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Biomedical subjects

E Nelson

Publications and source records attributed to E Nelson.

At least 145 records · Page 8Linked to original sources
PubMed1976

Endothelial cell damage by temporary arterial occlusion with surgical clips. Study of the clip site by scanning and transmission electron microscopy.

The effects of temporary vascular occlusion with surgical clips on the underlying endothelial lining were studied with scanning (SEM) and transmission (TEM) electron microscopy. Twenty-five rabbits were anesthetized and both common carotid arteries exposed. A Heifetz clip was used to occlude the right carotid artery for 5, 15, and 30 minutes, and 2 hours in five animals each. The clips were removed and the vessels immediately perfused with glutaraldehyde. In five remaining animals, the right carotid arteries were occluded for 30 minutes followed by removal of the clip and resumption of blood flow for 30 minutes prior to fixation. Combined SEM and TEM examination of the endothelium of compressed segments revealed "craters" and "balloons", blebs and vacuoles, swollen mitochondria, dilated granular endoplasmic reticulum, and subendothelial edema. There were also areas of endothelial cell flattening, discontinuity, and desquamation exposing the subendothelial tissues. Following restoration of flow, platelets and fibrin were found adherent to altered endothelial cells and to exposed subendothelial tissues. Endothelial craters and balloons were also found distal and, significantly less frequently, proximal to the site of occlusion. It is suggested that antiplatelet aggregating agents may prove beneficial for the prevention of thrombus formation at the site of the clip as well as craters and balloons distal to the clip following procedures requiring temporary vascular occlusion.

Animals↗
PubMed1976

Ischemic carotid endothelium. Transmission electron microscopic studies.

The endothelium of monkey and rabbit common carotid arteries subjected to ischemia was examined by transmission electron microscopy (TEM). The right carotid artery of 24 rhesus monkeys was occluded by proximal and distal placement of removable surgical clips for periods ranging from five minutes to four hours. A single clip was used to occlude the right carotid artery of 15 rabbits for periods ranging from 5 to 30 minutes. With TEM, numerous blebs, intracytoplasmic vacuoles, membranous whorls, and pseudopodia were found in the endothelium of arterial segments subjected to ischemia by double or single clipping for as little as five minutes. Following occlusion of one hour or longer, disruption of interendothelial junctions was also noted. These TEM findings were compared with earlier TEM studies of the response of endothelium to other injurious stimuli and with previous scanning electron microscopic studies in which the same ischemic models were utilized.

Animals↗
PubMed1975

The effect of formaldehyde on the toxicity and potency of pertussis vaccine.

Storage of concentrated suspensions of Bordetella pertussis organisms at 5 C for long periods of time in the presence of 0.02% thimerosal as well as heating at 56 C for 30 minutes cannot be relied upon to detoxify the vaccines. Our data show that the toxic thimerosal-killed vaccines can be rapidly detoxified by adding formalin to a final concentration of 0.025-0.05% and incubating at temperatures of 5-20 C for from one to three months. These formalin-detoxified vaccines are protective and meet present potency requirements for pertussis vaccine. Addition of larger amounts of formalin at higher temperatures may detoxify the vaccine but may also reduce the protective effect.

Animals↗
PubMed1975

Ischemic carotid endothelium. Scanning electron microscopical studies.

The normal luminal surface and the effect of ischemia on the endothelium of the common carotid arteries of rhesus monkeys were examined by scanning electron microscopy. Clamps were placed proximally and distally on the right common carotid arteries, totally occluding the vessels for periods ranging from five minutes to four hours. The clamps were then removed and fixation carried out by intravascular perfusion. The contralateral sham-operated carotids, as well as those from unoperated animals were used as control specimens. The most obvious effect of ischemia was the appearance of conical, crater-like defects in the cytoplasm of endothelial cells. Such "craters" were observed following as little as 15 minutes of ischemia, were much less frequent in sham-operated vessels, and were not seen in the unoperated control specimens.

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