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Biomedical subjects

A W Nelson

Publications and source records attributed to A W Nelson.

At least 37 records · Page 2Linked to original sources

Lumbar spondylectomy in the subhuman primate.

Removal of the 2nd or 3rd lumbar vertebrae (or both) has been accomplished in the subhuman primate (Macaca mulatta). Variations between this animal and the dog in posture, vertebral column anatomy, and spinal cord blood supply made no apparent difference in the results when compared with those in previous experiments. All macaques were able to clinb and to use their hind legs in a normal manner within 3 days after surgical operation. Once hair had regrown over the surgical incision, persons not familiar with the animals were not able to identify the animals that had undergone surgical operation. If a single vertebra was removed, use of spinous process and a single vertebral body plate was sufficient to stabilize the vertebral column. Except for 1 rhesus macaque whose spinous process plates were removed 20 days after the operation, vertebral columns of macaques (n = 3) that underwent single spondylectomy healed in nearly normal alignment. With the removal of 2 lumbar vertebrae, the previously described stabilization procedure was not sufficient to prevent kyphotic deformity of the vertebral column. Spinous process plates from 1 macaque were removed after 64 days. However, all these macaques (n = 3) could climb and use their legs as well as others in the colony.

Animals↗

Inverse effect of chronically elevated blood flow on atherogenesis in miniature swine.

The effect of chronically elevated blood flow on the development of atherosclerosis in miniature swine was studied. Fistulas connecting the right external iliac artery and vein were surgically created in four swine, while three were not fistulated. Pulsed Doppler velocity detection cuffs placed around the abdominal aorta and both iliac arteries of all pigs permitted chronic measurements of blood velocity, blood velocity distributions, and blood flow. All swine were fed an atherogenic diet consisting of 20% beef tallow, 3% cholesterol, and 5% cholic acid for 6 months. This diet elevated the serum cholesterol to values exceeding 500 mg/100 ml. Creation of the arteriovenous fistula (AVF) markedly elevated blood velocity and flow in the abdominal aorta and in the shunted iliac artery. In the shunted animals the aortic blood flow was 42.1 +/- 2.0 ml/sec compared with 17.3 +/- 1.4 ml/sec in the unshunted swine. The velocity distribution pattern across the vessel was also indicative of an elevated wall shear stress. After 6 months, the animals were killed and the arterial vessels examined macroscopically and microscopically for the presence of atherosclerotic lesions. In the shunted pigs, 17 +/- 15% of the lumenal surface was occupied by sudanophilic lesions, whereas 80 +/- 8% of the surface was covered by lesions in the unshunted (control) pigs. From these studies, it is apparent that mechanical factors related to blood flow rates can influence the development of atherosclerotic lesions in swine.

Animals↗

Thrombosis in association with atherosclerosis induced by dietary perturbations in dogs.

The distribution, severity, and complications of diet-induced atherosclerosis in dogs can be altered by changing the source of fat in the diet. Thrombosis and thromboembolic disease associated with atherosclerosis occurred with diets containing beef tallow and lard of coconut oil but were absent in dogs fed cottonseed oil as a source of fat. Experiemtnal animals with and without thrombosis are of value as models in elucidating the role of platelets and thrombostatic mechanisms in atherosclerosis.

Animals↗

The unified concept of shock.

In summary, the shock syndrome has a variety of causes although the same net physiologic insult results. The disease is a deficiency in tissue metabolism brought about by decreased capillary blood flow and cellular hypoxia. The therapeutic regimen employed in any given patient is dectated by the initial cause of shock as well as the physiologic changes that have occurred in the patient. Fluid and electrolyte therapy is the primary method of treatment. Modification of solutions and use of additional drugs may be indicated.

Acidosis↗