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Biomedical subjects

G J Cooper

Publications and source records attributed to G J Cooper.

177 records · Page 10Linked to original sources
PubMed1984

Iodine intake in an urban environment: a study of urine iodide excretion in Auckland.

Dietary iodine intake was estimated by measurement of iodide in random overnight 12 hr and 24 hr urine samples. Urinary iodide excretion was measured in 231 healthy females comprising 127 female secondary students (ages 16-19), 27 female tertiary students (17-23 yr), 42 female laundry workers (18-52 yr) and 26 pregnant women in the third trimester (18-40 yr). Urine iodide excretion was also examined in a group of 28 patients attending a thyroid clinic, with thyroid disease of diverse aetiology and in 34 patients taking the antiarrhythmic drug amiodarone for control of cardiac arrhythmias. The mean daily urine iodide excretion was 2.4 mumol/day (0.9-5.8 mumol/day) and iodide to creatinine ratio 0.21 mumol/mmol (0.09-0.29). Iodine deficiency (less than 0.4 mumol/day) was not observed in any subject. Excessive iodine (greater than 8 mumol/day) was found only in patients known to be taking iodine-containing drugs and in one normal individual. The urine iodide was normal in 154 female students, 14 of whom had a trivial thyroid enlargement. The study suggests that dietary sources other than iodised salt contribute significantly to dietary iodine intake and that residual goitre in the community is not secondary to deficiency or excess of dietary iodine.

Adolescent↗
PubMed1984

Cardiovascular distortion in experimental nonpenetrating chest impacts.

High-speed cineradiography and flash radiography were used to determine cardiac distortion and the motion of the heart within the thorax following nonpenetrating chest impact. Maximum ventricular distortion occurred approximately 3 ms after impact which was also the time of maximum chest wall displacement. Between +3 ms and +10 ms the heart moved posteriorly and regained much of its initial shape. Maximal posterior displacement of the body of the heart occurred at approximately +10 ms. Three-dimensional reconstruction showed that the heart moved caudally and to the right, with little rotation. The aortic arch moved cranially with consequent stretching of the thoracic aorta.

Animals↗
PubMed1983

Casualties from terrorist bombings.

The physical factors responsible for injury following an explosion in a room or building are: direct exposure to overpressure; blast-induced whole body displacement; impact of blast-energized debris; burns from flash and hot gases. The patterns of injury seen in the casualties from four terrorist bombings are described to illustrate the types and severity of particular wounds. The most common fatal injury is brain damage; 'blast lung' is uncommon in civilian terrorist bombings; flash burns, fractures, serious soft-tissue damage, and eardrum injuries are seen in people close to the bomb, who usually require hospital admission; many others taken to hospital can be treated for injury by debris and released. The environment and its internal structure and the position of the occupants of the space can influence the type and severity of injuries.

Barotrauma↗
PubMed1982

The biomechanical response of the thorax to nonpenetrating impact with particular reference to cardiac injuries.

Sternal injury, gross cardiac pathology, and cardiac dysrhythmias following nonpenetrating impact by a variety of impactors to the sternum of experimental animals are described. The biomechanical response of the chest wall to the impact and the associated transient pressure changes within the heart are presented, and a correlation between injury severity and chest wall displacement is demonstrated. A simple model is then developed to predict chest wall displacement if the mass, velocity, and dimensions of an impactor are known. The model demonstrates the dependence of chest-wall displacement upon preimpact kinetic energy, impact diameter, and target size.

Animals↗
PubMed1980

Alpha-aminoisobutyric acid transport in rat soleus muscle and its modification by membrane stabilizers and insulin.

The non-metabolizable amino acid alpha-aminoisobutyric acid (AIB) has been used to study the effects of insulin and a number of membrane stabilizers on amino acid transport in rat soleus muscle in an attempt to characterize the mechanisms present. 2. Insulin (5--100 millimicron./ml) increases the net uptake of AIB two- to threefold. Since insulin is without significant effects on AIB efflux, stimulation of net uptake appears to result directly from an increased AIB influx. 3. All classes of membrane stabilizer tested affected AIB fluxes but the responses observed varied for different classes of compounds. 4. The total anaesthetic, tetracaine, reduced AIB accumulation both in the absence and presence of insulin by a similar proportion. The effects on AIB efflux were dependent on the concentration of tetracaine used. Efflux was suppressed by concentrations up to 1 mM whereas 4 mM-tetracaine caused a massive stimulation of AIB efflux. Other local anaesthetics and barbiturates produced similar effects. 5. Another group of membrane stabilizers, exemplified by chlorpromazine, also suppressed AIB uptake, but at no concentration did they reduce AIB efflux. In fact, efflux of AIB began to be increased at concentrations of chlorpromazine which were giving only a modest inhibition of uptake. 6. Measurement of the initial rate of uptake showed that it involved two components. Tetracaine appears to inhibit the saturable component whilst leaving the non-saturable component relatively unaffected. 7. The active uptake of AIB was shown to be Na+-dependent, and under Na+-free conditions tetracaine had no effect on the initial rate of uptake. The non-saturable component was also shown to be Na+-sensitive, uptake from high extracellular concentrations of AIB being reduced in Na+-free media. 8. The possibility of the presence of a carrier-mediated AIB efflux mechanism was investigated. AIB efflux was stimulated by extracellular AIB (homo-exchange) or glycine (hetero-exchange), but not mannitol. This suggests the involvement of a carrier-mediated process in AIB efflux. 9. The present study has demonstrated a heterogeneity among different classes of membrane stabilizers in their actions on AIB efflux which is in marked contrast to previous observations of sugar and cation transport in this preparation. Possible reasons for these differences are discussed.

Aminoisobutyric Acids↗
PubMedDate not supplied

Vesicant burns.

(1) Of the 120,000 victims of sulphur mustard gas in World War I there were only 2-3% fatalities, and few long term effects. (2) The interactions of sulphur mustard with the skin are complete within a few minutes of exposure. Once the victim has been decontaminated there is no risk to the attendant and there is no active agent in the blister fluid. (3) The rate of wound healing is slow for sulphur mustard burns, but in general the wounds heal satisfactorily. (4) There is no specific therapy for poisoning by sulphur mustard.

Arsenic Poisoning↗
PubMedDate not supplied

Development of an ex vivo model to investigate the effects of altered haemodynamics on human bypass grafts.

The insertion of vein grafts into the arterial circulation may contribute to vessel wall thickening and accelerated atherosclerosis, a common feature of late vein graft failure. We aimed to develop a model suitable for investigation of the effects of altered haemodynamics on human saphenous vein following its implantation into the arterial circulation. Segments of human saphenous vein obtained from patients undergoing coronary artery bypass surgery were sutured at each end to PTFE and placed into a flow system. Pressure and flow rates to stimulate the arterial and venous systems were achieved. A theoretical model of the flow chamber was created and computational fluid dynamics software (FLOTRAN, Swanson Analysis Systems) was used to determine the flow profile within the model. In summary, a flow model has been developed to investigate the effect of altered haemodynamics on the molecular and pathological changes that occur in vein grafts incorporated into the arterial circulation.

Blood Flow Velocity↗
PubMedDate not supplied

A method using laser Doppler flowmetry to study intestinal and pancreatic perfusion during an acute intestinal ischaemic injury in rats with pancreatitis.

Intestinal ischaemia is implicated in the pathogenesis of severe acute pancreatitis, a disorder characterized by acinar necrosis. To study the relationship between pancreatic and intestinal microvascular perfusion during 40 min of intestinal ischaemia and 30 min of reperfusion in rodents with acute pancreatitis, a model utilizing laser Doppler flowmetry was developed. It is reported here together with practical solutions for (1) a modified method of vessel cannulation; (2) a novel method for the temperature-controlled optical coupling between laser Doppler probes and rodent tissues, and (3) a simple technique of inducing intestinal ischaemia-reperfusion while continuously monitoring the microvascular perfusion in both pancreas and intestine. The utility of the model is demonstrated in a pilot study that showed that the pancreatic perfusion fell acutely to 58% (p = 0.029) of baseline during the intestinal reperfusion phase. This reduced perfusion continued for 30 min despite recovery of both the intestinal perfusion and the mean arterial blood pressure to baseline levels.

Acute Disease↗
PubMedDate not supplied

The lima success story--whither other arterial grafts--are vein grafts obsolete?

The long-term benefit of myocardial revascularisation depends largely upon the continued patency of bypass grafts, but the long-term patency of vein grafts is poor. To improve the results of myocardial revascularisation, either measures to increase the patency of saphenous vein grafts or alternative conduits are required. Use of the left internal mammary artery as a graft is known to increase survival, and this has prompted wider use of other arterial grafts in the expectation that they will further enhance the long-term results of coronary artery bypass. This policy is based upon sound theory, but convincing evidence that it improves survival is lacking. Meanwhile, advances in the understanding of the pathology of vein graft occlusion have given rise to new methods of increasing vein graft patency. While these techniques are, as yet, only experimental, if translated into clinical practice, the places of arterial and venous grafts may require further assessment.

Coronary Artery Bypass↗