Search PubMed⌕ Search

Biomedical subjects

R Holliday

Publications and source records attributed to R Holliday.

171 records · Page 10Linked to original sources
PubMedDate not supplied

A re-examination of the effects of ionizing radiation on lifespan and transformation of human diploid fibroblasts.

Human diploid fibroblasts, strain MRC-5, were sequentially irradiated with 60Co gamma rays at intervals during their in vitro lifespan. The results indicate that 3 or 6 doses of 1 Gy can increase lifespan, and the same was true for cells treated with 3 doses of 3 Gy. Higher doses (5 x 3 Gy) did reduce growth potential, suggesting either that mid-late passage cells become more sensitive to radiation, or that doses beyond a given threshold reduce population lifespan by multiple cellular hits. The life extension induced by gamma rays might be due to an induced hypermethylation of DNA. Alternatively, oxygen radicals produced by irradiation might trigger an adaptive stress response which would remove damaged macromolecules and thereby increase the cells' growth potential. Whichever explanation is correct, the results show that the human fibroblast system is not appropriate for the study of the well known effect of ionizing radiation in shortening the lifespan of experimental animals. Contrary to earlier published results, populations of cells treated with cumulative doses of 15 Gy or 18 Gy and held for nearly 3 months after they had reached senescence (Phase III), produced no foci of transformed cells.

Cell Survival↗
PubMedDate not supplied

Marlex mesh erosion: a complication of horizontal banded gastroplasty.

One-hundred and thirty-eight obese patients underwent horizontal banded gastroplasty. The stoma in each case was reinforced with Marlex mesh. Fifty of these patients developed upper gastrointestinal symptoms sufficiently severe to require endoscopy. At endoscopy 12 were found to have erosion of the Marlex mesh into the stoma. Mesh erosion was found at various intervals postoperatively ranging from 5 weeks to 55 months with a mean of 23 months. Nine of the 12 had associated stenosis of the stoma and three had dehiscence of the staple line. There were no symptoms peculiar to Marlex erosion. Seven patients required surgical revision of the stoma, four were treated medically, and one was treated with a combination of stomal dilation and medical therapy.

Female↗
PubMedDate not supplied

Preoperative sagittal CT evaluation of the frontal recess.

Endoscopic surgical approaches for chronic frontal sinusitis require the reestablishment of adequate frontal sinus ventilation and drainage for relief of symptoms. After the resection of anterior ethmoid mucosal disease and cellular structure, the anterior to posterior depth of the nasofrontal beak to the base of skull at the insertion of the ethmoidal bulla (frontal sinus ostium) often represents a critical margin for functional success. However, little information concerning this dimension is available. Depending on intraoperative surgical judgment of this distance, extended endoscopic surgical procedures involving additional bone resection may be indicated. These approaches may be hazardous due to the proximity of the cranial cavity and orbit. In addition, secondary stenosis can result from the subsequent inflammatory response. Improved CT imaging, high resolution sagittal reformatting, and computer workstations provide the ability to obtain direct preoperative measurements of the frontal recess. We used a paramedian sagittal section and recorded the maximal anterior to posterior depth from the nasofrontal beak to the base of skull at the insertion of the ethmoidal bulla in 20 patients, 31 sides, undergoing primary endoscopic frontoethmoidectomy. In addition, we found a positive correlation between this distance and agger nasi air cell size measured in the same 31 sides.

Chronic Disease↗