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Biomedical subjects

A J Roberts

Publications and source records attributed to A J Roberts.

159 records · Page 9Linked to original sources
PubMed1974

Hypothermic asanguineous circulatory arrest in adult dogs.

A new technique for the institution of hypothermic asanguineous circulatory arrest (HACA) is described and evaluated. It employs rapid cooling and hemodilution at high flow rates. Survival and protection of neurologic and other organ function were obtained using asanguineous circulatory arrest, and the method appears to be an improvement over circulatory arrest using conventional methods for cooling. The total duration of extracorporeal circulation is much shorter than with currently used methods of circulatory arrest. Applications of this technique in general and transplantation surgery as well as cardiac surgery are discussed.

Alanine Transaminase↗
PubMedDate not supplied

A caries susceptibility classification of tooth surfaces by survival time.

Individual tooth surfaces have vastly different susceptibilities to caries and this susceptibility also varies over time. The aim of this study was to develop a method of grouping tooth surfaces into a caries susceptibility classification based on their survival experience. The data used in the study were from a 3-year caries clinical trial. The definition of survival time was taken to be the time from the start of the trial to when a surface is recorded as decayed or filled. Cluster analysis was used to divide the tooth surfaces into groups in such a way that surfaces in the same group have similar survival time distributions. The 13 groups identified were ordered from 1 to 13 starting with the group with the shortest survival time, i.e. the occlusal surfaces of the four first molars. Approximately 80% of symmetrical pairs of tooth surfaces were in the same group. The groups obtained using cluster analysis were compared to groups defined using dental/anatomical criteria. It is concluded that the cluster analysis method developed for grouping the tooth surfaces cn provide a useful descriptive measure of caries susceptibility which can be applied to data from any longitudinal study of caries.

Child↗
PubMedDate not supplied

Laser endarterectomy: a comparison of thrombotic potential following CO2 laser vs surgical endarterectomy.

Although laser endarterectomy has recently been suggested as useful in the treatment of arteriosclerotic obstructions, the "in vivo" clotting effects have not been well delineated. In this study, the common carotid and femoral arteries of ten mongrel dogs were exposed, and alternating 1 cm segments of each artery were treated with surgical endarterectomy and low-powered CO2 laser endarterectomy. Segments were then harvested, and subjected to histologic examination and vascular prostacyclin synthesis determinations, as measured by 6-keto PFG1a radioimmunoassay. Gross examination and light and scanning electron microscopy showed increased platelet aggregation and more extensive damaging of the underlying media of the laser compared to the surgical segments. Six-keto PFG1a levels were significantly lower (p = 0.001) in the laser compared to surgical sites (mean 232 +/- 72 pg/mg vs 515 +/- 144 pg/mg), or controls (895 +/- 337 pg/mg). These findings suggest that laser endothelial evaporation leads to increased thrombotic potential in the early post-operative period in comparison to surgical endarterectomy.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Clinical and angiographic experience with intraoperative transluminal balloon-catheter dilatation and coronary artery bypass graft surgery.

Between April, 1980 and October, 1983, 40 patients with chronic stable angina pectoris underwent intraoperative transluminal balloon-catheter dilatation and coronary artery bypass graft (CABG) surgery. The main indication for this combined procedure was diffuse symptomatic coronary artery disease with at least one coronary artery having two or more areas of narrowing. Intraoperative dilatation was performed upon 42 coronary arteries involving 57 narrowed arterial segments where dilatation was attempted. The balloon-tipped catheter could not be passed through two stenotic sites. There was no documented perforation but unrecognized intimal injury was observed in two patients at postoperative catheterization. There was one perioperative myocardial infarction, one operative death and 97% early relief of angina pectoris. In 25 distal arterial narrowings that were studied angiographically in the early postoperative period (mean 10 days), 15 (60%) were unchanged, 2 (8%) were worse and 8 (32%) were improved compared to the preoperative angiogram. Patients with discrete narrowings did better than those who had balloon dilatation for diffuse narrowings; 49% of the former as compared to 17% of the latter had angiographic evidence for improvement. During the follow-up period (mean 30 months), three patients developed recurrent angina pectoris and one died of congestive heart failure. Thirteen distal arterial narrowings were studied angiographically late postoperatively (mean 12 months). In these 13 areas, 6 (46%) were unchanged, 3 (23%) were worse and 4 (31%) were improved compared to preoperative angiograms. Additionally, 10 arterial narrowings were observed angiographically, both early and late postoperatively. Nine of these serially observed segments remained unchanged while one became worse.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗