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Biomedical subjects

R L Maynard

Publications and source records attributed to R L Maynard.

29 records · Page 2Linked to original sources
PubMed1993

The ultrastructure of rat lung following acute primary blast injury.

While a number of workers have described the effects of blast waves upon the lung at both the macroscopic and light microscopic level, studies involving the use of the electron microscope have not been reported. In the experiments reported here the ultrastructural changes seen in lungs from rats exposed to a blast wave impacting on the right side of the chest are described. Considerable damage to the right lower lobe was observed which took the form of tearing of the inter-alveolar septa with capillary rupture and intra-alveolar haemorrhage. Changes to the alveolar epithelium and type II pneumocytes were also noted. Lesions were also identified in the left lung; these included intra-alveolar oedema with a minimal amount of interstitial oedema together with increased pinocytosis and isolated rupture of the alveolar epithelium. 'Ballooning' of the endothelium into the lumen of the capillary was also observed. There was an indication that lesions noted in the left lung at the electron microscopic level may be progressive in the first 24 hours following injury.

Animals↗
PubMed1988

Wound ballistics: contemporary and future research.

Wound ballistics research has contributed much to the understanding of the pathophysiology of missile injury that now exists. From this store of knowledge treatment regimes have evolved which have greatly improved the lot of the soldier wounded in war. However, research must keep pace with changes that are taking place in weapons research and development so that the particular needs of the Army Medical Services on a future battlefield can be met. The differing needs of civilian and military medical services are highlighted. The marked differences that exist between the missile wound seen and treated in a late twentieth century hospital and the wounds likely to be encountered on the modern battlefield are enumerated and discussed.

Humans↗
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

Experimental penetrating head injury: some aspects of light microscopical and ultrastructural abnormalities.

A high velocity model of penetrating head injury has been developed in the rhesus monkey and a lower velocity model in the baboon. It is apparent that pathological changes are widespread and develop early although the pathogenesis of the diffuse vascular changes is unknown. The present study involved the sampling of grey and white matter from 20 monkeys with high velocity injury, and 10 baboons with low velocity injury together with similar material from a number of normal control animals. 30 minutes after a high velocity injury swelling of perivascular astrocytes was present, sometimes associated with an increase in extracellular fluid. Animals with lower velocity injuries survived for some hours. Astrocytic swelling and perivascular oedema associated with cellular necrosis was frequently found in this group. The pathogenesis of these lesions is discussed.

Animals↗
PubMed1983

An ultrastructural study of experimental high velocity penetrating head injury.

Experimental high velocity missile brain injury in the rhesus monkey produces widespread swelling of perivascular astrocytes within 30 min of injury. Possible mechanisms for this lesion include a direct effect of force, chemical mediation secondary to the extravasation of blood, alterations in the permeability of the blood brain barrier and ischaemia. The implications of this findings for the function of the blood brain barrier, for neurotransmission and for neuronal survival are discussed.

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↗