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Biomedical subjects

C A Rawlings

Publications and source records attributed to C A Rawlings.

114 records · Page 7Linked to original sources
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Efficacy of azathioprine versus cyclosporine on kidney graft survival in transfused and nontransfused unmatched mongrel dogs.

Sixteen mongrel dogs had bilateral nephrectomy and received a renal allograft from an unmatched mongrel. One group of eight dogs was treated orally with azathioprine and prednisone; another group of eight dogs was treated orally with cyclosporine and prednisone. Four dogs of each group received four blood transfusions each prior to surgery. Mean survival time was nearly the same in the azathioprine-treated and the cyclosporine-treated dogs. Transfusions prolonged survival in the azathioprine-treated group but not in the cyclosporine-treated group. Retrospective measurement of whole blood trough cyclosporine concentrations indicated marked variation between dogs and in the same dog at different times. This variation may have influenced graft survival. Only one dog survived the 9-month period of observation, indicating that refinements of the techniques used in this study will be required for long-term survival of renal allografts in unrelated mongrel dogs.

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Pulmonary arteriography and hemodynamics during feline heartworm disease. Effect of aspirin.

The ability of aspirin to block arterial disease and thromboembolism of the pulmonary arteries was studied in heartworm-infected cats. Three groups of cats were transplanted with four heartworms per cat and studied. One group of eight cats (aspirin group) received aspirin (97.5 mg, twice a week) for the five-month infection and another group of eight cats served as the nontreated control group (nontreated group). Based upon the results of the first two groups, the third group (adjusted aspirin group) of six cats was studied in which the aspirin dosage was adjusted in order to maintain an inhibition of in vitro platelet aggregation. Cats were studied by nonselective pulmonary arteriograms before heartworm transplantation and by selective arteriograms, aortograms, and pulmonary hemodynamics five months after heartworm transplant. Pulmonary hypertension, (mean pulmonary artery pressures greater than 16 mmHg), was discovered in three cats with one cat in each group. There were no differences in the mean pulmonary artery pressure or vascular resistance between the groups. Many of the arterial diameters for the nontreated and aspirin groups were greater after the five-month infection than before heartworm infection. All of the postinfection caudal arteries were tortuous and had aneurysms. Some of the caudal lung lobes had perfused areas that appeared to have a hypervascular microvasculature. The proportion of obstructed right and left distal caudal pulmonary arteries and the resulting nonperfused area of the caudal lung lobe in the nontreated and aspirin treated groups were each greater than in the adjusted aspirin group.(ABSTRACT TRUNCATED AT 250 WORDS)

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Morphologic changes in the lungs of cats experimentally infected with Dirofilaria immitis. Response to aspirin.

The morphologic response of the pulmonary arteries and lungs in cats was studied after a five month heartworm infection produced by transplantation of four adult heartworms/cat. One group of seven heartworm infected cats was not treated, another group of seven cats was treated with 97.5 mg of aspirin given twice a week, and the third group of six cats was given aspirin at a sufficient dosage to block in vitro platelet aggregation throughout the study. A fourth group of eight noninfected cats served as controls. Five months after heartworm infection, the cats were euthanized and the lungs perfusion fixed for light microscopy and scanning electron microscopy of the pulmonary arterial surfaces. All cats in the three heartworm-infected groups had live heartworms and the typical pulmonary arterial changes of heartworm disease at necropsy. The arterial surfaces, as viewed with scanning electron microscopy, had villus proliferations that were more numerous and exuberant than similar infections in dogs. Mean percentage of arterial surface involvement with villus proliferation of the nontreated heartworm infected cats was 67.3%; the aspirin treated cats, 73.8%; and the adjusted aspirin treated cats, 75.9%. The villi were myointimal proliferations in the small and medium-sized arteries. The more elastic arteries had a predominance of fibromuscular proliferation. All heartworm infected cats had arterial muscular hypertrophy of the small arteries, in contrast to only three of eight of the nonheartworm infected cats. The caudal lobar arteries were frequently obstructed with either villus proliferation, thrombi, and/or dead heartworms. The muscular arteries had branches with marked dilation, a condition associated with pulmonary hypertension in man. However, only three cats, one in each group, had pulmonary hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

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Effect of acetylsalicylic acid on pulmonary arteriosclerosis induced by a one-year Dirofilaria immitis infection.

The ability of aspirin to block arteriosclerosis that developed in response to chronic, low-level injury to pulmonary arteries was evaluated in 21 dogs during their 1-year infection with Dirofilaria immitis. Three groups, with seven dogs in each group, were studied before and after sustained injury produced by the transplantation of 28 adult Dirofilaria immitis into each dog. Group A received no treatment and served as controls; Group B received no treatment for 6 months and then received 7 mg/kg of aspirin daily) for 6 months; Group C received 7 mg/kg of aspirin daily for the entire year. The pulmonary arterial response was evaluated by hemodynamic and arteriographic studies at 6 and 12 months and by scanning electron microscopy at the end of the 12-month study. All groups developed a similar, mild pulmonary hypertension. The arteriographic changes of dilation and flow obstruction were worse in Groups A and B than in Group C at 6 months, and at 12 months both Groups B and C were less obstructed than Group A. Scanning electron microscopy revealed large, complex myointimal proliferations in Group A, whereas the two aspirin-treated groups had smaller, less complex lesions that covered a much smaller surface area. We concluded that: 1) aspirin markedly reduced the microscopic and macroscopic arteriosclerosis in Groups B and C; 2) aspirin in Group B not only arrested further development but also permitted resolution of arteriosclerosis while the arteries were still being injured.

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Long term comparison of fresh arterial allografts and autografts for coronary artery bypass in dogs.

Femoral artery grafts were anastomosed end-to-end to the left internal mammary artery proximally and end-to-side to the circumflex coronary artery distally in 21 adult mongrel dogs. Fourteen dogs received allografts and seven received autografts. All autografts studied from one to 11 months were patent. Eleven of the fourteen homografts studied from one to thirteen months were occluded. Histologically, extensive interstitial edema and leukocytic infiltration with subintimal fibrosis and thrombotic occlusion were seen. This study shows that fresh arterial autografts have excellent long term patency, but that most arterial allografts have early thrombotic occlusion.

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