gastric glands, stimulated by 8-bromoadenosine 3',5'-cyclic monophosphate (8BrcAMP), forskolin, or cholecystokinin octapeptide, was inhibited by the presence of amphotericin B in the incubation medium. However, amphotericin had no effect, or only a slight effect (less than 10% inhibition), on pepsinogen secretion stimulated by crude secretin. Incubation of glands with either of the mitochondrial inhibitors, rotenone or carbonyl cyanide m-chlorophenylhydrazone, reduced pepsinogen secretory responses both to 8BrcAMP and to crude secretin. This suggests that amphotericin inhibition, which is secretagogue specific, was not the result of a general metabolic inhibition. Amphotericin caused an increase in sodium and chloride content and a decrease in potassium content of glands. Experiments in which the medium content of either sodium, potassium, or chloride was varied, suggested that part of the amphotericin inhibition could be attributed to a rise in intracellular chloride content. Results did not support the involvement of changes in intracellular sodium or potassium content in the inhibitory mechanism of amphotericin. It was concluded that amphotericin caused a rapid and secretagogue-specific inhibition of pepsinogen secretion in isolated gastric glands, and that the mechanism of inhibition may, to some extent, involve changes in intracellular chloride content.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1983

pH dependence of pepsinogen and acid secretion in isolated gastric glands.

Rabbit isolated gastric glands were used to investigate the dependence of pepsinogen and acid secretions on extraglandular pH. Changing pH from 8.0 to 6.7 caused small increases in pepsinogen secretory responses to isoproterenol, carbachol, cholecystokinin octapeptide, Boots' secretin, and hyperosmolarity but caused large increases in responses to 8-bromoadenosine 3',5'-cyclic monophosphate (8BrcAMP), 8-bromoinosine 3',5'-cyclic monophosphate (8BrcIMP), and forskolin. The similar effect of pH on responses to 8BrcAMP, 8BrcIMP, and forskolin was suggested to reflect a commonality in their proposed mechanisms of action. It was concluded that reducing extraglandular pH indirectly caused an increase in activity of cAMP-dependent protein kinase or of a subsequent step in cAMP-dependent regulation of pepsinogen secretion. 8BrcAMP-stimulated acid secretion also increased as pH was changed from 8.0 to 6.7, and a similar explanation of the effect was suggested. However, histamine-stimulated acid secretion and adenyl cyclase activity decreased markedly as pH was lowered over this range. It was suggested that cAMP was rate limiting for stimulation by histamine and that the effect of pH on histamine-stimulated acid secretion could be attributed to an effect of pH on adenyl cyclase activity.

1-Methyl-3-isobutylxanthine↗
PubMed1983

Lack of interaction between acid and pepsinogen secretion in isolated gastric glands.

Gastric glands isolated from rabbit stomach were employed to study the relation between acid and pepsinogen secretion. The effects of adenosine and guanosine nucleotides were examined for both secretory processes. cAMP, dibutyryl cAMP (DBcAMP), and 8-bromo-cAMP (8BrcAMP) were found to stimulate both acid and pepsinogen secretion with a potency sequence of 8BrcAMP greater than DBcAMP greater than cAMP. Adenosine, ATP, and AMP were ineffective, indicating that the responses to adenosine cyclic nucleotides do not involve an adenosine receptor. 8BrcGMP was found to produce a weak stimulation of both acid and pepsinogen secretions, while GMP, cGMP, and DBcGMP were ineffective. DBcGMP was found to inhibit competitively the stimulation of pepsinogen secretion by cholecystokinin (CCK)-like peptides. No inhibition was found with cGMP or 8BrcGMP. Stimulation of pepsinogen secretion by carbachol or isoproterenol was not inhibited by DBcGMP nor was the stimulation of acid formation by CCK-like peptides. Thiocyanate inhibited acid formation but did not affect pepsinogen secretion stimulated by 8BrcAMP or carbachol, indicating that stimulation of pepsinogen secretion does not require simultaneous acid formation. Costimulation of acid formation by histamine and pepsinogen secretion by isoproterenol showed no interaction between the two secretory processes. The results are interpreted to suggest that correlations between acid and pepsinogen secretion observed in vivo do not result from direct interactions between parietal and chief cells.

Adenosine↗
PubMed1983

The prognosis of neck injuries resulting from rear-end vehicle collisions.

Injury of the neck may result when a motor vehicle is run into from behind; such injury is frequently the cause of prolonged disability and litigation. We report a series of 61 patients with these injuries. A classification, based upon the presenting symptoms and physical signs has been evolved. This classification is shown to be a reliable basis for formulating a prognosis. Factors which adversely affect prognosis include the presence of objective neurological signs, stiffness of the neck, muscle spasm, and pre-existing degenerative spondylosis.

Accidents, Traffic↗
PubMed1982

Undergraduate teaching of orthopaedic surgery.

Orthopaedics is an important component of clinical practice and education in this subject is important. In order to discover how best to teach it a questionnaire was presented to undergraduates at Bristol University at the conclusion of their course. From their replies a course length of 6 weeks with maximum clinical contact, small groups and minimum number of lectures is recommended. Orthopaedic courses nationally have also been analysed and found to rely overmuch upon lectures, to have student group which are too large and to combine orthopaedics with other courses too frequently. It is concluded that undergraduate and postgraduate medical training should be integrated and that 1 clinical year should contain courses which would be optional.

Education, Medical, Undergraduate↗
PubMed1981

Radionuclide uptake during the evolution of experimental acute osteomyelitis.

The findings of technetium 99m MDP and gallium 67 citrate scintigraphy are described in the first four days following experimental acute osteomyelitis of the tibia of rabbits. On the day of inoculation, defects in activity are observed in both the perfusion, and bone phases of technetium scintigraphy. Similar defects are achieved by saline injection. On subsequent days technetium scintigraphy reveals an increased activity in the perfusion stage but a persisting defect of activity in the bone phase. Gallium activity is increased throughout the period of the study in inoculated animals but not in those injected with saline. It is concluded that 99Tcm MDP, in its perfusion phase, and 67Ga citrate are highly sensitive indicators of bone inflammation and that early osteomyelitis is characterized by increased activity with these agents together with a technetium bone scan defect.

Acute Disease↗
PubMed1978

Chronic tenosynovitis of the posterior tibial tendon with new bone formation.

Chronic non-specific tenosynovitis of the posterior tibial tendon is a well-known clinical entity, characterised by pain, swelling and tenderness behind the medial malleolus. There are no reports in the literature of any case associated with any radiological abnormality. Three such cases are discussed, each presenting with the clinical findings typical of the syndrome but with associated radiological changes. These changes may pose diagnostic problems and several primary conditions need to be excluded. Surgical decompression of the tendon may be necessary to relieve symptoms, to prevent erosion and rupture of the tendon, and to establish the diagnosis.

Adult↗
PubMed1977

Traction.

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Adult↗