Biomedical subjects

R Dunford

Publications and source records attributed to R Dunford.

39 records · Page 3Linked to original sources

PubMed1985

Usefulness of subtraction radiography in the evaluation of periodontal therapy.

Subtraction radiography, a sensitive and accurate technique for identifying alveolar crestal change from standardized pairs of radiographs, is useful in monitoring periodontal therapy. One half of the radiographs were found to be appropriate for subtraction analysis using present technology for taking standardized radiographs. The criterion for usability was identical interpretation of subtraction images made in duplicate from a pair of radiographs. A set of radiographs was analyzed by subtraction radiography as well as by measurement of alveolar bone-crest height. Subtraction radiography was found to be more sensitive in detecting change. Whereas 53% pairs of radiographs showed a change on subtraction radiography, only 14% showed a change in crest height. Comparison of change by subtraction radiography and probing attachment level showed an overall correlation. Since these two measures assess different aspects of the periodontium, perfect correlation was not expected.

Alveolar Process↗

PubMed1981

Central venous bubbles and mixed venous nitrogen in goats following decompression.

Decompression of awake goats from saturation at 1, 2, and 3 ATA of air has been carried out using ultrasonic Doppler bubble detection, central venous blood inert gas measurement, and cardiac output measurement. The results of these experiments indicate that the decrease in nitrogen elimination rate as an apparent result of decompression cannot be due to excessive cardiac output or mass transport of a large amount of inert gas to the lungs as bubbles. Rather, the rapid drop in mixed venous nitrogen content is consistent with a generalized decrease in tissue-to-blood nitrogen elimination. This in turn appears to be due to a cardiovascular response to the decompression insult as was previously reported for dogs (D'Aoust et al., J. Appl. Physiol. 41: 348--355, 1976) at 1, 2, and 3 ATA; addition of ultrasonic Doppler monitoring and cardiac output in the present studies allowed measurement of the degree of latency in the appearance of bubbles at a central venous location. This time period includes that required for bubble formation, growth, and vascular transport of the bubbles to the Doppler detector. All results of these studies are consistent with the interpretation that due to a decompression insult, which probably includes bubble formation, some degree of hemostasis, and other hematologic sequelae, the transport of tissue inert gas to the capillary venous blood is retarded, thus providing the rapid apparent decrease in mixed venous blood inert gas content. These results demonstrate what is most likely a general response to a severe but not crucial decompression by the cardiovascular system.

Animals↗

PubMed1981

Venous gas bubble production following cold stress during a no-decompression dive.

The effect of cold stress on venous gas bubble production was studied using Doppler ultrasonic monitoring. Ten subjects participated in four exposure regimes carried out at 78 fsw on an underwater platform for 38 min of light exercise in 10 degrees C water. Two cold exposures (1/8-in. wet suit) and two warm exposures (insulated dry suit) were each followed by rewarming in a heated bath or by endogenous heat production while insulated in a sleeping bag. Results showed that for the cold dives compared to warm dives, air consumption increased 29%, rectal temperature dropped 0.8 degrees C by the end of the dive, mean skin temperature dropped 11 degrees C, and cooling rate correlated with mean skin fold and endomorphy (P less than 0.001). A threefold increase in bubble scores (P less than 0.025) was observed following the warm dives compared to the cold dives. The results suggest that inert gas uptake is reduced as a result of peripheral vasoconstriction when the cold stress is induced at the onset of the dive and maintained throughout.

Adult↗